29 files changed, 1066 insertions, 166 deletions
diff --git a/src/Makefile.am b/src/Makefile.am
index 60ecf07a59..d1693fa85c 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -158,6 +158,7 @@ BITCOIN_CORE_H = \
   rpc/register.h \
   rpc/util.h \
   scheduler.h \
+  script/descriptor.h \
   script/ismine.h \
   script/sigcache.h \
   script/sign.h \
@@ -387,6 +388,7 @@ libbitcoin_common_a_SOURCES = \
   policy/feerate.cpp \
   protocol.cpp \
   scheduler.cpp \
+  script/descriptor.cpp \
   script/ismine.cpp \
   script/sign.cpp \
   script/standard.cpp \
diff --git a/src/Makefile.test.include b/src/Makefile.test.include
index 02f2063504..6f401636f5 100644
--- a/src/Makefile.test.include
+++ b/src/Makefile.test.include
@@ -47,6 +47,7 @@ BITCOIN_TESTS =\
   test/crypto_tests.cpp \
   test/cuckoocache_tests.cpp \
   test/denialofservice_tests.cpp \
+  test/descriptor_tests.cpp \
   test/getarg_tests.cpp \
   test/hash_tests.cpp \
   test/key_io_tests.cpp \
diff --git a/src/bench/coin_selection.cpp b/src/bench/coin_selection.cpp
index 7510d53c88..20013d702b 100644
--- a/src/bench/coin_selection.cpp
+++ b/src/bench/coin_selection.cpp
@@ -21,7 +21,7 @@ static void addCoin(const CAmount& nValue, const CWallet& wallet, std::vector<Ou
 
     int nAge = 6 * 24;
     COutput output(wtx, nInput, nAge, true /* spendable */, true /* solvable */, true /* safe */);
-    groups.emplace_back(output.GetInputCoin(), 0, false, 0, 0);
+    groups.emplace_back(output.GetInputCoin(), 6, false, 0, 0);
 }
 
 // Simple benchmark for wallet coin selection. Note that it maybe be necessary
diff --git a/src/bench/mempool_eviction.cpp b/src/bench/mempool_eviction.cpp
index 4c947a519f..d37291b900 100644
--- a/src/bench/mempool_eviction.cpp
+++ b/src/bench/mempool_eviction.cpp
@@ -9,7 +9,7 @@
 #include <list>
 #include <vector>
 
-static void AddTx(const CTransactionRef& tx, const CAmount& nFee, CTxMemPool& pool)
+static void AddTx(const CTransactionRef& tx, const CAmount& nFee, CTxMemPool& pool) EXCLUSIVE_LOCKS_REQUIRED(pool.cs)
 {
     int64_t nTime = 0;
     unsigned int nHeight = 1;
@@ -108,6 +108,7 @@ static void MempoolEviction(benchmark::State& state)
     tx7.vout[1].nValue = 10 * COIN;
 
     CTxMemPool pool;
+    LOCK(pool.cs);
     // Create transaction references outside the "hot loop"
     const CTransactionRef tx1_r{MakeTransactionRef(tx1)};
     const CTransactionRef tx2_r{MakeTransactionRef(tx2)};
diff --git a/src/bitcoind.cpp b/src/bitcoind.cpp
index 5c711c0773..4d010c0d14 100644
--- a/src/bitcoind.cpp
+++ b/src/bitcoind.cpp
@@ -96,7 +96,7 @@ static bool AppInit(int argc, char* argv[])
             fprintf(stderr, "Error: Specified data directory \"%s\" does not exist.\n", gArgs.GetArg("-datadir", "").c_str());
             return false;
         }
-        if (!gArgs.ReadConfigFiles(error)) {
+        if (!gArgs.ReadConfigFiles(error, true)) {
             fprintf(stderr, "Error reading configuration file: %s\n", error.c_str());
             return false;
         }
diff --git a/src/chainparams.cpp b/src/chainparams.cpp
index 71762158f0..b517717c97 100644
--- a/src/chainparams.cpp
+++ b/src/chainparams.cpp
@@ -102,10 +102,10 @@ public:
         consensus.vDeployments[Consensus::DEPLOYMENT_SEGWIT].nTimeout = 1510704000; // November 15th, 2017.
 
         // The best chain should have at least this much work.
-        consensus.nMinimumChainWork = uint256S("0x000000000000000000000000000000000000000000f91c579d57cad4bc5278cc");
+        consensus.nMinimumChainWork = uint256S("0x0000000000000000000000000000000000000000028822fef1c230963535a90d");
 
         // By default assume that the signatures in ancestors of this block are valid.
-        consensus.defaultAssumeValid = uint256S("0x0000000000000000005214481d2d96f898e3d5416e43359c145944a909d242e0"); //506067
+        consensus.defaultAssumeValid = uint256S("0x0000000000000000002e63058c023a9a1de233554f28c7b21380b6c9003f36a8"); //534292
 
         /**
          * The message start string is designed to be unlikely to occur in normal data.
@@ -170,11 +170,10 @@ public:
         };
 
         chainTxData = ChainTxData{
-            // Data as of block 0000000000000000002d6cca6761c99b3c2e936f9a0e304b7c7651a993f461de (height 506081).
-            1516903077, // * UNIX timestamp of last known number of transactions
-            295363220,  // * total number of transactions between genesis and that timestamp
-                        //   (the tx=... number in the ChainStateFlushed debug.log lines)
-            3.5         // * estimated number of transactions per second after that timestamp
+            // Data from rpc: getchaintxstats 4096 0000000000000000002e63058c023a9a1de233554f28c7b21380b6c9003f36a8
+            /* nTime    */ 1532884444,
+            /* nTxCount */ 331282217,
+            /* dTxRate  */ 2.4
         };
 
         /* disable fallback fee on mainnet */
@@ -217,10 +216,10 @@ public:
         consensus.vDeployments[Consensus::DEPLOYMENT_SEGWIT].nTimeout = 1493596800; // May 1st 2017
 
         // The best chain should have at least this much work.
-        consensus.nMinimumChainWork = uint256S("0x00000000000000000000000000000000000000000000002830dab7f76dbb7d63");
+        consensus.nMinimumChainWork = uint256S("0x00000000000000000000000000000000000000000000007dbe94253893cbd463");
 
         // By default assume that the signatures in ancestors of this block are valid.
-        consensus.defaultAssumeValid = uint256S("0x0000000002e9e7b00e1f6dc5123a04aad68dd0f0968d8c7aa45f6640795c37b1"); //1135275
+        consensus.defaultAssumeValid = uint256S("0x0000000000000037a8cd3e06cd5edbfe9dd1dbcc5dacab279376ef7cfc2b4c75"); //1354312
 
         pchMessageStart[0] = 0x0b;
         pchMessageStart[1] = 0x11;
@@ -264,10 +263,10 @@ public:
         };
 
         chainTxData = ChainTxData{
-            // Data as of block 000000000000033cfa3c975eb83ecf2bb4aaedf68e6d279f6ed2b427c64caff9 (height 1260526)
-            1516903490,
-            17082348,
-            0.09
+            // Data from rpc: getchaintxstats 4096 0000000000000037a8cd3e06cd5edbfe9dd1dbcc5dacab279376ef7cfc2b4c75
+            /* nTime    */ 1531929919,
+            /* nTxCount */ 19438708,
+            /* dTxRate  */ 0.626
         };
 
