Merge #11403: SegWit wallet support

b224a47a1 Add address_types test (Pieter Wuille)
7ee54fd7c Support downgrading after recovered keypool witness keys (Pieter Wuille)
940a21932 SegWit wallet support (Pieter Wuille)
f37c64e47 Implicitly know about P2WPKH redeemscripts (Pieter Wuille)
57273f2b3 [test] Serialize CTransaction with witness by default (Pieter Wuille)
cf2c0b6f5 Support P2WPKH and P2SH-P2WPKH in dumpprivkey (Pieter Wuille)
37c03d3e0 Support P2WPKH addresses in create/addmultisig (Pieter Wuille)
3eaa003c8 Extend validateaddress information for P2SH-embedded witness (Pieter Wuille)
30a27dc5b Expose method to find key for a single-key destination (Pieter Wuille)
985c79552 Improve witness destination types and use them more (Pieter Wuille)
cbe197470 [refactor] GetAccount{PubKey,Address} -> GetAccountDestination (Pieter Wuille)
0c8ea6380 Abstract out IsSolvable from Witnessifier (Pieter Wuille)

Pull request description:

  This implements a minimum viable implementation of SegWit wallet support, based on top of #11389, and includes part of the functionality from #11089.

  Two new configuration options are added:
  * `-addresstype`, with options `legacy`, `p2sh`, and `bech32`. It controls what kind of addresses are produced by `getnewaddress`, `getaccountaddress`, and `createmultisigaddress`.
  * `-changetype`, with the same options, and by default equal to `-addresstype`, that controls what kind of change is used.

  All wallet private and public keys can be used for any type of address. Support for address types dependent on different derivation paths will need a major overhaul of how our internal detection of outputs work. I expect that that will happen for a next major version.

  The above also applies to imported keys, as having a distinction there but not for normal operations is a disaster for testing, and probably for comprehension of users. This has some ugly effects, like needing to associate the provided label to `importprivkey` with each style address for the corresponding key.

  To deal with witness outputs requiring a corresponding redeemscript in wallet, three approaches are used:
  * All SegWit addresses created through `getnewaddress` or multisig RPCs explicitly get their redeemscripts added to the wallet file. This means that downgrading after creating a witness address will work, as long as the wallet file is up to date.
  * All SegWit keys in the wallet get an _implicit_ redeemscript added, without it being written to the file. This means recovery of an old backup will work, as long as you use new software.
  * All keypool keys that are seen used in transactions explicitly get their redeemscripts added to the wallet files. This means that downgrading after recovering from a backup that includes a witness address will work.

  These approaches correspond to solutions 3a, 1a, and 5a respectively from https://gist.github.com/sipa/125cfa1615946d0c3f3eec2ad7f250a2. As argued there, there is no full solution for dealing with the case where you both downgrade and restore a backup, so that's also not implemented.

  `dumpwallet`, `importwallet`, `importmulti`, `signmessage` and `verifymessage` don't work with SegWit addresses yet. They're remaining TODOs, for this PR or a follow-up. Because of that, several tests unexpectedly run with `-addresstype=legacy` for now.

Tree-SHA512: d425dbe517c0422061ab8dacdc3a6ae47da071450932ed992c79559d922dff7b2574a31a8c94feccd3761c1dffb6422c50055e6dca8e3cf94a169bc95e39e959

7 files changed, 236 insertions, 47 deletions

diff --git a/src/wallet/crypter.cpp b/src/wallet/crypter.cpp
index fd7e1bb56c..6ad18721fd 100644
--- a/src/wallet/crypter.cpp
+++ b/src/wallet/crypter.cpp
@@ -245,6 +245,7 @@ bool CCryptoKeyStore::AddCryptedKey(const CPubKey &vchPubKey, const std::vector<
     }
 
     mapCryptedKeys[vchPubKey.GetID()] = make_pair(vchPubKey, vchCryptedSecret);
+    ImplicitlyLearnRelatedKeyScripts(vchPubKey);
     return true;
 }
 
