24 files changed, 1710 insertions, 1137 deletions

diff --git a/src/wallet/coincontrol.h b/src/wallet/coincontrol.h
index 458e770e03..52d6a291c9 100644
--- a/src/wallet/coincontrol.h
+++ b/src/wallet/coincontrol.h
@@ -18,8 +18,8 @@ class CCoinControl
 public:
     //! Custom change destination, if not set an address is generated
     CTxDestination destChange;
-    //! Custom change type, ignored if destChange is set, defaults to g_change_type
-    OutputType change_type;
+    //! Override the default change type if set, ignored if destChange is set
+    boost::optional<OutputType> m_change_type;
     //! If false, allows unselected inputs, but requires all selected inputs be used
     bool fAllowOtherInputs;
     //! Includes watch only addresses which match the ISMINE_WATCH_SOLVABLE criteria
@@ -43,7 +43,7 @@ public:
     void SetNull()
     {
         destChange = CNoDestination();
-        change_type = g_change_type;
+        m_change_type.reset();
         fAllowOtherInputs = false;
         fAllowWatchOnly = false;
         setSelected.clear();
diff --git a/src/wallet/coinselection.cpp b/src/wallet/coinselection.cpp
new file mode 100644
index 0000000000..8596ad2adc
--- /dev/null
+++ b/src/wallet/coinselection.cpp
@@ -0,0 +1,300 @@
+// Copyright (c) 2017 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <wallet/coinselection.h>
+#include <util.h>
+#include <utilmoneystr.h>
+
+// Descending order comparator
+struct {
+    bool operator()(const CInputCoin& a, const CInputCoin& b) const
+    {
+        return a.effective_value > b.effective_value;
+    }
+} descending;
+
+/*
+ * This is the Branch and Bound Coin Selection algorithm designed by Murch. It searches for an input
+ * set that can pay for the spending target and does not exceed the spending target by more than the
+ * cost of creating and spending a change output. The algorithm uses a depth-first search on a binary
+ * tree. In the binary tree, each node corresponds to the inclusion or the omission of a UTXO. UTXOs
+ * are sorted by their effective values and the trees is explored deterministically per the inclusion
+ * branch first. At each node, the algorithm checks whether the selection is within the target range.
+ * While the selection has not reached the target range, more UTXOs are included. When a selection's
+ * value exceeds the target range, the complete subtree deriving from this selection can be omitted.
+ * At that point, the last included UTXO is deselected and the corresponding omission branch explored
+ * instead. The search ends after the complete tree has been searched or after a limited number of tries.
+ *
+ * The search continues to search for better solutions after one solution has been found. The best
+ * solution is chosen by minimizing the waste metric. The waste metric is defined as the cost to
+ * spend the current inputs at the given fee rate minus the long term expected cost to spend the
+ * inputs, plus the amount the selection exceeds the spending target:
+ *
+ * waste = selectionTotal - target + inputs × (currentFeeRate - longTermFeeRate)
+ *
+ * The algorithm uses two additional optimizations. A lookahead keeps track of the total value of
+ * the unexplored UTXOs. A subtree is not explored if the lookahead indicates that the target range
+ * cannot be reached. Further, it is unnecessary to test equivalent combinations. This allows us
+ * to skip testing the inclusion of UTXOs that match the effective value and waste of an omitted
+ * predecessor.
+ *
+ * The Branch and Bound algorithm is described in detail in Murch's Master Thesis:
+ * https://murch.one/wp-content/uploads/2016/11/erhardt2016coinselection.pdf
+ *
+ * @param const std::vector<CInputCoin>& utxo_pool The set of UTXOs that we are choosing from.
+ *        These UTXOs will be sorted in descending order by effective value and the CInputCoins'
+ *        values are their effective values.
+ * @param const CAmount& target_value This is the value that we want to select. It is the lower
+ *        bound of the range.
+ * @param const CAmount& cost_of_change This is the cost of creating and spending a change output.
+ *        This plus target_value is the upper bound of the range.
+ * @param std::set<CInputCoin>& out_set -> This is an output parameter for the set of CInputCoins
+ *        that have been selected.
+ * @param CAmount& value_ret -> This is an output parameter for the total value of the CInputCoins
+ *        that were selected.
+ * @param CAmount not_input_fees -> The fees that need to be paid for the outputs and fixed size
+ *        overhead (version, locktime, marker and flag)
+ */
+
+static const size_t TOTAL_TRIES = 100000;
+
+bool SelectCoinsBnB(std::vector<CInputCoin>& utxo_pool, const CAmount& target_value, const CAmount& cost_of_change, std::set<CInputCoin>& out_set, CAmount& value_ret, CAmount not_input_fees)
+{
+    out_set.clear();
+    CAmount curr_value = 0;
+
+    std::vector<bool> curr_selection; // select the utxo at this index
+    curr_selection.reserve(utxo_pool.size());
+    CAmount actual_target = not_input_fees + target_value;
+
+    // Calculate curr_available_value
+    CAmount curr_available_value = 0;
+    for (const CInputCoin& utxo : utxo_pool) {
+        // Assert that this utxo is not negative. It should never be negative, effective value calculation should have removed it
+        assert(utxo.effective_value > 0);
+        curr_available_value += utxo.effective_value;
+    }
+    if (curr_available_value < actual_target) {
+        return false;
+    }
+
+    // Sort the utxo_pool
+    std::sort(utxo_pool.begin(), utxo_pool.end(), descending);
+
+    CAmount curr_waste = 0;
+    std::vector<bool> best_selection;
+    CAmount best_waste = MAX_MONEY;
+
+    // Depth First search loop for choosing the UTXOs
+    for (size_t i = 0; i < TOTAL_TRIES; ++i) {
+        // Conditions for starting a backtrack
+        bool backtrack = false;
+        if (curr_value + curr_available_value < actual_target ||                // Cannot possibly reach target with the amount remaining in the curr_available_value.
+            curr_value > actual_target + cost_of_change ||    // Selected value is out of range, go back and try other branch
+            (curr_waste > best_waste && (utxo_pool.at(0).fee - utxo_pool.at(0).long_term_fee) > 0)) { // Don't select things which we know will be more wasteful if the waste is increasing
+            backtrack = true;
+        } else if (curr_value >= actual_target) {       // Selected value is within range
+            curr_waste += (curr_value - actual_target); // This is the excess value which is added to the waste for the below comparison
+            // Adding another UTXO after this check could bring the waste down if the long term fee is higher than the current fee.
+            // However we are not going to explore that because this optimization for the waste is only done when we have hit our target
+            // value. Adding any more UTXOs will be just burning the UTXO; it will go entirely to fees. Thus we aren't going to
+            // explore any more UTXOs to avoid burning money like that.
+            if (curr_waste <= best_waste) {
+                best_selection = curr_selection;
+                best_selection.resize(utxo_pool.size());
+                best_waste = curr_waste;
+            }
+            curr_waste -= (curr_value - actual_target); // Remove the excess value as we will be selecting different coins now
+            backtrack = true;
+        }
+
+        // Backtracking, moving backwards
+        if (backtrack) {
+            // Walk backwards to find the last included UTXO that still needs to have its omission branch traversed.
+            while (!curr_selection.empty() && !curr_selection.back()) {
+                curr_selection.pop_back();
+                curr_available_value += utxo_pool.at(curr_selection.size()).effective_value;
+            };
+
+            if (curr_selection.empty()) { // We have walked back to the first utxo and no branch is untraversed. All solutions searched
+                break;
+            }
+
+            // Output was included on previous iterations, try excluding now.
+            curr_selection.back() = false;
+            CInputCoin& utxo = utxo_pool.at(curr_selection.size() - 1);
+            curr_value -= utxo.effective_value;
+            curr_waste -= utxo.fee - utxo.long_term_fee;
+        } else { // Moving forwards, continuing down this branch
+            CInputCoin& utxo = utxo_pool.at(curr_selection.size());
+
+            // Remove this utxo from the curr_available_value utxo amount
+            curr_available_value -= utxo.effective_value;
+
+            // Avoid searching a branch if the previous UTXO has the same value and same waste and was excluded. Since the ratio of fee to
+            // long term fee is the same, we only need to check if one of those values match in order to know that the waste is the same.
+            if (!curr_selection.empty() && !curr_selection.back() &&
+                utxo.effective_value == utxo_pool.at(curr_selection.size() - 1).effective_value &&
+                utxo.fee == utxo_pool.at(curr_selection.size() - 1).fee) {
+                curr_selection.push_back(false);
+            } else {
+                // Inclusion branch first (Largest First Exploration)
+                curr_selection.push_back(true);
+                curr_value += utxo.effective_value;
+                curr_waste += utxo.fee - utxo.long_term_fee;
+            }
+        }
+    }
+
+    // Check for solution
+    if (best_selection.empty()) {
+        return false;
+    }
+
+    // Set output set
+    value_ret = 0;
+    for (size_t i = 0; i < best_selection.size(); ++i) {
+        if (best_selection.at(i)) {
+            out_set.insert(utxo_pool.at(i));
+            value_ret += utxo_pool.at(i).txout.nValue;
+        }
+    }
+
+    return true;
+}
+
+static void ApproximateBestSubset(const std::vector<CInputCoin>& vValue, const CAmount& nTotalLower, const CAmount& nTargetValue,
+                                  std::vector<char>& vfBest, CAmount& nBest, int iterations = 1000)
+{
+    std::vector<char> vfIncluded;
+
+    vfBest.assign(vValue.size(), true);
+    nBest = nTotalLower;
+
+    FastRandomContext insecure_rand;
+
+    for (int nRep = 0; nRep < iterations && nBest != nTargetValue; nRep++)
+    {
+        vfIncluded.assign(vValue.size(), false);
+        CAmount nTotal = 0;
+        bool fReachedTarget = false;
+        for (int nPass = 0; nPass < 2 && !fReachedTarget; nPass++)
+        {
+            for (unsigned int i = 0; i < vValue.size(); i++)
+            {
+                //The solver here uses a randomized algorithm,
+                //the randomness serves no real security purpose but is just
+                //needed to prevent degenerate behavior and it is important
+                //that the rng is fast. We do not use a constant random sequence,
+                //because there may be some privacy improvement by making
+                //the selection random.
+                if (nPass == 0 ? insecure_rand.randbool() : !vfIncluded[i])
+                {
+                    nTotal += vValue[i].txout.nValue;
+                    vfIncluded[i] = true;
+                    if (nTotal >= nTargetValue)
+                    {
+                        fReachedTarget = true;
+                        if (nTotal < nBest)
+                        {
+                            nBest = nTotal;
+                            vfBest = vfIncluded;
+                        }
+                        nTotal -= vValue[i].txout.nValue;
+                        vfIncluded[i] = false;
+                    }
+                }
+            }
+        }
+    }
+}
+
+bool KnapsackSolver(const CAmount& nTargetValue, std::vector<CInputCoin>& vCoins, std::set<CInputCoin>& setCoinsRet, CAmount& nValueRet)
+{
+    setCoinsRet.clear();
+    nValueRet = 0;
+
+    // List of values less than target
+    boost::optional<CInputCoin> coinLowestLarger;
+    std::vector<CInputCoin> vValue;
+    CAmount nTotalLower = 0;
+
+    random_shuffle(vCoins.begin(), vCoins.end(), GetRandInt);
+
+    for (const CInputCoin &coin : vCoins)
+    {
+        if (coin.txout.nValue == nTargetValue)
+        {
+            setCoinsRet.insert(coin);
+            nValueRet += coin.txout.nValue;
+            return true;
+        }
+        else if (coin.txout.nValue < nTargetValue + MIN_CHANGE)
+        {
+            vValue.push_back(coin);
+            nTotalLower += coin.txout.nValue;
+        }
+        else if (!coinLowestLarger || coin.txout.nValue < coinLowestLarger->txout.nValue)
+        {
+            coinLowestLarger = coin;
+        }
+    }
+
+    if (nTotalLower == nTargetValue)
+    {
+        for (const auto& input : vValue)
+        {
+            setCoinsRet.insert(input);
+            nValueRet += input.txout.nValue;
+        }
+        return true;
+    }
+
+    if (nTotalLower < nTargetValue)
+    {
+        if (!coinLowestLarger)
+            return false;
+        setCoinsRet.insert(coinLowestLarger.get());
+        nValueRet += coinLowestLarger->txout.nValue;
+        return true;
+    }
+
+    // Solve subset sum by stochastic approximation
+    std::sort(vValue.begin(), vValue.end(), descending);
+    std::vector<char> vfBest;
+    CAmount nBest;
+
+    ApproximateBestSubset(vValue, nTotalLower, nTargetValue, vfBest, nBest);
+    if (nBest != nTargetValue && nTotalLower >= nTargetValue + MIN_CHANGE)
+        ApproximateBestSubset(vValue, nTotalLower, nTargetValue + MIN_CHANGE, vfBest, nBest);
+
+    // If we have a bigger coin and (either the stochastic approximation didn't find a good solution,
+    //                                   or the next bigger coin is closer), return the bigger coin
+    if (coinLowestLarger &&
+        ((nBest != nTargetValue && nBest < nTargetValue + MIN_CHANGE) || coinLowestLarger->txout.nValue <= nBest))
+    {
+        setCoinsRet.insert(coinLowestLarger.get());
+        nValueRet += coinLowestLarger->txout.nValue;
+    }
+    else {
+        for (unsigned int i = 0; i < vValue.size(); i++)
+            if (vfBest[i])
+            {
+                setCoinsRet.insert(vValue[i]);
+                nValueRet += vValue[i].txout.nValue;
+            }
+
+        if (LogAcceptCategory(BCLog::SELECTCOINS)) {
+            LogPrint(BCLog::SELECTCOINS, "SelectCoins() best subset: ");
+            for (unsigned int i = 0; i < vValue.size(); i++) {
+                if (vfBest[i]) {
+                    LogPrint(BCLog::SELECTCOINS, "%s ", FormatMoney(vValue[i].txout.nValue));
+                }
+            }
+            LogPrint(BCLog::SELECTCOINS, "total %s\n", FormatMoney(nBest));
+        }
+    }
+
+    return true;
+}
diff --git a/src/wallet/coinselection.h b/src/wallet/coinselection.h
new file mode 100644
index 0000000000..2b185879c6
--- /dev/null
+++ b/src/wallet/coinselection.h
@@ -0,0 +1,54 @@
+// Copyright (c) 2017 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_WALLET_COINSELECTION_H
+#define BITCOIN_WALLET_COINSELECTION_H
+
+#include <amount.h>
+#include <primitives/transaction.h>
+#include <random.h>
+
+//! target minimum change amount
+static const CAmount MIN_CHANGE = CENT;
+//! final minimum change amount after paying for fees
+static const CAmount MIN_FINAL_CHANGE = MIN_CHANGE/2;
+
+class CInputCoin {
+public:
+    CInputCoin(const CTransactionRef& tx, unsigned int i)
+    {
+        if (!tx)
+            throw std::invalid_argument("tx should not be null");
+        if (i >= tx->vout.size())
+            throw std::out_of_range("The output index is out of range");
+
+        outpoint = COutPoint(tx->GetHash(), i);
+        txout = tx->vout[i];
+        effective_value = txout.nValue;
+    }
+
+    COutPoint outpoint;
+    CTxOut txout;
+    CAmount effective_value;
+    CAmount fee = 0;
+    CAmount long_term_fee = 0;
+
+    bool operator<(const CInputCoin& rhs) const {
+        return outpoint < rhs.outpoint;
+    }
+
+    bool operator!=(const CInputCoin& rhs) const {
+        return outpoint != rhs.outpoint;
+    }
+
+    bool operator==(const CInputCoin& rhs) const {
+        return outpoint == rhs.outpoint;
+    }
+};
+
+bool SelectCoinsBnB(std::vector<CInputCoin>& utxo_pool, const CAmount& target_value, const CAmount& cost_of_change, std::set<CInputCoin>& out_set, CAmount& value_ret, CAmount not_input_fees);
+
+// Original coin selection algorithm as a fallback
+bool KnapsackSolver(const CAmount& nTargetValue, std::vector<CInputCoin>& vCoins, std::set<CInputCoin>& setCoinsRet, CAmount& nValueRet);
+#endif // BITCOIN_WALLET_COINSELECTION_H
diff --git a/src/wallet/crypter.h b/src/wallet/crypter.h
index f3ae7144b4..fdeb4cfee0 100644
--- a/src/wallet/crypter.h
+++ b/src/wallet/crypter.h
@@ -67,7 +67,7 @@ public:
 
 typedef std::vector<unsigned char, secure_allocator<unsigned char> > CKeyingMaterial;
 
-namespace wallet_crypto
+namespace crypto_tests
 {
     class TestCrypter;
 }
@@ -75,7 +75,7 @@ namespace wallet_crypto
 /** Encryption/decryption context with key information */
 class CCrypter
 {
-friend class wallet_crypto::TestCrypter; // for test access to chKey/chIV
+friend class crypto_tests::TestCrypter; // for test access to chKey/chIV
 private:
     std::vector<unsigned char, secure_allocator<unsigned char>> vchKey;
     std::vector<unsigned char, secure_allocator<unsigned char>> vchIV;
diff --git a/src/wallet/db.cpp b/src/wallet/db.cpp
index ebe7b48da0..553cae4d02 100644
--- a/src/wallet/db.cpp
+++ b/src/wallet/db.cpp
@@ -235,13 +235,13 @@ CDBEnv::VerifyResult CDBEnv::Verify(const std::string& strFile, recoverFunc_type
     Db db(dbenv.get(), 0);
     int result = db.verify(strFile.c_str(), nullptr, nullptr, 0);
     if (result == 0)
-        return VERIFY_OK;
+        return VerifyResult::VERIFY_OK;
     else if (recoverFunc == nullptr)
-        return RECOVER_FAIL;
+        return VerifyResult::RECOVER_FAIL;
 
     // Try to recover:
     bool fRecovered = (*recoverFunc)(fs::path(strPath) / strFile, out_backup_filename);
-    return (fRecovered ? RECOVER_OK : RECOVER_FAIL);
+    return (fRecovered ? VerifyResult::RECOVER_OK : VerifyResult::RECOVER_FAIL);
 }
 
 bool CDB::Recover(const fs::path& file_path, void *callbackDataIn, bool (*recoverKVcallback)(void* callbackData, CDataStream ssKey, CDataStream ssValue), std::string& newFilename)
@@ -347,7 +347,7 @@ bool CDB::VerifyDatabaseFile(const fs::path& file_path, std::string& warningStr,
     {
         std::string backup_filename;
         CDBEnv::VerifyResult r = env->Verify(walletFile, recoverFunc, backup_filename);
-        if (r == CDBEnv::RECOVER_OK)
+        if (r == CDBEnv::VerifyResult::RECOVER_OK)
         {
             warningStr = strprintf(_("Warning: Wallet file corrupt, data salvaged!"
                                      " Original %s saved as %s in %s; if"
@@ -355,7 +355,7 @@ bool CDB::VerifyDatabaseFile(const fs::path& file_path, std::string& warningStr,
                                      " restore from a backup."),
                                    walletFile, backup_filename, walletDir);
         }
-        if (r == CDBEnv::RECOVER_FAIL)
+        if (r == CDBEnv::VerifyResult::RECOVER_FAIL)
         {
             errorStr = strprintf(_("%s corrupt, salvage failed"), walletFile);
             return false;
diff --git a/src/wallet/db.h b/src/wallet/db.h
index b1ce451534..49a9f3f082 100644
--- a/src/wallet/db.h
+++ b/src/wallet/db.h
@@ -16,6 +16,7 @@
 
 #include <atomic>
 #include <map>
+#include <memory>
 #include <string>
 #include <vector>
 
@@ -53,7 +54,7 @@ public:
      * This must be called BEFORE strFile is opened.
      * Returns true if strFile is OK.
      */
-    enum VerifyResult { VERIFY_OK,
+    enum class VerifyResult { VERIFY_OK,
                         RECOVER_OK,
                         RECOVER_FAIL };
     typedef bool (*recoverFunc_type)(const fs::path& file_path, std::string& out_backup_filename);
diff --git a/src/wallet/feebumper.cpp b/src/wallet/feebumper.cpp
index 9cae660c60..82a5017de0 100644
--- a/src/wallet/feebumper.cpp
+++ b/src/wallet/feebumper.cpp
@@ -16,33 +16,6 @@
 #include <util.h>
 #include <net.h>
 
-// Calculate the size of the transaction assuming all signatures are max size
-// Use DummySignatureCreator, which inserts 72 byte signatures everywhere.
-// TODO: re-use this in CWallet::CreateTransaction (right now
-// CreateTransaction uses the constructed dummy-signed tx to do a priority
-// calculation, but we should be able to refactor after priority is removed).
-// NOTE: this requires that all inputs must be in mapWallet (eg the tx should
-// be IsAllFromMe).
-static int64_t CalculateMaximumSignedTxSize(const CTransaction &tx, const CWallet *wallet)
-{
-    CMutableTransaction txNew(tx);
-    std::vector<CInputCoin> vCoins;
-    // Look up the inputs.  We should have already checked that this transaction
-    // IsAllFromMe(ISMINE_SPENDABLE), so every input should already be in our
-    // wallet, with a valid index into the vout array.
-    for (auto& input : tx.vin) {
-        const auto mi = wallet->mapWallet.find(input.prevout.hash);
-        assert(mi != wallet->mapWallet.end() && input.prevout.n < mi->second.tx->vout.size());
-        vCoins.emplace_back(CInputCoin(&(mi->second), input.prevout.n));
-    }
-    if (!wallet->DummySignTx(txNew, vCoins)) {
-        // This should never happen, because IsAllFromMe(ISMINE_SPENDABLE)
-        // implies that we can sign for every input.
-        return -1;
-    }
-    return GetVirtualTransactionSize(txNew);
-}
-
 //! Check whether transaction has descendant in wallet or mempool, or has been
 //! mined, or conflicts with a mined transaction. Return a feebumper::Result.
 static feebumper::Result PreconditionChecks(const CWallet* wallet, const CWalletTx& wtx, std::vector<std::string>& errors)
@@ -262,23 +235,20 @@ Result CommitTransaction(CWallet* wallet, const uint256& txid, CMutableTransacti
         return result;
     }
 
-    CWalletTx wtxBumped(wallet, MakeTransactionRef(std::move(mtx)));
     // commit/broadcast the tx
+    CTransactionRef tx = MakeTransactionRef(std::move(mtx));
+    mapValue_t mapValue = oldWtx.mapValue;
+    mapValue["replaces_txid"] = oldWtx.GetHash().ToString();
+
     CReserveKey reservekey(wallet);
-    wtxBumped.mapValue = oldWtx.mapValue;
-    wtxBumped.mapValue["replaces_txid"] = oldWtx.GetHash().ToString();
-    wtxBumped.vOrderForm = oldWtx.vOrderForm;
-    wtxBumped.strFromAccount = oldWtx.strFromAccount;
-    wtxBumped.fTimeReceivedIsTxTime = true;
-    wtxBumped.fFromMe = true;
     CValidationState state;
-    if (!wallet->CommitTransaction(wtxBumped, reservekey, g_connman.get(), state)) {
+    if (!wallet->CommitTransaction(tx, std::move(mapValue), oldWtx.vOrderForm, oldWtx.strFromAccount, reservekey, g_connman.get(), state)) {
         // NOTE: CommitTransaction never returns false, so this should never happen.
         errors.push_back(strprintf("The transaction was rejected: %s", FormatStateMessage(state)));
         return Result::WALLET_ERROR;
     }
 
-    bumped_txid = wtxBumped.GetHash();
+    bumped_txid = tx->GetHash();
     if (state.IsInvalid()) {
         // This can happen if the mempool rejected the transaction.  Report
         // what happened in the "errors" response.
@@ -286,7 +256,7 @@ Result CommitTransaction(CWallet* wallet, const uint256& txid, CMutableTransacti
     }
 
     // mark the original tx as bumped
-    if (!wallet->MarkReplaced(oldWtx.GetHash(), wtxBumped.GetHash())) {
+    if (!wallet->MarkReplaced(oldWtx.GetHash(), bumped_txid)) {
         // TODO: see if JSON-RPC has a standard way of returning a response
         // along with an exception. It would be good to return information about
         // wtxBumped to the caller even if marking the original transaction
diff --git a/src/wallet/fees.cpp b/src/wallet/fees.cpp
index 385fdc963a..03c32d3b97 100644
--- a/src/wallet/fees.cpp
+++ b/src/wallet/fees.cpp
@@ -21,6 +21,22 @@ CAmount GetRequiredFee(unsigned int nTxBytes)
 
 CAmount GetMinimumFee(unsigned int nTxBytes, const CCoinControl& coin_control, const CTxMemPool& pool, const CBlockPolicyEstimator& estimator, FeeCalculation *feeCalc)
 {
+    CAmount fee_needed = GetMinimumFeeRate(coin_control, pool, estimator, feeCalc).GetFee(nTxBytes);
+    // Always obey the maximum
+    if (fee_needed > maxTxFee) {
+        fee_needed = maxTxFee;
+        if (feeCalc) feeCalc->reason = FeeReason::MAXTXFEE;
+    }
+    return fee_needed;
+}
+
+CFeeRate GetRequiredFeeRate()
+{
+    return std::max(CWallet::minTxFee, ::minRelayTxFee);
+}
+
+CFeeRate GetMinimumFeeRate(const CCoinControl& coin_control, const CTxMemPool& pool, const CBlockPolicyEstimator& estimator, FeeCalculation *feeCalc)
+{
     /* User control of how to calculate fee uses the following parameter precedence:
        1. coin_control.m_feerate
        2. coin_control.m_confirm_target
@@ -28,15 +44,15 @@ CAmount GetMinimumFee(unsigned int nTxBytes, const CCoinControl& coin_control, c
        4. nTxConfirmTarget (user-set global variable)
        The first parameter that is set is used.
     */
-    CAmount fee_needed;
+    CFeeRate feerate_needed ;
     if (coin_control.m_feerate) { // 1.
-        fee_needed = coin_control.m_feerate->GetFee(nTxBytes);
+        feerate_needed = *(coin_control.m_feerate);
         if (feeCalc) feeCalc->reason = FeeReason::PAYTXFEE;
         // Allow to override automatic min/max check over coin control instance
-        if (coin_control.fOverrideFeeRate) return fee_needed;
+        if (coin_control.fOverrideFeeRate) return feerate_needed;
     }
     else if (!coin_control.m_confirm_target && ::payTxFee != CFeeRate(0)) { // 3. TODO: remove magic value of 0 for global payTxFee
-        fee_needed = ::payTxFee.GetFee(nTxBytes);
+        feerate_needed = ::payTxFee;
         if (feeCalc) feeCalc->reason = FeeReason::PAYTXFEE;
     }
     else { // 2. or 4.
@@ -48,38 +64,32 @@ CAmount GetMinimumFee(unsigned int nTxBytes, const CCoinControl& coin_control, c
         if (coin_control.m_fee_mode == FeeEstimateMode::CONSERVATIVE) conservative_estimate = true;
         else if (coin_control.m_fee_mode == FeeEstimateMode::ECONOMICAL) conservative_estimate = false;
 
-        fee_needed = estimator.estimateSmartFee(target, feeCalc, conservative_estimate).GetFee(nTxBytes);
-        if (fee_needed == 0) {
+        feerate_needed = estimator.estimateSmartFee(target, feeCalc, conservative_estimate);
+        if (feerate_needed == CFeeRate(0)) {
             // if we don't have enough data for estimateSmartFee, then use fallbackFee
-            fee_needed = CWallet::fallbackFee.GetFee(nTxBytes);
+            feerate_needed = CWallet::fallbackFee;
             if (feeCalc) feeCalc->reason = FeeReason::FALLBACK;
 
             // directly return if fallback fee is disabled (feerate 0 == disabled)
-            if (CWallet::fallbackFee.GetFee(1000) == 0) return fee_needed;
+            if (CWallet::fallbackFee == CFeeRate(0)) return feerate_needed;
         }
         // Obey mempool min fee when using smart fee estimation
-        CAmount min_mempool_fee = pool.GetMinFee(gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000).GetFee(nTxBytes);
-        if (fee_needed < min_mempool_fee) {
-            fee_needed = min_mempool_fee;
+        CFeeRate min_mempool_feerate = pool.GetMinFee(gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000);
+        if (feerate_needed < min_mempool_feerate) {
+            feerate_needed = min_mempool_feerate;
             if (feeCalc) feeCalc->reason = FeeReason::MEMPOOL_MIN;
         }
     }
 
     // prevent user from paying a fee below minRelayTxFee or minTxFee
-    CAmount required_fee = GetRequiredFee(nTxBytes);
-    if (required_fee > fee_needed) {
-        fee_needed = required_fee;
+    CFeeRate required_feerate = GetRequiredFeeRate();
+    if (required_feerate > feerate_needed) {
+        feerate_needed = required_feerate;
         if (feeCalc) feeCalc->reason = FeeReason::REQUIRED;
     }
-    // But always obey the maximum
-    if (fee_needed > maxTxFee) {
-        fee_needed = maxTxFee;
-        if (feeCalc) feeCalc->reason = FeeReason::MAXTXFEE;
-    }
-    return fee_needed;
+    return feerate_needed;
 }
 