         /* enable fallback fee on testnet */
diff --git a/src/chainparams.h b/src/chainparams.h
index dd029b9d5b..344cbb1a8a 100644
--- a/src/chainparams.h
+++ b/src/chainparams.h
@@ -32,9 +32,9 @@ struct CCheckpointData {
  * See also: CChainParams::TxData, GuessVerificationProgress.
  */
 struct ChainTxData {
-    int64_t nTime;
-    int64_t nTxCount;
-    double dTxRate;
+    int64_t nTime;    //!< UNIX timestamp of last known number of transactions
+    int64_t nTxCount; //!< total number of transactions between genesis and that timestamp
+    double dTxRate;   //!< estimated number of transactions per second after that timestamp
 };
 
 /**
diff --git a/src/init.cpp b/src/init.cpp
index 18402ef5d7..21445929dc 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -382,7 +382,7 @@ void SetupServerArgs()
 #endif
     gArgs.AddArg("-prune=<n>", strprintf("Reduce storage requirements by enabling pruning (deleting) of old blocks. This allows the pruneblockchain RPC to be called to delete specific blocks, and enables automatic pruning of old blocks if a target size in MiB is provided. This mode is incompatible with -txindex and -rescan. "
             "Warning: Reverting this setting requires re-downloading the entire blockchain. "
-            "(default: 0 = disable pruning blocks, 1 = allow manual pruning via RPC, >%u = automatically prune block files to stay under the specified target size in MiB)", MIN_DISK_SPACE_FOR_BLOCK_FILES / 1024 / 1024), false, OptionsCategory::OPTIONS);
+            "(default: 0 = disable pruning blocks, 1 = allow manual pruning via RPC, >=%u = automatically prune block files to stay under the specified target size in MiB)", MIN_DISK_SPACE_FOR_BLOCK_FILES / 1024 / 1024), false, OptionsCategory::OPTIONS);
     gArgs.AddArg("-reindex", "Rebuild chain state and block index from the blk*.dat files on disk", false, OptionsCategory::OPTIONS);
     gArgs.AddArg("-reindex-chainstate", "Rebuild chain state from the currently indexed blocks", false, OptionsCategory::OPTIONS);
 #ifndef WIN32
diff --git a/src/interfaces/node.cpp b/src/interfaces/node.cpp
index db371d104e..106dd38f60 100644
--- a/src/interfaces/node.cpp
+++ b/src/interfaces/node.cpp
@@ -53,7 +53,7 @@ class NodeImpl : public Node
     {
         return gArgs.ParseParameters(argc, argv, error);
     }
-    bool readConfigFiles(std::string& error) override { return gArgs.ReadConfigFiles(error); }
+    bool readConfigFiles(std::string& error) override { return gArgs.ReadConfigFiles(error, true); }
     bool softSetArg(const std::string& arg, const std::string& value) override { return gArgs.SoftSetArg(arg, value); }
     bool softSetBoolArg(const std::string& arg, bool value) override { return gArgs.SoftSetBoolArg(arg, value); }
     void selectParams(const std::string& network) override { SelectParams(network); }
diff --git a/src/net.cpp b/src/net.cpp
index 0ebfefa757..5be91fd4f3 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -1798,7 +1798,6 @@ void CConnman::ThreadOpenConnections(const std::vector<std::string> connect)
         CAddress addrConnect;
 
         // Only connect out to one peer per network group (/16 for IPv4).
-        // Do this here so we don't have to critsect vNodes inside mapAddresses critsect.
         int nOutbound = 0;
         std::set<std::vector<unsigned char> > setConnected;
         {
diff --git a/src/netaddress.cpp b/src/netaddress.cpp
index 5ccbabd03d..193582d14e 100644
--- a/src/netaddress.cpp
+++ b/src/netaddress.cpp
@@ -300,6 +300,9 @@ bool CNetAddr::GetInAddr(struct in_addr* pipv4Addr) const
 
 bool CNetAddr::GetIn6Addr(struct in6_addr* pipv6Addr) const
 {
+    if (!IsIPv6()) {
+        return false;
+    }
     memcpy(pipv6Addr, ip, 16);
     return true;
 }
diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index 012e3e3ac1..46dec4ca6e 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -20,6 +20,7 @@
 #include <policy/policy.h>
 #include <primitives/transaction.h>
 #include <rpc/server.h>
+#include <script/descriptor.h>
 #include <streams.h>
 #include <sync.h>
 #include <txdb.h>
@@ -1984,67 +1985,38 @@ public:
     }
 };
 