diff --git a/src/wallet/init.cpp b/src/wallet/init.cpp
index 71e7111b1a..0f453f154f 100644
--- a/src/wallet/init.cpp
+++ b/src/wallet/init.cpp
@@ -16,6 +16,8 @@
 std::string GetWalletHelpString(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("-changetype", _("What type of change to use (\"legacy\", \"p2sh-segwit\", or \"bech32\", default is same as -addresstype)"));
     strUsage += HelpMessageOpt("-disablewallet", _("Do not load the wallet and disable wallet RPC calls"));
     strUsage += HelpMessageOpt("-keypool=<n>", strprintf(_("Set key pool size to <n> (default: %u)"), DEFAULT_KEYPOOL_SIZE));
     strUsage += HelpMessageOpt("-fallbackfee=<amt>", strprintf(_("A fee rate (in %s/kB) that will be used when fee estimation has insufficient data (default: %s)"),
@@ -175,6 +177,16 @@ 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", "")));
+    }
+
+    g_change_type = ParseOutputType(gArgs.GetArg("-changetype", ""), g_address_type);
+    if (g_change_type == OUTPUT_TYPE_NONE) {
+        return InitError(strprintf(_("Unknown change type '%s'"), gArgs.GetArg("-changetype", "")));
+    }
+
     return true;
 }
 
diff --git a/src/wallet/rpcdump.cpp b/src/wallet/rpcdump.cpp
index fc84fe6468..645e776b68 100644
--- a/src/wallet/rpcdump.cpp
+++ b/src/wallet/rpcdump.cpp
@@ -131,7 +131,11 @@ UniValue importprivkey(const JSONRPCRequest& request)
     CKeyID vchAddress = pubkey.GetID();
     {
         pwallet->MarkDirty();
-        pwallet->SetAddressBook(vchAddress, strLabel, "receive");
+
+        // We don't know which corresponding address will be used; label them all
+        for (const auto& dest : GetAllDestinationsForKey(pubkey)) {
+            pwallet->SetAddressBook(dest, strLabel, "receive");
+        }
 
         // Don't throw error in case a key is already there
         if (pwallet->HaveKey(vchAddress)) {
@@ -143,6 +147,7 @@ UniValue importprivkey(const JSONRPCRequest& request)
         if (!pwallet->AddKeyPubKey(key, pubkey)) {
             throw JSONRPCError(RPC_WALLET_ERROR, "Error adding key to wallet");
         }
+        pwallet->LearnAllRelatedScripts(pubkey);
 
         // whenever a key is imported, we need to scan the whole chain
         pwallet->UpdateTimeFirstKey(1);
@@ -433,8 +438,11 @@ UniValue importpubkey(const JSONRPCRequest& request)
 
     LOCK2(cs_main, pwallet->cs_wallet);
 
-    ImportAddress(pwallet, pubKey.GetID(), strLabel);
+    for (const auto& dest : GetAllDestinationsForKey(pubKey)) {
+        ImportAddress(pwallet, dest, strLabel);
+    }
     ImportScript(pwallet, GetScriptForRawPubKey(pubKey), strLabel, false);
+    pwallet->LearnAllRelatedScripts(pubKey);
 
     if (fRescan)
     {
@@ -595,12 +603,12 @@ UniValue dumpprivkey(const JSONRPCRequest& request)
     if (!IsValidDestination(dest)) {
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid Bitcoin address");
     }
-    const CKeyID *keyID = boost::get<CKeyID>(&dest);
-    if (!keyID) {
+    auto keyid = GetKeyForDestination(*pwallet, dest);
+    if (keyid.IsNull()) {
         throw JSONRPCError(RPC_TYPE_ERROR, "Address does not refer to a key");
     }
     CKey vchSecret;
-    if (!pwallet->GetKey(*keyID, vchSecret)) {
+    if (!pwallet->GetKey(keyid, vchSecret)) {
         throw JSONRPCError(RPC_WALLET_ERROR, "Private key for address " + strAddress + " is not known");
     }
     return CBitcoinSecret(vchSecret).ToString();
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index df9bdd39bb..e307623fd5 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -136,14 +136,15 @@ UniValue getnewaddress(const JSONRPCRequest& request)
         return NullUniValue;
     }
 