-
 CFeeRate GetDiscardRate(const CBlockPolicyEstimator& estimator)
 {
     unsigned int highest_target = estimator.HighestTargetTracked(FeeEstimateHorizon::LONG_HALFLIFE);
diff --git a/src/wallet/fees.h b/src/wallet/fees.h
index 225aff08ad..a627af70b0 100644
--- a/src/wallet/fees.h
+++ b/src/wallet/fees.h
@@ -27,6 +27,18 @@ CAmount GetRequiredFee(unsigned int nTxBytes);
 CAmount GetMinimumFee(unsigned int nTxBytes, const CCoinControl& coin_control, const CTxMemPool& pool, const CBlockPolicyEstimator& estimator, FeeCalculation *feeCalc);
 
 /**
+ * Return the minimum required feerate taking into account the
+ * floating relay feerate and user set minimum transaction feerate
+ */
+CFeeRate GetRequiredFeeRate();
+
+/**
+ * Estimate the minimum fee rate considering user set parameters
+ * and the required fee
+ */
+CFeeRate GetMinimumFeeRate(const CCoinControl& coin_control, const CTxMemPool& pool, const CBlockPolicyEstimator& estimator, FeeCalculation *feeCalc);
+
+/**
  * Return the maximum feerate for discarding change.
  */
 CFeeRate GetDiscardRate(const CBlockPolicyEstimator& estimator);
diff --git a/src/wallet/init.cpp b/src/wallet/init.cpp
index e028cf4210..c860eede05 100644
--- a/src/wallet/init.cpp
+++ b/src/wallet/init.cpp
@@ -3,21 +3,57 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#include <wallet/init.h>
-
 #include <chainparams.h>
+#include <init.h>
 #include <net.h>
 #include <util.h>
 #include <utilmoneystr.h>
 #include <validation.h>
+#include <walletinitinterface.h>
 #include <wallet/rpcwallet.h>
 #include <wallet/wallet.h>
 #include <wallet/walletutil.h>
 
-std::string GetWalletHelpString(bool showDebug)
+class WalletInit : public WalletInitInterface {
+public:
+
+    //! Return the wallets help message.
+    std::string GetHelpString(bool showDebug) override;
+
+    //! Wallets parameter interaction
+    bool ParameterInteraction() override;
+
+    //! Register wallet RPCs.
+    void RegisterRPC(CRPCTable &tableRPC) override;
+
+    //! Responsible for reading and validating the -wallet arguments and verifying the wallet database.
+    //  This function will perform salvage on the wallet if requested, as long as only one wallet is
+    //  being loaded (WalletParameterInteraction forbids -salvagewallet, -zapwallettxes or -upgradewallet with multiwallet).
+    bool Verify() override;
+
+    //! Load wallet databases.
+    bool Open() override;
+
+    //! Complete startup of wallets.
+    void Start(CScheduler& scheduler) override;
+
+    //! Flush all wallets in preparation for shutdown.
+    void Flush() override;
+
+    //! Stop all wallets. Wallets will be flushed first.
+    void Stop() override;
+
+    //! Close all wallets.
+    void Close() override;
+};
+
+static WalletInit g_wallet_init;
+WalletInitInterface* const g_wallet_init_interface = &g_wallet_init;
+
+std::string WalletInit::GetHelpString(bool showDebug)
 {
     std::string strUsage = HelpMessageGroup(_("Wallet options:"));
-    strUsage += HelpMessageOpt("-addresstype", strprintf("What type of addresses to use (\"legacy\", \"p2sh-segwit\", or \"bech32\", default: \"%s\")", FormatOutputType(OUTPUT_TYPE_DEFAULT)));
+    strUsage += HelpMessageOpt("-addresstype", strprintf("What type of addresses to use (\"legacy\", \"p2sh-segwit\", or \"bech32\", default: \"%s\")", FormatOutputType(DEFAULT_ADDRESS_TYPE)));
     strUsage += HelpMessageOpt("-changetype", "What type of change to use (\"legacy\", \"p2sh-segwit\", or \"bech32\"). Default is same as -addresstype, except when -addresstype=p2sh-segwit a native segwit output is used when sending to a native segwit address)");
     strUsage += HelpMessageOpt("-disablewallet", _("Do not load the wallet and disable wallet RPC calls"));
     strUsage += HelpMessageOpt("-discardfee=<amt>", strprintf(_("The fee rate (in %s/kB) that indicates your tolerance for discarding change by adding it to the fee (default: %s). "
@@ -56,7 +92,7 @@ std::string GetWalletHelpString(bool showDebug)
     return strUsage;
 }
 
-bool WalletParameterInteraction()
+bool WalletInit::ParameterInteraction()
 {
     if (gArgs.GetBoolArg("-disablewallet", DEFAULT_DISABLE_WALLET)) {
         for (const std::string& wallet : gArgs.GetArgs("-wallet")) {
@@ -181,22 +217,10 @@ bool WalletParameterInteraction()
     bSpendZeroConfChange = gArgs.GetBoolArg("-spendzeroconfchange", DEFAULT_SPEND_ZEROCONF_CHANGE);
     fWalletRbf = gArgs.GetBoolArg("-walletrbf", DEFAULT_WALLET_RBF);
 
-    g_address_type = ParseOutputType(gArgs.GetArg("-addresstype", ""));
-    if (g_address_type == OUTPUT_TYPE_NONE) {
-        return InitError(strprintf("Unknown address type '%s'", gArgs.GetArg("-addresstype", "")));
-    }
-
-    // If changetype is set in config file or parameter, check that it's valid.
-    // Default to OUTPUT_TYPE_NONE if not set.
-    g_change_type = ParseOutputType(gArgs.GetArg("-changetype", ""), OUTPUT_TYPE_NONE);
-    if (g_change_type == OUTPUT_TYPE_NONE && !gArgs.GetArg("-changetype", "").empty()) {
-        return InitError(strprintf("Unknown change type '%s'", gArgs.GetArg("-changetype", "")));
-    }
-
     return true;
 }
 
-void RegisterWalletRPC(CRPCTable &t)
+void WalletInit::RegisterRPC(CRPCTable &t)
 {
     if (gArgs.GetBoolArg("-disablewallet", DEFAULT_DISABLE_WALLET)) {
         return;
@@ -205,7 +229,7 @@ void RegisterWalletRPC(CRPCTable &t)
     RegisterWalletRPCCommands(t);
 }
 
-bool VerifyWallets()
+bool WalletInit::Verify()
 {
     if (gArgs.GetBoolArg("-disablewallet", DEFAULT_DISABLE_WALLET)) {
         return true;
@@ -280,7 +304,7 @@ bool VerifyWallets()
     return true;
 }
 
-bool OpenWallets()
+bool WalletInit::Open()
 {
     if (gArgs.GetBoolArg("-disablewallet", DEFAULT_DISABLE_WALLET)) {
         LogPrintf("Wallet disabled!\n");
@@ -298,25 +322,29 @@ bool OpenWallets()
     return true;
 }
 
-void StartWallets(CScheduler& scheduler) {
+void WalletInit::Start(CScheduler& scheduler)
+{
     for (CWalletRef pwallet : vpwallets) {
         pwallet->postInitProcess(scheduler);
     }
 }
 
-void FlushWallets() {
+void WalletInit::Flush()
+{
     for (CWalletRef pwallet : vpwallets) {
         pwallet->Flush(false);
     }
 }
 
-void StopWallets() {
+void WalletInit::Stop()
+{
     for (CWalletRef pwallet : vpwallets) {
         pwallet->Flush(true);
     }
 }
 
-void CloseWallets() {
+void WalletInit::Close()
+{
     for (CWalletRef pwallet : vpwallets) {
         delete pwallet;
     }
diff --git a/src/wallet/init.h b/src/wallet/init.h
deleted file mode 100644
index 0b3ee2dda2..0000000000
--- a/src/wallet/init.h
+++ /dev/null
@@ -1,43 +0,0 @@
-// Copyright (c) 2009-2010 Satoshi Nakamoto
-// Copyright (c) 2009-2017 The Bitcoin Core developers
-// Distributed under the MIT software license, see the accompanying
-// file COPYING or http://www.opensource.org/licenses/mit-license.php.
-
-#ifndef BITCOIN_WALLET_INIT_H
-#define BITCOIN_WALLET_INIT_H
-
-#include <string>
-
-class CRPCTable;
-class CScheduler;
-
-//! Return the wallets help message.
-std::string GetWalletHelpString(bool showDebug);
-
-//! Wallets parameter interaction
-bool WalletParameterInteraction();
-
-//! Register wallet RPCs.
-void RegisterWalletRPC(CRPCTable &tableRPC);
-
-//! Responsible for reading and validating the -wallet arguments and verifying the wallet database.
-//  This function will perform salvage on the wallet if requested, as long as only one wallet is
-//  being loaded (WalletParameterInteraction forbids -salvagewallet, -zapwallettxes or -upgradewallet with multiwallet).
-bool VerifyWallets();
-
-//! Load wallet databases.
-bool OpenWallets();
-
-//! Complete startup of wallets.
-void StartWallets(CScheduler& scheduler);
-
-//! Flush all wallets in preparation for shutdown.
-void FlushWallets();
-
-//! Stop all wallets. Wallets will be flushed first.
-void StopWallets();
-
-//! Close all wallets.
-void CloseWallets();
-
-#endif // BITCOIN_WALLET_INIT_H
diff --git a/src/wallet/rpcdump.cpp b/src/wallet/rpcdump.cpp
index 0edc8d8d66..a3594aa692 100644
--- a/src/wallet/rpcdump.cpp
+++ b/src/wallet/rpcdump.cpp
@@ -6,7 +6,6 @@
 #include <key_io.h>
 #include <rpc/safemode.h>
 #include <rpc/server.h>
-#include <wallet/init.h>
 #include <validation.h>
 #include <script/script.h>
 #include <script/standard.h>
@@ -28,10 +27,6 @@
 #include <univalue.h>
 
 
-std::string static EncodeDumpTime(int64_t nTime) {
-    return DateTimeStrFormat("%Y-%m-%dT%H:%M:%SZ", nTime);
-}
-
 int64_t static DecodeDumpTime(const std::string &str) {
     static const boost::posix_time::ptime epoch = boost::posix_time::from_time_t(0);
     static const std::locale loc(std::locale::classic(),
@@ -87,7 +82,7 @@ bool GetWalletAddressesForKey(CWallet * const pwallet, const CKeyID &keyid, std:
         }
     }
     if (!fLabelFound) {
-        strAddr = EncodeDestination(GetDestinationForKey(key.GetPubKey(), g_address_type));
+        strAddr = EncodeDestination(GetDestinationForKey(key.GetPubKey(), pwallet->m_default_address_type));
     }
     return fLabelFound;
 }
@@ -104,6 +99,7 @@ UniValue importprivkey(const JSONRPCRequest& request)
         throw std::runtime_error(
             "importprivkey \"privkey\" ( \"label\" ) ( rescan )\n"
             "\nAdds a private key (as returned by dumpprivkey) to your wallet. Requires a new wallet backup.\n"
+            "Hint: use importmulti to import more than one private key.\n"
             "\nArguments:\n"
             "1. \"privkey\"          (string, required) The private key (see dumpprivkey)\n"
             "2. \"label\"            (string, optional, default=\"\") An optional label\n"
@@ -354,9 +350,10 @@ UniValue importprunedfunds(const JSONRPCRequest& request)
     if (merkleBlock.txn.ExtractMatches(vMatch, vIndex) == merkleBlock.header.hashMerkleRoot) {
 
         LOCK(cs_main);
-
-        if (!mapBlockIndex.count(merkleBlock.header.GetHash()) || !chainActive.Contains(mapBlockIndex[merkleBlock.header.GetHash()]))
+        const CBlockIndex* pindex = LookupBlockIndex(merkleBlock.header.GetHash());
+        if (!pindex || !chainActive.Contains(pindex)) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found in chain");
+        }
 
         std::vector<uint256>::const_iterator it;
         if ((it = std::find(vMatch.begin(), vMatch.end(), hashTx))==vMatch.end()) {
@@ -409,7 +406,7 @@ UniValue removeprunedfunds(const JSONRPCRequest& request)
     vHash.push_back(hash);
     std::vector<uint256> vHashOut;
 
-    if (pwallet->ZapSelectTx(vHash, vHashOut) != DB_LOAD_OK) {
+    if (pwallet->ZapSelectTx(vHash, vHashOut) != DBErrors::LOAD_OK) {
         throw JSONRPCError(RPC_WALLET_ERROR, "Could not properly delete the transaction.");
     }
 
@@ -722,9 +719,9 @@ UniValue dumpwallet(const JSONRPCRequest& request)
 
     // produce output
     file << strprintf("# Wallet dump created by Bitcoin %s\n", CLIENT_BUILD);
-    file << strprintf("# * Created on %s\n", EncodeDumpTime(GetTime()));
+    file << strprintf("# * Created on %s\n", FormatISO8601DateTime(GetTime()));
     file << strprintf("# * Best block at time of backup was %i (%s),\n", chainActive.Height(), chainActive.Tip()->GetBlockHash().ToString());
-    file << strprintf("#   mined on %s\n", EncodeDumpTime(chainActive.Tip()->GetBlockTime()));
+    file << strprintf("#   mined on %s\n", FormatISO8601DateTime(chainActive.Tip()->GetBlockTime()));
     file << "\n";
 
     // add the base58check encoded extended master if the wallet uses HD
@@ -741,7 +738,7 @@ UniValue dumpwallet(const JSONRPCRequest& request)
     }
     for (std::vector<std::pair<int64_t, CKeyID> >::const_iterator it = vKeyBirth.begin(); it != vKeyBirth.end(); it++) {
         const CKeyID &keyid = it->second;
-        std::string strTime = EncodeDumpTime(it->first);
+        std::string strTime = FormatISO8601DateTime(it->first);
         std::string strAddr;
         std::string strLabel;
         CKey key;
@@ -769,7 +766,7 @@ UniValue dumpwallet(const JSONRPCRequest& request)
         // get birth times for scripts with metadata
         auto it = pwallet->m_script_metadata.find(scriptid);
         if (it != pwallet->m_script_metadata.end()) {
-            create_time = EncodeDumpTime(it->second.nCreateTime);
+            create_time = FormatISO8601DateTime(it->second.nCreateTime);
         }
         if(pwallet->GetCScript(scriptid, script)) {
             file << strprintf("%s %s script=1", HexStr(script.begin(), script.end()), create_time);
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 457abec1bc..c34b166a41 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -95,7 +95,7 @@ void WalletTxToJSON(const CWalletTx& wtx, UniValue& entry)
     {
         entry.pushKV("blockhash", wtx.hashBlock.GetHex());
         entry.pushKV("blockindex", wtx.nIndex);
-        entry.pushKV("blocktime", mapBlockIndex[wtx.hashBlock]->GetBlockTime());
+        entry.pushKV("blocktime", LookupBlockIndex(wtx.hashBlock)->GetBlockTime());
     } else {
         entry.pushKV("trusted", wtx.IsTrusted());
     }
@@ -113,9 +113,9 @@ void WalletTxToJSON(const CWalletTx& wtx, UniValue& entry)
     if (confirms <= 0) {
         LOCK(mempool.cs);
         RBFTransactionState rbfState = IsRBFOptIn(*wtx.tx, mempool);
-        if (rbfState == RBF_TRANSACTIONSTATE_UNKNOWN)
+        if (rbfState == RBFTransactionState::UNKNOWN)
             rbfStatus = "unknown";
-        else if (rbfState == RBF_TRANSACTIONSTATE_REPLACEABLE_BIP125)
+        else if (rbfState == RBFTransactionState::REPLACEABLE_BIP125)
             rbfStatus = "yes";
     }
     entry.pushKV("bip125-replaceable", rbfStatus);
@@ -124,12 +124,12 @@ void WalletTxToJSON(const CWalletTx& wtx, UniValue& entry)
         entry.pushKV(item.first, item.second);
 }
 
-std::string AccountFromValue(const UniValue& value)
+std::string LabelFromValue(const UniValue& value)
 {
-    std::string strAccount = value.get_str();
-    if (strAccount == "*")
-        throw JSONRPCError(RPC_WALLET_INVALID_ACCOUNT_NAME, "Invalid account name");
-    return strAccount;
+    std::string label = value.get_str();
+    if (label == "*")
+        throw JSONRPCError(RPC_WALLET_INVALID_LABEL_NAME, "Invalid label name");
+    return label;
 }
 
 UniValue getnewaddress(const JSONRPCRequest& request)
@@ -141,12 +141,12 @@ UniValue getnewaddress(const JSONRPCRequest& request)
 
     if (request.fHelp || request.params.size() > 2)
         throw std::runtime_error(
-            "getnewaddress ( \"account\" \"address_type\" )\n"
+            "getnewaddress ( \"label\" \"address_type\" )\n"
             "\nReturns a new Bitcoin address for receiving payments.\n"
-            "If 'account' is specified (DEPRECATED), it is added to the address book \n"
-            "so payments received with the address will be credited to 'account'.\n"
+            "If 'label' is specified, it is added to the address book \n"
+            "so payments received with the address will be associated with 'label'.\n"
             "\nArguments:\n"
-            "1. \"account\"        (string, optional) DEPRECATED. The account name for the address to be linked to. If not provided, the default account \"\" is used. It can also be set to the empty string \"\" to represent the default account. The account does not need to exist, it will be created if there is no account by the given name.\n"
+            "1. \"label\"          (string, optional) The label name for the address to be linked to. If not provided, the default label \"\" is used. It can also be set to the empty string \"\" to represent the default label. The label does not need to exist, it will be created if there is no label by the given name.\n"
             "2. \"address_type\"   (string, optional) The address type to use. Options are \"legacy\", \"p2sh-segwit\", and \"bech32\". Default is set by -addresstype.\n"
             "\nResult:\n"
             "\"address\"    (string) The new bitcoin address\n"
@@ -157,15 +157,15 @@ UniValue getnewaddress(const JSONRPCRequest& request)
 
     LOCK2(cs_main, pwallet->cs_wallet);
 
-    // Parse the account first so we don't generate a key if there's an error
-    std::string strAccount;
+    // Parse the label first so we don't generate a key if there's an error
+    std::string label;
     if (!request.params[0].isNull())
-        strAccount = AccountFromValue(request.params[0]);
+        label = LabelFromValue(request.params[0]);
 
-    OutputType output_type = g_address_type;
+    OutputType output_type = pwallet->m_default_address_type;
     if (!request.params[1].isNull()) {
-        output_type = ParseOutputType(request.params[1].get_str(), g_address_type);
-        if (output_type == OUTPUT_TYPE_NONE) {
+        output_type = ParseOutputType(request.params[1].get_str(), pwallet->m_default_address_type);
+        if (output_type == OutputType::NONE) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("Unknown address type '%s'", request.params[1].get_str()));
         }
     }
@@ -182,23 +182,23 @@ UniValue getnewaddress(const JSONRPCRequest& request)
     pwallet->LearnRelatedScripts(newKey, output_type);
     CTxDestination dest = GetDestinationForKey(newKey, output_type);
 
-    pwallet->SetAddressBook(dest, strAccount, "receive");
+    pwallet->SetAddressBook(dest, label, "receive");
 
     return EncodeDestination(dest);
 }
 
 
-CTxDestination GetAccountDestination(CWallet* const pwallet, std::string strAccount, bool bForceNew=false)
+CTxDestination GetLabelDestination(CWallet* const pwallet, const std::string& label, bool bForceNew=false)
 {
     CTxDestination dest;
-    if (!pwallet->GetAccountDestination(dest, strAccount, bForceNew)) {
+    if (!pwallet->GetLabelDestination(dest, label, bForceNew)) {
         throw JSONRPCError(RPC_WALLET_KEYPOOL_RAN_OUT, "Error: Keypool ran out, please call keypoolrefill first");
     }
 
     return dest;
 }
 
-UniValue getaccountaddress(const JSONRPCRequest& request)
+UniValue getlabeladdress(const JSONRPCRequest& request)
 {
     CWallet * const pwallet = GetWalletForJSONRPCRequest(request);
     if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
@@ -207,27 +207,27 @@ UniValue getaccountaddress(const JSONRPCRequest& request)
 
     if (request.fHelp || request.params.size() != 1)
         throw std::runtime_error(
-            "getaccountaddress \"account\"\n"
-            "\nDEPRECATED. Returns the current Bitcoin address for receiving payments to this account.\n"
+            "getlabeladdress \"label\"\n"
+            "\nReturns the current Bitcoin address for receiving payments to this label.\n"
             "\nArguments:\n"
-            "1. \"account\"       (string, required) The account name for the address. It can also be set to the empty string \"\" to represent the default account. The account does not need to exist, it will be created and a new address created  if there is no account by the given name.\n"
+            "1. \"label\"         (string, required) The label name for the address. It can also be set to the empty string \"\" to represent the default label. The label does not need to exist, it will be created and a new address created  if there is no label by the given name.\n"
             "\nResult:\n"
-            "\"address\"          (string) The account bitcoin address\n"
+            "\"address\"          (string) The label bitcoin address\n"
             "\nExamples:\n"
-            + HelpExampleCli("getaccountaddress", "")
-            + HelpExampleCli("getaccountaddress", "\"\"")
-            + HelpExampleCli("getaccountaddress", "\"myaccount\"")
-            + HelpExampleRpc("getaccountaddress", "\"myaccount\"")
+            + HelpExampleCli("getlabeladdress", "")
+            + HelpExampleCli("getlabeladdress", "\"\"")
+            + HelpExampleCli("getlabeladdress", "\"mylabel\"")
+            + HelpExampleRpc("getlabeladdress", "\"mylabel\"")
         );
 
     LOCK2(cs_main, pwallet->cs_wallet);
 
-    // Parse the account first so we don't generate a key if there's an error
-    std::string strAccount = AccountFromValue(request.params[0]);
+    // Parse the label first so we don't generate a key if there's an error
+    std::string label = LabelFromValue(request.params[0]);
 
     UniValue ret(UniValue::VSTR);
 
-    ret = EncodeDestination(GetAccountDestination(pwallet, strAccount));
+    ret = EncodeDestination(GetLabelDestination(pwallet, label));
     return ret;
 }
 
@@ -259,10 +259,10 @@ UniValue getrawchangeaddress(const JSONRPCRequest& request)
         pwallet->TopUpKeyPool();
     }
 
-    OutputType output_type = g_change_type != OUTPUT_TYPE_NONE ? g_change_type : g_address_type;
+    OutputType output_type = pwallet->m_default_change_type != OutputType::NONE ? pwallet->m_default_change_type : pwallet->m_default_address_type;
     if (!request.params[0].isNull()) {
         output_type = ParseOutputType(request.params[0].get_str(), output_type);
-        if (output_type == OUTPUT_TYPE_NONE) {
+        if (output_type == OutputType::NONE) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("Unknown address type '%s'", request.params[0].get_str()));
         }
     }
@@ -281,7 +281,7 @@ UniValue getrawchangeaddress(const JSONRPCRequest& request)
 }
 
 
-UniValue setaccount(const JSONRPCRequest& request)
+UniValue setlabel(const JSONRPCRequest& request)
 {
     CWallet * const pwallet = GetWalletForJSONRPCRequest(request);
     if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
@@ -290,14 +290,14 @@ UniValue setaccount(const JSONRPCRequest& request)
 
     if (request.fHelp || request.params.size() < 1 || request.params.size() > 2)
         throw std::runtime_error(
-            "setaccount \"address\" \"account\"\n"
-            "\nDEPRECATED. Sets the account associated with the given address.\n"
+            "setlabel \"address\" \"label\"\n"
+            "\nSets the label associated with the given address.\n"
             "\nArguments:\n"
-            "1. \"address\"         (string, required) The bitcoin address to be associated with an account.\n"
-            "2. \"account\"         (string, required) The account to assign the address to.\n"
+            "1. \"address\"         (string, required) The bitcoin address to be associated with a label.\n"
+            "2. \"label\"           (string, required) The label to assign the address to.\n"
             "\nExamples:\n"
-            + HelpExampleCli("setaccount", "\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX\" \"tabby\"")
-            + HelpExampleRpc("setaccount", "\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX\", \"tabby\"")
+            + HelpExampleCli("setlabel", "\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX\" \"tabby\"")
+            + HelpExampleRpc("setlabel", "\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX\", \"tabby\"")
         );
 
     LOCK2(cs_main, pwallet->cs_wallet);
@@ -307,23 +307,23 @@ UniValue setaccount(const JSONRPCRequest& request)
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid Bitcoin address");
     }
 
-    std::string strAccount;
+    std::string label;
     if (!request.params[1].isNull())
-        strAccount = AccountFromValue(request.params[1]);
+        label = LabelFromValue(request.params[1]);
 
-    // Only add the account if the address is yours.
+    // Only add the label if the address is yours.
     if (IsMine(*pwallet, dest)) {
-        // Detect when changing the account of an address that is the 'unused current key' of another account:
+        // Detect when changing the label of an address that is the 'unused current key' of another label:
         if (pwallet->mapAddressBook.count(dest)) {
-            std::string strOldAccount = pwallet->mapAddressBook[dest].name;
-            if (dest == GetAccountDestination(pwallet, strOldAccount)) {
-                GetAccountDestination(pwallet, strOldAccount, true);
+            std::string old_label = pwallet->mapAddressBook[dest].name;
+            if (dest == GetLabelDestination(pwallet, old_label)) {
+                GetLabelDestination(pwallet, old_label, true);
             }
         }
-        pwallet->SetAddressBook(dest, strAccount, "receive");
+        pwallet->SetAddressBook(dest, label, "receive");
     }
     else
-        throw JSONRPCError(RPC_MISC_ERROR, "setaccount can only be used with own address");
+        throw JSONRPCError(RPC_MISC_ERROR, "setlabel can only be used with own address");
 
     return NullUniValue;
 }
@@ -390,7 +390,7 @@ UniValue getaddressesbyaccount(const JSONRPCRequest& request)
 
     LOCK2(cs_main, pwallet->cs_wallet);
 
-    std::string strAccount = AccountFromValue(request.params[0]);
+    std::string strAccount = LabelFromValue(request.params[0]);
 
     // Find all addresses that have the given account
     UniValue ret(UniValue::VARR);
@@ -404,7 +404,7 @@ UniValue getaddressesbyaccount(const JSONRPCRequest& request)
     return ret;
 }
 
-static void SendMoney(CWallet * const pwallet, const CTxDestination &address, CAmount nValue, bool fSubtractFeeFromAmount, CWalletTx& wtxNew, const CCoinControl& coin_control)
+static CTransactionRef SendMoney(CWallet * const pwallet, const CTxDestination &address, CAmount nValue, bool fSubtractFeeFromAmount, const CCoinControl& coin_control, mapValue_t mapValue, std::string fromAccount)
 {
     CAmount curBalance = pwallet->GetBalance();
 
@@ -430,16 +430,18 @@ static void SendMoney(CWallet * const pwallet, const CTxDestination &address, CA
     int nChangePosRet = -1;
     CRecipient recipient = {scriptPubKey, nValue, fSubtractFeeFromAmount};
     vecSend.push_back(recipient);
-    if (!pwallet->CreateTransaction(vecSend, wtxNew, reservekey, nFeeRequired, nChangePosRet, strError, coin_control)) {
+    CTransactionRef tx;
+    if (!pwallet->CreateTransaction(vecSend, tx, reservekey, nFeeRequired, nChangePosRet, strError, coin_control)) {
         if (!fSubtractFeeFromAmount && nValue + nFeeRequired > curBalance)
             strError = strprintf("Error: This transaction requires a transaction fee of at least %s", FormatMoney(nFeeRequired));
         throw JSONRPCError(RPC_WALLET_ERROR, strError);
     }
     CValidationState state;
-    if (!pwallet->CommitTransaction(wtxNew, reservekey, g_connman.get(), state)) {
+    if (!pwallet->CommitTransaction(tx, std::move(mapValue), {} /* orderForm */, std::move(fromAccount), reservekey, g_connman.get(), state)) {
         strError = strprintf("Error: The transaction was rejected! Reason given: %s", FormatStateMessage(state));
         throw JSONRPCError(RPC_WALLET_ERROR, strError);
     }
+    return tx;
 }
 
 UniValue sendtoaddress(const JSONRPCRequest& request)
@@ -498,11 +500,11 @@ UniValue sendtoaddress(const JSONRPCRequest& request)
         throw JSONRPCError(RPC_TYPE_ERROR, "Invalid amount for send");
 