-static const char *g_default_scantxoutset_script_types[] = { "P2PKH", "P2SH_P2WPKH", "P2WPKH" };
-
-enum class OutputScriptType {
-    UNKNOWN,
-    P2PK,
-    P2PKH,
-    P2SH_P2WPKH,
-    P2WPKH
-};
-
-static inline OutputScriptType GetOutputScriptTypeFromString(const std::string& outputtype)
-{
-    if (outputtype == "P2PK") return OutputScriptType::P2PK;
-    else if (outputtype == "P2PKH") return OutputScriptType::P2PKH;
-    else if (outputtype == "P2SH_P2WPKH") return OutputScriptType::P2SH_P2WPKH;
-    else if (outputtype == "P2WPKH") return OutputScriptType::P2WPKH;
-    else return OutputScriptType::UNKNOWN;
-}
-
-CTxDestination GetDestinationForKey(const CPubKey& key, OutputScriptType type)
-{
-    switch (type) {
-    case OutputScriptType::P2PKH: return key.GetID();
-    case OutputScriptType::P2SH_P2WPKH:
-    case OutputScriptType::P2WPKH: {
-        if (!key.IsCompressed()) return key.GetID();
-        CTxDestination witdest = WitnessV0KeyHash(key.GetID());
-        if (type == OutputScriptType::P2SH_P2WPKH) {
-            CScript witprog = GetScriptForDestination(witdest);
-            return CScriptID(witprog);
-        } else {
-            return witdest;
-        }
-    }
-    default: assert(false);
-    }
-}
-
 UniValue scantxoutset(const JSONRPCRequest& request)
 {
     if (request.fHelp || request.params.size() < 1 || request.params.size() > 2)
         throw std::runtime_error(
             "scantxoutset <action> ( <scanobjects> )\n"
-            "\nScans the unspent transaction output set for possible entries that matches common scripts of given public keys.\n"
-            "Using addresses as scanobjects will _not_ detect unspent P2PK txouts\n"
+            "\nEXPERIMENTAL warning: this call may be removed or changed in future releases.\n"
+            "\nScans the unspent transaction output set for entries that match certain output descriptors.\n"
+            "Examples of output descriptors are:\n"
+            "    addr(<address>)                      Outputs whose scriptPubKey corresponds to the specified address (does not include P2PK)\n"
+            "    raw(<hex script>)                    Outputs whose scriptPubKey equals the specified hex scripts\n"
+            "    combo(<pubkey>)                      P2PK, P2PKH, P2WPKH, and P2SH-P2WPKH outputs for the given pubkey\n"
+            "    pkh(<pubkey>)                        P2PKH outputs for the given pubkey\n"
+            "    sh(multi(<n>,<pubkey>,<pubkey>,...)) P2SH-multisig outputs for the given threshold and pubkeys\n"
+            "\nIn the above, <pubkey> either refers to a fixed public key in hexadecimal notation, or to an xpub/xprv optionally followed by one\n"
+            "or more path elements separated by \"/\", and optionally ending in \"/*\" (unhardened), or \"/*'\" or \"/*h\" (hardened) to specify all\n"
+            "unhardened or hardened child keys.\n"
+            "In the latter case, a range needs to be specified by below if different from 1000.\n"
+            "For more information on output descriptors, see the documentation at TODO\n"
             "\nArguments:\n"
             "1. \"action\"                       (string, required) The action to execute\n"
             "                                      \"start\" for starting a scan\n"
             "                                      \"abort\" for aborting the current scan (returns true when abort was successful)\n"
             "                                      \"status\" for progress report (in %) of the current scan\n"
-            "2. \"scanobjects\"                  (array, optional) Array of scan objects (only one object type per scan object allowed)\n"
-            "      [\n"
-            "        { \"address\" : \"<address>\" },       (string, optional) Bitcoin address\n"
-            "        { \"script\"  : \"<scriptPubKey>\" },  (string, optional) HEX encoded script (scriptPubKey)\n"
-            "        { \"pubkey\"  :                      (object, optional) Public key\n"
-            "          {\n"
-            "            \"pubkey\" : \"<pubkey\">,         (string, required) HEX encoded public key\n"
-            "            \"script_types\" : [ ... ],      (array, optional) Array of script-types to derive from the pubkey (possible values: \"P2PK\", \"P2PKH\", \"P2SH-P2WPKH\", \"P2WPKH\")\n"
-            "          }\n"
+            "2. \"scanobjects\"                  (array, required) Array of scan objects\n"
+            "    [                             Every scan object is either a string descriptor or an object:\n"
+            "        \"descriptor\",             (string, optional) An output descriptor\n"
+            "        {                         (object, optional) An object with output descriptor and metadata\n"
+            "          \"desc\": \"descriptor\",   (string, required) An output descriptor\n"
+            "          \"range\": n,             (numeric, optional) Up to what child index HD chains should be explored (default: 1000)\n"
             "        },\n"
-            "      ]\n"
+            "        ...\n"
+            "    ]\n"
             "\nResult:\n"
             "{\n"
             "  \"unspents\": [\n"
@@ -2090,79 +2062,35 @@ UniValue scantxoutset(const JSONRPCRequest& request)
 
         // loop through the scan objects
         for (const UniValue& scanobject : request.params[1].get_array().getValues()) {
-            if (!scanobject.isObject()) {
-                throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid scan object");
-            }
-            UniValue address_uni = find_value(scanobject, "address");
-            UniValue pubkey_uni  = find_value(scanobject, "pubkey");
-            UniValue script_uni  = find_value(scanobject, "script");
-
-            // make sure only one object type is present
-            if (1 != !address_uni.isNull() + !pubkey_uni.isNull() + !script_uni.isNull()) {
-                throw JSONRPCError(RPC_INVALID_PARAMETER, "Only one object type is allowed per scan object");
-            } else if (!address_uni.isNull() && !address_uni.isStr()) {
-                throw JSONRPCError(RPC_INVALID_PARAMETER, "Scanobject \"address\" must contain a single string as value");
-            } else if (!pubkey_uni.isNull() && !pubkey_uni.isObject()) {
-                throw JSONRPCError(RPC_INVALID_PARAMETER, "Scanobject \"pubkey\" must contain an object as value");
-            } else if (!script_uni.isNull() && !script_uni.isStr()) {
-                throw JSONRPCError(RPC_INVALID_PARAMETER, "Scanobject \"script\" must contain a single string as value");
-            } else if (address_uni.isStr()) {
-                // type: address
-                // decode destination and derive the scriptPubKey
-                // add the script to the scan containers
-                CTxDestination dest = DecodeDestination(address_uni.get_str());
-                if (!IsValidDestination(dest)) {
-                    throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid address");
-                }
-                CScript script = GetScriptForDestination(dest);
-                assert(!script.empty());
-                needles.insert(script);
-            } else if (pubkey_uni.isObject()) {
-                // type: pubkey
-                // derive script(s) according to the script_type parameter
-                UniValue script_types_uni = find_value(pubkey_uni, "script_types");
-                UniValue pubkeydata_uni = find_value(pubkey_uni, "pubkey");
-
-                // check the script types and use the default if not provided
-                if (!script_types_uni.isNull() && !script_types_uni.isArray()) {
-                    throw JSONRPCError(RPC_INVALID_PARAMETER, "script_types must be an array");
-                } else if (script_types_uni.isNull()) {
-                    // use the default script types
-                    script_types_uni = UniValue(UniValue::VARR);
-                    for (const char *t : g_default_scantxoutset_script_types) {
-                        script_types_uni.push_back(t);
-                    }
-                }
-
-                // check the acctual pubkey
-                if (!pubkeydata_uni.isStr() || !IsHex(pubkeydata_uni.get_str())) {
-                    throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Public key must be hex encoded");
-                }
-                CPubKey pubkey(ParseHexV(pubkeydata_uni, "pubkey"));
-                if (!pubkey.IsFullyValid()) {
-                    throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid public key");
+            std::string desc_str;
+            int range = 1000;
+            if (scanobject.isStr()) {
+                desc_str = scanobject.get_str();
+            } else if (scanobject.isObject()) {
+                UniValue desc_uni = find_value(scanobject, "desc");
+                if (desc_uni.isNull()) throw JSONRPCError(RPC_INVALID_PARAMETER, "Descriptor needs to be provided in scan object");
+                desc_str = desc_uni.get_str();
+                UniValue range_uni = find_value(scanobject, "range");
+                if (!range_uni.isNull()) {
+                    range = range_uni.get_int();
+                    if (range < 0 || range > 1000000) throw JSONRPCError(RPC_INVALID_PARAMETER, "range out of range");
                 }
+            } else {
+                throw JSONRPCError(RPC_INVALID_PARAMETER, "Scan object needs to be either a string or an object");
+            }
 