-    if (request.fHelp || request.params.size() > 1)
+    if (request.fHelp || request.params.size() > 2)
         throw std::runtime_error(
-            "getnewaddress ( \"account\" )\n"
+            "getnewaddress ( \"account\" \"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"
             "\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"
+            "2. \"address_type\"   (string, optional) The address type to use. Options are \"legacy\", \"p2sh\", and \"bech32\". Default is set by -addresstype.\n"
             "\nResult:\n"
             "\"address\"    (string) The new bitcoin address\n"
             "\nExamples:\n"
@@ -158,6 +159,14 @@ UniValue getnewaddress(const JSONRPCRequest& request)
     if (!request.params[0].isNull())
         strAccount = AccountFromValue(request.params[0]);
 
+    OutputType output_type = g_address_type;
+    if (!request.params[1].isNull()) {
+        output_type = ParseOutputType(request.params[1].get_str(), g_address_type);
+        if (output_type == OUTPUT_TYPE_NONE) {
+            throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("Unknown address type '%s'", request.params[1].get_str()));
+        }
+    }
+
     if (!pwallet->IsLocked()) {
         pwallet->TopUpKeyPool();
     }
@@ -167,22 +176,23 @@ UniValue getnewaddress(const JSONRPCRequest& request)
     if (!pwallet->GetKeyFromPool(newKey)) {
         throw JSONRPCError(RPC_WALLET_KEYPOOL_RAN_OUT, "Error: Keypool ran out, please call keypoolrefill first");
     }
-    CKeyID keyID = newKey.GetID();
+    pwallet->LearnRelatedScripts(newKey, output_type);
+    CTxDestination dest = GetDestinationForKey(newKey, output_type);
 
-    pwallet->SetAddressBook(keyID, strAccount, "receive");
+    pwallet->SetAddressBook(dest, strAccount, "receive");
 
-    return EncodeDestination(keyID);
+    return EncodeDestination(dest);
 }
 
 
-CTxDestination GetAccountAddress(CWallet* const pwallet, std::string strAccount, bool bForceNew=false)
+CTxDestination GetAccountDestination(CWallet* const pwallet, std::string strAccount, bool bForceNew=false)
 {
-    CPubKey pubKey;
-    if (!pwallet->GetAccountPubkey(pubKey, strAccount, bForceNew)) {
+    CTxDestination dest;
+    if (!pwallet->GetAccountDestination(dest, strAccount, bForceNew)) {
         throw JSONRPCError(RPC_WALLET_KEYPOOL_RAN_OUT, "Error: Keypool ran out, please call keypoolrefill first");
     }
 
-    return pubKey.GetID();
+    return dest;
 }
 
 UniValue getaccountaddress(const JSONRPCRequest& request)
@@ -214,7 +224,7 @@ UniValue getaccountaddress(const JSONRPCRequest& request)
 
     UniValue ret(UniValue::VSTR);
 
-    ret = EncodeDestination(GetAccountAddress(pwallet, strAccount));
+    ret = EncodeDestination(GetAccountDestination(pwallet, strAccount));
     return ret;
 }
 
@@ -226,11 +236,13 @@ UniValue getrawchangeaddress(const JSONRPCRequest& request)
         return NullUniValue;
     }
 
-    if (request.fHelp || request.params.size() > 0)
+    if (request.fHelp || request.params.size() > 1)
         throw std::runtime_error(
-            "getrawchangeaddress\n"
+            "getrawchangeaddress ( \"address_type\" )\n"
             "\nReturns a new Bitcoin address, for receiving change.\n"
             "This is for use with raw transactions, NOT normal use.\n"
+            "\nArguments:\n"
+            "1. \"address_type\"           (string, optional) The address type to use. Options are \"legacy\", \"p2sh\", and \"bech32\". Default is set by -changetype.\n"
             "\nResult:\n"
             "\"address\"    (string) The address\n"
             "\nExamples:\n"
@@ -244,6 +256,14 @@ UniValue getrawchangeaddress(const JSONRPCRequest& request)
         pwallet->TopUpKeyPool();
     }
 