     // Wallet comments
-    CWalletTx wtx;
+    mapValue_t mapValue;
     if (!request.params[2].isNull() && !request.params[2].get_str().empty())
-        wtx.mapValue["comment"] = request.params[2].get_str();
+        mapValue["comment"] = request.params[2].get_str();
     if (!request.params[3].isNull() && !request.params[3].get_str().empty())
-        wtx.mapValue["to"]      = request.params[3].get_str();
+        mapValue["to"] = request.params[3].get_str();
 
     bool fSubtractFeeFromAmount = false;
     if (!request.params[4].isNull()) {
@@ -527,9 +529,8 @@ UniValue sendtoaddress(const JSONRPCRequest& request)
 
     EnsureWalletIsUnlocked(pwallet);
 
-    SendMoney(pwallet, dest, nAmount, fSubtractFeeFromAmount, wtx, coin_control);
-
-    return wtx.GetHash().GetHex();
+    CTransactionRef tx = SendMoney(pwallet, dest, nAmount, fSubtractFeeFromAmount, coin_control, std::move(mapValue), {} /* fromAccount */);
+    return tx->GetHash().GetHex();
 }
 
 UniValue listaddressgroupings(const JSONRPCRequest& request)
@@ -551,7 +552,7 @@ UniValue listaddressgroupings(const JSONRPCRequest& request)
             "    [\n"
             "      \"address\",            (string) The bitcoin address\n"
             "      amount,                 (numeric) The amount in " + CURRENCY_UNIT + "\n"
-            "      \"account\"             (string, optional) DEPRECATED. The account\n"
+            "      \"label\"               (string, optional) The label\n"
             "    ]\n"
             "    ,...\n"
             "  ]\n"
@@ -719,7 +720,7 @@ UniValue getreceivedbyaddress(const JSONRPCRequest& request)
 }
 
 
-UniValue getreceivedbyaccount(const JSONRPCRequest& request)
+UniValue getreceivedbylabel(const JSONRPCRequest& request)
 {
     CWallet * const pwallet = GetWalletForJSONRPCRequest(request);
     if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
@@ -728,22 +729,22 @@ UniValue getreceivedbyaccount(const JSONRPCRequest& request)
 
     if (request.fHelp || request.params.size() < 1 || request.params.size() > 2)
         throw std::runtime_error(
-            "getreceivedbyaccount \"account\" ( minconf )\n"
-            "\nDEPRECATED. Returns the total amount received by addresses with <account> in transactions with at least [minconf] confirmations.\n"
+            "getreceivedbylabel \"label\" ( minconf )\n"
+            "\nReturns the total amount received by addresses with <label> in transactions with at least [minconf] confirmations.\n"
             "\nArguments:\n"
-            "1. \"account\"      (string, required) The selected account, may be the default account using \"\".\n"
+            "1. \"label\"        (string, required) The selected label, may be the default label using \"\".\n"
             "2. minconf          (numeric, optional, default=1) Only include transactions confirmed at least this many times.\n"
             "\nResult:\n"
-            "amount              (numeric) The total amount in " + CURRENCY_UNIT + " received for this account.\n"
+            "amount              (numeric) The total amount in " + CURRENCY_UNIT + " received for this label.\n"
             "\nExamples:\n"
-            "\nAmount received by the default account with at least 1 confirmation\n"
-            + HelpExampleCli("getreceivedbyaccount", "\"\"") +
-            "\nAmount received at the tabby account including unconfirmed amounts with zero confirmations\n"
-            + HelpExampleCli("getreceivedbyaccount", "\"tabby\" 0") +
+            "\nAmount received by the default label with at least 1 confirmation\n"
+            + HelpExampleCli("getreceivedbylabel", "\"\"") +
+            "\nAmount received at the tabby label including unconfirmed amounts with zero confirmations\n"
+            + HelpExampleCli("getreceivedbylabel", "\"tabby\" 0") +
             "\nThe amount with at least 6 confirmations\n"
-            + HelpExampleCli("getreceivedbyaccount", "\"tabby\" 6") +
+            + HelpExampleCli("getreceivedbylabel", "\"tabby\" 6") +
             "\nAs a json rpc call\n"
-            + HelpExampleRpc("getreceivedbyaccount", "\"tabby\", 6")
+            + HelpExampleRpc("getreceivedbylabel", "\"tabby\", 6")
         );
 
     ObserveSafeMode();
@@ -759,9 +760,9 @@ UniValue getreceivedbyaccount(const JSONRPCRequest& request)
     if (!request.params[1].isNull())
         nMinDepth = request.params[1].get_int();
 
-    // Get the set of pub keys assigned to account
-    std::string strAccount = AccountFromValue(request.params[0]);
-    std::set<CTxDestination> setAddress = pwallet->GetAccountAddresses(strAccount);
+    // Get the set of pub keys assigned to label
+    std::string label = LabelFromValue(request.params[0]);
+    std::set<CTxDestination> setAddress = pwallet->GetLabelAddresses(label);
 
     // Tally
     CAmount nAmount = 0;
@@ -919,8 +920,8 @@ UniValue movecmd(const JSONRPCRequest& request)
     ObserveSafeMode();
     LOCK2(cs_main, pwallet->cs_wallet);
 
-    std::string strFrom = AccountFromValue(request.params[0]);
-    std::string strTo = AccountFromValue(request.params[1]);
+    std::string strFrom = LabelFromValue(request.params[0]);
+    std::string strTo = LabelFromValue(request.params[1]);
     CAmount nAmount = AmountFromValue(request.params[2]);
     if (nAmount <= 0)
         throw JSONRPCError(RPC_TYPE_ERROR, "Invalid amount for send");
@@ -983,7 +984,7 @@ UniValue sendfrom(const JSONRPCRequest& request)
 
     LOCK2(cs_main, pwallet->cs_wallet);
 
-    std::string strAccount = AccountFromValue(request.params[0]);
+    std::string strAccount = LabelFromValue(request.params[0]);
     CTxDestination dest = DecodeDestination(request.params[1].get_str());
     if (!IsValidDestination(dest)) {
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid Bitcoin address");
@@ -995,12 +996,11 @@ UniValue sendfrom(const JSONRPCRequest& request)
     if (!request.params[3].isNull())
         nMinDepth = request.params[3].get_int();
 
-    CWalletTx wtx;
-    wtx.strFromAccount = strAccount;
+    mapValue_t mapValue;
     if (!request.params[4].isNull() && !request.params[4].get_str().empty())
-        wtx.mapValue["comment"] = request.params[4].get_str();
+        mapValue["comment"] = request.params[4].get_str();
     if (!request.params[5].isNull() && !request.params[5].get_str().empty())
-        wtx.mapValue["to"]      = request.params[5].get_str();
+        mapValue["to"] = request.params[5].get_str();
 
     EnsureWalletIsUnlocked(pwallet);
 
@@ -1010,9 +1010,8 @@ UniValue sendfrom(const JSONRPCRequest& request)
         throw JSONRPCError(RPC_WALLET_INSUFFICIENT_FUNDS, "Account has insufficient funds");
 
     CCoinControl no_coin_control; // This is a deprecated API
-    SendMoney(pwallet, dest, nAmount, false, wtx, no_coin_control);
-
-    return wtx.GetHash().GetHex();
+    CTransactionRef tx = SendMoney(pwallet, dest, nAmount, false, no_coin_control, std::move(mapValue), std::move(strAccount));
+    return tx->GetHash().GetHex();
 }
 
 
@@ -1077,16 +1076,15 @@ UniValue sendmany(const JSONRPCRequest& request)
         throw JSONRPCError(RPC_CLIENT_P2P_DISABLED, "Error: Peer-to-peer functionality missing or disabled");
     }
 
-    std::string strAccount = AccountFromValue(request.params[0]);
+    std::string strAccount = LabelFromValue(request.params[0]);
     UniValue sendTo = request.params[1].get_obj();
     int nMinDepth = 1;
     if (!request.params[2].isNull())
         nMinDepth = request.params[2].get_int();
 
-    CWalletTx wtx;
-    wtx.strFromAccount = strAccount;
+    mapValue_t mapValue;
     if (!request.params[3].isNull() && !request.params[3].get_str().empty())
-        wtx.mapValue["comment"] = request.params[3].get_str();
+        mapValue["comment"] = request.params[3].get_str();
 
     UniValue subtractFeeFromAmount(UniValue::VARR);
     if (!request.params[4].isNull())
@@ -1147,21 +1145,25 @@ UniValue sendmany(const JSONRPCRequest& request)
     if (totalAmount > nBalance)
         throw JSONRPCError(RPC_WALLET_INSUFFICIENT_FUNDS, "Account has insufficient funds");
 
+    // Shuffle recipient list
+    std::shuffle(vecSend.begin(), vecSend.end(), FastRandomContext());
+
     // Send
     CReserveKey keyChange(pwallet);
     CAmount nFeeRequired = 0;
     int nChangePosRet = -1;
     std::string strFailReason;
-    bool fCreated = pwallet->CreateTransaction(vecSend, wtx, keyChange, nFeeRequired, nChangePosRet, strFailReason, coin_control);
+    CTransactionRef tx;
+    bool fCreated = pwallet->CreateTransaction(vecSend, tx, keyChange, nFeeRequired, nChangePosRet, strFailReason, coin_control);
     if (!fCreated)
         throw JSONRPCError(RPC_WALLET_INSUFFICIENT_FUNDS, strFailReason);
     CValidationState state;
-    if (!pwallet->CommitTransaction(wtx, keyChange, g_connman.get(), state)) {
+    if (!pwallet->CommitTransaction(tx, std::move(mapValue), {} /* orderForm */, std::move(strAccount), keyChange, g_connman.get(), state)) {
         strFailReason = strprintf("Transaction commit failed:: %s", FormatStateMessage(state));
         throw JSONRPCError(RPC_WALLET_ERROR, strFailReason);
     }
 
-    return wtx.GetHash().GetHex();
+    return tx->GetHash().GetHex();
 }
 
 UniValue addmultisigaddress(const JSONRPCRequest& request)
@@ -1172,12 +1174,12 @@ UniValue addmultisigaddress(const JSONRPCRequest& request)
     }
 
     if (request.fHelp || request.params.size() < 2 || request.params.size() > 4) {
-        std::string msg = "addmultisigaddress nrequired [\"key\",...] ( \"account\" \"address_type\" )\n"
+        std::string msg = "addmultisigaddress nrequired [\"key\",...] ( \"label\" \"address_type\" )\n"
             "\nAdd a nrequired-to-sign multisignature address to the wallet. Requires a new wallet backup.\n"
             "Each key is a Bitcoin address or hex-encoded public key.\n"
             "This functionality is only intended for use with non-watchonly addresses.\n"
             "See `importaddress` for watchonly p2sh address support.\n"
-            "If 'account' is specified (DEPRECATED), assign address to that account.\n"
+            "If 'label' is specified, assign address to that label.\n"
 
             "\nArguments:\n"
             "1. nrequired                      (numeric, required) The number of required signatures out of the n keys or addresses.\n"
@@ -1186,7 +1188,7 @@ UniValue addmultisigaddress(const JSONRPCRequest& request)
             "       \"address\"                  (string) bitcoin address or hex-encoded public key\n"
             "       ...,\n"
             "     ]\n"
-            "3. \"account\"                      (string, optional) DEPRECATED. An account to assign the addresses to.\n"
+            "3. \"label\"                        (string, optional) A label to assign the addresses to.\n"
             "4. \"address_type\"                 (string, optional) The address type to use. Options are \"legacy\", \"p2sh-segwit\", and \"bech32\". Default is set by -addresstype.\n"
 
             "\nResult:\n"
@@ -1205,9 +1207,9 @@ UniValue addmultisigaddress(const JSONRPCRequest& request)
 
     LOCK2(cs_main, pwallet->cs_wallet);
 
-    std::string strAccount;
+    std::string label;
     if (!request.params[2].isNull())
-        strAccount = AccountFromValue(request.params[2]);
+        label = LabelFromValue(request.params[2]);
 
     int required = request.params[0].get_int();
 
@@ -1222,10 +1224,10 @@ UniValue addmultisigaddress(const JSONRPCRequest& request)
         }
     }
 
-    OutputType output_type = g_address_type;
+    OutputType output_type = pwallet->m_default_address_type;
     if (!request.params[3].isNull()) {
         output_type = ParseOutputType(request.params[3].get_str(), output_type);
-        if (output_type == OUTPUT_TYPE_NONE) {
+        if (output_type == OutputType::NONE) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("Unknown address type '%s'", request.params[3].get_str()));
         }
     }
@@ -1234,7 +1236,7 @@ UniValue addmultisigaddress(const JSONRPCRequest& request)
     CScript inner = CreateMultisigRedeemscript(required, pubkeys);
     pwallet->AddCScript(inner);
     CTxDestination dest = pwallet->AddAndGetDestinationForScript(inner, output_type);
-    pwallet->SetAddressBook(dest, strAccount, "send");
+    pwallet->SetAddressBook(dest, label, "send");
 
     UniValue result(UniValue::VOBJ);
     result.pushKV("address", EncodeDestination(dest));
@@ -1386,14 +1388,14 @@ struct tallyitem
     }
 };
 
-UniValue ListReceived(CWallet * const pwallet, const UniValue& params, bool fByAccounts)
+UniValue ListReceived(CWallet * const pwallet, const UniValue& params, bool by_label)
 {
     // Minimum confirmations
     int nMinDepth = 1;
     if (!params[0].isNull())
         nMinDepth = params[0].get_int();
 
-    // Whether to include empty accounts
+    // Whether to include empty labels
     bool fIncludeEmpty = false;
     if (!params[1].isNull())
         fIncludeEmpty = params[1].get_bool();
@@ -1405,7 +1407,7 @@ UniValue ListReceived(CWallet * const pwallet, const UniValue& params, bool fByA
 
     bool has_filtered_address = false;
     CTxDestination filtered_address = CNoDestination();
-    if (!fByAccounts && params.size() > 3) {
+    if (!by_label && params.size() > 3) {
         if (!IsValidDestinationString(params[3].get_str())) {
             throw JSONRPCError(RPC_WALLET_ERROR, "address_filter parameter was invalid");
         }
@@ -1450,7 +1452,7 @@ UniValue ListReceived(CWallet * const pwallet, const UniValue& params, bool fByA
 
     // Reply
     UniValue ret(UniValue::VARR);
-    std::map<std::string, tallyitem> mapAccountTally;
+    std::map<std::string, tallyitem> label_tally;
 
     // Create mapAddressBook iterator
     // If we aren't filtering, go from begin() to end()
@@ -1467,7 +1469,7 @@ UniValue ListReceived(CWallet * const pwallet, const UniValue& params, bool fByA
     for (auto item_it = start; item_it != end; ++item_it)
     {
         const CTxDestination& address = item_it->first;
-        const std::string& strAccount = item_it->second.name;
+        const std::string& label = item_it->second.name;
         auto it = mapTally.find(address);
         if (it == mapTally.end() && !fIncludeEmpty)
             continue;
@@ -1482,9 +1484,9 @@ UniValue ListReceived(CWallet * const pwallet, const UniValue& params, bool fByA
             fIsWatchonly = (*it).second.fIsWatchonly;
         }
 
-        if (fByAccounts)
+        if (by_label)
         {
-            tallyitem& _item = mapAccountTally[strAccount];
+            tallyitem& _item = label_tally[label];
             _item.nAmount += nAmount;
             _item.nConf = std::min(_item.nConf, nConf);
             _item.fIsWatchonly = fIsWatchonly;
@@ -1495,11 +1497,10 @@ UniValue ListReceived(CWallet * const pwallet, const UniValue& params, bool fByA
             if(fIsWatchonly)
                 obj.pushKV("involvesWatchonly", true);
             obj.pushKV("address",       EncodeDestination(address));
-            obj.pushKV("account",       strAccount);
+            obj.pushKV("account",       label);
             obj.pushKV("amount",        ValueFromAmount(nAmount));
             obj.pushKV("confirmations", (nConf == std::numeric_limits<int>::max() ? 0 : nConf));
-            if (!fByAccounts)
-                obj.pushKV("label", strAccount);
+            obj.pushKV("label", label);
             UniValue transactions(UniValue::VARR);
             if (it != mapTally.end())
             {
@@ -1513,9 +1514,9 @@ UniValue ListReceived(CWallet * const pwallet, const UniValue& params, bool fByA
         }
     }
 
-    if (fByAccounts)
+    if (by_label)
     {
-        for (const auto& entry : mapAccountTally)
+        for (const auto& entry : label_tally)
         {
             CAmount nAmount = entry.second.nAmount;
             int nConf = entry.second.nConf;
@@ -1525,6 +1526,7 @@ UniValue ListReceived(CWallet * const pwallet, const UniValue& params, bool fByA
             obj.pushKV("account",       entry.first);
             obj.pushKV("amount",        ValueFromAmount(nAmount));
             obj.pushKV("confirmations", (nConf == std::numeric_limits<int>::max() ? 0 : nConf));
+            obj.pushKV("label",         entry.first);
             ret.push_back(obj);
         }
     }
@@ -1553,10 +1555,10 @@ UniValue listreceivedbyaddress(const JSONRPCRequest& request)
             "  {\n"
             "    \"involvesWatchonly\" : true,        (bool) Only returned if imported addresses were involved in transaction\n"
             "    \"address\" : \"receivingaddress\",  (string) The receiving address\n"
-            "    \"account\" : \"accountname\",       (string) DEPRECATED. The account of the receiving address. The default account is \"\".\n"
+            "    \"account\" : \"accountname\",       (string) DEPRECATED. Backwards compatible alias for label.\n"
             "    \"amount\" : x.xxx,                  (numeric) The total amount in " + CURRENCY_UNIT + " received by the address\n"
             "    \"confirmations\" : n,               (numeric) The number of confirmations of the most recent transaction included\n"
-            "    \"label\" : \"label\",               (string) A comment for the address/transaction, if any\n"
+            "    \"label\" : \"label\",               (string) The label of the receiving address. The default label is \"\".\n"
             "    \"txids\": [\n"
             "       n,                                (numeric) The ids of transactions received with the address \n"
             "       ...\n"
@@ -1583,7 +1585,7 @@ UniValue listreceivedbyaddress(const JSONRPCRequest& request)
     return ListReceived(pwallet, request.params, false);
 }
 
-UniValue listreceivedbyaccount(const JSONRPCRequest& request)
+UniValue listreceivedbylabel(const JSONRPCRequest& request)
 {
     CWallet * const pwallet = GetWalletForJSONRPCRequest(request);
     if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
@@ -1592,29 +1594,29 @@ UniValue listreceivedbyaccount(const JSONRPCRequest& request)
 
     if (request.fHelp || request.params.size() > 3)
         throw std::runtime_error(
-            "listreceivedbyaccount ( minconf include_empty include_watchonly)\n"
-            "\nDEPRECATED. List balances by account.\n"
+            "listreceivedbylabel ( minconf include_empty include_watchonly)\n"
+            "\nList received transactions by label.\n"
             "\nArguments:\n"
             "1. minconf           (numeric, optional, default=1) The minimum number of confirmations before payments are included.\n"
-            "2. include_empty     (bool, optional, default=false) Whether to include accounts that haven't received any payments.\n"
+            "2. include_empty     (bool, optional, default=false) Whether to include labels that haven't received any payments.\n"
             "3. include_watchonly (bool, optional, default=false) Whether to include watch-only addresses (see 'importaddress').\n"
 
             "\nResult:\n"
             "[\n"
             "  {\n"
             "    \"involvesWatchonly\" : true,   (bool) Only returned if imported addresses were involved in transaction\n"
-            "    \"account\" : \"accountname\",  (string) The account name of the receiving account\n"
-            "    \"amount\" : x.xxx,             (numeric) The total amount received by addresses with this account\n"
+            "    \"account\" : \"accountname\",  (string) DEPRECATED. Backwards compatible alias for label.\n"
+            "    \"amount\" : x.xxx,             (numeric) The total amount received by addresses with this label\n"
             "    \"confirmations\" : n,          (numeric) The number of confirmations of the most recent transaction included\n"
-            "    \"label\" : \"label\"           (string) A comment for the address/transaction, if any\n"
+            "    \"label\" : \"label\"           (string) The label of the receiving address. The default label is \"\".\n"
             "  }\n"
             "  ,...\n"
             "]\n"
 
             "\nExamples:\n"
-            + HelpExampleCli("listreceivedbyaccount", "")
-            + HelpExampleCli("listreceivedbyaccount", "6 true")
-            + HelpExampleRpc("listreceivedbyaccount", "6, true, true")
+            + HelpExampleCli("listreceivedbylabel", "")
+            + HelpExampleCli("listreceivedbylabel", "6 true")
+            + HelpExampleRpc("listreceivedbylabel", "6, true, true")
         );
 
     ObserveSafeMode();
@@ -2016,7 +2018,7 @@ UniValue listsinceblock(const JSONRPCRequest& request)
             "  ],\n"
             "  \"removed\": [\n"
             "    <structure is the same as \"transactions\" above, only present if include_removed=true>\n"
-            "    Note: transactions that were readded in the active chain will appear as-is in this array, and may thus have a positive confirmation count.\n"
+            "    Note: transactions that were re-added in the active chain will appear as-is in this array, and may thus have a positive confirmation count.\n"
             "  ],\n"
             "  \"lastblock\": \"lastblockhash\"     (string) The hash of the block (target_confirmations-1) from the best block on the main chain. This is typically used to feed back into listsinceblock the next time you call it. So you would generally use a target_confirmations of say 6, so you will be continually re-notified of transactions until they've reached 6 confirmations plus any new ones\n"
             "}\n"
@@ -2043,11 +2045,10 @@ UniValue listsinceblock(const JSONRPCRequest& request)
         uint256 blockId;
 
         blockId.SetHex(request.params[0].get_str());
-        BlockMap::iterator it = mapBlockIndex.find(blockId);
-        if (it == mapBlockIndex.end()) {
+        paltindex = pindex = LookupBlockIndex(blockId);
+        if (!pindex) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found");
         }
-        paltindex = pindex = it->second;
         if (chainActive[pindex->nHeight] != pindex) {
             // the block being asked for is a part of a deactivated chain;
             // we don't want to depend on its perceived height in the block
@@ -2365,8 +2366,6 @@ UniValue walletpassphrase(const JSONRPCRequest& request)
 
     LOCK2(cs_main, pwallet->cs_wallet);
 
-    if (request.fHelp)
-        return true;
     if (!pwallet->IsCrypted()) {
         throw JSONRPCError(RPC_WALLET_WRONG_ENC_STATE, "Error: running with an unencrypted wallet, but walletpassphrase was called.");
     }
@@ -2431,8 +2430,6 @@ UniValue walletpassphrasechange(const JSONRPCRequest& request)
 
     LOCK2(cs_main, pwallet->cs_wallet);
 
-    if (request.fHelp)
-        return true;
     if (!pwallet->IsCrypted()) {
         throw JSONRPCError(RPC_WALLET_WRONG_ENC_STATE, "Error: running with an unencrypted wallet, but walletpassphrasechange was called.");
     }
@@ -2487,8 +2484,6 @@ UniValue walletlock(const JSONRPCRequest& request)
 
     LOCK2(cs_main, pwallet->cs_wallet);
 
-    if (request.fHelp)
-        return true;
     if (!pwallet->IsCrypted()) {
         throw JSONRPCError(RPC_WALLET_WRONG_ENC_STATE, "Error: running with an unencrypted wallet, but walletlock was called.");
     }
@@ -2534,8 +2529,6 @@ UniValue encryptwallet(const JSONRPCRequest& request)
 
     LOCK2(cs_main, pwallet->cs_wallet);
 
-    if (request.fHelp)
-        return true;
     if (pwallet->IsCrypted()) {
         throw JSONRPCError(RPC_WALLET_WRONG_ENC_STATE, "Error: running with an encrypted wallet, but encryptwallet was called.");
     }
@@ -2937,7 +2930,8 @@ UniValue listunspent(const JSONRPCRequest& request)
             "    \"txid\" : \"txid\",          (string) the transaction id \n"
             "    \"vout\" : n,               (numeric) the vout value\n"
             "    \"address\" : \"address\",    (string) the bitcoin address\n"
-            "    \"account\" : \"account\",    (string) DEPRECATED. The associated account, or \"\" for the default account\n"
+            "    \"label\" : \"label\",        (string) The associated label, or \"\" for the default label\n"
+            "    \"account\" : \"account\",    (string) DEPRECATED. Backwards compatible alias for label.\n"
             "    \"scriptPubKey\" : \"key\",   (string) the script key\n"
             "    \"amount\" : x.xxx,         (numeric) the transaction output amount in " + CURRENCY_UNIT + "\n"
             "    \"confirmations\" : n,      (numeric) The number of confirmations\n"
@@ -3041,6 +3035,7 @@ UniValue listunspent(const JSONRPCRequest& request)
             entry.pushKV("address", EncodeDestination(address));
 
             if (pwallet->mapAddressBook.count(address)) {
+                entry.pushKV("label", pwallet->mapAddressBook[address].name);
                 entry.pushKV("account", pwallet->mapAddressBook[address].name);
             }
 
@@ -3185,8 +3180,8 @@ UniValue fundrawtransaction(const JSONRPCRequest& request)
             if (options.exists("changeAddress")) {
                 throw JSONRPCError(RPC_INVALID_PARAMETER, "Cannot specify both changeAddress and address_type options");
             }
-            coinControl.change_type = ParseOutputType(options["change_type"].get_str(), coinControl.change_type);
-            if (coinControl.change_type == OUTPUT_TYPE_NONE) {
+            coinControl.m_change_type = ParseOutputType(options["change_type"].get_str(), pwallet->m_default_change_type);
+            if (coinControl.m_change_type == OutputType::NONE) {
                 throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("Unknown change type '%s'", options["change_type"].get_str()));
             }
         }
@@ -3580,7 +3575,7 @@ UniValue rescanblockchain(const JSONRPCRequest& request)
                 throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid stop_height");
             }
             else if (pindexStop->nHeight < pindexStart->nHeight) {
-                throw JSONRPCError(RPC_INVALID_PARAMETER, "stop_height must be greater then start_height");
+                throw JSONRPCError(RPC_INVALID_PARAMETER, "stop_height must be greater than start_height");
             }
         }
     }
@@ -3836,21 +3831,23 @@ static const CRPCCommand commands[] =
     { "hidden",             "resendwallettransactions",         &resendwallettransactions,      {} },
     { "wallet",             "abandontransaction",               &abandontransaction,            {"txid"} },
     { "wallet",             "abortrescan",                      &abortrescan,                   {} },
-    { "wallet",             "addmultisigaddress",               &addmultisigaddress,            {"nrequired","keys","account","address_type"} },
+    { "wallet",             "addmultisigaddress",               &addmultisigaddress,            {"nrequired","keys","label|account","address_type"} },
     { "hidden",             "addwitnessaddress",                &addwitnessaddress,             {"address","p2sh"} },
     { "wallet",             "backupwallet",                     &backupwallet,                  {"destination"} },
     { "wallet",             "bumpfee",                          &bumpfee,                       {"txid", "options"} },
     { "wallet",             "dumpprivkey",                      &dumpprivkey,                   {"address"}  },
     { "wallet",             "dumpwallet",                       &dumpwallet,                    {"filename"} },
     { "wallet",             "encryptwallet",                    &encryptwallet,                 {"passphrase"} },
-    { "wallet",             "getaccountaddress",                &getaccountaddress,             {"account"} },
+    { "wallet",             "getlabeladdress",                  &getlabeladdress,               {"label"} },
+    { "wallet",             "getaccountaddress",                &getlabeladdress,               {"account"} },
     { "wallet",             "getaccount",                       &getaccount,                    {"address"} },
     { "wallet",             "getaddressesbyaccount",            &getaddressesbyaccount,         {"account"} },
     { "wallet",             "getaddressinfo",                   &getaddressinfo,                {"address"} },
     { "wallet",             "getbalance",                       &getbalance,                    {"account","minconf","include_watchonly"} },
-    { "wallet",             "getnewaddress",                    &getnewaddress,                 {"account","address_type"} },
+    { "wallet",             "getnewaddress",                    &getnewaddress,                 {"label|account","address_type"} },
     { "wallet",             "getrawchangeaddress",              &getrawchangeaddress,           {"address_type"} },
-    { "wallet",             "getreceivedbyaccount",             &getreceivedbyaccount,          {"account","minconf"} },
+    { "wallet",             "getreceivedbylabel",               &getreceivedbylabel,            {"label","minconf"} },
+    { "wallet",             "getreceivedbyaccount",             &getreceivedbylabel,            {"account","minconf"} },
     { "wallet",             "getreceivedbyaddress",             &getreceivedbyaddress,          {"address","minconf"} },
     { "wallet",             "gettransaction",                   &gettransaction,                {"txid","include_watchonly"} },
     { "wallet",             "getunconfirmedbalance",            &getunconfirmedbalance,         {} },
@@ -3865,7 +3862,8 @@ static const CRPCCommand commands[] =
     { "wallet",             "listaccounts",                     &listaccounts,                  {"minconf","include_watchonly"} },
     { "wallet",             "listaddressgroupings",             &listaddressgroupings,          {} },
     { "wallet",             "listlockunspent",                  &listlockunspent,               {} },
-    { "wallet",             "listreceivedbyaccount",            &listreceivedbyaccount,         {"minconf","include_empty","include_watchonly"} },
+    { "wallet",             "listreceivedbylabel",              &listreceivedbylabel,           {"minconf","include_empty","include_watchonly"} },
+    { "wallet",             "listreceivedbyaccount",            &listreceivedbylabel,           {"minconf","include_empty","include_watchonly"} },
     { "wallet",             "listreceivedbyaddress",            &listreceivedbyaddress,         {"minconf","include_empty","include_watchonly","address_filter"} },
     { "wallet",             "listsinceblock",                   &listsinceblock,                {"blockhash","target_confirmations","include_watchonly","include_removed"} },
     { "wallet",             "listtransactions",                 &listtransactions,              {"account","count","skip","include_watchonly"} },
@@ -3876,7 +3874,8 @@ static const CRPCCommand commands[] =
     { "wallet",             "sendfrom",                         &sendfrom,                      {"fromaccount","toaddress","amount","minconf","comment","comment_to"} },
     { "wallet",             "sendmany",                         &sendmany,                      {"fromaccount","amounts","minconf","comment","subtractfeefrom","replaceable","conf_target","estimate_mode"} },
     { "wallet",             "sendtoaddress",                    &sendtoaddress,                 {"address","amount","comment","comment_to","subtractfeefromamount","replaceable","conf_target","estimate_mode"} },
-    { "wallet",             "setaccount",                       &setaccount,                    {"address","account"} },
+    { "wallet",             "setlabel",                         &setlabel,                      {"address","label"} },
+    { "wallet",             "setaccount",                       &setlabel,                      {"address","account"} },
     { "wallet",             "settxfee",                         &settxfee,                      {"amount"} },
     { "wallet",             "signmessage",                      &signmessage,                   {"address","message"} },
     { "wallet",             "signrawtransactionwithwallet",     &signrawtransactionwithwallet,  {"hexstring","prevtxs","sighashtype"} },
diff --git a/src/wallet/test/accounting_tests.cpp b/src/wallet/test/accounting_tests.cpp
index 7b20bd7b02..cc6e491f53 100644
--- a/src/wallet/test/accounting_tests.cpp
+++ b/src/wallet/test/accounting_tests.cpp
@@ -18,7 +18,7 @@ GetResults(CWallet& wallet, std::map<CAmount, CAccountingEntry>& results)
     std::list<CAccountingEntry> aes;
 
     results.clear();
-    BOOST_CHECK(wallet.ReorderTransactions() == DB_LOAD_OK);
+    BOOST_CHECK(wallet.ReorderTransactions() == DBErrors::LOAD_OK);
     wallet.ListAccountCreditDebit("", aes);
     for (CAccountingEntry& ae : aes)
     {
@@ -29,7 +29,7 @@ GetResults(CWallet& wallet, std::map<CAmount, CAccountingEntry>& results)
 BOOST_AUTO_TEST_CASE(acc_orderupgrade)
 {
     std::vector<CWalletTx*> vpwtx;
-    CWalletTx wtx;
+    CWalletTx wtx(nullptr /* pwallet */, MakeTransactionRef());
     CAccountingEntry ae;
     std::map<CAmount, CAccountingEntry> results;
 