-                // loop through the script types and derive the script
-                for (const UniValue& script_type_uni : script_types_uni.get_array().getValues()) {
-                    OutputScriptType script_type = GetOutputScriptTypeFromString(script_type_uni.get_str());
-                    if (script_type == OutputScriptType::UNKNOWN) throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid script type");
-                    CScript script;
-                    if (script_type == OutputScriptType::P2PK) {
-                        // support legacy P2PK scripts
-                        script << ToByteVector(pubkey) << OP_CHECKSIG;
-                    } else {
-                        script = GetScriptForDestination(GetDestinationForKey(pubkey, script_type));
-                    }
-                    assert(!script.empty());
-                    needles.insert(script);
+            FlatSigningProvider provider;
+            auto desc = Parse(desc_str, provider);
+            if (!desc) {
+                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("Invalid descriptor '%s'", desc_str));
+            }
+            if (!desc->IsRange()) range = 0;
+            for (int i = 0; i <= range; ++i) {
+                std::vector<CScript> scripts;
+                if (!desc->Expand(i, provider, scripts, provider)) {
+                    throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("Cannot derive script without private keys: '%s'", desc_str));
                 }
-            } else if (script_uni.isStr()) {
-                // type: script
-                // check and add the script to the scan containers (needles array)
-                CScript script(ParseHexV(script_uni, "script"));
-                // TODO: check script: max length, has OP, is unspenable etc.
-                needles.insert(script);
+                needles.insert(scripts.begin(), scripts.end());
             }
         }
 
diff --git a/src/scheduler.h b/src/scheduler.h
index 7169dceee5..66fd44d179 100644
--- a/src/scheduler.h
+++ b/src/scheduler.h
@@ -86,9 +86,13 @@ private:
 
 /**
  * Class used by CScheduler clients which may schedule multiple jobs
- * which are required to be run serially. Does not require such jobs
- * to be executed on the same thread, but no two jobs will be executed
- * at the same time.
+ * which are required to be run serially. Jobs may not be run on the
+ * same thread, but no two jobs will be executed
+ * at the same time and memory will be release-acquire consistent
+ * (the scheduler will internally do an acquire before invoking a callback
+ * as well as a release at the end). In practice this means that a callback
+ * B() will be able to observe all of the effects of callback A() which executed
+ * before it.
  */
 class SingleThreadedSchedulerClient {
 private:
@@ -103,6 +107,13 @@ private:
 
 public:
     explicit SingleThreadedSchedulerClient(CScheduler *pschedulerIn) : m_pscheduler(pschedulerIn) {}
+
+    /**
+     * Add a callback to be executed. Callbacks are executed serially
+     * and memory is release-acquire consistent between callback executions.
+     * Practially, this means that callbacks can behave as if they are executed
+     * in order by a single thread.
+     */
     void AddToProcessQueue(std::function<void (void)> func);
 