+    OutputType output_type = g_change_type;
+    if (!request.params[0].isNull()) {
+        output_type = ParseOutputType(request.params[0].get_str(), g_change_type);
+        if (output_type == OUTPUT_TYPE_NONE) {
+            throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("Unknown address type '%s'", request.params[0].get_str()));
+        }
+    }
+
     CReserveKey reservekey(pwallet);
     CPubKey vchPubKey;
     if (!reservekey.GetReservedKey(vchPubKey, true))
@@ -251,9 +271,10 @@ UniValue getrawchangeaddress(const JSONRPCRequest& request)
 
     reservekey.KeepKey();
 
-    CKeyID keyID = vchPubKey.GetID();
+    pwallet->LearnRelatedScripts(vchPubKey, output_type);
+    CTxDestination dest = GetDestinationForKey(vchPubKey, output_type);
 
-    return EncodeDestination(keyID);
+    return EncodeDestination(dest);
 }
 
 
@@ -292,8 +313,8 @@ UniValue setaccount(const JSONRPCRequest& request)
         // Detect when changing the account of an address that is the 'unused current key' of another account:
         if (pwallet->mapAddressBook.count(dest)) {
             std::string strOldAccount = pwallet->mapAddressBook[dest].name;
-            if (dest == GetAccountAddress(pwallet, strOldAccount)) {
-                GetAccountAddress(pwallet, strOldAccount, true);
+            if (dest == GetAccountDestination(pwallet, strOldAccount)) {
+                GetAccountDestination(pwallet, strOldAccount, true);
             }
         }
         pwallet->SetAddressBook(dest, strAccount, "receive");
@@ -1188,11 +1209,12 @@ UniValue addmultisigaddress(const JSONRPCRequest& request)
 
     // Construct using pay-to-script-hash:
     CScript inner = _createmultisig_redeemScript(pwallet, request.params);
-    CScriptID innerID(inner);
     pwallet->AddCScript(inner);
 
-    pwallet->SetAddressBook(innerID, strAccount, "send");
-    return EncodeDestination(innerID);
+    CTxDestination dest = pwallet->AddAndGetDestinationForScript(inner, g_address_type);
+
+    pwallet->SetAddressBook(dest, strAccount, "send");
+    return EncodeDestination(dest);
 }
 
 class Witnessifier : public boost::static_visitor<bool>
@@ -1208,12 +1230,7 @@ public:
         if (pwallet) {
             CScript basescript = GetScriptForDestination(keyID);
             CScript witscript = GetScriptForWitness(basescript);
-            SignatureData sigs;
-            // This check is to make sure that the script we created can actually be solved for and signed by us
-            // if we were to have the private keys. This is just to make sure that the script is valid and that,
-            // if found in a transaction, we would still accept and relay that transaction.
-            if (!ProduceSignature(DummySignatureCreator(pwallet), witscript, sigs) ||
-                !VerifyScript(sigs.scriptSig, witscript, &sigs.scriptWitness, MANDATORY_SCRIPT_VERIFY_FLAGS | SCRIPT_VERIFY_WITNESS_PUBKEYTYPE, DummySignatureCreator(pwallet).Checker())) {
+            if (!IsSolvable(*pwallet, witscript)) {
                 return false;
             }
             return ExtractDestination(witscript, result);
@@ -1232,12 +1249,7 @@ public:
                 return true;
             }
             CScript witscript = GetScriptForWitness(subscript);
-            SignatureData sigs;
-            // This check is to make sure that the script we created can actually be solved for and signed by us
-            // if we were to have the private keys. This is just to make sure that the script is valid and that,
-            // if found in a transaction, we would still accept and relay that transaction.
-            if (!ProduceSignature(DummySignatureCreator(pwallet), witscript, sigs) ||
-                !VerifyScript(sigs.scriptSig, witscript, &sigs.scriptWitness, MANDATORY_SCRIPT_VERIFY_FLAGS | SCRIPT_VERIFY_WITNESS_PUBKEYTYPE, DummySignatureCreator(pwallet).Checker())) {
+            if (!IsSolvable(*pwallet, witscript)) {
                 return false;
             }
             return ExtractDestination(witscript, result);
@@ -1321,7 +1333,7 @@ UniValue addwitnessaddress(const JSONRPCRequest& request)
             throw JSONRPCError(RPC_WALLET_ERROR, "Cannot convert between witness address types");
         }
     } else {
-        pwallet->AddCScript(witprogram);
+        pwallet->AddCScript(witprogram); // Implicit for single-key now, but necessary for multisig and for compatibility with older software
         pwallet->SetAddressBook(w.result, "", "receive");
     }
 