@@ -44,7 +44,7 @@ BOOST_AUTO_TEST_CASE(acc_orderupgrade)
 
     wtx.mapValue["comment"] = "z";
     m_wallet.AddToWallet(wtx);
-    vpwtx.push_back(&m_wallet.mapWallet[wtx.GetHash()]);
+    vpwtx.push_back(&m_wallet.mapWallet.at(wtx.GetHash()));
     vpwtx[0]->nTimeReceived = (unsigned int)1333333335;
     vpwtx[0]->nOrderPos = -1;
 
@@ -86,7 +86,7 @@ BOOST_AUTO_TEST_CASE(acc_orderupgrade)
         wtx.SetTx(MakeTransactionRef(std::move(tx)));
     }
     m_wallet.AddToWallet(wtx);
-    vpwtx.push_back(&m_wallet.mapWallet[wtx.GetHash()]);
+    vpwtx.push_back(&m_wallet.mapWallet.at(wtx.GetHash()));
     vpwtx[1]->nTimeReceived = (unsigned int)1333333336;
 
     wtx.mapValue["comment"] = "x";
@@ -96,7 +96,7 @@ BOOST_AUTO_TEST_CASE(acc_orderupgrade)
         wtx.SetTx(MakeTransactionRef(std::move(tx)));
     }
     m_wallet.AddToWallet(wtx);
-    vpwtx.push_back(&m_wallet.mapWallet[wtx.GetHash()]);
+    vpwtx.push_back(&m_wallet.mapWallet.at(wtx.GetHash()));
     vpwtx[2]->nTimeReceived = (unsigned int)1333333329;
     vpwtx[2]->nOrderPos = -1;
 
diff --git a/src/wallet/test/coinselector_tests.cpp b/src/wallet/test/coinselector_tests.cpp
new file mode 100644
index 0000000000..184a8a3f1f
--- /dev/null
+++ b/src/wallet/test/coinselector_tests.cpp
@@ -0,0 +1,575 @@
+// Copyright (c) 2017 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include "wallet/wallet.h"
+#include "wallet/coinselection.h"
+#include "wallet/coincontrol.h"
+#include "amount.h"
+#include "primitives/transaction.h"
+#include "random.h"
+#include "test/test_bitcoin.h"
+#include "wallet/test/wallet_test_fixture.h"
+
+#include <boost/test/unit_test.hpp>
+#include <random>
+
+BOOST_FIXTURE_TEST_SUITE(coinselector_tests, WalletTestingSetup)
+
+// how many times to run all the tests to have a chance to catch errors that only show up with particular random shuffles
+#define RUN_TESTS 100
+
+// some tests fail 1% of the time due to bad luck.
+// we repeat those tests this many times and only complain if all iterations of the test fail
+#define RANDOM_REPEATS 5
+
+std::vector<std::unique_ptr<CWalletTx>> wtxn;
+
+typedef std::set<CInputCoin> CoinSet;
+
+static std::vector<COutput> vCoins;
+static CWallet testWallet("dummy", CWalletDBWrapper::CreateDummy());
+static CAmount balance = 0;
+
+CoinEligibilityFilter filter_standard(1, 6, 0);
+CoinEligibilityFilter filter_confirmed(1, 1, 0);
+CoinEligibilityFilter filter_standard_extra(6, 6, 0);
+CoinSelectionParams coin_selection_params(false, 0, 0, CFeeRate(0), 0);
+
+static void add_coin(const CAmount& nValue, int nInput, std::vector<CInputCoin>& set)
+{
+    CMutableTransaction tx;
+    tx.vout.resize(nInput + 1);
+    tx.vout[nInput].nValue = nValue;
+    set.emplace_back(MakeTransactionRef(tx), nInput);
+}
+
+static void add_coin(const CAmount& nValue, int nInput, CoinSet& set)
+{
+    CMutableTransaction tx;
+    tx.vout.resize(nInput + 1);
+    tx.vout[nInput].nValue = nValue;
+    set.emplace(MakeTransactionRef(tx), nInput);
+}
+
+static void add_coin(const CAmount& nValue, int nAge = 6*24, bool fIsFromMe = false, int nInput=0)
+{
+    balance += nValue;
+    static int nextLockTime = 0;
+    CMutableTransaction tx;
+    tx.nLockTime = nextLockTime++;        // so all transactions get different hashes
+    tx.vout.resize(nInput + 1);
+    tx.vout[nInput].nValue = nValue;
+    if (fIsFromMe) {
+        // IsFromMe() returns (GetDebit() > 0), and GetDebit() is 0 if vin.empty(),
+        // so stop vin being empty, and cache a non-zero Debit to fake out IsFromMe()
+        tx.vin.resize(1);
+    }
+    std::unique_ptr<CWalletTx> wtx(new CWalletTx(&testWallet, MakeTransactionRef(std::move(tx))));
+    if (fIsFromMe)
+    {
+        wtx->fDebitCached = true;
+        wtx->nDebitCached = 1;
+    }
+    COutput output(wtx.get(), nInput, nAge, true /* spendable */, true /* solvable */, true /* safe */);
+    vCoins.push_back(output);
+    testWallet.AddToWallet(*wtx.get());
+    wtxn.emplace_back(std::move(wtx));
+}
+
+static void empty_wallet(void)
+{
+    vCoins.clear();
+    wtxn.clear();
+    balance = 0;
+}
+
+static bool equal_sets(CoinSet a, CoinSet b)
+{
+    std::pair<CoinSet::iterator, CoinSet::iterator> ret = mismatch(a.begin(), a.end(), b.begin());
+    return ret.first == a.end() && ret.second == b.end();
+}
+
+static CAmount make_hard_case(int utxos, std::vector<CInputCoin>& utxo_pool)
+{
+    utxo_pool.clear();
+    CAmount target = 0;
+    for (int i = 0; i < utxos; ++i) {
+        target += (CAmount)1 << (utxos+i);
+        add_coin((CAmount)1 << (utxos+i), 2*i, utxo_pool);
+        add_coin(((CAmount)1 << (utxos+i)) + ((CAmount)1 << (utxos-1-i)), 2*i + 1, utxo_pool);
+    }
+    return target;
+}
+
+// Branch and bound coin selection tests
+BOOST_AUTO_TEST_CASE(bnb_search_test)
+{
+
+    LOCK(testWallet.cs_wallet);
+
+    // Setup
+    std::vector<CInputCoin> utxo_pool;
+    CoinSet selection;
+    CoinSet actual_selection;
+    CAmount value_ret = 0;
+    CAmount not_input_fees = 0;
+
+    /////////////////////////
+    // Known Outcome tests //
+    /////////////////////////
+    BOOST_TEST_MESSAGE("Testing known outcomes");
+
+    // Empty utxo pool
+    BOOST_CHECK(!SelectCoinsBnB(utxo_pool, 1 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
+    selection.clear();
+
+    // Add utxos
+    add_coin(1 * CENT, 1, utxo_pool);
+    add_coin(2 * CENT, 2, utxo_pool);
+    add_coin(3 * CENT, 3, utxo_pool);
+    add_coin(4 * CENT, 4, utxo_pool);
+
+    // Select 1 Cent
+    add_coin(1 * CENT, 1, actual_selection);
+    BOOST_CHECK(SelectCoinsBnB(utxo_pool, 1 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
+    BOOST_CHECK(equal_sets(selection, actual_selection));
+    actual_selection.clear();
+    selection.clear();
+
+    // Select 2 Cent
+    add_coin(2 * CENT, 2, actual_selection);
+    BOOST_CHECK(SelectCoinsBnB(utxo_pool, 2 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
+    BOOST_CHECK(equal_sets(selection, actual_selection));
+    actual_selection.clear();
+    selection.clear();
+
+    // Select 5 Cent
+    add_coin(3 * CENT, 3, actual_selection);
+    add_coin(2 * CENT, 2, actual_selection);
+    BOOST_CHECK(SelectCoinsBnB(utxo_pool, 5 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
+    BOOST_CHECK(equal_sets(selection, actual_selection));
+    actual_selection.clear();
+    selection.clear();
+
+    // Select 11 Cent, not possible
+    BOOST_CHECK(!SelectCoinsBnB(utxo_pool, 11 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
+    actual_selection.clear();
+    selection.clear();
+
+    // Select 10 Cent
+    add_coin(5 * CENT, 5, utxo_pool);
+    add_coin(4 * CENT, 4, actual_selection);
+    add_coin(3 * CENT, 3, actual_selection);
+    add_coin(2 * CENT, 2, actual_selection);
+    add_coin(1 * CENT, 1, actual_selection);
+    BOOST_CHECK(SelectCoinsBnB(utxo_pool, 10 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
+    BOOST_CHECK(equal_sets(selection, actual_selection));
+    actual_selection.clear();
+    selection.clear();
+
+    // Negative effective value
+    // Select 10 Cent but have 1 Cent not be possible because too small
+    add_coin(5 * CENT, 5, actual_selection);
+    add_coin(3 * CENT, 3, actual_selection);
+    add_coin(2 * CENT, 2, actual_selection);
+    BOOST_CHECK(SelectCoinsBnB(utxo_pool, 10 * CENT, 5000, selection, value_ret, not_input_fees));
+
+    // Select 0.25 Cent, not possible
+    BOOST_CHECK(!SelectCoinsBnB(utxo_pool, 0.25 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
+    actual_selection.clear();
+    selection.clear();
+
+    // Iteration exhaustion test
+    CAmount target = make_hard_case(17, utxo_pool);
+    BOOST_CHECK(!SelectCoinsBnB(utxo_pool, target, 0, selection, value_ret, not_input_fees)); // Should exhaust
+    target = make_hard_case(14, utxo_pool);
+    BOOST_CHECK(SelectCoinsBnB(utxo_pool, target, 0, selection, value_ret, not_input_fees)); // Should not exhaust
+
+    // Test same value early bailout optimization
+    add_coin(7 * CENT, 7, actual_selection);
+    add_coin(7 * CENT, 7, actual_selection);
+    add_coin(7 * CENT, 7, actual_selection);
+    add_coin(7 * CENT, 7, actual_selection);
+    add_coin(2 * CENT, 7, actual_selection);
+    add_coin(7 * CENT, 7, utxo_pool);
+    add_coin(7 * CENT, 7, utxo_pool);
+    add_coin(7 * CENT, 7, utxo_pool);
+    add_coin(7 * CENT, 7, utxo_pool);
+    add_coin(2 * CENT, 7, utxo_pool);
+    for (int i = 0; i < 50000; ++i) {
+        add_coin(5 * CENT, 7, utxo_pool);
+    }
+    BOOST_CHECK(SelectCoinsBnB(utxo_pool, 30 * CENT, 5000, selection, value_ret, not_input_fees));
+
+    ////////////////////
+    // Behavior tests //
+    ////////////////////
+    // Select 1 Cent with pool of only greater than 5 Cent
+    utxo_pool.clear();
+    for (int i = 5; i <= 20; ++i) {
+        add_coin(i * CENT, i, utxo_pool);
+    }
+    // Run 100 times, to make sure it is never finding a solution
+    for (int i = 0; i < 100; ++i) {
+        BOOST_CHECK(!SelectCoinsBnB(utxo_pool, 1 * CENT, 2 * CENT, selection, value_ret, not_input_fees));
+    }
+
+    // Make sure that effective value is working in SelectCoinsMinConf when BnB is used
+    CoinSelectionParams coin_selection_params_bnb(true, 0, 0, CFeeRate(3000), 0);
+    CoinSet setCoinsRet;
+    CAmount nValueRet;
+    bool bnb_used;
+    empty_wallet();
+    add_coin(1);
+    vCoins.at(0).nInputBytes = 40; // Make sure that it has a negative effective value. The next check should assert if this somehow got through. Otherwise it will fail
+    BOOST_CHECK(!testWallet.SelectCoinsMinConf( 1 * CENT, filter_standard, vCoins, setCoinsRet, nValueRet, coin_selection_params_bnb, bnb_used));
+
+    // Make sure that we aren't using BnB when there are preset inputs
+    empty_wallet();
+    add_coin(5 * CENT);
+    add_coin(3 * CENT);
+    add_coin(2 * CENT);
+    CCoinControl coin_control;
+    coin_control.fAllowOtherInputs = true;
+    coin_control.Select(COutPoint(vCoins.at(0).tx->GetHash(), vCoins.at(0).i));
+    BOOST_CHECK(testWallet.SelectCoins(vCoins, 10 * CENT, setCoinsRet, nValueRet, coin_control, coin_selection_params_bnb, bnb_used));
+    BOOST_CHECK(!bnb_used);
+    BOOST_CHECK(!coin_selection_params_bnb.use_bnb);
+}
+
+BOOST_AUTO_TEST_CASE(knapsack_solver_test)
+{
+    CoinSet setCoinsRet, setCoinsRet2;
+    CAmount nValueRet;
+    bool bnb_used;
+
+    LOCK(testWallet.cs_wallet);
+
+    // test multiple times to allow for differences in the shuffle order
+    for (int i = 0; i < RUN_TESTS; i++)
+    {
+        empty_wallet();
+
+        // with an empty wallet we can't even pay one cent
+        BOOST_CHECK(!testWallet.SelectCoinsMinConf( 1 * CENT, filter_standard, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+
+        add_coin(1*CENT, 4);        // add a new 1 cent coin
+
+        // with a new 1 cent coin, we still can't find a mature 1 cent
+        BOOST_CHECK(!testWallet.SelectCoinsMinConf( 1 * CENT, filter_standard, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+
+        // but we can find a new 1 cent
+        BOOST_CHECK( testWallet.SelectCoinsMinConf( 1 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK_EQUAL(nValueRet, 1 * CENT);
+
+        add_coin(2*CENT);           // add a mature 2 cent coin
+
+        // we can't make 3 cents of mature coins
+        BOOST_CHECK(!testWallet.SelectCoinsMinConf( 3 * CENT, filter_standard, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+
+        // we can make 3 cents of new coins
+        BOOST_CHECK( testWallet.SelectCoinsMinConf( 3 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK_EQUAL(nValueRet, 3 * CENT);
+
+        add_coin(5*CENT);           // add a mature 5 cent coin,
+        add_coin(10*CENT, 3, true); // a new 10 cent coin sent from one of our own addresses
+        add_coin(20*CENT);          // and a mature 20 cent coin
+
+        // now we have new: 1+10=11 (of which 10 was self-sent), and mature: 2+5+20=27.  total = 38
+
+        // we can't make 38 cents only if we disallow new coins:
+        BOOST_CHECK(!testWallet.SelectCoinsMinConf(38 * CENT, filter_standard, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        // we can't even make 37 cents if we don't allow new coins even if they're from us
+        BOOST_CHECK(!testWallet.SelectCoinsMinConf(38 * CENT, filter_standard_extra, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        // but we can make 37 cents if we accept new coins from ourself
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(37 * CENT, filter_standard, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK_EQUAL(nValueRet, 37 * CENT);
+        // and we can make 38 cents if we accept all new coins
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(38 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK_EQUAL(nValueRet, 38 * CENT);
+
+        // try making 34 cents from 1,2,5,10,20 - we can't do it exactly
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(34 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK_EQUAL(nValueRet, 35 * CENT);       // but 35 cents is closest
+        BOOST_CHECK_EQUAL(setCoinsRet.size(), 3U);     // the best should be 20+10+5.  it's incredibly unlikely the 1 or 2 got included (but possible)
+
+        // when we try making 7 cents, the smaller coins (1,2,5) are enough.  We should see just 2+5
+        BOOST_CHECK( testWallet.SelectCoinsMinConf( 7 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK_EQUAL(nValueRet, 7 * CENT);
+        BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
+
+        // when we try making 8 cents, the smaller coins (1,2,5) are exactly enough.
+        BOOST_CHECK( testWallet.SelectCoinsMinConf( 8 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK(nValueRet == 8 * CENT);
+        BOOST_CHECK_EQUAL(setCoinsRet.size(), 3U);
+
+        // when we try making 9 cents, no subset of smaller coins is enough, and we get the next bigger coin (10)
+        BOOST_CHECK( testWallet.SelectCoinsMinConf( 9 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK_EQUAL(nValueRet, 10 * CENT);
+        BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
+
+        // now clear out the wallet and start again to test choosing between subsets of smaller coins and the next biggest coin
+        empty_wallet();
+
+        add_coin( 6*CENT);
+        add_coin( 7*CENT);
+        add_coin( 8*CENT);
+        add_coin(20*CENT);
+        add_coin(30*CENT); // now we have 6+7+8+20+30 = 71 cents total
+
+        // check that we have 71 and not 72
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(71 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK(!testWallet.SelectCoinsMinConf(72 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+
+        // now try making 16 cents.  the best smaller coins can do is 6+7+8 = 21; not as good at the next biggest coin, 20
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(16 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK_EQUAL(nValueRet, 20 * CENT); // we should get 20 in one coin
+        BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
+
+        add_coin( 5*CENT); // now we have 5+6+7+8+20+30 = 75 cents total
+
+        // now if we try making 16 cents again, the smaller coins can make 5+6+7 = 18 cents, better than the next biggest coin, 20
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(16 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK_EQUAL(nValueRet, 18 * CENT); // we should get 18 in 3 coins
+        BOOST_CHECK_EQUAL(setCoinsRet.size(), 3U);
+
+        add_coin( 18*CENT); // now we have 5+6+7+8+18+20+30
+
+        // and now if we try making 16 cents again, the smaller coins can make 5+6+7 = 18 cents, the same as the next biggest coin, 18
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(16 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK_EQUAL(nValueRet, 18 * CENT);  // we should get 18 in 1 coin
+        BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U); // because in the event of a tie, the biggest coin wins
+
+        // now try making 11 cents.  we should get 5+6
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(11 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK_EQUAL(nValueRet, 11 * CENT);
+        BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
+
+        // check that the smallest bigger coin is used
+        add_coin( 1*COIN);
+        add_coin( 2*COIN);
+        add_coin( 3*COIN);
+        add_coin( 4*COIN); // now we have 5+6+7+8+18+20+30+100+200+300+400 = 1094 cents
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(95 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK_EQUAL(nValueRet, 1 * COIN);  // we should get 1 BTC in 1 coin
+        BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
+
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(195 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK_EQUAL(nValueRet, 2 * COIN);  // we should get 2 BTC in 1 coin
+        BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
+
+        // empty the wallet and start again, now with fractions of a cent, to test small change avoidance
+
+        empty_wallet();
+        add_coin(MIN_CHANGE * 1 / 10);
+        add_coin(MIN_CHANGE * 2 / 10);
+        add_coin(MIN_CHANGE * 3 / 10);
+        add_coin(MIN_CHANGE * 4 / 10);
+        add_coin(MIN_CHANGE * 5 / 10);
+
+        // try making 1 * MIN_CHANGE from the 1.5 * MIN_CHANGE
+        // we'll get change smaller than MIN_CHANGE whatever happens, so can expect MIN_CHANGE exactly
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(MIN_CHANGE, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK_EQUAL(nValueRet, MIN_CHANGE);
+
+        // but if we add a bigger coin, small change is avoided
+        add_coin(1111*MIN_CHANGE);
+
+        // try making 1 from 0.1 + 0.2 + 0.3 + 0.4 + 0.5 + 1111 = 1112.5
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(1 * MIN_CHANGE, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK_EQUAL(nValueRet, 1 * MIN_CHANGE); // we should get the exact amount
+
+        // if we add more small coins:
+        add_coin(MIN_CHANGE * 6 / 10);
+        add_coin(MIN_CHANGE * 7 / 10);
+
+        // and try again to make 1.0 * MIN_CHANGE
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(1 * MIN_CHANGE, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK_EQUAL(nValueRet, 1 * MIN_CHANGE); // we should get the exact amount
+
+        // run the 'mtgox' test (see http://blockexplorer.com/tx/29a3efd3ef04f9153d47a990bd7b048a4b2d213daaa5fb8ed670fb85f13bdbcf)
+        // they tried to consolidate 10 50k coins into one 500k coin, and ended up with 50k in change
+        empty_wallet();
+        for (int j = 0; j < 20; j++)
+            add_coin(50000 * COIN);
+
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(500000 * COIN, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK_EQUAL(nValueRet, 500000 * COIN); // we should get the exact amount
+        BOOST_CHECK_EQUAL(setCoinsRet.size(), 10U); // in ten coins
+
+        // if there's not enough in the smaller coins to make at least 1 * MIN_CHANGE change (0.5+0.6+0.7 < 1.0+1.0),
+        // we need to try finding an exact subset anyway
+
+        // sometimes it will fail, and so we use the next biggest coin:
+        empty_wallet();
+        add_coin(MIN_CHANGE * 5 / 10);
+        add_coin(MIN_CHANGE * 6 / 10);
+        add_coin(MIN_CHANGE * 7 / 10);
+        add_coin(1111 * MIN_CHANGE);
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(1 * MIN_CHANGE, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK_EQUAL(nValueRet, 1111 * MIN_CHANGE); // we get the bigger coin
+        BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
+
+        // but sometimes it's possible, and we use an exact subset (0.4 + 0.6 = 1.0)
+        empty_wallet();
+        add_coin(MIN_CHANGE * 4 / 10);
+        add_coin(MIN_CHANGE * 6 / 10);
+        add_coin(MIN_CHANGE * 8 / 10);
+        add_coin(1111 * MIN_CHANGE);
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(MIN_CHANGE, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK_EQUAL(nValueRet, MIN_CHANGE);   // we should get the exact amount
+        BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U); // in two coins 0.4+0.6
+
+        // test avoiding small change
+        empty_wallet();
+        add_coin(MIN_CHANGE * 5 / 100);
+        add_coin(MIN_CHANGE * 1);
+        add_coin(MIN_CHANGE * 100);
+
+        // trying to make 100.01 from these three coins
+        BOOST_CHECK(testWallet.SelectCoinsMinConf(MIN_CHANGE * 10001 / 100, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK_EQUAL(nValueRet, MIN_CHANGE * 10105 / 100); // we should get all coins
+        BOOST_CHECK_EQUAL(setCoinsRet.size(), 3U);
+
+        // but if we try to make 99.9, we should take the bigger of the two small coins to avoid small change
+        BOOST_CHECK(testWallet.SelectCoinsMinConf(MIN_CHANGE * 9990 / 100, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK_EQUAL(nValueRet, 101 * MIN_CHANGE);
+        BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
+
+        // test with many inputs
+        for (CAmount amt=1500; amt < COIN; amt*=10) {
+             empty_wallet();
+             // Create 676 inputs (=  (old MAX_STANDARD_TX_SIZE == 100000)  / 148 bytes per input)
+             for (uint16_t j = 0; j < 676; j++)
+                 add_coin(amt);
+             BOOST_CHECK(testWallet.SelectCoinsMinConf(2000, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+             if (amt - 2000 < MIN_CHANGE) {
+                 // needs more than one input:
+                 uint16_t returnSize = std::ceil((2000.0 + MIN_CHANGE)/amt);
+                 CAmount returnValue = amt * returnSize;
+                 BOOST_CHECK_EQUAL(nValueRet, returnValue);
+                 BOOST_CHECK_EQUAL(setCoinsRet.size(), returnSize);
+             } else {
+                 // one input is sufficient:
+                 BOOST_CHECK_EQUAL(nValueRet, amt);
+                 BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
+             }
+        }
+
+        // test randomness
+        {
+            empty_wallet();
+            for (int i2 = 0; i2 < 100; i2++)
+                add_coin(COIN);
+
+            // picking 50 from 100 coins doesn't depend on the shuffle,
+            // but does depend on randomness in the stochastic approximation code
+            BOOST_CHECK(testWallet.SelectCoinsMinConf(50 * COIN, filter_standard, vCoins, setCoinsRet , nValueRet, coin_selection_params, bnb_used));
+            BOOST_CHECK(testWallet.SelectCoinsMinConf(50 * COIN, filter_standard, vCoins, setCoinsRet2, nValueRet, coin_selection_params, bnb_used));
+            BOOST_CHECK(!equal_sets(setCoinsRet, setCoinsRet2));
+
+            int fails = 0;
+            for (int j = 0; j < RANDOM_REPEATS; j++)
+            {
+                // selecting 1 from 100 identical coins depends on the shuffle; this test will fail 1% of the time
+                // run the test RANDOM_REPEATS times and only complain if all of them fail
+                BOOST_CHECK(testWallet.SelectCoinsMinConf(COIN, filter_standard, vCoins, setCoinsRet , nValueRet, coin_selection_params, bnb_used));
+                BOOST_CHECK(testWallet.SelectCoinsMinConf(COIN, filter_standard, vCoins, setCoinsRet2, nValueRet, coin_selection_params, bnb_used));
+                if (equal_sets(setCoinsRet, setCoinsRet2))
+                    fails++;
+            }
+            BOOST_CHECK_NE(fails, RANDOM_REPEATS);
+
+            // add 75 cents in small change.  not enough to make 90 cents,
+            // then try making 90 cents.  there are multiple competing "smallest bigger" coins,
+            // one of which should be picked at random
+            add_coin(5 * CENT);
+            add_coin(10 * CENT);
+            add_coin(15 * CENT);
+            add_coin(20 * CENT);
+            add_coin(25 * CENT);
+
+            fails = 0;
+            for (int j = 0; j < RANDOM_REPEATS; j++)
+            {
+                // selecting 1 from 100 identical coins depends on the shuffle; this test will fail 1% of the time
+                // run the test RANDOM_REPEATS times and only complain if all of them fail
+                BOOST_CHECK(testWallet.SelectCoinsMinConf(90*CENT, filter_standard, vCoins, setCoinsRet , nValueRet, coin_selection_params, bnb_used));
+                BOOST_CHECK(testWallet.SelectCoinsMinConf(90*CENT, filter_standard, vCoins, setCoinsRet2, nValueRet, coin_selection_params, bnb_used));
+                if (equal_sets(setCoinsRet, setCoinsRet2))
+                    fails++;
+            }
+            BOOST_CHECK_NE(fails, RANDOM_REPEATS);
+        }
+    }
+    empty_wallet();
+}
+
+BOOST_AUTO_TEST_CASE(ApproximateBestSubset)
+{
+    CoinSet setCoinsRet;
+    CAmount nValueRet;
+    bool bnb_used;
+
+    LOCK(testWallet.cs_wallet);
+
+    empty_wallet();
+
+    // Test vValue sort order
+    for (int i = 0; i < 1000; i++)
+        add_coin(1000 * COIN);
+    add_coin(3 * COIN);
+
+    BOOST_CHECK(testWallet.SelectCoinsMinConf(1003 * COIN, filter_standard, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+    BOOST_CHECK_EQUAL(nValueRet, 1003 * COIN);
+    BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
+
+    empty_wallet();
+}
+
+// Tests that with the ideal conditions, the coin selector will always be able to find a solution that can pay the target value
+BOOST_AUTO_TEST_CASE(SelectCoins_test)
+{
+    // Random generator stuff
+    std::default_random_engine generator;
+    std::exponential_distribution<double> distribution (100);
+    FastRandomContext rand;
+
+    // Output stuff
+    CAmount out_value = 0;
+    CoinSet out_set;
+    CAmount target = 0;
+    bool bnb_used;
+
+    // Run this test 100 times
+    for (int i = 0; i < 100; ++i)
+    {
+        // Reset
+        out_value = 0;
+        target = 0;
+        out_set.clear();
+        empty_wallet();
+
+        // Make a wallet with 1000 exponentially distributed random inputs
+        for (int j = 0; j < 1000; ++j)
+        {
+            add_coin((CAmount)(distribution(generator)*10000000));
+        }
+
+        // Generate a random fee rate in the range of 100 - 400
+        CFeeRate rate(rand.randrange(300) + 100);
+
+        // Generate a random target value between 1000 and wallet balance
+        target = rand.randrange(balance - 1000) + 1000;
+
+        // Perform selection
+        CoinSelectionParams coin_selection_params_knapsack(false, 34, 148, CFeeRate(0), 0);
+        CoinSelectionParams coin_selection_params_bnb(true, 34, 148, CFeeRate(0), 0);
+        BOOST_CHECK(testWallet.SelectCoinsMinConf(target, filter_standard, vCoins, out_set, out_value, coin_selection_params_bnb, bnb_used) ||
+                    testWallet.SelectCoinsMinConf(target, filter_standard, vCoins, out_set, out_value, coin_selection_params_knapsack, bnb_used));
+        BOOST_CHECK_GE(out_value, target);
+    }
+}
+
+BOOST_AUTO_TEST_SUITE_END()
diff --git a/src/wallet/test/crypto_tests.cpp b/src/wallet/test/crypto_tests.cpp
index 89b2c4e796..d8c0cdf0f9 100644
--- a/src/wallet/test/crypto_tests.cpp
+++ b/src/wallet/test/crypto_tests.cpp
@@ -10,7 +10,7 @@
 