     // Processes all remaining queue members on the calling thread, blocking until queue is empty
diff --git a/src/script/descriptor.cpp b/src/script/descriptor.cpp
new file mode 100644
index 0000000000..f366b99ec3
--- /dev/null
+++ b/src/script/descriptor.cpp
@@ -0,0 +1,566 @@
+// Copyright (c) 2018 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 <script/descriptor.h>
+
+#include <key_io.h>
+#include <pubkey.h>
+#include <script/script.h>
+#include <script/standard.h>
+
+#include <span.h>
+#include <util.h>
+#include <utilstrencodings.h>
+
+#include <memory>
+#include <string>
+#include <vector>
+
+namespace {
+
+////////////////////////////////////////////////////////////////////////////
+// Internal representation                                                //
+////////////////////////////////////////////////////////////////////////////
+
+typedef std::vector<uint32_t> KeyPath;
+
+std::string FormatKeyPath(const KeyPath& path)
+{
+    std::string ret;
+    for (auto i : path) {
+        ret += strprintf("/%i", (i << 1) >> 1);
+        if (i >> 31) ret += '\'';
+    }
+    return ret;
+}
+
+/** Interface for public key objects in descriptors. */
+struct PubkeyProvider
+{
+    virtual ~PubkeyProvider() = default;
+
+    /** Derive a public key. */
+    virtual bool GetPubKey(int pos, const SigningProvider& arg, CPubKey& out) const = 0;
+
+    /** Whether this represent multiple public keys at different positions. */
+    virtual bool IsRange() const = 0;
+
+    /** Get the size of the generated public key(s) in bytes (33 or 65). */
+    virtual size_t GetSize() const = 0;
+
+    /** Get the descriptor string form. */
+    virtual std::string ToString() const = 0;
+
+    /** Get the descriptor string form including private data (if available in arg). */
+    virtual bool ToPrivateString(const SigningProvider& arg, std::string& out) const = 0;
+};
+
+/** An object representing a parsed constant public key in a descriptor. */
+class ConstPubkeyProvider final : public PubkeyProvider
+{
+    CPubKey m_pubkey;
+
+public:
+    ConstPubkeyProvider(const CPubKey& pubkey) : m_pubkey(pubkey) {}
+    bool GetPubKey(int pos, const SigningProvider& arg, CPubKey& out) const override
+    {
+        out = m_pubkey;
+        return true;
+    }
+    bool IsRange() const override { return false; }
+    size_t GetSize() const override { return m_pubkey.size(); }
+    std::string ToString() const override { return HexStr(m_pubkey.begin(), m_pubkey.end()); }
+    bool ToPrivateString(const SigningProvider& arg, std::string& ret) const override
+    {
+        CKey key;
+        if (!arg.GetKey(m_pubkey.GetID(), key)) return false;
+        ret = EncodeSecret(key);
+        return true;
+    }
+};
+
+enum class DeriveType {
+    NO,
+    UNHARDENED,
+    HARDENED,
+};
+
+/** An object representing a parsed extended public key in a descriptor. */
+class BIP32PubkeyProvider final : public PubkeyProvider
+{
+    CExtPubKey m_extkey;
+    KeyPath m_path;
+    DeriveType m_derive;
+
+    bool GetExtKey(const SigningProvider& arg, CExtKey& ret) const
+    {
+        CKey key;
+        if (!arg.GetKey(m_extkey.pubkey.GetID(), key)) return false;
+        ret.nDepth = m_extkey.nDepth;
+        std::copy(m_extkey.vchFingerprint, m_extkey.vchFingerprint + 4, ret.vchFingerprint);
+        ret.nChild = m_extkey.nChild;
+        ret.chaincode = m_extkey.chaincode;
+        ret.key = key;
+        return true;
+    }
+
+    bool IsHardened() const
+    {
+        if (m_derive == DeriveType::HARDENED) return true;
+        for (auto entry : m_path) {
+            if (entry >> 31) return true;
+        }
+        return false;
+    }
+
+public:
+    BIP32PubkeyProvider(const CExtPubKey& extkey, KeyPath path, DeriveType derive) : m_extkey(extkey), m_path(std::move(path)), m_derive(derive) {}
+    bool IsRange() const override { return m_derive != DeriveType::NO; }
+    size_t GetSize() const override { return 33; }
+    bool GetPubKey(int pos, const SigningProvider& arg, CPubKey& out) const override
+    {
+        if (IsHardened()) {
+            CExtKey key;
+            if (!GetExtKey(arg, key)) return false;
+            for (auto entry : m_path) {
+                key.Derive(key, entry);
+            }
+            if (m_derive == DeriveType::UNHARDENED) key.Derive(key, pos);
+            if (m_derive == DeriveType::HARDENED) key.Derive(key, pos | 0x80000000UL);
+            out = key.Neuter().pubkey;
+        } else {
+            // TODO: optimize by caching
+            CExtPubKey key = m_extkey;
+            for (auto entry : m_path) {
+                key.Derive(key, entry);
+            }
+            if (m_derive == DeriveType::UNHARDENED) key.Derive(key, pos);
+            assert(m_derive != DeriveType::HARDENED);
+            out = key.pubkey;
+        }
+        return true;
+    }
+    std::string ToString() const override
+    {
+        std::string ret = EncodeExtPubKey(m_extkey) + FormatKeyPath(m_path);
+        if (IsRange()) {
+            ret += "/*";
+            if (m_derive == DeriveType::HARDENED) ret += '\'';
+        }
+        return ret;
+    }
+    bool ToPrivateString(const SigningProvider& arg, std::string& out) const override
+    {
+        CExtKey key;
+        if (!GetExtKey(arg, key)) return false;
+        out = EncodeExtKey(key) + FormatKeyPath(m_path);
+        if (IsRange()) {
+            out += "/*";
+            if (m_derive == DeriveType::HARDENED) out += '\'';
+        }
+        return true;
+    }
+};
+
+/** A parsed addr(A) descriptor. */
+class AddressDescriptor final : public Descriptor
+{
+    CTxDestination m_destination;
+
+public:
+    AddressDescriptor(CTxDestination destination) : m_destination(std::move(destination)) {}
+
+    bool IsRange() const override { return false; }
+    std::string ToString() const override { return "addr(" + EncodeDestination(m_destination) + ")"; }
+    bool ToPrivateString(const SigningProvider& arg, std::string& out) const override { out = ToString(); return true; }
+    bool Expand(int pos, const SigningProvider& arg, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const override
+    {
+        output_scripts = std::vector<CScript>{GetScriptForDestination(m_destination)};
+        return true;
+    }
+};
+
+/** A parsed raw(H) descriptor. */
+class RawDescriptor final : public Descriptor
+{
+    CScript m_script;
+
+public:
+    RawDescriptor(CScript script) : m_script(std::move(script)) {}
+
+    bool IsRange() const override { return false; }
+    std::string ToString() const override { return "raw(" + HexStr(m_script.begin(), m_script.end()) + ")"; }
+    bool ToPrivateString(const SigningProvider& arg, std::string& out) const override { out = ToString(); return true; }
+    bool Expand(int pos, const SigningProvider& arg, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const override
+    {
+        output_scripts = std::vector<CScript>{m_script};
+        return true;
+    }
+};
+
+/** A parsed pk(P), pkh(P), or wpkh(P) descriptor. */
+class SingleKeyDescriptor final : public Descriptor
+{
+    const std::function<CScript(const CPubKey&)> m_script_fn;
+    const std::string m_fn_name;
+    std::unique_ptr<PubkeyProvider> m_provider;
+
+public:
+    SingleKeyDescriptor(std::unique_ptr<PubkeyProvider> prov, const std::function<CScript(const CPubKey&)>& fn, const std::string& name) : m_script_fn(fn), m_fn_name(name), m_provider(std::move(prov)) {}
+
+    bool IsRange() const override { return m_provider->IsRange(); }
+    std::string ToString() const override { return m_fn_name + "(" + m_provider->ToString() + ")"; }
+    bool ToPrivateString(const SigningProvider& arg, std::string& out) const override
+    {
+        std::string ret;
+        if (!m_provider->ToPrivateString(arg, ret)) return false;
+        out = m_fn_name + "(" + std::move(ret) + ")";
+        return true;
+    }
+    bool Expand(int pos, const SigningProvider& arg, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const override
+    {
+        CPubKey key;
+        if (!m_provider->GetPubKey(pos, arg, key)) return false;
+        output_scripts = std::vector<CScript>{m_script_fn(key)};
+        out.pubkeys.emplace(key.GetID(), std::move(key));
+        return true;
+    }
+};
+
+CScript P2PKHGetScript(const CPubKey& pubkey) { return GetScriptForDestination(pubkey.GetID()); }
+CScript P2PKGetScript(const CPubKey& pubkey) { return GetScriptForRawPubKey(pubkey); }
+CScript P2WPKHGetScript(const CPubKey& pubkey) { return GetScriptForDestination(WitnessV0KeyHash(pubkey.GetID())); }
+
+/** A parsed multi(...) descriptor. */
+class MultisigDescriptor : public Descriptor
+{
+    int m_threshold;
+    std::vector<std::unique_ptr<PubkeyProvider>> m_providers;
+
+public:
+    MultisigDescriptor(int threshold, std::vector<std::unique_ptr<PubkeyProvider>> providers) : m_threshold(threshold), m_providers(std::move(providers)) {}
+
+    bool IsRange() const override
+    {
+        for (const auto& p : m_providers) {
+            if (p->IsRange()) return true;
+        }
+        return false;
+    }
+
+    std::string ToString() const override
+    {
+        std::string ret = strprintf("multi(%i", m_threshold);
+        for (const auto& p : m_providers) {
+            ret += "," + p->ToString();
+        }
+        return std::move(ret) + ")";
+    }
+
+    bool ToPrivateString(const SigningProvider& arg, std::string& out) const override
+    {
+        std::string ret = strprintf("multi(%i", m_threshold);
+        for (const auto& p : m_providers) {
+            std::string sub;
+            if (!p->ToPrivateString(arg, sub)) return false;
+            ret += "," + std::move(sub);
+        }
+        out = std::move(ret) + ")";
+        return true;
+    }
+
+    bool Expand(int pos, const SigningProvider& arg, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const override
+    {
+        std::vector<CPubKey> pubkeys;
+        pubkeys.reserve(m_providers.size());
+        for (const auto& p : m_providers) {
+            CPubKey key;
+            if (!p->GetPubKey(pos, arg, key)) return false;
+            pubkeys.push_back(key);
+        }
+        for (const CPubKey& key : pubkeys) {
+            out.pubkeys.emplace(key.GetID(), std::move(key));
+        }
+        output_scripts = std::vector<CScript>{GetScriptForMultisig(m_threshold, pubkeys)};
+        return true;
+    }
+};
+
+/** A parsed sh(S) or wsh(S) descriptor. */
+class ConvertorDescriptor : public Descriptor
+{
+    const std::function<CScript(const CScript&)> m_convert_fn;
+    const std::string m_fn_name;
+    std::unique_ptr<Descriptor> m_descriptor;
+
+public:
+    ConvertorDescriptor(std::unique_ptr<Descriptor> descriptor, const std::function<CScript(const CScript&)>& fn, const std::string& name) : m_convert_fn(fn), m_fn_name(name), m_descriptor(std::move(descriptor)) {}
+
+    bool IsRange() const override { return m_descriptor->IsRange(); }
+    std::string ToString() const override { return m_fn_name + "(" + m_descriptor->ToString() + ")"; }
+    bool ToPrivateString(const SigningProvider& arg, std::string& out) const override
+    {
+        std::string ret;
+        if (!m_descriptor->ToPrivateString(arg, ret)) return false;
+        out = m_fn_name + "(" + std::move(ret) + ")";
+        return true;
+    }
+    bool Expand(int pos, const SigningProvider& arg, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const override
+    {
+        std::vector<CScript> sub;
+        if (!m_descriptor->Expand(pos, arg, sub, out)) return false;
+        output_scripts.clear();
+        for (const auto& script : sub) {
+            CScriptID id(script);
+            out.scripts.emplace(CScriptID(script), script);
+            output_scripts.push_back(m_convert_fn(script));
+        }
+        return true;
+    }
+};
+
+CScript ConvertP2SH(const CScript& script) { return GetScriptForDestination(CScriptID(script)); }
+CScript ConvertP2WSH(const CScript& script) { return GetScriptForDestination(WitnessV0ScriptHash(script)); }
+
+/** A parsed combo(P) descriptor. */
+class ComboDescriptor final : public Descriptor
+{
+    std::unique_ptr<PubkeyProvider> m_provider;
+
+public:
+    ComboDescriptor(std::unique_ptr<PubkeyProvider> provider) : m_provider(std::move(provider)) {}
+
+    bool IsRange() const override { return m_provider->IsRange(); }
+    std::string ToString() const override { return "combo(" + m_provider->ToString() + ")"; }
+    bool ToPrivateString(const SigningProvider& arg, std::string& out) const override
+    {
+        std::string ret;
+        if (!m_provider->ToPrivateString(arg, ret)) return false;
+        out = "combo(" + std::move(ret) + ")";
+        return true;
+    }
+    bool Expand(int pos, const SigningProvider& arg, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const override
+    {
+        CPubKey key;
+        if (!m_provider->GetPubKey(pos, arg, key)) return false;
+        CKeyID keyid = key.GetID();
+        {
+            CScript p2pk = GetScriptForRawPubKey(key);
+            CScript p2pkh = GetScriptForDestination(keyid);
+            output_scripts = std::vector<CScript>{std::move(p2pk), std::move(p2pkh)};
+            out.pubkeys.emplace(keyid, key);
+        }
+        if (key.IsCompressed()) {
+            CScript p2wpkh = GetScriptForDestination(WitnessV0KeyHash(keyid));
+            CScriptID p2wpkh_id(p2wpkh);
+            CScript p2sh_p2wpkh = GetScriptForDestination(p2wpkh_id);
+            out.scripts.emplace(p2wpkh_id, p2wpkh);
+            output_scripts.push_back(std::move(p2wpkh));
+            output_scripts.push_back(std::move(p2sh_p2wpkh));
+        }
+        return true;
+    }
+};
+
+////////////////////////////////////////////////////////////////////////////
+// Parser                                                                 //
+////////////////////////////////////////////////////////////////////////////
+
+enum class ParseScriptContext {
+    TOP,
+    P2SH,
+    P2WSH,
+};
+
+/** Parse a constant. If succesful, sp is updated to skip the constant and return true. */
+bool Const(const std::string& str, Span<const char>& sp)
+{
+    if ((size_t)sp.size() >= str.size() && std::equal(str.begin(), str.end(), sp.begin())) {
+        sp = sp.subspan(str.size());
+        return true;
+    }
+    return false;
+}
+
+/** Parse a function call. If succesful, sp is updated to be the function's argument(s). */
+bool Func(const std::string& str, Span<const char>& sp)
+{
+    if ((size_t)sp.size() >= str.size() + 2 && sp[str.size()] == '(' && sp[sp.size() - 1] == ')' && std::equal(str.begin(), str.end(), sp.begin())) {
+        sp = sp.subspan(str.size() + 1, sp.size() - str.size() - 2);
+        return true;
+    }
+    return false;
+}
+
+/** Return the expression that sp begins with, and update sp to skip it. */
+Span<const char> Expr(Span<const char>& sp)
+{
+    int level = 0;
+    auto it = sp.begin();
+    while (it != sp.end()) {
+        if (*it == '(') {
+            ++level;
+        } else if (level && *it == ')') {
+            --level;
+        } else if (level == 0 && (*it == ')' || *it == ',')) {
+            break;
+        }
+        ++it;
+    }
+    Span<const char> ret = sp.first(it - sp.begin());
+    sp = sp.subspan(it - sp.begin());
+    return ret;
+}
+
+/** Split a string on every instance of sep, returning a vector. */
+std::vector<Span<const char>> Split(const Span<const char>& sp, char sep)
+{
+    std::vector<Span<const char>> ret;
+    auto it = sp.begin();
+    auto start = it;
+    while (it != sp.end()) {
+        if (*it == sep) {
+            ret.emplace_back(start, it);
+            start = it + 1;
+        }
+        ++it;
+    }
+    ret.emplace_back(start, it);
+    return ret;
+}
+
+/** Parse a key path, being passed a split list of elements (the first element is ignored). */
+bool ParseKeyPath(const std::vector<Span<const char>>& split, KeyPath& out)
+{
+    for (size_t i = 1; i < split.size(); ++i) {
+        Span<const char> elem = split[i];
+        bool hardened = false;
+        if (elem.size() > 0 && (elem[elem.size() - 1] == '\'' || elem[elem.size() - 1] == 'h')) {
+            elem = elem.first(elem.size() - 1);
+            hardened = true;
+        }
+        uint32_t p;
+        if (!ParseUInt32(std::string(elem.begin(), elem.end()), &p) || p > 0x7FFFFFFFUL) return false;
+        out.push_back(p | (((uint32_t)hardened) << 31));
+    }
+    return true;
+}
+
+std::unique_ptr<PubkeyProvider> ParsePubkey(const Span<const char>& sp, bool permit_uncompressed, FlatSigningProvider& out)
+{
+    auto split = Split(sp, '/');
+    std::string str(split[0].begin(), split[0].end());
+    if (split.size() == 1) {
+        if (IsHex(str)) {
+            std::vector<unsigned char> data = ParseHex(str);
+            CPubKey pubkey(data);
+            if (pubkey.IsFullyValid() && (permit_uncompressed || pubkey.IsCompressed())) return MakeUnique<ConstPubkeyProvider>(pubkey);
+        }
+        CKey key = DecodeSecret(str);
+        if (key.IsValid() && (permit_uncompressed || key.IsCompressed())) {
+            CPubKey pubkey = key.GetPubKey();
+            out.keys.emplace(pubkey.GetID(), key);
+            return MakeUnique<ConstPubkeyProvider>(pubkey);
+        }
+    }
+    CExtKey extkey = DecodeExtKey(str);
+    CExtPubKey extpubkey = DecodeExtPubKey(str);
+    if (!extkey.key.IsValid() && !extpubkey.pubkey.IsValid()) return nullptr;
+    KeyPath path;
+    DeriveType type = DeriveType::NO;
+    if (split.back() == MakeSpan("*").first(1)) {
+        split.pop_back();
+        type = DeriveType::UNHARDENED;