@@ -3466,8 +3478,8 @@ static const CRPCCommand commands[] =
     { "wallet",             "getaccount",               &getaccount,               {"address"} },
     { "wallet",             "getaddressesbyaccount",    &getaddressesbyaccount,    {"account"} },
     { "wallet",             "getbalance",               &getbalance,               {"account","minconf","include_watchonly"} },
-    { "wallet",             "getnewaddress",            &getnewaddress,            {"account"} },
-    { "wallet",             "getrawchangeaddress",      &getrawchangeaddress,      {} },
+    { "wallet",             "getnewaddress",            &getnewaddress,            {"account","address_type"} },
+    { "wallet",             "getrawchangeaddress",      &getrawchangeaddress,      {"address_type"} },
     { "wallet",             "getreceivedbyaccount",     &getreceivedbyaccount,     {"account","minconf"} },
     { "wallet",             "getreceivedbyaddress",     &getreceivedbyaddress,     {"address","minconf"} },
     { "wallet",             "gettransaction",           &gettransaction,           {"txid","include_watchonly"} },
diff --git a/src/wallet/test/wallet_test_fixture.cpp b/src/wallet/test/wallet_test_fixture.cpp
index b2e297755e..7797f85f07 100644
--- a/src/wallet/test/wallet_test_fixture.cpp
+++ b/src/wallet/test/wallet_test_fixture.cpp
@@ -13,6 +13,8 @@ WalletTestingSetup::WalletTestingSetup(const std::string& chainName):
     bitdb.MakeMock();
 
     bool fFirstRun;
+    g_address_type = OUTPUT_TYPE_DEFAULT;
+    g_change_type = OUTPUT_TYPE_DEFAULT;
     std::unique_ptr<CWalletDBWrapper> dbw(new CWalletDBWrapper(&bitdb, "wallet_test.dat"));
     pwalletMain = MakeUnique<CWallet>(std::move(dbw));
     pwalletMain->LoadWallet(fFirstRun);
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index e8b21b3d6f..da721ea008 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -42,6 +42,8 @@ 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;
 
 const char * DEFAULT_WALLET_DAT = "wallet.dat";
 const uint32_t BIP32_HARDENED_KEY_LIMIT = 0x80000000;
@@ -821,7 +823,7 @@ bool CWallet::AccountMove(std::string strFrom, std::string strTo, CAmount nAmoun
     return true;
 }
 
-bool CWallet::GetAccountPubkey(CPubKey &pubKey, std::string strAccount, bool bForceNew)
+bool CWallet::GetAccountDestination(CTxDestination &dest, std::string strAccount, bool bForceNew)
 {
     CWalletDB walletdb(*dbw);
 
@@ -832,8 +834,8 @@ bool CWallet::GetAccountPubkey(CPubKey &pubKey, std::string strAccount, bool bFo
         if (!account.vchPubKey.IsValid())
             bForceNew = true;
         else {
-            // Check if the current key has been used
-            CScript scriptPubKey = GetScriptForDestination(account.vchPubKey.GetID());
+            // 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));
             for (std::map<uint256, CWalletTx>::iterator it = mapWallet.begin();
                  it != mapWallet.end() && account.vchPubKey.IsValid();
                  ++it)
@@ -850,12 +852,14 @@ bool CWallet::GetAccountPubkey(CPubKey &pubKey, std::string strAccount, bool bFo
         if (!GetKeyFromPool(account.vchPubKey, false))
             return false;
 