 #include <boost/test/unit_test.hpp>
 
-BOOST_FIXTURE_TEST_SUITE(wallet_crypto, BasicTestingSetup)
+BOOST_FIXTURE_TEST_SUITE(crypto_tests, BasicTestingSetup)
 
 class TestCrypter
 {
diff --git a/src/wallet/test/wallet_test_fixture.cpp b/src/wallet/test/wallet_test_fixture.cpp
index 77ccd0b8d8..5c550742c8 100644
--- a/src/wallet/test/wallet_test_fixture.cpp
+++ b/src/wallet/test/wallet_test_fixture.cpp
@@ -12,8 +12,6 @@ WalletTestingSetup::WalletTestingSetup(const std::string& chainName):
     TestingSetup(chainName), m_wallet("mock", CWalletDBWrapper::CreateMock())
 {
     bool fFirstRun;
-    g_address_type = OUTPUT_TYPE_DEFAULT;
-    g_change_type = OUTPUT_TYPE_DEFAULT;
     m_wallet.LoadWallet(fFirstRun);
     RegisterValidationInterface(&m_wallet);
 
diff --git a/src/wallet/test/wallet_test_fixture.h b/src/wallet/test/wallet_test_fixture.h
index 663836a955..b328b3543b 100644
--- a/src/wallet/test/wallet_test_fixture.h
+++ b/src/wallet/test/wallet_test_fixture.h
@@ -2,13 +2,15 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#ifndef BITCOIN_WALLET_TEST_FIXTURE_H
-#define BITCOIN_WALLET_TEST_FIXTURE_H
+#ifndef BITCOIN_WALLET_TEST_WALLET_TEST_FIXTURE_H
+#define BITCOIN_WALLET_TEST_WALLET_TEST_FIXTURE_H
 
 #include <test/test_bitcoin.h>
 
 #include <wallet/wallet.h>
 
+#include <memory>
+
 /** Testing setup and teardown for wallet.
  */
 struct WalletTestingSetup: public TestingSetup {
@@ -18,5 +20,4 @@ struct WalletTestingSetup: public TestingSetup {
     CWallet m_wallet;
 };
 
-#endif
-
+#endif // BITCOIN_WALLET_TEST_WALLET_TEST_FIXTURE_H
diff --git a/src/wallet/test/wallet_tests.cpp b/src/wallet/test/wallet_tests.cpp
index 41348b50a4..e93e0f1966 100644
--- a/src/wallet/test/wallet_tests.cpp
+++ b/src/wallet/test/wallet_tests.cpp
@@ -4,6 +4,7 @@
 
 #include <wallet/wallet.h>
 
+#include <memory>
 #include <set>
 #include <stdint.h>
 #include <utility>
@@ -23,345 +24,8 @@ extern UniValue importmulti(const JSONRPCRequest& request);
 extern UniValue dumpwallet(const JSONRPCRequest& request);
 extern UniValue importwallet(const JSONRPCRequest& request);
 
-// how many times to run all the tests to have a chance to catch errors that only show up with particular random shuffles
-#define RUN_TESTS 100
-
-// some tests fail 1% of the time due to bad luck.
-// we repeat those tests this many times and only complain if all iterations of the test fail
-#define RANDOM_REPEATS 5
-
-std::vector<std::unique_ptr<CWalletTx>> wtxn;
-
-typedef std::set<CInputCoin> CoinSet;
-
 BOOST_FIXTURE_TEST_SUITE(wallet_tests, WalletTestingSetup)
 
-static const CWallet testWallet("dummy", CWalletDBWrapper::CreateDummy());
-static std::vector<COutput> vCoins;
-
-static void add_coin(const CAmount& nValue, int nAge = 6*24, bool fIsFromMe = false, int nInput=0)
-{
-    static int nextLockTime = 0;
-    CMutableTransaction tx;
-    tx.nLockTime = nextLockTime++;        // so all transactions get different hashes
-    tx.vout.resize(nInput+1);
-    tx.vout[nInput].nValue = nValue;
-    if (fIsFromMe) {
-        // IsFromMe() returns (GetDebit() > 0), and GetDebit() is 0 if vin.empty(),
-        // so stop vin being empty, and cache a non-zero Debit to fake out IsFromMe()
-        tx.vin.resize(1);
-    }
-    std::unique_ptr<CWalletTx> wtx(new CWalletTx(&testWallet, MakeTransactionRef(std::move(tx))));
-    if (fIsFromMe)
-    {
-        wtx->fDebitCached = true;
-        wtx->nDebitCached = 1;
-    }
-    COutput output(wtx.get(), nInput, nAge, true /* spendable */, true /* solvable */, true /* safe */);
-    vCoins.push_back(output);
-    wtxn.emplace_back(std::move(wtx));
-}
-
-static void empty_wallet(void)
-{
-    vCoins.clear();
-    wtxn.clear();
-}
-
-static bool equal_sets(CoinSet a, CoinSet b)
-{
-    std::pair<CoinSet::iterator, CoinSet::iterator> ret = mismatch(a.begin(), a.end(), b.begin());
-    return ret.first == a.end() && ret.second == b.end();
-}
-
-BOOST_AUTO_TEST_CASE(coin_selection_tests)
-{
-    CoinSet setCoinsRet, setCoinsRet2;
-    CAmount nValueRet;
-
-    LOCK(testWallet.cs_wallet);
-
-    // test multiple times to allow for differences in the shuffle order
-    for (int i = 0; i < RUN_TESTS; i++)
-    {
-        empty_wallet();
-
-        // with an empty wallet we can't even pay one cent
-        BOOST_CHECK(!testWallet.SelectCoinsMinConf( 1 * CENT, 1, 6, 0, vCoins, setCoinsRet, nValueRet));
-
-        add_coin(1*CENT, 4);        // add a new 1 cent coin
-
-        // with a new 1 cent coin, we still can't find a mature 1 cent
-        BOOST_CHECK(!testWallet.SelectCoinsMinConf( 1 * CENT, 1, 6, 0, vCoins, setCoinsRet, nValueRet));
-
-        // but we can find a new 1 cent
-        BOOST_CHECK( testWallet.SelectCoinsMinConf( 1 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK_EQUAL(nValueRet, 1 * CENT);
-
-        add_coin(2*CENT);           // add a mature 2 cent coin
-
-        // we can't make 3 cents of mature coins
-        BOOST_CHECK(!testWallet.SelectCoinsMinConf( 3 * CENT, 1, 6, 0, vCoins, setCoinsRet, nValueRet));
-
-        // we can make 3 cents of new coins
-        BOOST_CHECK( testWallet.SelectCoinsMinConf( 3 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK_EQUAL(nValueRet, 3 * CENT);
-
-        add_coin(5*CENT);           // add a mature 5 cent coin,
-        add_coin(10*CENT, 3, true); // a new 10 cent coin sent from one of our own addresses
-        add_coin(20*CENT);          // and a mature 20 cent coin
-
-        // now we have new: 1+10=11 (of which 10 was self-sent), and mature: 2+5+20=27.  total = 38
-
-        // we can't make 38 cents only if we disallow new coins:
-        BOOST_CHECK(!testWallet.SelectCoinsMinConf(38 * CENT, 1, 6, 0, vCoins, setCoinsRet, nValueRet));
-        // we can't even make 37 cents if we don't allow new coins even if they're from us
-        BOOST_CHECK(!testWallet.SelectCoinsMinConf(38 * CENT, 6, 6, 0, vCoins, setCoinsRet, nValueRet));
-        // but we can make 37 cents if we accept new coins from ourself
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(37 * CENT, 1, 6, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK_EQUAL(nValueRet, 37 * CENT);
-        // and we can make 38 cents if we accept all new coins
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(38 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK_EQUAL(nValueRet, 38 * CENT);
-
-        // try making 34 cents from 1,2,5,10,20 - we can't do it exactly
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(34 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK_EQUAL(nValueRet, 35 * CENT);       // but 35 cents is closest
-        BOOST_CHECK_EQUAL(setCoinsRet.size(), 3U);     // the best should be 20+10+5.  it's incredibly unlikely the 1 or 2 got included (but possible)
-
-        // when we try making 7 cents, the smaller coins (1,2,5) are enough.  We should see just 2+5
-        BOOST_CHECK( testWallet.SelectCoinsMinConf( 7 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK_EQUAL(nValueRet, 7 * CENT);
-        BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
-
-        // when we try making 8 cents, the smaller coins (1,2,5) are exactly enough.
-        BOOST_CHECK( testWallet.SelectCoinsMinConf( 8 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK(nValueRet == 8 * CENT);
-        BOOST_CHECK_EQUAL(setCoinsRet.size(), 3U);
-
-        // when we try making 9 cents, no subset of smaller coins is enough, and we get the next bigger coin (10)
-        BOOST_CHECK( testWallet.SelectCoinsMinConf( 9 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK_EQUAL(nValueRet, 10 * CENT);
-        BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
-
-        // now clear out the wallet and start again to test choosing between subsets of smaller coins and the next biggest coin
-        empty_wallet();
-
-        add_coin( 6*CENT);
-        add_coin( 7*CENT);
-        add_coin( 8*CENT);
-        add_coin(20*CENT);
-        add_coin(30*CENT); // now we have 6+7+8+20+30 = 71 cents total
-
-        // check that we have 71 and not 72
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(71 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK(!testWallet.SelectCoinsMinConf(72 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-
-        // now try making 16 cents.  the best smaller coins can do is 6+7+8 = 21; not as good at the next biggest coin, 20
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(16 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK_EQUAL(nValueRet, 20 * CENT); // we should get 20 in one coin
-        BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
-
-        add_coin( 5*CENT); // now we have 5+6+7+8+20+30 = 75 cents total
-
-        // now if we try making 16 cents again, the smaller coins can make 5+6+7 = 18 cents, better than the next biggest coin, 20
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(16 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK_EQUAL(nValueRet, 18 * CENT); // we should get 18 in 3 coins
-        BOOST_CHECK_EQUAL(setCoinsRet.size(), 3U);
-
-        add_coin( 18*CENT); // now we have 5+6+7+8+18+20+30
-
-        // and now if we try making 16 cents again, the smaller coins can make 5+6+7 = 18 cents, the same as the next biggest coin, 18
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(16 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK_EQUAL(nValueRet, 18 * CENT);  // we should get 18 in 1 coin
-        BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U); // because in the event of a tie, the biggest coin wins
-
-        // now try making 11 cents.  we should get 5+6
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(11 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK_EQUAL(nValueRet, 11 * CENT);
-        BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
-
-        // check that the smallest bigger coin is used
-        add_coin( 1*COIN);
-        add_coin( 2*COIN);
-        add_coin( 3*COIN);
-        add_coin( 4*COIN); // now we have 5+6+7+8+18+20+30+100+200+300+400 = 1094 cents
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(95 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK_EQUAL(nValueRet, 1 * COIN);  // we should get 1 BTC in 1 coin
-        BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
-
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(195 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK_EQUAL(nValueRet, 2 * COIN);  // we should get 2 BTC in 1 coin
-        BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
-
-        // empty the wallet and start again, now with fractions of a cent, to test small change avoidance
-
-        empty_wallet();
-        add_coin(MIN_CHANGE * 1 / 10);
-        add_coin(MIN_CHANGE * 2 / 10);
-        add_coin(MIN_CHANGE * 3 / 10);
-        add_coin(MIN_CHANGE * 4 / 10);
-        add_coin(MIN_CHANGE * 5 / 10);
-
-        // try making 1 * MIN_CHANGE from the 1.5 * MIN_CHANGE
-        // we'll get change smaller than MIN_CHANGE whatever happens, so can expect MIN_CHANGE exactly
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(MIN_CHANGE, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK_EQUAL(nValueRet, MIN_CHANGE);
-
-        // but if we add a bigger coin, small change is avoided
-        add_coin(1111*MIN_CHANGE);
-
-        // try making 1 from 0.1 + 0.2 + 0.3 + 0.4 + 0.5 + 1111 = 1112.5
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(1 * MIN_CHANGE, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK_EQUAL(nValueRet, 1 * MIN_CHANGE); // we should get the exact amount
-
-        // if we add more small coins:
-        add_coin(MIN_CHANGE * 6 / 10);
-        add_coin(MIN_CHANGE * 7 / 10);
-
-        // and try again to make 1.0 * MIN_CHANGE
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(1 * MIN_CHANGE, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK_EQUAL(nValueRet, 1 * MIN_CHANGE); // we should get the exact amount
-
-        // run the 'mtgox' test (see http://blockexplorer.com/tx/29a3efd3ef04f9153d47a990bd7b048a4b2d213daaa5fb8ed670fb85f13bdbcf)
-        // they tried to consolidate 10 50k coins into one 500k coin, and ended up with 50k in change
-        empty_wallet();
-        for (int j = 0; j < 20; j++)
-            add_coin(50000 * COIN);
-
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(500000 * COIN, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK_EQUAL(nValueRet, 500000 * COIN); // we should get the exact amount
-        BOOST_CHECK_EQUAL(setCoinsRet.size(), 10U); // in ten coins
-
-        // if there's not enough in the smaller coins to make at least 1 * MIN_CHANGE change (0.5+0.6+0.7 < 1.0+1.0),
-        // we need to try finding an exact subset anyway
-
-        // sometimes it will fail, and so we use the next biggest coin:
-        empty_wallet();
-        add_coin(MIN_CHANGE * 5 / 10);
-        add_coin(MIN_CHANGE * 6 / 10);
-        add_coin(MIN_CHANGE * 7 / 10);
-        add_coin(1111 * MIN_CHANGE);
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(1 * MIN_CHANGE, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK_EQUAL(nValueRet, 1111 * MIN_CHANGE); // we get the bigger coin
-        BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
-
-        // but sometimes it's possible, and we use an exact subset (0.4 + 0.6 = 1.0)
-        empty_wallet();
-        add_coin(MIN_CHANGE * 4 / 10);
-        add_coin(MIN_CHANGE * 6 / 10);
-        add_coin(MIN_CHANGE * 8 / 10);
-        add_coin(1111 * MIN_CHANGE);
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(MIN_CHANGE, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK_EQUAL(nValueRet, MIN_CHANGE);   // we should get the exact amount
-        BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U); // in two coins 0.4+0.6
-
-        // test avoiding small change
-        empty_wallet();
-        add_coin(MIN_CHANGE * 5 / 100);
-        add_coin(MIN_CHANGE * 1);
-        add_coin(MIN_CHANGE * 100);
-
-        // trying to make 100.01 from these three coins
-        BOOST_CHECK(testWallet.SelectCoinsMinConf(MIN_CHANGE * 10001 / 100, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK_EQUAL(nValueRet, MIN_CHANGE * 10105 / 100); // we should get all coins
-        BOOST_CHECK_EQUAL(setCoinsRet.size(), 3U);
-
-        // but if we try to make 99.9, we should take the bigger of the two small coins to avoid small change
-        BOOST_CHECK(testWallet.SelectCoinsMinConf(MIN_CHANGE * 9990 / 100, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK_EQUAL(nValueRet, 101 * MIN_CHANGE);
-        BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
-
-        // test with many inputs
-        for (CAmount amt=1500; amt < COIN; amt*=10) {
-             empty_wallet();
-             // Create 676 inputs (=  (old MAX_STANDARD_TX_SIZE == 100000)  / 148 bytes per input)
-             for (uint16_t j = 0; j < 676; j++)
-                 add_coin(amt);
-             BOOST_CHECK(testWallet.SelectCoinsMinConf(2000, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
-             if (amt - 2000 < MIN_CHANGE) {
-                 // needs more than one input:
-                 uint16_t returnSize = std::ceil((2000.0 + MIN_CHANGE)/amt);
-                 CAmount returnValue = amt * returnSize;
-                 BOOST_CHECK_EQUAL(nValueRet, returnValue);
-                 BOOST_CHECK_EQUAL(setCoinsRet.size(), returnSize);
-             } else {
-                 // one input is sufficient:
-                 BOOST_CHECK_EQUAL(nValueRet, amt);
-                 BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
-             }
-        }
-
-        // test randomness
-        {
-            empty_wallet();
-            for (int i2 = 0; i2 < 100; i2++)
-                add_coin(COIN);
-
-            // picking 50 from 100 coins doesn't depend on the shuffle,
-            // but does depend on randomness in the stochastic approximation code
-            BOOST_CHECK(testWallet.SelectCoinsMinConf(50 * COIN, 1, 6, 0, vCoins, setCoinsRet , nValueRet));
-            BOOST_CHECK(testWallet.SelectCoinsMinConf(50 * COIN, 1, 6, 0, vCoins, setCoinsRet2, nValueRet));
-            BOOST_CHECK(!equal_sets(setCoinsRet, setCoinsRet2));
-
-            int fails = 0;
-            for (int j = 0; j < RANDOM_REPEATS; j++)
-            {
-                // selecting 1 from 100 identical coins depends on the shuffle; this test will fail 1% of the time
-                // run the test RANDOM_REPEATS times and only complain if all of them fail
-                BOOST_CHECK(testWallet.SelectCoinsMinConf(COIN, 1, 6, 0, vCoins, setCoinsRet , nValueRet));
-                BOOST_CHECK(testWallet.SelectCoinsMinConf(COIN, 1, 6, 0, vCoins, setCoinsRet2, nValueRet));
-                if (equal_sets(setCoinsRet, setCoinsRet2))
-                    fails++;
-            }
-            BOOST_CHECK_NE(fails, RANDOM_REPEATS);
-
-            // add 75 cents in small change.  not enough to make 90 cents,
-            // then try making 90 cents.  there are multiple competing "smallest bigger" coins,
-            // one of which should be picked at random
-            add_coin(5 * CENT);
-            add_coin(10 * CENT);
-            add_coin(15 * CENT);
-            add_coin(20 * CENT);
-            add_coin(25 * CENT);
-
-            fails = 0;
-            for (int j = 0; j < RANDOM_REPEATS; j++)
-            {
-                // selecting 1 from 100 identical coins depends on the shuffle; this test will fail 1% of the time
-                // run the test RANDOM_REPEATS times and only complain if all of them fail
-                BOOST_CHECK(testWallet.SelectCoinsMinConf(90*CENT, 1, 6, 0, vCoins, setCoinsRet , nValueRet));
-                BOOST_CHECK(testWallet.SelectCoinsMinConf(90*CENT, 1, 6, 0, vCoins, setCoinsRet2, nValueRet));
-                if (equal_sets(setCoinsRet, setCoinsRet2))
-                    fails++;
-            }
-            BOOST_CHECK_NE(fails, RANDOM_REPEATS);
-        }
-    }
-    empty_wallet();
-}
-
-BOOST_AUTO_TEST_CASE(ApproximateBestSubset)
-{
-    CoinSet setCoinsRet;
-    CAmount nValueRet;
-
-    LOCK(testWallet.cs_wallet);
-
-    empty_wallet();
-
-    // Test vValue sort order
-    for (int i = 0; i < 1000; i++)
-        add_coin(1000 * COIN);
-    add_coin(3 * COIN);
-
-    BOOST_CHECK(testWallet.SelectCoinsMinConf(1003 * COIN, 1, 6, 0, vCoins, setCoinsRet, nValueRet));
-    BOOST_CHECK_EQUAL(nValueRet, 1003 * COIN);
-    BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
-
-    empty_wallet();
-}
-
 static void AddKey(CWallet& wallet, const CKey& key)
 {
     LOCK(wallet.cs_wallet);
@@ -451,9 +115,6 @@ BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
 // than or equal to key birthday.
 BOOST_FIXTURE_TEST_CASE(importwallet_rescan, TestChain100Setup)
 {
-    g_address_type = OUTPUT_TYPE_DEFAULT;
-    g_change_type = OUTPUT_TYPE_DEFAULT;
-
     // Create two blocks with same timestamp to verify that importwallet rescan
     // will pick up both blocks, not just the first.
     const int64_t BLOCK_TIME = chainActive.Tip()->GetBlockTimeMax() + 5;
@@ -553,7 +214,10 @@ static int64_t AddTx(CWallet& wallet, uint32_t lockTime, int64_t mockTime, int64
     if (block) {
         wtx.SetMerkleBranch(block, 0);
     }
-    wallet.AddToWallet(wtx);
+    {
+        LOCK(cs_main);
+        wallet.AddToWallet(wtx);
+    }
     LOCK(wallet.cs_wallet);
     return wallet.mapWallet.at(wtx.GetHash()).nTimeSmart;
 }
@@ -606,8 +270,6 @@ public:
     ListCoinsTestingSetup()
     {
         CreateAndProcessBlock({}, GetScriptForRawPubKey(coinbaseKey.GetPubKey()));
-        g_address_type = OUTPUT_TYPE_DEFAULT;
-        g_change_type = OUTPUT_TYPE_DEFAULT;
         wallet = MakeUnique<CWallet>("mock", CWalletDBWrapper::CreateMock());
         bool firstRun;
         wallet->LoadWallet(firstRun);
@@ -624,23 +286,23 @@ public:
 
     CWalletTx& AddTx(CRecipient recipient)
     {
-        CWalletTx wtx;
+        CTransactionRef tx;
         CReserveKey reservekey(wallet.get());
         CAmount fee;
         int changePos = -1;
         std::string error;
         CCoinControl dummy;
-        BOOST_CHECK(wallet->CreateTransaction({recipient}, wtx, reservekey, fee, changePos, error, dummy));
+        BOOST_CHECK(wallet->CreateTransaction({recipient}, tx, reservekey, fee, changePos, error, dummy));
         CValidationState state;
-        BOOST_CHECK(wallet->CommitTransaction(wtx, reservekey, nullptr, state));
+        BOOST_CHECK(wallet->CommitTransaction(tx, {}, {}, {}, reservekey, nullptr, state));
         CMutableTransaction blocktx;
         {
             LOCK(wallet->cs_wallet);
-            blocktx = CMutableTransaction(*wallet->mapWallet.at(wtx.GetHash()).tx);
+            blocktx = CMutableTransaction(*wallet->mapWallet.at(tx->GetHash()).tx);
         }
         CreateAndProcessBlock({CMutableTransaction(blocktx)}, GetScriptForRawPubKey(coinbaseKey.GetPubKey()));
         LOCK(wallet->cs_wallet);
-        auto it = wallet->mapWallet.find(wtx.GetHash());
+        auto it = wallet->mapWallet.find(tx->GetHash());
         BOOST_CHECK(it != wallet->mapWallet.end());
         it->second.SetMerkleBranch(chainActive.Tip(), 1);
         return it->second;
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 0c468878e1..8dac547abb 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -8,10 +8,10 @@
 #include <checkpoints.h>
 #include <chain.h>
 #include <wallet/coincontrol.h>
+#include <wallet/coinselection.h>
 #include <consensus/consensus.h>
 #include <consensus/validation.h>
 #include <fs.h>
-#include <wallet/init.h>
 #include <key.h>
 #include <key_io.h>
 #include <keystore.h>
@@ -41,8 +41,6 @@ CFeeRate payTxFee(DEFAULT_TRANSACTION_FEE);
 unsigned int nTxConfirmTarget = DEFAULT_TX_CONFIRM_TARGET;
 bool bSpendZeroConfChange = DEFAULT_SPEND_ZEROCONF_CHANGE;
 bool fWalletRbf = DEFAULT_WALLET_RBF;
-OutputType g_address_type = OUTPUT_TYPE_NONE;
-OutputType g_change_type = OUTPUT_TYPE_NONE;
 bool g_wallet_allow_fallback_fee = true; //<! will be defined via chainparams
 
 const uint32_t BIP32_HARDENED_KEY_LIMIT = 0x80000000;
@@ -68,15 +66,6 @@ const uint256 CMerkleTx::ABANDON_HASH(uint256S("00000000000000000000000000000000
  * @{
  */
 
-struct CompareValueOnly
-{
-    bool operator()(const CInputCoin& t1,
-                    const CInputCoin& t2) const
-    {
-        return t1.txout.nValue < t2.txout.nValue;
-    }
-};
-
 std::string COutput::ToString() const
 {
     return strprintf("COutput(%s, %d, %d) [%s]", tx->GetHash().ToString(), i, nDepth, FormatMoney(tx->tx->vout[i].nValue));
@@ -531,7 +520,7 @@ void CWallet::SyncMetaData(std::pair<TxSpends::iterator, TxSpends::iterator> ran
     int nMinOrderPos = std::numeric_limits<int>::max();
     const CWalletTx* copyFrom = nullptr;
     for (TxSpends::iterator it = range.first; it != range.second; ++it) {
-        const CWalletTx* wtx = &mapWallet[it->second];
+        const CWalletTx* wtx = &mapWallet.at(it->second);
         if (wtx->nOrderPos < nMinOrderPos) {
             nMinOrderPos = wtx->nOrderPos;;
             copyFrom = wtx;
@@ -544,7 +533,7 @@ void CWallet::SyncMetaData(std::pair<TxSpends::iterator, TxSpends::iterator> ran
     for (TxSpends::iterator it = range.first; it != range.second; ++it)
     {
         const uint256& hash = it->second;
-        CWalletTx* copyTo = &mapWallet[hash];
+        CWalletTx* copyTo = &mapWallet.at(hash);
         if (copyFrom == copyTo) continue;
         assert(copyFrom && "Oldest wallet transaction in range assumed to have been found.");
         if (!copyFrom->IsEquivalentTo(*copyTo)) continue;
@@ -737,11 +726,11 @@ DBErrors CWallet::ReorderTransactions()
             if (pwtx)
             {
                 if (!walletdb.WriteTx(*pwtx))
-                    return DB_LOAD_FAIL;
+                    return DBErrors::LOAD_FAIL;
             }
             else
                 if (!walletdb.WriteAccountingEntry(pacentry->nEntryNo, *pacentry))
-                    return DB_LOAD_FAIL;
+                    return DBErrors::LOAD_FAIL;
         }
         else
         {
@@ -761,16 +750,16 @@ DBErrors CWallet::ReorderTransactions()
             if (pwtx)
             {
                 if (!walletdb.WriteTx(*pwtx))
-                    return DB_LOAD_FAIL;
+                    return DBErrors::LOAD_FAIL;
             }
             else
                 if (!walletdb.WriteAccountingEntry(pacentry->nEntryNo, *pacentry))
-                    return DB_LOAD_FAIL;
+                    return DBErrors::LOAD_FAIL;
         }
     }
     walletdb.WriteOrderPosNext(nOrderPosNext);
 