+    } else if (split.back() == MakeSpan("*'").first(2) || split.back() == MakeSpan("*h").first(2)) {
+        split.pop_back();
+        type = DeriveType::HARDENED;
+    }
+    if (!ParseKeyPath(split, path)) return nullptr;
+    if (extkey.key.IsValid()) {
+        extpubkey = extkey.Neuter();
+        out.keys.emplace(extpubkey.pubkey.GetID(), extkey.key);
+    }
+    return MakeUnique<BIP32PubkeyProvider>(extpubkey, std::move(path), type);
+}
+
+/** Parse a script in a particular context. */
+std::unique_ptr<Descriptor> ParseScript(Span<const char>& sp, ParseScriptContext ctx, FlatSigningProvider& out)
+{
+    auto expr = Expr(sp);
+    if (Func("pk", expr)) {
+        auto pubkey = ParsePubkey(expr, ctx != ParseScriptContext::P2WSH, out);
+        if (!pubkey) return nullptr;
+        return MakeUnique<SingleKeyDescriptor>(std::move(pubkey), P2PKGetScript, "pk");
+    }
+    if (Func("pkh", expr)) {
+        auto pubkey = ParsePubkey(expr, ctx != ParseScriptContext::P2WSH, out);
+        if (!pubkey) return nullptr;
+        return MakeUnique<SingleKeyDescriptor>(std::move(pubkey), P2PKHGetScript, "pkh");
+    }
+    if (ctx == ParseScriptContext::TOP && Func("combo", expr)) {
+        auto pubkey = ParsePubkey(expr, true, out);
+        if (!pubkey) return nullptr;
+        return MakeUnique<ComboDescriptor>(std::move(pubkey));
+    }
+    if (Func("multi", expr)) {
+        auto threshold = Expr(expr);
+        uint32_t thres;
+        std::vector<std::unique_ptr<PubkeyProvider>> providers;
+        if (!ParseUInt32(std::string(threshold.begin(), threshold.end()), &thres)) return nullptr;
+        size_t script_size = 0;
+        while (expr.size()) {
+            if (!Const(",", expr)) return nullptr;
+            auto arg = Expr(expr);
+            auto pk = ParsePubkey(arg, ctx != ParseScriptContext::P2WSH, out);
+            if (!pk) return nullptr;
+            script_size += pk->GetSize() + 1;
+            providers.emplace_back(std::move(pk));
+        }
+        if (providers.size() < 1 || providers.size() > 16 || thres < 1 || thres > providers.size()) return nullptr;
+        if (ctx == ParseScriptContext::TOP) {
+            if (providers.size() > 3) return nullptr; // Not more than 3 pubkeys for raw multisig
+        }
+        if (ctx == ParseScriptContext::P2SH) {
+            if (script_size + 3 > 520) return nullptr; // Enforce P2SH script size limit
+        }
+        return MakeUnique<MultisigDescriptor>(thres, std::move(providers));
+    }
+    if (ctx != ParseScriptContext::P2WSH && Func("wpkh", expr)) {
+        auto pubkey = ParsePubkey(expr, false, out);
+        if (!pubkey) return nullptr;
+        return MakeUnique<SingleKeyDescriptor>(std::move(pubkey), P2WPKHGetScript, "wpkh");
+    }
+    if (ctx == ParseScriptContext::TOP && Func("sh", expr)) {
+        auto desc = ParseScript(expr, ParseScriptContext::P2SH, out);
+        if (!desc || expr.size()) return nullptr;
+        return MakeUnique<ConvertorDescriptor>(std::move(desc), ConvertP2SH, "sh");
+    }
+    if (ctx != ParseScriptContext::P2WSH && Func("wsh", expr)) {
+        auto desc = ParseScript(expr, ParseScriptContext::P2WSH, out);
+        if (!desc || expr.size()) return nullptr;
+        return MakeUnique<ConvertorDescriptor>(std::move(desc), ConvertP2WSH, "wsh");
+    }
+    if (ctx == ParseScriptContext::TOP && Func("addr", expr)) {
+        CTxDestination dest = DecodeDestination(std::string(expr.begin(), expr.end()));
+        if (!IsValidDestination(dest)) return nullptr;
+        return MakeUnique<AddressDescriptor>(std::move(dest));
+    }
+    if (ctx == ParseScriptContext::TOP && Func("raw", expr)) {
+        std::string str(expr.begin(), expr.end());
+        if (!IsHex(str)) return nullptr;
+        auto bytes = ParseHex(str);
+        return MakeUnique<RawDescriptor>(CScript(bytes.begin(), bytes.end()));
+    }
+    return nullptr;
+}
+
+} // namespace
+
+std::unique_ptr<Descriptor> Parse(const std::string& descriptor, FlatSigningProvider& out)
+{
+    Span<const char> sp(descriptor.data(), descriptor.size());
+    auto ret = ParseScript(sp, ParseScriptContext::TOP, out);
+    if (sp.size() == 0 && ret) return ret;
+    return nullptr;
+}
diff --git a/src/script/descriptor.h b/src/script/descriptor.h
new file mode 100644
index 0000000000..e079c72e92
--- /dev/null
+++ b/src/script/descriptor.h
@@ -0,0 +1,102 @@
+// Copyright (c) 2018 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_SCRIPT_DESCRIPTOR_H
+#define BITCOIN_SCRIPT_DESCRIPTOR_H
+
+#include <script/script.h>
+#include <script/sign.h>
+
+#include <vector>
+
+// Descriptors are strings that describe a set of scriptPubKeys, together with
+// all information necessary to solve them. By combining all information into
+// one, they avoid the need to separately import keys and scripts.
+//
+// Descriptors may be ranged, which occurs when the public keys inside are
+// specified in the form of HD chains (xpubs).
+//
+// Descriptors always represent public information - public keys and scripts -
+// but in cases where private keys need to be conveyed along with a descriptor,
+// they can be included inside by changing public keys to private keys (WIF
+// format), and changing xpubs by xprvs.
+//
+// 1. Examples
+//
+// A P2PK descriptor with a fixed public key:
+// - pk(0279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798)
+//
+// A P2SH-P2WSH-P2PKH descriptor with a fixed public key:
+// - sh(wsh(pkh(02e493dbf1c10d80f3581e4904930b1404cc6c13900ee0758474fa94abe8c4cd13)))
+//
+// A bare 1-of-2 multisig descriptor:
+// - multi(1,022f8bde4d1a07209355b4a7250a5c5128e88b84bddc619ab7cba8d569b240efe4,025cbdf0646e5db4eaa398f365f2ea7a0e3d419b7e0330e39ce92bddedcac4f9bc)
+//
+// A chain of P2PKH outputs (this needs the corresponding private key to derive):
+// - pkh(xpub68Gmy5EdvgibQVfPdqkBBCHxA5htiqg55crXYuXoQRKfDBFA1WEjWgP6LHhwBZeNK1VTsfTFUHCdrfp1bgwQ9xv5ski8PX9rL2dZXvgGDnw/1'/2/*)
+//
+// 2. Grammar description:
+//
+// X: xpub or xprv encoded extended key
+// I: decimal encoded integer
+// H: Hex encoded byte array
+// A: Address in P2PKH, P2SH, or Bech32 encoding
+//
+// S (Scripts):
+// * pk(P): Pay-to-pubkey (P2PK) output for public key P.
+// * pkh(P): Pay-to-pubkey-hash (P2PKH) output for public key P.
+// * wpkh(P): Pay-to-witness-pubkey-hash (P2WPKH) output for public key P.
+// * sh(S): Pay-to-script-hash (P2SH) output for script S
+// * wsh(S): Pay-to-witness-script-hash (P2WSH) output for script S
+// * combo(P): combination of P2PK, P2PKH, P2WPKH, and P2SH-P2WPKH for public key P.
+// * multi(I,L): k-of-n multisig for given public keys
+// * addr(A): Output to address
+// * raw(H): scriptPubKey with raw bytes
+//
+// P (Public keys):
+// * H: fixed public key (or WIF-encoded private key)
+// * E: extended public key
+// * E/*: (ranged) all unhardened direct children of an extended public key
+// * E/*': (ranged) all hardened direct children of an extended public key
+//
+// L (Comma-separated lists of public keys):
+// * P
+// * L,P
+//
+// E (Extended public keys):
+// * X
+// * E/I: unhardened child
+// * E/I': hardened child
+// * E/Ih: hardened child (alternative notation)
+//
+// The top level is S.
+
+/** Interface for parsed descriptor objects. */
+struct Descriptor {
+    virtual ~Descriptor() = default;
+
+    /** Whether the expansion of this descriptor depends on the position. */
+    virtual bool IsRange() const = 0;
+
+    /** Convert the descriptor back to a string, undoing parsing. */
+    virtual std::string ToString() const = 0;
+
+    /** Convert the descriptor to a private string. This fails if the provided provider does not have the relevant private keys. */
+    virtual bool ToPrivateString(const SigningProvider& provider, std::string& out) const = 0;
+
+    /** Expand a descriptor at a specified position.
+     *
+     * pos: the position at which to expand the descriptor. If IsRange() is false, this is ignored.
+     * provider: the provider to query for private keys in case of hardened derivation.
+     * output_script: the expanded scriptPubKeys will be put here.
+     * out: scripts and public keys necessary for solving the expanded scriptPubKeys will be put here (may be equal to provider).
+     */
+    virtual bool Expand(int pos, const SigningProvider& provider, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const = 0;
+};
+
+/** Parse a descriptor string. Included private keys are put in out. Returns nullptr if parsing fails. */
+std::unique_ptr<Descriptor> Parse(const std::string& descriptor, FlatSigningProvider& out);
+
+#endif // BITCOIN_SCRIPT_DESCRIPTOR_H
+
diff --git a/src/script/sign.cpp b/src/script/sign.cpp
index d10b1c4fd7..fa09adbaf8 100644
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -11,7 +11,6 @@
 #include <script/standard.h>
 #include <uint256.h>
 