-        SetAddressBook(account.vchPubKey.GetID(), strAccount, "receive");
+        LearnRelatedScripts(account.vchPubKey, g_address_type);
+        dest = GetDestinationForKey(account.vchPubKey, g_address_type);
+        SetAddressBook(dest, strAccount, "receive");
         walletdb.WriteAccount(strAccount, account);
+    } else {
+        dest = GetDestinationForKey(account.vchPubKey, g_address_type);
     }
 
-    pubKey = account.vchPubKey;
-
     return true;
 }
 
@@ -2735,7 +2739,8 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletT
                     return false;
                 }
 
-                scriptChange = GetScriptForDestination(vchPubKey.GetID());
+                LearnRelatedScripts(vchPubKey, g_change_type);
+                scriptChange = GetScriptForDestination(GetDestinationForKey(vchPubKey, g_change_type));
             }
             CTxOut change_prototype_txout(0, scriptChange);
             size_t change_prototype_size = GetSerializeSize(change_prototype_txout, SER_DISK, 0);
@@ -3624,6 +3629,7 @@ void CWallet::MarkReserveKeysAsUsed(int64_t keypool_id)
         if (walletdb.ReadPool(index, keypool)) { //TODO: This should be unnecessary
             m_pool_key_to_index.erase(keypool.vchPubKey.GetID());
         }
+        LearnAllRelatedScripts(keypool.vchPubKey);
         walletdb.ErasePool(index);
         LogPrintf("keypool index %d removed\n", index);
         it = setKeyPool->erase(it);
@@ -4128,3 +4134,106 @@ bool CWalletTx::AcceptToMemoryPool(const CAmount& nAbsurdFee, CValidationState&
     fInMempool = ret;
     return ret;
 }
+
+static const std::string OUTPUT_TYPE_STRING_LEGACY = "legacy";
+static const std::string OUTPUT_TYPE_STRING_P2SH_SEGWIT = "p2sh-segwit";
+static const std::string OUTPUT_TYPE_STRING_BECH32 = "bech32";
+
+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;
+    } else if (type == OUTPUT_TYPE_STRING_P2SH_SEGWIT) {
+        return OUTPUT_TYPE_P2SH_SEGWIT;
+    } else if (type == OUTPUT_TYPE_STRING_BECH32) {
+        return OUTPUT_TYPE_BECH32;
+    } else {
+        return OUTPUT_TYPE_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;
+    default: assert(false);
+    }
+}
+
+void CWallet::LearnRelatedScripts(const CPubKey& key, OutputType type)
+{
+    if (key.IsCompressed() && (type == OUTPUT_TYPE_P2SH_SEGWIT || type == OUTPUT_TYPE_BECH32)) {
+        CTxDestination witdest = WitnessV0KeyHash(key.GetID());
+        CScript witprog = GetScriptForDestination(witdest);
+        // Make sure the resulting program is solvable.
+        assert(IsSolvable(*this, witprog));
+        AddCScript(witprog);
+    }
+}
+
+void CWallet::LearnAllRelatedScripts(const CPubKey& key)
+{
+    // OUTPUT_TYPE_P2SH_SEGWIT always adds all necessary scripts for all types.
+    LearnRelatedScripts(key, OUTPUT_TYPE_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: {
+        if (!key.IsCompressed()) return key.GetID();
+        CTxDestination witdest = WitnessV0KeyHash(key.GetID());
+        CScript witprog = GetScriptForDestination(witdest);
+        if (type == OUTPUT_TYPE_P2SH_SEGWIT) {
+            return CScriptID(witprog);
+        } else {
+            return witdest;
+        }
+    }
+    default: assert(false);
+    }
+}
+
+std::vector<CTxDestination> GetAllDestinationsForKey(const CPubKey& key)
+{
+    CKeyID keyid = key.GetID();
+    if (key.IsCompressed()) {
+        CTxDestination segwit = WitnessV0KeyHash(keyid);
+        CTxDestination p2sh = CScriptID(GetScriptForDestination(segwit));
+        return std::vector<CTxDestination>{std::move(keyid), std::move(p2sh), std::move(segwit)};
+    } else {
+        return std::vector<CTxDestination>{std::move(keyid)};
+    }
+}
+
+CTxDestination CWallet::AddAndGetDestinationForScript(const CScript& script, OutputType type)
+{
+    // Note that scripts over 520 bytes are not yet supported.
+    switch (type) {
+    case OUTPUT_TYPE_LEGACY:
+        return CScriptID(script);
+    case OUTPUT_TYPE_P2SH_SEGWIT:
+    case OUTPUT_TYPE_BECH32: {
+        WitnessV0ScriptHash hash;
+        CSHA256().Write(script.data(), script.size()).Finalize(hash.begin());
+        CTxDestination witdest = hash;
+        CScript witprog = GetScriptForDestination(witdest);
+        // Check if the resulting program is solvable (i.e. doesn't use an uncompressed key)
+        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) {
+            return witdest;
+        } else {
+            return CScriptID(witprog);
+        }
+    }
+    default: assert(false);
+    }
+}
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index 08950869b7..53a2c6b9d5 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -99,6 +99,19 @@ enum WalletFeature
     FEATURE_LATEST = FEATURE_COMPRPUBKEY // HD is optional, use FEATURE_COMPRPUBKEY as latest version
 };
 