-    return DB_LOAD_OK;
+    return DBErrors::LOAD_OK;
 }
 
 int64_t CWallet::IncOrderPosNext(CWalletDB *pwalletdb)
@@ -819,19 +808,19 @@ bool CWallet::AccountMove(std::string strFrom, std::string strTo, CAmount nAmoun
     return true;
 }
 
-bool CWallet::GetAccountDestination(CTxDestination &dest, std::string strAccount, bool bForceNew)
+bool CWallet::GetLabelDestination(CTxDestination &dest, const std::string& label, bool bForceNew)
 {
     CWalletDB walletdb(*dbw);
 
     CAccount account;
-    walletdb.ReadAccount(strAccount, account);
+    walletdb.ReadAccount(label, account);
 
     if (!bForceNew) {
         if (!account.vchPubKey.IsValid())
             bForceNew = true;
         else {
             // Check if the current key has been used (TODO: check other addresses with the same key)
-            CScript scriptPubKey = GetScriptForDestination(GetDestinationForKey(account.vchPubKey, g_address_type));
+            CScript scriptPubKey = GetScriptForDestination(GetDestinationForKey(account.vchPubKey, m_default_address_type));
             for (std::map<uint256, CWalletTx>::iterator it = mapWallet.begin();
                  it != mapWallet.end() && account.vchPubKey.IsValid();
                  ++it)
@@ -848,12 +837,12 @@ bool CWallet::GetAccountDestination(CTxDestination &dest, std::string strAccount
         if (!GetKeyFromPool(account.vchPubKey, false))
             return false;
 
-        LearnRelatedScripts(account.vchPubKey, g_address_type);
-        dest = GetDestinationForKey(account.vchPubKey, g_address_type);
-        SetAddressBook(dest, strAccount, "receive");
-        walletdb.WriteAccount(strAccount, account);
+        LearnRelatedScripts(account.vchPubKey, m_default_address_type);
+        dest = GetDestinationForKey(account.vchPubKey, m_default_address_type);
+        SetAddressBook(dest, label, "receive");
+        walletdb.WriteAccount(label, account);
     } else {
-        dest = GetDestinationForKey(account.vchPubKey, g_address_type);
+        dest = GetDestinationForKey(account.vchPubKey, m_default_address_type);
     }
 
     return true;
@@ -888,7 +877,7 @@ bool CWallet::MarkReplaced(const uint256& originalHash, const uint256& newHash)
 
     bool success = true;
     if (!walletdb.WriteTx(wtx)) {
-        LogPrintf("%s: Updating walletdb tx %s failed", __func__, wtx.GetHash().ToString());
+        LogPrintf("%s: Updating walletdb tx %s failed\n", __func__, wtx.GetHash().ToString());
         success = false;
     }
 
@@ -1147,11 +1136,9 @@ void CWallet::MarkConflicted(const uint256& hashBlock, const uint256& hashTx)
     LOCK2(cs_main, cs_wallet);
 
     int conflictconfirms = 0;
-    if (mapBlockIndex.count(hashBlock)) {
-        CBlockIndex* pindex = mapBlockIndex[hashBlock];
-        if (chainActive.Contains(pindex)) {
-            conflictconfirms = -(chainActive.Height() - pindex->nHeight + 1);
-        }
+    CBlockIndex* pindex = LookupBlockIndex(hashBlock);
+    if (pindex && chainActive.Contains(pindex)) {
+        conflictconfirms = -(chainActive.Height() - pindex->nHeight + 1);
     }
     // If number of conflict confirms cannot be determined, this means
     // that the block is still unknown or not yet part of the main chain,
@@ -1279,7 +1266,7 @@ void CWallet::BlockUntilSyncedToCurrentChain() {
         // chainActive.Tip()...
         // We could also take cs_wallet here, and call m_last_block_processed
         // protected by cs_wallet instead of cs_main, but as long as we need
-        // cs_main here anyway, its easier to just call it cs_main-protected.
+        // cs_main here anyway, it's easier to just call it cs_main-protected.
         LOCK(cs_main);
         const CBlockIndex* initialChainTip = chainActive.Tip();
 
@@ -1543,6 +1530,79 @@ int CWalletTx::GetRequestCount() const
     return nRequests;
 }
 
+// Helper for producing a max-sized low-S signature (eg 72 bytes)
+bool CWallet::DummySignInput(CTxIn &tx_in, const CTxOut &txout) const
+{
+    // Fill in dummy signatures for fee calculation.
+    const CScript& scriptPubKey = txout.scriptPubKey;
+    SignatureData sigdata;
+
+    if (!ProduceSignature(DummySignatureCreator(this), scriptPubKey, sigdata))
+    {
+        return false;
+    } else {
+        UpdateInput(tx_in, sigdata);
+    }
+    return true;
+}
+
+// Helper for producing a bunch of max-sized low-S signatures (eg 72 bytes)
+bool CWallet::DummySignTx(CMutableTransaction &txNew, const std::vector<CTxOut> &txouts) const
+{
+    // Fill in dummy signatures for fee calculation.
+    int nIn = 0;
+    for (const auto& txout : txouts)
+    {
+        if (!DummySignInput(txNew.vin[nIn], txout)) {
+            return false;
+        }
+
+        nIn++;
+    }
+    return true;
+}
+
+int64_t CalculateMaximumSignedTxSize(const CTransaction &tx, const CWallet *wallet)
+{
+    std::vector<CTxOut> txouts;
+    // Look up the inputs.  We should have already checked that this transaction
+    // IsAllFromMe(ISMINE_SPENDABLE), so every input should already be in our
+    // wallet, with a valid index into the vout array, and the ability to sign.
+    for (auto& input : tx.vin) {
+        const auto mi = wallet->mapWallet.find(input.prevout.hash);
+        if (mi == wallet->mapWallet.end()) {
+            return -1;
+        }
+        assert(input.prevout.n < mi->second.tx->vout.size());
+        txouts.emplace_back(mi->second.tx->vout[input.prevout.n]);
+    }
+    return CalculateMaximumSignedTxSize(tx, wallet, txouts);
+}
+
+// txouts needs to be in the order of tx.vin
+int64_t CalculateMaximumSignedTxSize(const CTransaction &tx, const CWallet *wallet, const std::vector<CTxOut>& txouts)
+{
+    CMutableTransaction txNew(tx);
+    if (!wallet->DummySignTx(txNew, txouts)) {
+        // This should never happen, because IsAllFromMe(ISMINE_SPENDABLE)
+        // implies that we can sign for every input.
+        return -1;
+    }
+    return GetVirtualTransactionSize(txNew);
+}
+
+int CalculateMaximumSignedInputSize(const CTxOut& txout, const CWallet* wallet)
+{
+    CMutableTransaction txn;
+    txn.vin.push_back(CTxIn(COutPoint()));
+    if (!wallet->DummySignInput(txn.vin[0], txout)) {
+        // This should never happen, because IsAllFromMe(ISMINE_SPENDABLE)
+        // implies that we can sign for every input.
+        return -1;
+    }
+    return GetVirtualTransactionInputSize(txn.vin[0]);
+}
+
 void CWalletTx::GetAmounts(std::list<COutputEntry>& listReceived,
                            std::list<COutputEntry>& listSent, CAmount& nFee, std::string& strSentAccount, const isminefilter& filter) const
 {
@@ -2159,7 +2219,7 @@ CAmount CWallet::GetLegacyBalance(const isminefilter& filter, int minDepth, cons
         for (const CTxOut& out : wtx.tx->vout) {
             if (outgoing && IsChange(out)) {
                 debit -= out.nValue;
-            } else if (IsMine(out) & filter && depth >= minDepth && (!account || *account == GetAccountName(out.scriptPubKey))) {
+            } else if (IsMine(out) & filter && depth >= minDepth && (!account || *account == GetLabelName(out.scriptPubKey))) {
                 balance += out.nValue;
             }
         }
@@ -2364,171 +2424,88 @@ const CTxOut& CWallet::FindNonChangeParentOutput(const CTransaction& tx, int out
     return ptx->vout[n];
 }
 
-static void ApproximateBestSubset(const std::vector<CInputCoin>& vValue, const CAmount& nTotalLower, const CAmount& nTargetValue,
-                                  std::vector<char>& vfBest, CAmount& nBest, int iterations = 1000)
+bool CWallet::OutputEligibleForSpending(const COutput& output, const CoinEligibilityFilter& eligibility_filter) const
 {
-    std::vector<char> vfIncluded;
+    if (!output.fSpendable)
+        return false;
 
-    vfBest.assign(vValue.size(), true);
-    nBest = nTotalLower;
+    if (output.nDepth < (output.tx->IsFromMe(ISMINE_ALL) ? eligibility_filter.conf_mine : eligibility_filter.conf_theirs))
+        return false;
 
-    FastRandomContext insecure_rand;
+    if (!mempool.TransactionWithinChainLimit(output.tx->GetHash(), eligibility_filter.max_ancestors))
+        return false;
 
-    for (int nRep = 0; nRep < iterations && nBest != nTargetValue; nRep++)
-    {
-        vfIncluded.assign(vValue.size(), false);
-        CAmount nTotal = 0;
-        bool fReachedTarget = false;
-        for (int nPass = 0; nPass < 2 && !fReachedTarget; nPass++)
-        {
-            for (unsigned int i = 0; i < vValue.size(); i++)
-            {
-                //The solver here uses a randomized algorithm,
-                //the randomness serves no real security purpose but is just
-                //needed to prevent degenerate behavior and it is important
-                //that the rng is fast. We do not use a constant random sequence,
-                //because there may be some privacy improvement by making
-                //the selection random.
-                if (nPass == 0 ? insecure_rand.randbool() : !vfIncluded[i])
-                {
-                    nTotal += vValue[i].txout.nValue;
-                    vfIncluded[i] = true;
-                    if (nTotal >= nTargetValue)
-                    {
-                        fReachedTarget = true;
-                        if (nTotal < nBest)
-                        {
-                            nBest = nTotal;
-                            vfBest = vfIncluded;
-                        }
-                        nTotal -= vValue[i].txout.nValue;
-                        vfIncluded[i] = false;
-                    }
-                }
-            }
-        }
-    }
+    return true;
 }
 
-bool CWallet::SelectCoinsMinConf(const CAmount& nTargetValue, const int nConfMine, const int nConfTheirs, const uint64_t nMaxAncestors, std::vector<COutput> vCoins,
-                                 std::set<CInputCoin>& setCoinsRet, CAmount& nValueRet) const
+bool CWallet::SelectCoinsMinConf(const CAmount& nTargetValue, const CoinEligibilityFilter& eligibility_filter, std::vector<COutput> vCoins,
+                                 std::set<CInputCoin>& setCoinsRet, CAmount& nValueRet, const CoinSelectionParams& coin_selection_params, bool& bnb_used) const
 {
     setCoinsRet.clear();
     nValueRet = 0;
 
-    // List of values less than target
-    boost::optional<CInputCoin> coinLowestLarger;
-    std::vector<CInputCoin> vValue;
-    CAmount nTotalLower = 0;
-
-    random_shuffle(vCoins.begin(), vCoins.end(), GetRandInt);
-
-    for (const COutput &output : vCoins)
-    {
-        if (!output.fSpendable)
-            continue;
-
-        const CWalletTx *pcoin = output.tx;
-
-        if (output.nDepth < (pcoin->IsFromMe(ISMINE_ALL) ? nConfMine : nConfTheirs))
-            continue;
-
-        if (!mempool.TransactionWithinChainLimit(pcoin->GetHash(), nMaxAncestors))
-            continue;
-
-        int i = output.i;
+    std::vector<CInputCoin> utxo_pool;
+    if (coin_selection_params.use_bnb) {
 
-        CInputCoin coin = CInputCoin(pcoin, i);
+        // Get long term estimate
+        FeeCalculation feeCalc;
+        CCoinControl temp;
+        temp.m_confirm_target = 1008;
+        CFeeRate long_term_feerate = GetMinimumFeeRate(temp, ::mempool, ::feeEstimator, &feeCalc);
 
-        if (coin.txout.nValue == nTargetValue)
-        {
-            setCoinsRet.insert(coin);
-            nValueRet += coin.txout.nValue;
-            return true;
-        }
-        else if (coin.txout.nValue < nTargetValue + MIN_CHANGE)
-        {
-            vValue.push_back(coin);
-            nTotalLower += coin.txout.nValue;
-        }
-        else if (!coinLowestLarger || coin.txout.nValue < coinLowestLarger->txout.nValue)
-        {
-            coinLowestLarger = coin;
-        }
-    }
+        // Calculate cost of change
+        CAmount cost_of_change = GetDiscardRate(::feeEstimator).GetFee(coin_selection_params.change_spend_size) + coin_selection_params.effective_fee.GetFee(coin_selection_params.change_output_size);
 
-    if (nTotalLower == nTargetValue)
-    {
-        for (const auto& input : vValue)
+        // Filter by the min conf specs and add to utxo_pool and calculate effective value
+        for (const COutput &output : vCoins)
         {
-            setCoinsRet.insert(input);
-            nValueRet += input.txout.nValue;
-        }
-        return true;
-    }
-
-    if (nTotalLower < nTargetValue)
-    {
-        if (!coinLowestLarger)
-            return false;
-        setCoinsRet.insert(coinLowestLarger.get());
-        nValueRet += coinLowestLarger->txout.nValue;
-        return true;
-    }
-
-    // Solve subset sum by stochastic approximation
-    std::sort(vValue.begin(), vValue.end(), CompareValueOnly());
-    std::reverse(vValue.begin(), vValue.end());
-    std::vector<char> vfBest;
-    CAmount nBest;
-
-    ApproximateBestSubset(vValue, nTotalLower, nTargetValue, vfBest, nBest);
-    if (nBest != nTargetValue && nTotalLower >= nTargetValue + MIN_CHANGE)
-        ApproximateBestSubset(vValue, nTotalLower, nTargetValue + MIN_CHANGE, vfBest, nBest);
+            if (!OutputEligibleForSpending(output, eligibility_filter))
+                continue;
 
-    // If we have a bigger coin and (either the stochastic approximation didn't find a good solution,
-    //                                   or the next bigger coin is closer), return the bigger coin
-    if (coinLowestLarger &&
-        ((nBest != nTargetValue && nBest < nTargetValue + MIN_CHANGE) || coinLowestLarger->txout.nValue <= nBest))
-    {
-        setCoinsRet.insert(coinLowestLarger.get());
-        nValueRet += coinLowestLarger->txout.nValue;
-    }
-    else {
-        for (unsigned int i = 0; i < vValue.size(); i++)
-            if (vfBest[i])
-            {
-                setCoinsRet.insert(vValue[i]);
-                nValueRet += vValue[i].txout.nValue;
+            CInputCoin coin(output.tx->tx, output.i);
+            coin.effective_value = coin.txout.nValue - (output.nInputBytes < 0 ? 0 : coin_selection_params.effective_fee.GetFee(output.nInputBytes));
+            // Only include outputs that are positive effective value (i.e. not dust)
+            if (coin.effective_value > 0) {
+                coin.fee = output.nInputBytes < 0 ? 0 : coin_selection_params.effective_fee.GetFee(output.nInputBytes);
+                coin.long_term_fee = output.nInputBytes < 0 ? 0 : long_term_feerate.GetFee(output.nInputBytes);
+                utxo_pool.push_back(coin);
             }
+        }
+        // Calculate the fees for things that aren't inputs
+        CAmount not_input_fees = coin_selection_params.effective_fee.GetFee(coin_selection_params.tx_noinputs_size);
+        bnb_used = true;
+        return SelectCoinsBnB(utxo_pool, nTargetValue, cost_of_change, setCoinsRet, nValueRet, not_input_fees);
+    } else {
+        // Filter by the min conf specs and add to utxo_pool
+        for (const COutput &output : vCoins)
+        {
+            if (!OutputEligibleForSpending(output, eligibility_filter))
+                continue;
 
-        if (LogAcceptCategory(BCLog::SELECTCOINS)) {
-            LogPrint(BCLog::SELECTCOINS, "SelectCoins() best subset: ");
-            for (unsigned int i = 0; i < vValue.size(); i++) {
-                if (vfBest[i]) {
-                    LogPrint(BCLog::SELECTCOINS, "%s ", FormatMoney(vValue[i].txout.nValue));
-                }
-            }
-            LogPrint(BCLog::SELECTCOINS, "total %s\n", FormatMoney(nBest));
+            CInputCoin coin = CInputCoin(output.tx->tx, output.i);
+            utxo_pool.push_back(coin);
         }
+        bnb_used = false;
+        return KnapsackSolver(nTargetValue, utxo_pool, setCoinsRet, nValueRet);
     }
-
-    return true;
 }
 
-bool CWallet::SelectCoins(const std::vector<COutput>& vAvailableCoins, const CAmount& nTargetValue, std::set<CInputCoin>& setCoinsRet, CAmount& nValueRet, const CCoinControl* coinControl) const
+bool CWallet::SelectCoins(const std::vector<COutput>& vAvailableCoins, const CAmount& nTargetValue, std::set<CInputCoin>& setCoinsRet, CAmount& nValueRet, const CCoinControl& coin_control, CoinSelectionParams& coin_selection_params, bool& bnb_used) const
 {
     std::vector<COutput> vCoins(vAvailableCoins);
 
     // coin control -> return all selected outputs (we want all selected to go into the transaction for sure)
-    if (coinControl && coinControl->HasSelected() && !coinControl->fAllowOtherInputs)
+    if (coin_control.HasSelected() && !coin_control.fAllowOtherInputs)
     {
+        // We didn't use BnB here, so set it to false.
+        bnb_used = false;
+
         for (const COutput& out : vCoins)
         {
             if (!out.fSpendable)
                  continue;
             nValueRet += out.tx->tx->vout[out.i].nValue;
-            setCoinsRet.insert(CInputCoin(out.tx, out.i));
+            setCoinsRet.insert(CInputCoin(out.tx->tx, out.i));
         }
         return (nValueRet >= nTargetValue);
     }
@@ -2538,10 +2515,13 @@ bool CWallet::SelectCoins(const std::vector<COutput>& vAvailableCoins, const CAm
     CAmount nValueFromPresetInputs = 0;
 
     std::vector<COutPoint> vPresetInputs;
-    if (coinControl)
-        coinControl->ListSelected(vPresetInputs);
+    coin_control.ListSelected(vPresetInputs);
     for (const COutPoint& outpoint : vPresetInputs)
     {
+        // For now, don't use BnB if preset inputs are selected. TODO: Enable this later
+        bnb_used = false;
+        coin_selection_params.use_bnb = false;
+
         std::map<uint256, CWalletTx>::const_iterator it = mapWallet.find(outpoint.hash);
         if (it != mapWallet.end())
         {
@@ -2549,16 +2529,17 @@ bool CWallet::SelectCoins(const std::vector<COutput>& vAvailableCoins, const CAm
             // Clearly invalid input, fail
             if (pcoin->tx->vout.size() <= outpoint.n)
                 return false;
+            // Just to calculate the marginal byte size
             nValueFromPresetInputs += pcoin->tx->vout[outpoint.n].nValue;
-            setPresetCoins.insert(CInputCoin(pcoin, outpoint.n));
+            setPresetCoins.insert(CInputCoin(pcoin->tx, outpoint.n));
         } else
             return false; // TODO: Allow non-wallet inputs
     }
 
     // remove preset inputs from vCoins
-    for (std::vector<COutput>::iterator it = vCoins.begin(); it != vCoins.end() && coinControl && coinControl->HasSelected();)
+    for (std::vector<COutput>::iterator it = vCoins.begin(); it != vCoins.end() && coin_control.HasSelected();)
     {
-        if (setPresetCoins.count(CInputCoin(it->tx, it->i)))
+        if (setPresetCoins.count(CInputCoin(it->tx->tx, it->i)))
             it = vCoins.erase(it);
         else
             ++it;
@@ -2568,13 +2549,13 @@ bool CWallet::SelectCoins(const std::vector<COutput>& vAvailableCoins, const CAm
     bool fRejectLongChains = gArgs.GetBoolArg("-walletrejectlongchains", DEFAULT_WALLET_REJECT_LONG_CHAINS);
 
     bool res = nTargetValue <= nValueFromPresetInputs ||
-        SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, 1, 6, 0, vCoins, setCoinsRet, nValueRet) ||
-        SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, 1, 1, 0, vCoins, setCoinsRet, nValueRet) ||
-        (bSpendZeroConfChange && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, 0, 1, 2, vCoins, setCoinsRet, nValueRet)) ||
-        (bSpendZeroConfChange && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, 0, 1, std::min((size_t)4, nMaxChainLength/3), vCoins, setCoinsRet, nValueRet)) ||
-        (bSpendZeroConfChange && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, 0, 1, nMaxChainLength/2, vCoins, setCoinsRet, nValueRet)) ||
-        (bSpendZeroConfChange && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, 0, 1, nMaxChainLength, vCoins, setCoinsRet, nValueRet)) ||
-        (bSpendZeroConfChange && !fRejectLongChains && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, 0, 1, std::numeric_limits<uint64_t>::max(), vCoins, setCoinsRet, nValueRet));
+        SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, CoinEligibilityFilter(1, 6, 0), vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used) ||
+        SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, CoinEligibilityFilter(1, 1, 0), vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used) ||
+        (bSpendZeroConfChange && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, CoinEligibilityFilter(0, 1, 2), vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used)) ||
+        (bSpendZeroConfChange && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, CoinEligibilityFilter(0, 1, std::min((size_t)4, nMaxChainLength/3)), vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used)) ||
+        (bSpendZeroConfChange && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, CoinEligibilityFilter(0, 1, nMaxChainLength/2), vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used)) ||
+        (bSpendZeroConfChange && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, CoinEligibilityFilter(0, 1, nMaxChainLength), vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used)) ||
+        (bSpendZeroConfChange && !fRejectLongChains && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, CoinEligibilityFilter(0, 1, std::numeric_limits<uint64_t>::max()), vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
 
     // because SelectCoinsMinConf clears the setCoinsRet, we now add the possible inputs to the coinset
     setCoinsRet.insert(setPresetCoins.begin(), setPresetCoins.end());
@@ -2631,13 +2612,13 @@ bool CWallet::FundTransaction(CMutableTransaction& tx, CAmount& nFeeRet, int& nC
     LOCK2(cs_main, cs_wallet);
 
     CReserveKey reservekey(this);
-    CWalletTx wtx;
-    if (!CreateTransaction(vecSend, wtx, reservekey, nFeeRet, nChangePosInOut, strFailReason, coinControl, false)) {
+    CTransactionRef tx_new;
+    if (!CreateTransaction(vecSend, tx_new, reservekey, nFeeRet, nChangePosInOut, strFailReason, coinControl, false)) {
         return false;
     }
 
     if (nChangePosInOut != -1) {
-        tx.vout.insert(tx.vout.begin() + nChangePosInOut, wtx.tx->vout[nChangePosInOut]);
+        tx.vout.insert(tx.vout.begin() + nChangePosInOut, tx_new->vout[nChangePosInOut]);
         // We don't have the normal Create/Commit cycle, and don't want to risk
         // reusing change, so just remove the key from the keypool here.
         reservekey.KeepKey();
@@ -2646,11 +2627,11 @@ bool CWallet::FundTransaction(CMutableTransaction& tx, CAmount& nFeeRet, int& nC
     // Copy output sizes from new transaction; they may have had the fee
     // subtracted from them.
     for (unsigned int idx = 0; idx < tx.vout.size(); idx++) {
-        tx.vout[idx].nValue = wtx.tx->vout[idx].nValue;
+        tx.vout[idx].nValue = tx_new->vout[idx].nValue;
     }
 
     // Add new txins while keeping original txin scriptSig/order.
-    for (const CTxIn& txin : wtx.tx->vin) {
+    for (const CTxIn& txin : tx_new->vin) {
         if (!coinControl.IsSelected(txin.prevout)) {
             tx.vin.push_back(txin);
 
@@ -2666,14 +2647,14 @@ bool CWallet::FundTransaction(CMutableTransaction& tx, CAmount& nFeeRet, int& nC
 OutputType CWallet::TransactionChangeType(OutputType change_type, const std::vector<CRecipient>& vecSend)
 {
     // If -changetype is specified, always use that change type.
-    if (change_type != OUTPUT_TYPE_NONE) {
+    if (change_type != OutputType::NONE) {
         return change_type;
     }
 
-    // if g_address_type is legacy, use legacy address as change (even
+    // if m_default_address_type is legacy, use legacy address as change (even
     // if some of the outputs are P2WPKH or P2WSH).
-    if (g_address_type == OUTPUT_TYPE_LEGACY) {
-        return OUTPUT_TYPE_LEGACY;
+    if (m_default_address_type == OutputType::LEGACY) {
+        return OutputType::LEGACY;
     }
 
     // if any destination is P2WPKH or P2WSH, use P2WPKH for the change
@@ -2683,15 +2664,15 @@ OutputType CWallet::TransactionChangeType(OutputType change_type, const std::vec
         int witnessversion = 0;
         std::vector<unsigned char> witnessprogram;
         if (recipient.scriptPubKey.IsWitnessProgram(witnessversion, witnessprogram)) {
-            return OUTPUT_TYPE_BECH32;
+            return OutputType::BECH32;
         }
     }
 
-    // else use g_address_type for change
-    return g_address_type;
+    // else use m_default_address_type for change
+    return m_default_address_type;
 }
 
-bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletTx& wtxNew, CReserveKey& reservekey, CAmount& nFeeRet,
+bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CTransactionRef& tx, CReserveKey& reservekey, CAmount& nFeeRet,
                                 int& nChangePosInOut, std::string& strFailReason, const CCoinControl& coin_control, bool sign)
 {
     CAmount nValue = 0;
@@ -2715,8 +2696,6 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletT
         return false;
     }
 
-    wtxNew.fTimeReceivedIsTxTime = true;
-    wtxNew.BindWallet(this);
     CMutableTransaction txNew;
 
     // Discourage fee sniping.
@@ -2752,13 +2731,14 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletT
     assert(txNew.nLockTime < LOCKTIME_THRESHOLD);
     FeeCalculation feeCalc;
     CAmount nFeeNeeded;
-    unsigned int nBytes;
+    int nBytes;
     {
         std::set<CInputCoin> setCoins;
         LOCK2(cs_main, cs_wallet);
         {
             std::vector<COutput> vAvailableCoins;
             AvailableCoins(vAvailableCoins, true, &coin_control);
+            CoinSelectionParams coin_selection_params; // Parameters for coin selection, init with dummy
 
             // Create change script that will be used if we need change
             // TODO: pass in scriptChange instead of reservekey so
@@ -2786,31 +2766,40 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletT
                     return false;
                 }
 
-                const OutputType change_type = TransactionChangeType(coin_control.change_type, vecSend);
+                const OutputType change_type = TransactionChangeType(coin_control.m_change_type ? *coin_control.m_change_type : m_default_change_type, vecSend);
 
                 LearnRelatedScripts(vchPubKey, change_type);
                 scriptChange = GetScriptForDestination(GetDestinationForKey(vchPubKey, change_type));
             }
             CTxOut change_prototype_txout(0, scriptChange);
-            size_t change_prototype_size = GetSerializeSize(change_prototype_txout, SER_DISK, 0);
+            coin_selection_params.change_output_size = GetSerializeSize(change_prototype_txout, SER_DISK, 0);
 
             CFeeRate discard_rate = GetDiscardRate(::feeEstimator);
+
+            // Get the fee rate to use effective values in coin selection
+            CFeeRate nFeeRateNeeded = GetMinimumFeeRate(coin_control, ::mempool, ::feeEstimator, &feeCalc);
+
             nFeeRet = 0;
             bool pick_new_inputs = true;
             CAmount nValueIn = 0;
+
+            // BnB selector is the only selector used when this is true.
+            // That should only happen on the first pass through the loop.
+            coin_selection_params.use_bnb = nSubtractFeeFromAmount == 0; // If we are doing subtract fee from recipient, then don't use BnB
             // Start with no fee and loop until there is enough fee
             while (true)
             {
                 nChangePosInOut = nChangePosRequest;
                 txNew.vin.clear();
                 txNew.vout.clear();
-                wtxNew.fFromMe = true;
                 bool fFirst = true;
 
                 CAmount nValueToSelect = nValue;
                 if (nSubtractFeeFromAmount == 0)
                     nValueToSelect += nFeeRet;
+
                 // vouts to the payees
+                coin_selection_params.tx_noinputs_size = 11; // Static vsize overhead + outputs vsize. 4 nVersion, 4 nLocktime, 1 input count, 1 output count, 1 witness overhead (dummy, flag, stack size)
                 for (const auto& recipient : vecSend)
                 {
                     CTxOut txout(recipient.nAmount, recipient.scriptPubKey);
@@ -2826,6 +2815,8 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletT
                             txout.nValue -= nFeeRet % nSubtractFeeFromAmount;
                         }
                     }
+                    // Include the fee cost for outputs. Note this is only used for BnB right now
+                    coin_selection_params.tx_noinputs_size += ::GetSerializeSize(txout, SER_NETWORK, PROTOCOL_VERSION);
 
                     if (IsDust(txout, ::dustRelayFee))
                     {
@@ -2844,18 +2835,27 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletT
                 }
 