+enum OutputType
+{
+    OUTPUT_TYPE_NONE,
+    OUTPUT_TYPE_LEGACY,
+    OUTPUT_TYPE_P2SH_SEGWIT,
+    OUTPUT_TYPE_BECH32,
+
+    OUTPUT_TYPE_DEFAULT = OUTPUT_TYPE_P2SH_SEGWIT
+};
+
+extern OutputType g_address_type;
+extern OutputType g_change_type;
+
 
 /** A key pool entry */
 class CKeyPool
@@ -923,7 +936,7 @@ public:
     int64_t IncOrderPosNext(CWalletDB *pwalletdb = nullptr);
     DBErrors ReorderTransactions();
     bool AccountMove(std::string strFrom, std::string strTo, CAmount nAmount, std::string strComment = "");
-    bool GetAccountPubkey(CPubKey &pubKey, std::string strAccount, bool bForceNew = false);
+    bool GetAccountDestination(CTxDestination &dest, std::string strAccount, bool bForceNew = false);
 
     void MarkDirty();
     bool AddToWallet(const CWalletTx& wtxIn, bool fFlushOnClose=true);
@@ -1129,6 +1142,26 @@ public:
      * deadlock
      */
     void BlockUntilSyncedToCurrentChain();
+
+    /**
+     * Explicitly make the wallet learn the related scripts for outputs to the
+     * given key. This is purely to make the wallet file compatible with older
+     * software, as CBasicKeyStore automatically does this implicitly for all
+     * keys now.
+     */
+    void LearnRelatedScripts(const CPubKey& key, OutputType);
+
+    /**
+     * Same as LearnRelatedScripts, but when the OutputType is not known (and could
+     * be anything).
+     */
+    void LearnAllRelatedScripts(const CPubKey& key);
+
+    /**
+     * Get a destination of the requested type (if possible) to the specified script.
+     * This function will automatically add the necessary scripts to the wallet.
+     */
+    CTxDestination AddAndGetDestinationForScript(const CScript& script, OutputType);
 };
 
 /** A key allocated from the key pool. */
@@ -1218,4 +1251,16 @@ bool CWallet::DummySignTx(CMutableTransaction &txNew, const ContainerType &coins
     return true;
 }
 
+OutputType ParseOutputType(const std::string& str, OutputType default_type = OUTPUT_TYPE_DEFAULT);
+const std::string& FormatOutputType(OutputType type);
+
+/**
+ * Get a destination of the requested type (if possible) to the specified key.
+ * The caller must make sure LearnRelatedScripts has been called beforehand.
+ */
+CTxDestination GetDestinationForKey(const CPubKey& key, OutputType);
+
+/** Get all destinations (potentially) supported by the wallet for the given key. */
+std::vector<CTxDestination> GetAllDestinationsForKey(const CPubKey& key);
+
 #endif // BITCOIN_WALLET_WALLET_H