                 // Choose coins to use
+                bool bnb_used;
                 if (pick_new_inputs) {
                     nValueIn = 0;
                     setCoins.clear();
-                    if (!SelectCoins(vAvailableCoins, nValueToSelect, setCoins, nValueIn, &coin_control))
+                    coin_selection_params.change_spend_size = CalculateMaximumSignedInputSize(change_prototype_txout, this);
+                    coin_selection_params.effective_fee = nFeeRateNeeded;
+                    if (!SelectCoins(vAvailableCoins, nValueToSelect, setCoins, nValueIn, coin_control, coin_selection_params, bnb_used))
                     {
-                        strFailReason = _("Insufficient funds");
-                        return false;
+                        // If BnB was used, it was the first pass. No longer the first pass and continue loop with knapsack.
+                        if (bnb_used) {
+                            coin_selection_params.use_bnb = false;
+                            continue;
+                        }
+                        else {
+                            strFailReason = _("Insufficient funds");
+                            return false;
+                        }
                     }
                 }
 
                 const CAmount nChange = nValueIn - nValueToSelect;
-
                 if (nChange > 0)
                 {
                     // Fill a vout to ourself
@@ -2863,7 +2863,8 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletT
 
                     // Never create dust outputs; if we would, just
                     // add the dust to the fee.
-                    if (IsDust(newTxOut, discard_rate))
+                    // The nChange when BnB is used is always going to go to fees.
+                    if (IsDust(newTxOut, discard_rate) || bnb_used)
                     {
                         nChangePosInOut = -1;
                         nFeeRet += nChange;
@@ -2888,33 +2889,16 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletT
                     nChangePosInOut = -1;
                 }
 
-                // Fill vin
-                //
-                // Note how the sequence number is set to non-maxint so that
-                // the nLockTime set above actually works.
+                // Dummy fill vin for maximum size estimation
                 //
-                // BIP125 defines opt-in RBF as any nSequence < maxint-1, so
-                // we use the highest possible value in that range (maxint-2)
-                // to avoid conflicting with other possible uses of nSequence,
-                // and in the spirit of "smallest possible change from prior
-                // behavior."
-                const uint32_t nSequence = coin_control.signalRbf ? MAX_BIP125_RBF_SEQUENCE : (CTxIn::SEQUENCE_FINAL - 1);
-                for (const auto& coin : setCoins)
-                    txNew.vin.push_back(CTxIn(coin.outpoint,CScript(),
-                                              nSequence));
-
-                // Fill in dummy signatures for fee calculation.
-                if (!DummySignTx(txNew, setCoins)) {
-                    strFailReason = _("Signing transaction failed");
-                    return false;
+                for (const auto& coin : setCoins) {
+                    txNew.vin.push_back(CTxIn(coin.outpoint,CScript()));
                 }
 
-                nBytes = GetVirtualTransactionSize(txNew);
-
-                // Remove scriptSigs to eliminate the fee calculation dummy signatures
-                for (auto& vin : txNew.vin) {
-                    vin.scriptSig = CScript();
-                    vin.scriptWitness.SetNull();
+                nBytes = CalculateMaximumSignedTxSize(txNew, this);
+                if (nBytes < 0) {
+                    strFailReason = _("Signing transaction failed");
+                    return false;
                 }
 
                 nFeeNeeded = GetMinimumFee(nBytes, coin_control, ::mempool, ::feeEstimator, &feeCalc);
@@ -2944,7 +2928,7 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletT
                     // (because of reduced tx size) and so we should add a
                     // change output. Only try this once.
                     if (nChangePosInOut == -1 && nSubtractFeeFromAmount == 0 && pick_new_inputs) {
-                        unsigned int tx_size_with_change = nBytes + change_prototype_size + 2; // Add 2 as a buffer in case increasing # of outputs changes compact size
+                        unsigned int tx_size_with_change = nBytes + coin_selection_params.change_output_size + 2; // Add 2 as a buffer in case increasing # of outputs changes compact size
                         CAmount fee_needed_with_change = GetMinimumFee(tx_size_with_change, coin_control, ::mempool, ::feeEstimator, nullptr);
                         CAmount minimum_value_for_change = GetDustThreshold(change_prototype_txout, discard_rate);
                         if (nFeeRet >= fee_needed_with_change + minimum_value_for_change) {
@@ -2992,17 +2976,36 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletT
 
                 // Include more fee and try again.
                 nFeeRet = nFeeNeeded;
+                coin_selection_params.use_bnb = false;
                 continue;
             }
         }
 
         if (nChangePosInOut == -1) reservekey.ReturnKey(); // Return any reserved key if we don't have change
 
+        // Shuffle selected coins and fill in final vin
+        txNew.vin.clear();
+        std::vector<CInputCoin> selected_coins(setCoins.begin(), setCoins.end());
+        std::shuffle(selected_coins.begin(), selected_coins.end(), FastRandomContext());
+
+        // Note how the sequence number is set to non-maxint so that
+        // the nLockTime set above actually works.
+        //
+        // BIP125 defines opt-in RBF as any nSequence < maxint-1, so
+        // we use the highest possible value in that range (maxint-2)
+        // to avoid conflicting with other possible uses of nSequence,
+        // and in the spirit of "smallest possible change from prior
+        // behavior."
+        const uint32_t nSequence = coin_control.signalRbf ? MAX_BIP125_RBF_SEQUENCE : (CTxIn::SEQUENCE_FINAL - 1);
+        for (const auto& coin : selected_coins) {
+            txNew.vin.push_back(CTxIn(coin.outpoint, CScript(), nSequence));
+        }
+
         if (sign)
         {
             CTransaction txNewConst(txNew);
             int nIn = 0;
-            for (const auto& coin : setCoins)
+            for (const auto& coin : selected_coins)
             {
                 const CScript& scriptPubKey = coin.txout.scriptPubKey;
                 SignatureData sigdata;
@@ -3019,11 +3022,11 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletT
             }
         }
 
-        // Embed the constructed transaction data in wtxNew.
-        wtxNew.SetTx(MakeTransactionRef(std::move(txNew)));
+        // Return the constructed transaction data.
+        tx = MakeTransactionRef(std::move(txNew));
 
         // Limit size
-        if (GetTransactionWeight(*wtxNew.tx) >= MAX_STANDARD_TX_WEIGHT)
+        if (GetTransactionWeight(*tx) >= MAX_STANDARD_TX_WEIGHT)
         {
             strFailReason = _("Transaction too large");
             return false;
@@ -3033,7 +3036,7 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletT
     if (gArgs.GetBoolArg("-walletrejectlongchains", DEFAULT_WALLET_REJECT_LONG_CHAINS)) {
         // Lastly, ensure this tx will pass the mempool's chain limits
         LockPoints lp;
-        CTxMemPoolEntry entry(wtxNew.tx, 0, 0, 0, false, 0, lp);
+        CTxMemPoolEntry entry(tx, 0, 0, 0, false, 0, lp);
         CTxMemPool::setEntries setAncestors;
         size_t nLimitAncestors = gArgs.GetArg("-limitancestorcount", DEFAULT_ANCESTOR_LIMIT);
         size_t nLimitAncestorSize = gArgs.GetArg("-limitancestorsize", DEFAULT_ANCESTOR_SIZE_LIMIT)*1000;
@@ -3060,10 +3063,18 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletT
 /**
  * Call after CreateTransaction unless you want to abort
  */
-bool CWallet::CommitTransaction(CWalletTx& wtxNew, CReserveKey& reservekey, CConnman* connman, CValidationState& state)
+bool CWallet::CommitTransaction(CTransactionRef tx, mapValue_t mapValue, std::vector<std::pair<std::string, std::string>> orderForm, std::string fromAccount, CReserveKey& reservekey, CConnman* connman, CValidationState& state)
 {
     {
         LOCK2(cs_main, cs_wallet);
+
+        CWalletTx wtxNew(this, std::move(tx));
+        wtxNew.mapValue = std::move(mapValue);
+        wtxNew.vOrderForm = std::move(orderForm);
+        wtxNew.strFromAccount = std::move(fromAccount);
+        wtxNew.fTimeReceivedIsTxTime = true;
+        wtxNew.fFromMe = true;
+
         LogPrintf("CommitTransaction:\n%s", wtxNew.tx->ToString());
         {
             // Take key pair from key pool so it won't be used again
@@ -3076,7 +3087,7 @@ bool CWallet::CommitTransaction(CWalletTx& wtxNew, CReserveKey& reservekey, CCon
             // Notify that old coins are spent
             for (const CTxIn& txin : wtxNew.tx->vin)
             {
-                CWalletTx &coin = mapWallet[txin.prevout.hash];
+                CWalletTx &coin = mapWallet.at(txin.prevout.hash);
                 coin.BindWallet(this);
                 NotifyTransactionChanged(this, coin.GetHash(), CT_UPDATED);
             }
@@ -3087,7 +3098,7 @@ bool CWallet::CommitTransaction(CWalletTx& wtxNew, CReserveKey& reservekey, CCon
 
         // Get the inserted-CWalletTx from mapWallet so that the
         // fInMempool flag is cached properly
-        CWalletTx& wtx = mapWallet[wtxNew.GetHash()];
+        CWalletTx& wtx = mapWallet.at(wtxNew.GetHash());
 
         if (fBroadcastTransactions)
         {
@@ -3134,7 +3145,7 @@ DBErrors CWallet::LoadWallet(bool& fFirstRunRet)
 
     fFirstRunRet = false;
     DBErrors nLoadWalletRet = CWalletDB(*dbw,"cr+").LoadWallet(this);
-    if (nLoadWalletRet == DB_NEED_REWRITE)
+    if (nLoadWalletRet == DBErrors::NEED_REWRITE)
     {
         if (dbw->Rewrite("\x04pool"))
         {
@@ -3150,12 +3161,12 @@ DBErrors CWallet::LoadWallet(bool& fFirstRunRet)
     // This wallet is in its first run if all of these are empty
     fFirstRunRet = mapKeys.empty() && mapCryptedKeys.empty() && mapWatchKeys.empty() && setWatchOnly.empty() && mapScripts.empty();
 
-    if (nLoadWalletRet != DB_LOAD_OK)
+    if (nLoadWalletRet != DBErrors::LOAD_OK)
         return nLoadWalletRet;
 
     uiInterface.LoadWallet(this);
 
-    return DB_LOAD_OK;
+    return DBErrors::LOAD_OK;
 }
 
 DBErrors CWallet::ZapSelectTx(std::vector<uint256>& vHashIn, std::vector<uint256>& vHashOut)
@@ -3165,7 +3176,7 @@ DBErrors CWallet::ZapSelectTx(std::vector<uint256>& vHashIn, std::vector<uint256
     for (uint256 hash : vHashOut)
         mapWallet.erase(hash);
 
-    if (nZapSelectTxRet == DB_NEED_REWRITE)
+    if (nZapSelectTxRet == DBErrors::NEED_REWRITE)
     {
         if (dbw->Rewrite("\x04pool"))
         {
@@ -3178,19 +3189,19 @@ DBErrors CWallet::ZapSelectTx(std::vector<uint256>& vHashIn, std::vector<uint256
         }
     }
 
-    if (nZapSelectTxRet != DB_LOAD_OK)
+    if (nZapSelectTxRet != DBErrors::LOAD_OK)
         return nZapSelectTxRet;
 
     MarkDirty();
 
-    return DB_LOAD_OK;
+    return DBErrors::LOAD_OK;
 
 }
 
 DBErrors CWallet::ZapWalletTx(std::vector<CWalletTx>& vWtx)
 {
     DBErrors nZapWalletTxRet = CWalletDB(*dbw,"cr+").ZapWalletTx(vWtx);
-    if (nZapWalletTxRet == DB_NEED_REWRITE)
+    if (nZapWalletTxRet == DBErrors::NEED_REWRITE)
     {
         if (dbw->Rewrite("\x04pool"))
         {
@@ -3204,10 +3215,10 @@ DBErrors CWallet::ZapWalletTx(std::vector<CWalletTx>& vWtx)
         }
     }
 
-    if (nZapWalletTxRet != DB_LOAD_OK)
+    if (nZapWalletTxRet != DBErrors::LOAD_OK)
         return nZapWalletTxRet;
 
-    return DB_LOAD_OK;
+    return DBErrors::LOAD_OK;
 }
 
 
@@ -3249,7 +3260,7 @@ bool CWallet::DelAddressBook(const CTxDestination& address)
     return CWalletDB(*dbw).EraseName(EncodeDestination(address));
 }
 
-const std::string& CWallet::GetAccountName(const CScript& scriptPubKey) const
+const std::string& CWallet::GetLabelName(const CScript& scriptPubKey) const
 {
     CTxDestination address;
     if (ExtractDestination(scriptPubKey, address) && !scriptPubKey.IsUnspendable()) {
@@ -3259,9 +3270,9 @@ const std::string& CWallet::GetAccountName(const CScript& scriptPubKey) const
         }
     }
     // A scriptPubKey that doesn't have an entry in the address book is
-    // associated with the default account ("").
-    const static std::string DEFAULT_ACCOUNT_NAME;
-    return DEFAULT_ACCOUNT_NAME;
+    // associated with the default label ("").
+    const static std::string DEFAULT_LABEL_NAME;
+    return DEFAULT_LABEL_NAME;
 }
 
 /**
@@ -3543,7 +3554,7 @@ std::set< std::set<CTxDestination> > CWallet::GetAddressGroupings()
                 CTxDestination address;
                 if(!IsMine(txin)) /* If this input isn't mine, ignore it */
                     continue;
-                if(!ExtractDestination(mapWallet[txin.prevout.hash].tx->vout[txin.prevout.n].scriptPubKey, address))
+                if(!ExtractDestination(mapWallet.at(txin.prevout.hash).tx->vout[txin.prevout.n].scriptPubKey, address))
                     continue;
                 grouping.insert(address);
                 any_mine = true;
@@ -3617,7 +3628,7 @@ std::set< std::set<CTxDestination> > CWallet::GetAddressGroupings()
     return ret;
 }
 
-std::set<CTxDestination> CWallet::GetAccountAddresses(const std::string& strAccount) const
+std::set<CTxDestination> CWallet::GetLabelAddresses(const std::string& label) const
 {
     LOCK(cs_wallet);
     std::set<CTxDestination> result;
@@ -3625,7 +3636,7 @@ std::set<CTxDestination> CWallet::GetAccountAddresses(const std::string& strAcco
     {
         const CTxDestination& address = item.first;
         const std::string& strName = item.second.name;
-        if (strName == strAccount)
+        if (strName == label)
             result.insert(address);
     }
     return result;
@@ -3767,10 +3778,10 @@ void CWallet::GetKeyBirthTimes(std::map<CTxDestination, int64_t> &mapKeyBirth) c
     for (const auto& entry : mapWallet) {
         // iterate over all wallet transactions...
         const CWalletTx &wtx = entry.second;
-        BlockMap::const_iterator blit = mapBlockIndex.find(wtx.hashBlock);
-        if (blit != mapBlockIndex.end() && chainActive.Contains(blit->second)) {
+        CBlockIndex* pindex = LookupBlockIndex(wtx.hashBlock);
+        if (pindex && chainActive.Contains(pindex)) {
             // ... which are already in a block
-            int nHeight = blit->second->nHeight;
+            int nHeight = pindex->nHeight;
             for (const CTxOut &txout : wtx.tx->vout) {
                 // iterate over all their outputs
                 CAffectedKeysVisitor(*this, vAffected).Process(txout.scriptPubKey);
@@ -3778,7 +3789,7 @@ void CWallet::GetKeyBirthTimes(std::map<CTxDestination, int64_t> &mapKeyBirth) c
                     // ... and all their affected keys
                     std::map<CKeyID, CBlockIndex*>::iterator rit = mapKeyFirstBlock.find(keyid);
                     if (rit != mapKeyFirstBlock.end() && nHeight < rit->second->nHeight)
-                        rit->second = blit->second;
+                        rit->second = pindex;
                 }
                 vAffected.clear();
             }
@@ -3815,7 +3826,7 @@ unsigned int CWallet::ComputeTimeSmart(const CWalletTx& wtx) const
 {
     unsigned int nTimeSmart = wtx.nTimeReceived;
     if (!wtx.hashUnset()) {
-        if (mapBlockIndex.count(wtx.hashBlock)) {
+        if (const CBlockIndex* pindex = LookupBlockIndex(wtx.hashBlock)) {
             int64_t latestNow = wtx.nTimeReceived;
             int64_t latestEntry = 0;
 
@@ -3846,7 +3857,7 @@ unsigned int CWallet::ComputeTimeSmart(const CWalletTx& wtx) const
                 }
             }
 
-            int64_t blocktime = mapBlockIndex[wtx.hashBlock]->GetBlockTime();
+            int64_t blocktime = pindex->GetBlockTime();
             nTimeSmart = std::max(latestEntry, std::min(blocktime, latestNow));
         } else {
             LogPrintf("%s: found %s in block %s not in index\n", __func__, wtx.GetHash().ToString(), wtx.hashBlock.ToString());
@@ -3919,7 +3930,7 @@ CWallet* CWallet::CreateWalletFromFile(const std::string& name, const fs::path&
 
         std::unique_ptr<CWallet> tempWallet = MakeUnique<CWallet>(name, CWalletDBWrapper::Create(path));
         DBErrors nZapWalletRet = tempWallet->ZapWalletTx(vWtx);
-        if (nZapWalletRet != DB_LOAD_OK) {
+        if (nZapWalletRet != DBErrors::LOAD_OK) {
             InitError(strprintf(_("Error loading %s: Wallet corrupted"), walletFile));
             return nullptr;
         }
@@ -3931,23 +3942,23 @@ CWallet* CWallet::CreateWalletFromFile(const std::string& name, const fs::path&
     bool fFirstRun = true;
     CWallet *walletInstance = new CWallet(name, CWalletDBWrapper::Create(path));
     DBErrors nLoadWalletRet = walletInstance->LoadWallet(fFirstRun);
-    if (nLoadWalletRet != DB_LOAD_OK)
+    if (nLoadWalletRet != DBErrors::LOAD_OK)
     {
-        if (nLoadWalletRet == DB_CORRUPT) {
+        if (nLoadWalletRet == DBErrors::CORRUPT) {
             InitError(strprintf(_("Error loading %s: Wallet corrupted"), walletFile));
             return nullptr;
         }
-        else if (nLoadWalletRet == DB_NONCRITICAL_ERROR)
+        else if (nLoadWalletRet == DBErrors::NONCRITICAL_ERROR)
         {
             InitWarning(strprintf(_("Error reading %s! All keys read correctly, but transaction data"
                                          " or address book entries might be missing or incorrect."),
                 walletFile));
         }
-        else if (nLoadWalletRet == DB_TOO_NEW) {
+        else if (nLoadWalletRet == DBErrors::TOO_NEW) {
             InitError(strprintf(_("Error loading %s: Wallet requires newer version of %s"), walletFile, _(PACKAGE_NAME)));
             return nullptr;
         }
-        else if (nLoadWalletRet == DB_NEED_REWRITE)
+        else if (nLoadWalletRet == DBErrors::NEED_REWRITE)
         {
             InitError(strprintf(_("Wallet needed to be rewritten: restart %s to complete"), _(PACKAGE_NAME)));
             return nullptr;
@@ -3998,8 +4009,7 @@ CWallet* CWallet::CreateWalletFromFile(const std::string& name, const fs::path&
         }
 
         walletInstance->SetBestChain(chainActive.GetLocator());
-    }
-    else if (gArgs.IsArgSet("-usehd")) {
+    } else if (gArgs.IsArgSet("-usehd")) {
         bool useHD = gArgs.GetBoolArg("-usehd", true);
         if (walletInstance->IsHDEnabled() && !useHD) {
             InitError(strprintf(_("Error loading %s: You can't disable HD on an already existing HD wallet"), walletFile));
@@ -4011,11 +4021,27 @@ CWallet* CWallet::CreateWalletFromFile(const std::string& name, const fs::path&
         }
     }
 
+    walletInstance->m_default_address_type = ParseOutputType(gArgs.GetArg("-addresstype", ""), DEFAULT_ADDRESS_TYPE);
+    if (walletInstance->m_default_address_type == OutputType::NONE) {
+        InitError(strprintf("Unknown address type '%s'", gArgs.GetArg("-addresstype", "")));
+        return nullptr;
+    }
+
+    // If changetype is set in config file or parameter, check that it's valid.
+    // Default to OutputType::NONE if not set.
+    walletInstance->m_default_change_type = ParseOutputType(gArgs.GetArg("-changetype", ""), OutputType::NONE);
+    if (walletInstance->m_default_change_type == OutputType::NONE && !gArgs.GetArg("-changetype", "").empty()) {
+        InitError(strprintf("Unknown change type '%s'", gArgs.GetArg("-changetype", "")));
+        return nullptr;
+    }
+
     LogPrintf(" wallet      %15dms\n", GetTimeMillis() - nStart);
 
     // Try to top up keypool. No-op if the wallet is locked.
     walletInstance->TopUpKeyPool();
 
+    LOCK(cs_main);
+
     CBlockIndex *pindexRescan = chainActive.Genesis();
     if (!gArgs.GetBoolArg("-rescan", false))
     {
@@ -4159,10 +4185,7 @@ int CMerkleTx::GetDepthInMainChain(const CBlockIndex* &pindexRet) const
     AssertLockHeld(cs_main);
 
     // Find the block it claims to be in
-    BlockMap::iterator mi = mapBlockIndex.find(hashBlock);
-    if (mi == mapBlockIndex.end())
-        return 0;
-    CBlockIndex* pindex = (*mi).second;
+    CBlockIndex* pindex = LookupBlockIndex(hashBlock);
     if (!pindex || !chainActive.Contains(pindex))
         return 0;
 
@@ -4183,8 +4206,8 @@ bool CWalletTx::AcceptToMemoryPool(const CAmount& nAbsurdFee, CValidationState&
     // We must set fInMempool here - while it will be re-set to true by the
     // entered-mempool callback, if we did not there would be a race where a
     // user could call sendmoney in a loop and hit spurious out of funds errors
-    // because we think that the transaction they just generated's change is
-    // unavailable as we're not yet aware its in mempool.
+    // because we think that this newly generated transaction's change is
+    // unavailable as we're not yet aware that it is in the mempool.
     bool ret = ::AcceptToMemoryPool(mempool, state, tx, nullptr /* pfMissingInputs */,
                                 nullptr /* plTxnReplaced */, false /* bypass_limits */, nAbsurdFee);
     fInMempool |= ret;
@@ -4200,29 +4223,29 @@ OutputType ParseOutputType(const std::string& type, OutputType default_type)
     if (type.empty()) {
         return default_type;
     } else if (type == OUTPUT_TYPE_STRING_LEGACY) {
-        return OUTPUT_TYPE_LEGACY;
+        return OutputType::LEGACY;
     } else if (type == OUTPUT_TYPE_STRING_P2SH_SEGWIT) {
-        return OUTPUT_TYPE_P2SH_SEGWIT;
+        return OutputType::P2SH_SEGWIT;
     } else if (type == OUTPUT_TYPE_STRING_BECH32) {
-        return OUTPUT_TYPE_BECH32;
+        return OutputType::BECH32;
     } else {
-        return OUTPUT_TYPE_NONE;
+        return OutputType::NONE;
     }
 }
 
 const std::string& FormatOutputType(OutputType type)
 {
     switch (type) {
-    case OUTPUT_TYPE_LEGACY: return OUTPUT_TYPE_STRING_LEGACY;
-    case OUTPUT_TYPE_P2SH_SEGWIT: return OUTPUT_TYPE_STRING_P2SH_SEGWIT;
-    case OUTPUT_TYPE_BECH32: return OUTPUT_TYPE_STRING_BECH32;
+    case OutputType::LEGACY: return OUTPUT_TYPE_STRING_LEGACY;
+    case OutputType::P2SH_SEGWIT: return OUTPUT_TYPE_STRING_P2SH_SEGWIT;
+    case OutputType::BECH32: return OUTPUT_TYPE_STRING_BECH32;
     default: assert(false);
     }
 }
 
 void CWallet::LearnRelatedScripts(const CPubKey& key, OutputType type)
 {
-    if (key.IsCompressed() && (type == OUTPUT_TYPE_P2SH_SEGWIT || type == OUTPUT_TYPE_BECH32)) {
+    if (key.IsCompressed() && (type == OutputType::P2SH_SEGWIT || type == OutputType::BECH32)) {
         CTxDestination witdest = WitnessV0KeyHash(key.GetID());
         CScript witprog = GetScriptForDestination(witdest);
         // Make sure the resulting program is solvable.
@@ -4233,20 +4256,20 @@ void CWallet::LearnRelatedScripts(const CPubKey& key, OutputType type)
 
 void CWallet::LearnAllRelatedScripts(const CPubKey& key)
 {
-    // OUTPUT_TYPE_P2SH_SEGWIT always adds all necessary scripts for all types.
-    LearnRelatedScripts(key, OUTPUT_TYPE_P2SH_SEGWIT);
+    // OutputType::P2SH_SEGWIT always adds all necessary scripts for all types.
+    LearnRelatedScripts(key, OutputType::P2SH_SEGWIT);
 }
 
 CTxDestination GetDestinationForKey(const CPubKey& key, OutputType type)
 {
     switch (type) {
-    case OUTPUT_TYPE_LEGACY: return key.GetID();
-    case OUTPUT_TYPE_P2SH_SEGWIT:
-    case OUTPUT_TYPE_BECH32: {
+    case OutputType::LEGACY: return key.GetID();
+    case OutputType::P2SH_SEGWIT:
+    case OutputType::BECH32: {
         if (!key.IsCompressed()) return key.GetID();
         CTxDestination witdest = WitnessV0KeyHash(key.GetID());
         CScript witprog = GetScriptForDestination(witdest);
-        if (type == OUTPUT_TYPE_P2SH_SEGWIT) {
+        if (type == OutputType::P2SH_SEGWIT) {
             return CScriptID(witprog);
         } else {
             return witdest;
@@ -4272,10 +4295,10 @@ CTxDestination CWallet::AddAndGetDestinationForScript(const CScript& script, Out
 {
     // Note that scripts over 520 bytes are not yet supported.
     switch (type) {
-    case OUTPUT_TYPE_LEGACY:
+    case OutputType::LEGACY:
         return CScriptID(script);
-    case OUTPUT_TYPE_P2SH_SEGWIT:
-    case OUTPUT_TYPE_BECH32: {
+    case OutputType::P2SH_SEGWIT:
+    case OutputType::BECH32: {
         WitnessV0ScriptHash hash;
         CSHA256().Write(script.data(), script.size()).Finalize(hash.begin());
         CTxDestination witdest = hash;
@@ -4284,7 +4307,7 @@ CTxDestination CWallet::AddAndGetDestinationForScript(const CScript& script, Out
         if (!IsSolvable(*this, witprog)) return CScriptID(script);
         // Add the redeemscript, so that P2WSH and P2SH-P2WSH outputs are recognized as ours.
         AddCScript(witprog);
-        if (type == OUTPUT_TYPE_BECH32) {
+        if (type == OutputType::BECH32) {
             return witdest;
         } else {
             return CScriptID(witprog);
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index 3e2d1794d8..898c32c708 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -17,12 +17,14 @@
 #include <script/sign.h>
 #include <util.h>
 #include <wallet/crypter.h>
+#include <wallet/coinselection.h>
 #include <wallet/walletdb.h>
 #include <wallet/rpcwallet.h>
 
 #include <algorithm>
 #include <atomic>
 #include <map>
+#include <memory>
 #include <set>
 #include <stdexcept>
 #include <stdint.h>
@@ -42,6 +44,7 @@ extern bool bSpendZeroConfChange;
 extern bool fWalletRbf;
 extern bool g_wallet_allow_fallback_fee;
 
+//! Default for -keypool
 static const unsigned int DEFAULT_KEYPOOL_SIZE = 1000;
 //! -paytxfee default
 static const CAmount DEFAULT_TRANSACTION_FEE = 0;
@@ -53,10 +56,6 @@ static const CAmount DEFAULT_DISCARD_FEE = 10000;
 static const CAmount DEFAULT_TRANSACTION_MINFEE = 1000;
 //! minimum recommended increment for BIP 125 replacement txs
 static const CAmount WALLET_INCREMENTAL_RELAY_FEE = 5000;
-//! target minimum change amount
-static const CAmount MIN_CHANGE = CENT;
-//! final minimum change amount after paying for fees
-static const CAmount MIN_FINAL_CHANGE = MIN_CHANGE/2;
 //! Default for -spendzeroconfchange
 static const bool DEFAULT_SPEND_ZEROCONF_CHANGE = true;
 //! Default for -walletrejectlongchains
@@ -99,18 +98,15 @@ enum WalletFeature
     FEATURE_LATEST = FEATURE_COMPRPUBKEY // HD is optional, use FEATURE_COMPRPUBKEY as latest version
 };
 
-enum OutputType : int
-{
-    OUTPUT_TYPE_NONE,
-    OUTPUT_TYPE_LEGACY,
-    OUTPUT_TYPE_P2SH_SEGWIT,
-    OUTPUT_TYPE_BECH32,
-
-    OUTPUT_TYPE_DEFAULT = OUTPUT_TYPE_P2SH_SEGWIT
+enum class OutputType {
+    NONE,
+    LEGACY,
+    P2SH_SEGWIT,
+    BECH32,
 };
 
-extern OutputType g_address_type;
-extern OutputType g_change_type;
+//! Default for -addresstype
+constexpr OutputType DEFAULT_ADDRESS_TYPE{OutputType::P2SH_SEGWIT};
 
 
 /** A key pool entry */
@@ -269,6 +265,9 @@ public:
     bool IsCoinBase() const { return tx->IsCoinBase(); }
 };
 
+//Get the marginal bytes of spending the specified output
+int CalculateMaximumSignedInputSize(const CTxOut& txout, const CWallet* pwallet);
+
 /** 
  * A transaction with a bunch of additional info that only the owner cares about.
  * It includes any unrecorded transactions needed to link it back to the block chain.
@@ -348,11 +347,6 @@ public:
     mutable CAmount nAvailableWatchCreditCached;
     mutable CAmount nChangeCached;
 
-    CWalletTx()
-    {
-        Init(nullptr);
-    }
-
     CWalletTx(const CWallet* pwalletIn, CTransactionRef arg) : CMerkleTx(std::move(arg))
     {
         Init(pwalletIn);
@@ -390,42 +384,36 @@ public:
         nOrderPos = -1;
     }
 
-    ADD_SERIALIZE_METHODS;
-
-    template <typename Stream, typename Operation>
-    inline void SerializationOp(Stream& s, Operation ser_action) {
-        if (ser_action.ForRead())
-            Init(nullptr);
+    template<typename Stream>
+    void Serialize(Stream& s) const
+    {
         char fSpent = false;
+        mapValue_t mapValueCopy = mapValue;
 
-        if (!ser_action.ForRead())
-        {
-            mapValue["fromaccount"] = strFromAccount;
-
-            WriteOrderPos(nOrderPos, mapValue);
-
-            if (nTimeSmart)
-                mapValue["timesmart"] = strprintf("%u", nTimeSmart);
+        mapValueCopy["fromaccount"] = strFromAccount;
+        WriteOrderPos(nOrderPos, mapValueCopy);
+        if (nTimeSmart) {
+            mapValueCopy["timesmart"] = strprintf("%u", nTimeSmart);
         }
 
-        READWRITE(*static_cast<CMerkleTx*>(this));
+        s << *static_cast<const CMerkleTx*>(this);
         std::vector<CMerkleTx> vUnused; //!< Used to be vtxPrev
-        READWRITE(vUnused);
-        READWRITE(mapValue);
-        READWRITE(vOrderForm);
-        READWRITE(fTimeReceivedIsTxTime);
-        READWRITE(nTimeReceived);
-        READWRITE(fFromMe);
-        READWRITE(fSpent);
-
-        if (ser_action.ForRead())
-        {
-            strFromAccount = mapValue["fromaccount"];
+        s << vUnused << mapValueCopy << vOrderForm << fTimeReceivedIsTxTime << nTimeReceived << fFromMe << fSpent;
+    }
+
+    template<typename Stream>
+    void Unserialize(Stream& s)
+    {
+        Init(nullptr);
+        char fSpent;
 
-            ReadOrderPos(nOrderPos, mapValue);
+        s >> *static_cast<CMerkleTx*>(this);
+        std::vector<CMerkleTx> vUnused; //!< Used to be vtxPrev
+        s >> vUnused >> mapValue >> vOrderForm >> fTimeReceivedIsTxTime >> nTimeReceived >> fFromMe >> fSpent;
 
-            nTimeSmart = mapValue.count("timesmart") ? (unsigned int)atoi64(mapValue["timesmart"]) : 0;
-        }
+        strFromAccount = std::move(mapValue["fromaccount"]);
+        ReadOrderPos(nOrderPos, mapValue);
+        nTimeSmart = mapValue.count("timesmart") ? (unsigned int)atoi64(mapValue["timesmart"]) : 0;
 
         mapValue.erase("fromaccount");
         mapValue.erase("spent");
@@ -462,6 +450,12 @@ public:
     CAmount GetAvailableWatchOnlyCredit(const bool fUseCache=true) const;
     CAmount GetChange() const;
 
+    // Get the marginal bytes if spending the specified output from this transaction
+    int GetSpendSize(unsigned int out) const
+    {
+        return CalculateMaximumSignedInputSize(tx->vout[out], pwallet);
+    }
+
     void GetAmounts(std::list<COutputEntry>& listReceived,
                     std::list<COutputEntry>& listSent, CAmount& nFee, std::string& strSentAccount, const isminefilter& filter) const;
 
@@ -488,36 +482,6 @@ public:
     std::set<uint256> GetConflicts() const;
 };
 
-
-class CInputCoin {
-public:
-    CInputCoin(const CWalletTx* walletTx, unsigned int i)
-    {
-        if (!walletTx)
-            throw std::invalid_argument("walletTx should not be null");
-        if (i >= walletTx->tx->vout.size())
-            throw std::out_of_range("The output index is out of range");
-
-        outpoint = COutPoint(walletTx->GetHash(), i);
-        txout = walletTx->tx->vout[i];
-    }
-
-    COutPoint outpoint;
-    CTxOut txout;
-
-    bool operator<(const CInputCoin& rhs) const {
-        return outpoint < rhs.outpoint;
-    }
-
-    bool operator!=(const CInputCoin& rhs) const {
-        return outpoint != rhs.outpoint;
-    }
-
-    bool operator==(const CInputCoin& rhs) const {
-        return outpoint == rhs.outpoint;
-    }
-};
-
 class COutput
 {
 public:
@@ -525,6 +489,9 @@ public:
     int i;
     int nDepth;
 
+    /** Pre-computed estimated size of this output as a fully-signed input in a transaction. Can be -1 if it could not be calculated */
+    int nInputBytes;
+
     /** Whether we have the private keys to spend this output */
     bool fSpendable;
 
@@ -540,7 +507,12 @@ public:
 
     COutput(const CWalletTx *txIn, int iIn, int nDepthIn, bool fSpendableIn, bool fSolvableIn, bool fSafeIn)
     {
-        tx = txIn; i = iIn; nDepth = nDepthIn; fSpendable = fSpendableIn; fSolvable = fSolvableIn; fSafe = fSafeIn;
+        tx = txIn; i = iIn; nDepth = nDepthIn; fSpendable = fSpendableIn; fSolvable = fSolvableIn; fSafe = fSafeIn; nInputBytes = -1;
+        // If known and signable by the given wallet, compute nInputBytes
+        // Failure will keep this value -1
+        if (fSpendable && tx) {
+            nInputBytes = tx->GetSpendSize(i);
+        }
     }
 
     std::string ToString() const;
@@ -608,48 +580,49 @@ public:
         nEntryNo = 0;
     }
 
-    ADD_SERIALIZE_METHODS;
-
-    template <typename Stream, typename Operation>
-    inline void SerializationOp(Stream& s, Operation ser_action) {
+    template <typename Stream>
+    void Serialize(Stream& s) const {
         int nVersion = s.GetVersion();
-        if (!(s.GetType() & SER_GETHASH))
-            READWRITE(nVersion);
+        if (!(s.GetType() & SER_GETHASH)) {
+            s << nVersion;
+        }
         //! Note: strAccount is serialized as part of the key, not here.
-        READWRITE(nCreditDebit);
-        READWRITE(nTime);
-        READWRITE(LIMITED_STRING(strOtherAccount, 65536));
-
-        if (!ser_action.ForRead())
-        {
-            WriteOrderPos(nOrderPos, mapValue);
-
-            if (!(mapValue.empty() && _ssExtra.empty()))
-            {
-                CDataStream ss(s.GetType(), s.GetVersion());
-                ss.insert(ss.begin(), '\0');
-                ss << mapValue;
-                ss.insert(ss.end(), _ssExtra.begin(), _ssExtra.end());
-                strComment.append(ss.str());
-            }
+        s << nCreditDebit << nTime << strOtherAccount;
+
+        mapValue_t mapValueCopy = mapValue;
+        WriteOrderPos(nOrderPos, mapValueCopy);
+
+        std::string strCommentCopy = strComment;
+        if (!mapValueCopy.empty() || !_ssExtra.empty()) {
+            CDataStream ss(s.GetType(), s.GetVersion());
+            ss.insert(ss.begin(), '\0');
+            ss << mapValueCopy;
+            ss.insert(ss.end(), _ssExtra.begin(), _ssExtra.end());
+            strCommentCopy.append(ss.str());
         }
+        s << strCommentCopy;
+    }
 
-        READWRITE(LIMITED_STRING(strComment, 65536));
+    template <typename Stream>
+    void Unserialize(Stream& s) {
+        int nVersion = s.GetVersion();
+        if (!(s.GetType() & SER_GETHASH)) {
+            s >> nVersion;
+        }
+        //! Note: strAccount is serialized as part of the key, not here.
+        s >> nCreditDebit >> nTime >> LIMITED_STRING(strOtherAccount, 65536) >> LIMITED_STRING(strComment, 65536);
 
         size_t nSepPos = strComment.find("\0", 0, 1);
-        if (ser_action.ForRead())
-        {
-            mapValue.clear();
-            if (std::string::npos != nSepPos)
-            {
-                CDataStream ss(std::vector<char>(strComment.begin() + nSepPos + 1, strComment.end()), s.GetType(), s.GetVersion());
-                ss >> mapValue;
-                _ssExtra = std::vector<char>(ss.begin(), ss.end());
-            }
-            ReadOrderPos(nOrderPos, mapValue);
+        mapValue.clear();
+        if (std::string::npos != nSepPos) {
+            CDataStream ss(std::vector<char>(strComment.begin() + nSepPos + 1, strComment.end()), s.GetType(), s.GetVersion());
+            ss >> mapValue;
+            _ssExtra = std::vector<char>(ss.begin(), ss.end());
         }
-        if (std::string::npos != nSepPos)
+        ReadOrderPos(nOrderPos, mapValue);
+        if (std::string::npos != nSepPos) {
             strComment.erase(nSepPos);
+        }
 
         mapValue.erase("n");
     }
@@ -658,6 +631,26 @@ private:
     std::vector<char> _ssExtra;
 };
 
+struct CoinSelectionParams
+{
+    bool use_bnb = true;
+    size_t change_output_size = 0;
+    size_t change_spend_size = 0;
+    CFeeRate effective_fee = CFeeRate(0);
+    size_t tx_noinputs_size = 0;
+
+    CoinSelectionParams(bool use_bnb, size_t change_output_size, size_t change_spend_size, CFeeRate effective_fee, size_t tx_noinputs_size) : use_bnb(use_bnb), change_output_size(change_output_size), change_spend_size(change_spend_size), effective_fee(effective_fee), tx_noinputs_size(tx_noinputs_size) {}
+    CoinSelectionParams() {}
+};
+
+struct CoinEligibilityFilter
+{
+    const int conf_mine;
+    const int conf_theirs;
+    const uint64_t max_ancestors;
+
+    CoinEligibilityFilter(int conf_mine, int conf_theirs, uint64_t max_ancestors) : conf_mine(conf_mine), conf_theirs(conf_theirs), max_ancestors(max_ancestors) {}
+};
 
 class WalletRescanReserver; //forward declarations for ScanForWalletTransactions/RescanFromTime
 /** 
@@ -673,14 +666,6 @@ private:
     std::mutex mutexScanning;
     friend class WalletRescanReserver;
 
-
-    /**
-     * Select a set of coins such that nValueRet >= nTargetValue and at least
-     * all coins from coinControl are selected; Never select unconfirmed coins
-     * if they are not ours
-     */
-    bool SelectCoins(const std::vector<COutput>& vAvailableCoins, const CAmount& nTargetValue, std::set<CInputCoin>& setCoinsRet, CAmount& nValueRet, const CCoinControl *coinControl = nullptr) const;
-
     CWalletDB *pwalletdbEncryption;
 
     //! the current wallet version: clients below this version are not able to load the wallet
@@ -773,6 +758,14 @@ public:
         return *dbw;
     }
 
+    /**
+     * Select a set of coins such that nValueRet >= nTargetValue and at least
+     * all coins from coinControl are selected; Never select unconfirmed coins
+     * if they are not ours
+     */
+    bool SelectCoins(const std::vector<COutput>& vAvailableCoins, const CAmount& nTargetValue, std::set<CInputCoin>& setCoinsRet, CAmount& nValueRet,
+                    const CCoinControl& coin_control, CoinSelectionParams& coin_selection_params, bool& bnb_used) const;
+
     /** Get a name for this wallet for logging/debugging purposes.
      */
     const std::string& GetName() const { return m_name; }
@@ -860,7 +853,8 @@ public:
      * completion the coin set and corresponding actual target value is
      * assembled
      */
-    bool SelectCoinsMinConf(const CAmount& nTargetValue, int nConfMine, int nConfTheirs, uint64_t nMaxAncestors, std::vector<COutput> vCoins, std::set<CInputCoin>& setCoinsRet, CAmount& nValueRet) const;
+    bool SelectCoinsMinConf(const CAmount& nTargetValue, const CoinEligibilityFilter& eligibility_filter, std::vector<COutput> vCoins,
+        std::set<CInputCoin>& setCoinsRet, CAmount& nValueRet, const CoinSelectionParams& coin_selection_params, bool& bnb_used) const;
 
     bool IsSpent(const uint256& hash, unsigned int n) const;
 
@@ -935,7 +929,7 @@ public:
     int64_t IncOrderPosNext(CWalletDB *pwalletdb = nullptr);
     DBErrors ReorderTransactions();
     bool AccountMove(std::string strFrom, std::string strTo, CAmount nAmount, std::string strComment = "");
-    bool GetAccountDestination(CTxDestination &dest, std::string strAccount, bool bForceNew = false);
+    bool GetLabelDestination(CTxDestination &dest, const std::string& label, bool bForceNew = false);
 
     void MarkDirty();
     bool AddToWallet(const CWalletTx& wtxIn, bool fFlushOnClose=true);
@@ -974,19 +968,27 @@ public:
      * selected by SelectCoins(); Also create the change output, when needed
      * @note passing nChangePosInOut as -1 will result in setting a random position
      */
-    bool CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletTx& wtxNew, CReserveKey& reservekey, CAmount& nFeeRet, int& nChangePosInOut,
+    bool CreateTransaction(const std::vector<CRecipient>& vecSend, CTransactionRef& tx, CReserveKey& reservekey, CAmount& nFeeRet, int& nChangePosInOut,
                            std::string& strFailReason, const CCoinControl& coin_control, bool sign = true);
-    bool CommitTransaction(CWalletTx& wtxNew, CReserveKey& reservekey, CConnman* connman, CValidationState& state);
+    bool CommitTransaction(CTransactionRef tx, mapValue_t mapValue, std::vector<std::pair<std::string, std::string>> orderForm, std::string fromAccount, CReserveKey& reservekey, CConnman* connman, CValidationState& state);
 
     void ListAccountCreditDebit(const std::string& strAccount, std::list<CAccountingEntry>& entries);
     bool AddAccountingEntry(const CAccountingEntry&);
     bool AddAccountingEntry(const CAccountingEntry&, CWalletDB *pwalletdb);
-    template <typename ContainerType>
-    bool DummySignTx(CMutableTransaction &txNew, const ContainerType &coins) const;
+    bool DummySignTx(CMutableTransaction &txNew, const std::set<CTxOut> &txouts) const
+    {
+        std::vector<CTxOut> v_txouts(txouts.size());
+        std::copy(txouts.begin(), txouts.end(), v_txouts.begin());
+        return DummySignTx(txNew, v_txouts);
+    }
+    bool DummySignTx(CMutableTransaction &txNew, const std::vector<CTxOut> &txouts) const;
+    bool DummySignInput(CTxIn &tx_in, const CTxOut &txout) const;
 
     static CFeeRate minTxFee;
     static CFeeRate fallbackFee;
     static CFeeRate m_discard_rate;
+    OutputType m_default_address_type{DEFAULT_ADDRESS_TYPE};
+    OutputType m_default_change_type{OutputType::NONE}; // Default to OutputType::NONE if not set by -changetype
 
     bool NewKeyPool();
     size_t KeypoolCountExternalKeys();
@@ -1005,7 +1007,7 @@ public:
     std::set< std::set<CTxDestination> > GetAddressGroupings();
     std::map<CTxDestination, CAmount> GetAddressBalances();
 
-    std::set<CTxDestination> GetAccountAddresses(const std::string& strAccount) const;
+    std::set<CTxDestination> GetLabelAddresses(const std::string& label) const;
 
     isminetype IsMine(const CTxIn& txin) const;
     /**
@@ -1035,7 +1037,7 @@ public:
 
     bool DelAddressBook(const CTxDestination& address);
 
-    const std::string& GetAccountName(const CScript& scriptPubKey) const;
+    const std::string& GetLabelName(const CScript& scriptPubKey) const;
 
     void Inventory(const uint256 &hash) override
     {
@@ -1163,6 +1165,9 @@ public:
      * This function will automatically add the necessary scripts to the wallet.
      */
     CTxDestination AddAndGetDestinationForScript(const CScript& script, OutputType);
+
+    /** Whether a given output is spendable by this wallet */
+    bool OutputEligibleForSpending(const COutput& output, const CoinEligibilityFilter& eligibility_filter) const;
 };
 
 /** A key allocated from the key pool. */
@@ -1227,32 +1232,7 @@ public:
     }
 };
 
-// Helper for producing a bunch of max-sized low-S signatures (eg 72 bytes)
-// ContainerType is meant to hold pair<CWalletTx *, int>, and be iterable
-// so that each entry corresponds to each vIn, in order.
-template <typename ContainerType>
-bool CWallet::DummySignTx(CMutableTransaction &txNew, const ContainerType &coins) const
-{
-    // Fill in dummy signatures for fee calculation.
-    int nIn = 0;
-    for (const auto& coin : coins)
-    {
-        const CScript& scriptPubKey = coin.txout.scriptPubKey;
-        SignatureData sigdata;
-
-        if (!ProduceSignature(DummySignatureCreator(this), scriptPubKey, sigdata))
-        {
-            return false;
-        } else {
-            UpdateTransaction(txNew, nIn, sigdata);
-        }
-
-        nIn++;
-    }
-    return true;
-}
-
-OutputType ParseOutputType(const std::string& str, OutputType default_type = OUTPUT_TYPE_DEFAULT);
+OutputType ParseOutputType(const std::string& str, OutputType default_type);
 const std::string& FormatOutputType(OutputType type);
 
 /**
@@ -1299,4 +1279,10 @@ public:
     }
 };
 
+// Calculate the size of the transaction assuming all signatures are max size
+// Use DummySignatureCreator, which inserts 72 byte signatures everywhere.
+// NOTE: this requires that all inputs must be in mapWallet (eg the tx should
+// be IsAllFromMe).
+int64_t CalculateMaximumSignedTxSize(const CTransaction &tx, const CWallet *wallet);
+int64_t CalculateMaximumSignedTxSize(const CTransaction &tx, const CWallet *wallet, const std::vector<CTxOut>& txouts);
 #endif // BITCOIN_WALLET_WALLET_H
diff --git a/src/wallet/walletdb.cpp b/src/wallet/walletdb.cpp
index 0b0880a2ba..77cdfe7dd0 100644
--- a/src/wallet/walletdb.cpp
+++ b/src/wallet/walletdb.cpp
@@ -265,7 +265,7 @@ ReadKeyValue(CWallet* pwallet, CDataStream& ssKey, CDataStream& ssValue,
         {
             uint256 hash;
             ssKey >> hash;
-            CWalletTx wtx;
+            CWalletTx wtx(nullptr /* pwallet */, MakeTransactionRef());
             ssValue >> wtx;
             CValidationState state;
             if (!(CheckTransaction(*wtx.tx, state) && (wtx.GetHash() == hash) && state.IsValid()))
@@ -522,7 +522,7 @@ DBErrors CWalletDB::LoadWallet(CWallet* pwallet)
 {
     CWalletScanState wss;
     bool fNoncriticalErrors = false;
-    DBErrors result = DB_LOAD_OK;
+    DBErrors result = DBErrors::LOAD_OK;
 
     LOCK(pwallet->cs_wallet);
     try {
@@ -530,7 +530,7 @@ DBErrors CWalletDB::LoadWallet(CWallet* pwallet)
         if (batch.Read((std::string)"minversion", nMinVersion))
         {
             if (nMinVersion > CLIENT_VERSION)
-                return DB_TOO_NEW;
+                return DBErrors::TOO_NEW;
             pwallet->LoadMinVersion(nMinVersion);
         }
 
@@ -539,7 +539,7 @@ DBErrors CWalletDB::LoadWallet(CWallet* pwallet)
         if (!pcursor)
         {
             LogPrintf("Error getting wallet database cursor\n");
-            return DB_CORRUPT;
+            return DBErrors::CORRUPT;
         }
 
         while (true)
@@ -553,7 +553,7 @@ DBErrors CWalletDB::LoadWallet(CWallet* pwallet)
             else if (ret != 0)
             {
                 LogPrintf("Error reading next record from wallet database\n");
-                return DB_CORRUPT;
+                return DBErrors::CORRUPT;
             }
 
             // Try to be tolerant of single corrupt records:
@@ -563,7 +563,7 @@ DBErrors CWalletDB::LoadWallet(CWallet* pwallet)
                 // losing keys is considered a catastrophic error, anything else
                 // we assume the user can live with:
                 if (IsKeyType(strType) || strType == "defaultkey")
-                    result = DB_CORRUPT;
+                    result = DBErrors::CORRUPT;
                 else
                 {
                     // Leave other errors alone, if we try to fix them we might make things worse.
@@ -582,15 +582,15 @@ DBErrors CWalletDB::LoadWallet(CWallet* pwallet)
         throw;
     }
     catch (...) {
-        result = DB_CORRUPT;
+        result = DBErrors::CORRUPT;
     }
 
-    if (fNoncriticalErrors && result == DB_LOAD_OK)
-        result = DB_NONCRITICAL_ERROR;
+    if (fNoncriticalErrors && result == DBErrors::LOAD_OK)
+        result = DBErrors::NONCRITICAL_ERROR;
 
     // Any wallet corruption at all: skip any rewriting or
     // upgrading, we don't want to make it worse.
-    if (result != DB_LOAD_OK)
+    if (result != DBErrors::LOAD_OK)
         return result;
 
     LogPrintf("nFileVersion = %d\n", wss.nFileVersion);
@@ -603,11 +603,11 @@ DBErrors CWalletDB::LoadWallet(CWallet* pwallet)
         pwallet->UpdateTimeFirstKey(1);
 
     for (uint256 hash : wss.vWalletUpgrade)
-        WriteTx(pwallet->mapWallet[hash]);
+        WriteTx(pwallet->mapWallet.at(hash));
 
     // Rewrite encrypted wallets of versions 0.4.0 and 0.5.0rc:
     if (wss.fIsEncrypted && (wss.nFileVersion == 40000 || wss.nFileVersion == 50000))
-        return DB_NEED_REWRITE;
+        return DBErrors::NEED_REWRITE;
 
     if (wss.nFileVersion < CLIENT_VERSION) // Update
         WriteVersion(CLIENT_VERSION);
@@ -626,14 +626,14 @@ DBErrors CWalletDB::LoadWallet(CWallet* pwallet)
 
 DBErrors CWalletDB::FindWalletTx(std::vector<uint256>& vTxHash, std::vector<CWalletTx>& vWtx)
 {
-    DBErrors result = DB_LOAD_OK;
+    DBErrors result = DBErrors::LOAD_OK;
 
     try {
         int nMinVersion = 0;
         if (batch.Read((std::string)"minversion", nMinVersion))
         {
             if (nMinVersion > CLIENT_VERSION)
-                return DB_TOO_NEW;
+                return DBErrors::TOO_NEW;
         }
 
         // Get cursor
@@ -641,7 +641,7 @@ DBErrors CWalletDB::FindWalletTx(std::vector<uint256>& vTxHash, std::vector<CWal
         if (!pcursor)
         {
             LogPrintf("Error getting wallet database cursor\n");
-            return DB_CORRUPT;
+            return DBErrors::CORRUPT;
         }
 
         while (true)
@@ -655,7 +655,7 @@ DBErrors CWalletDB::FindWalletTx(std::vector<uint256>& vTxHash, std::vector<CWal
             else if (ret != 0)
             {
                 LogPrintf("Error reading next record from wallet database\n");
-                return DB_CORRUPT;
+                return DBErrors::CORRUPT;
             }
 
             std::string strType;
@@ -664,7 +664,7 @@ DBErrors CWalletDB::FindWalletTx(std::vector<uint256>& vTxHash, std::vector<CWal
                 uint256 hash;
                 ssKey >> hash;
 
-                CWalletTx wtx;
+                CWalletTx wtx(nullptr /* pwallet */, MakeTransactionRef());
                 ssValue >> wtx;
 
                 vTxHash.push_back(hash);
@@ -677,7 +677,7 @@ DBErrors CWalletDB::FindWalletTx(std::vector<uint256>& vTxHash, std::vector<CWal
         throw;
     }
     catch (...) {
-        result = DB_CORRUPT;
+        result = DBErrors::CORRUPT;
     }
 
     return result;
@@ -689,7 +689,7 @@ DBErrors CWalletDB::ZapSelectTx(std::vector<uint256>& vTxHashIn, std::vector<uin
     std::vector<uint256> vTxHash;
     std::vector<CWalletTx> vWtx;
     DBErrors err = FindWalletTx(vTxHash, vWtx);
-    if (err != DB_LOAD_OK) {
+    if (err != DBErrors::LOAD_OK) {
         return err;
     }
 
@@ -716,9 +716,9 @@ DBErrors CWalletDB::ZapSelectTx(std::vector<uint256>& vTxHashIn, std::vector<uin
     }
 
     if (delerror) {
-        return DB_CORRUPT;
+        return DBErrors::CORRUPT;
     }
-    return DB_LOAD_OK;
+    return DBErrors::LOAD_OK;
 }
 
 DBErrors CWalletDB::ZapWalletTx(std::vector<CWalletTx>& vWtx)
@@ -726,16 +726,16 @@ DBErrors CWalletDB::ZapWalletTx(std::vector<CWalletTx>& vWtx)
     // build list of wallet TXs
     std::vector<uint256> vTxHash;
     DBErrors err = FindWalletTx(vTxHash, vWtx);
-    if (err != DB_LOAD_OK)
+    if (err != DBErrors::LOAD_OK)
         return err;
 
     // erase each wallet TX
     for (uint256& hash : vTxHash) {
         if (!EraseTx(hash))
-            return DB_CORRUPT;
+            return DBErrors::CORRUPT;
     }
 
-    return DB_LOAD_OK;
+    return DBErrors::LOAD_OK;
 }
 
 void MaybeCompactWalletDB()
diff --git a/src/wallet/walletdb.h b/src/wallet/walletdb.h
index 7d754c7284..606b7dace7 100644
--- a/src/wallet/walletdb.h
+++ b/src/wallet/walletdb.h
@@ -46,14 +46,14 @@ class uint160;
 class uint256;
 
 /** Error statuses for the wallet database */
-enum DBErrors
+enum class DBErrors
 {
-    DB_LOAD_OK,
-    DB_CORRUPT,
-    DB_NONCRITICAL_ERROR,
-    DB_TOO_NEW,
-    DB_LOAD_FAIL,
-    DB_NEED_REWRITE
+    LOAD_OK,
+    CORRUPT,
+    NONCRITICAL_ERROR,
+    TOO_NEW,
+    LOAD_FAIL,
+    NEED_REWRITE
 };
 
 /* simple HD chain data model */
diff --git a/src/wallet/walletutil.h b/src/wallet/walletutil.h
index 50ff736402..f12acacd00 100644
--- a/src/wallet/walletutil.h
+++ b/src/wallet/walletutil.h
@@ -2,8 +2,8 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#ifndef BITCOIN_WALLET_UTIL_H
-#define BITCOIN_WALLET_UTIL_H
+#ifndef BITCOIN_WALLET_WALLETUTIL_H
+#define BITCOIN_WALLET_WALLETUTIL_H
 
 #include <chainparamsbase.h>
 #include <util.h>
@@ -11,4 +11,4 @@
 //! Get the path of the wallet directory.
 fs::path GetWalletDir();
 
-#endif // BITCOIN_WALLET_UTIL_H
+#endif // BITCOIN_WALLET_WALLETUTIL_H