-
 typedef std::vector<unsigned char> valtype;
 
 MutableTransactionSignatureCreator::MutableTransactionSignatureCreator(const CMutableTransaction* txToIn, unsigned int nInIn, const CAmount& amountIn, int nHashTypeIn) : txTo(txToIn), nIn(nInIn), nHashType(nHashTypeIn), amount(amountIn), checker(txTo, nIn, amountIn) {}
@@ -437,6 +436,18 @@ public:
         return true;
     }
 };
+
+template<typename M, typename K, typename V>
+bool LookupHelper(const M& map, const K& key, V& value)
+{
+    auto it = map.find(key);
+    if (it != map.end()) {
+        value = it->second;
+        return true;
+    }
+    return false;
+}
+
 }
 
 const BaseSignatureCreator& DUMMY_SIGNATURE_CREATOR = DummySignatureCreator();
@@ -460,7 +471,6 @@ bool IsSolvable(const SigningProvider& provider, const CScript& script)
     return false;
 }
 
-
 bool PartiallySignedTransaction::IsNull() const
 {
     return !tx && inputs.empty() && outputs.empty() && unknown.empty();
@@ -618,3 +628,19 @@ bool PublicOnlySigningProvider::GetPubKey(const CKeyID &address, CPubKey& pubkey
 {
     return m_provider->GetPubKey(address, pubkey);
 }
+
+bool FlatSigningProvider::GetCScript(const CScriptID& scriptid, CScript& script) const { return LookupHelper(scripts, scriptid, script); }
+bool FlatSigningProvider::GetPubKey(const CKeyID& keyid, CPubKey& pubkey) const { return LookupHelper(pubkeys, keyid, pubkey); }
+bool FlatSigningProvider::GetKey(const CKeyID& keyid, CKey& key) const { return LookupHelper(keys, keyid, key); }
+
+FlatSigningProvider Merge(const FlatSigningProvider& a, const FlatSigningProvider& b)
+{
+    FlatSigningProvider ret;
+    ret.scripts = a.scripts;
+    ret.scripts.insert(b.scripts.begin(), b.scripts.end());
+    ret.pubkeys = a.pubkeys;
+    ret.pubkeys.insert(b.pubkeys.begin(), b.pubkeys.end());
+    ret.keys = a.keys;
+    ret.keys.insert(b.keys.begin(), b.keys.end());
+    return ret;
+}
diff --git a/src/script/sign.h b/src/script/sign.h
index d12d0b5874..96ef59fbe8 100644
--- a/src/script/sign.h
+++ b/src/script/sign.h
@@ -43,6 +43,19 @@ public:
     bool GetPubKey(const CKeyID &address, CPubKey& pubkey) const;
 };
 
+struct FlatSigningProvider final : public SigningProvider
+{
+    std::map<CScriptID, CScript> scripts;
+    std::map<CKeyID, CPubKey> pubkeys;
+    std::map<CKeyID, CKey> keys;
+
+    bool GetCScript(const CScriptID& scriptid, CScript& script) const override;
+    bool GetPubKey(const CKeyID& keyid, CPubKey& pubkey) const override;
+    bool GetKey(const CKeyID& keyid, CKey& key) const override;
+};
+
+FlatSigningProvider Merge(const FlatSigningProvider& a, const FlatSigningProvider& b);
+
 /** Interface for signature creators. */
 class BaseSignatureCreator {
 public:
diff --git a/src/span.h b/src/span.h
index 707fc21918..77de059fa6 100644
--- a/src/span.h
+++ b/src/span.h
@@ -7,6 +7,7 @@
 
 #include <type_traits>
 #include <cstddef>
+#include <algorithm>
 
 /** A Span is an object that can refer to a contiguous sequence of objects.
  *
@@ -21,9 +22,25 @@ class Span
 public:
     constexpr Span() noexcept : m_data(nullptr), m_size(0) {}
     constexpr Span(C* data, std::ptrdiff_t size) noexcept : m_data(data), m_size(size) {}
+    constexpr Span(C* data, C* end) noexcept : m_data(data), m_size(end - data) {}
 
     constexpr C* data() const noexcept { return m_data; }
+    constexpr C* begin() const noexcept { return m_data; }
+    constexpr C* end() const noexcept { return m_data + m_size; }
     constexpr std::ptrdiff_t size() const noexcept { return m_size; }
+    constexpr C& operator[](std::ptrdiff_t pos) const noexcept { return m_data[pos]; }
+
+    constexpr Span<C> subspan(std::ptrdiff_t offset) const noexcept { return Span<C>(m_data + offset, m_size - offset); }
+    constexpr Span<C> subspan(std::ptrdiff_t offset, std::ptrdiff_t count) const noexcept { return Span<C>(m_data + offset, count); }
+    constexpr Span<C> first(std::ptrdiff_t count) const noexcept { return Span<C>(m_data, count); }
+    constexpr Span<C> last(std::ptrdiff_t count) const noexcept { return Span<C>(m_data + m_size - count, count); }
+
+    friend constexpr bool operator==(const Span& a, const Span& b) noexcept { return a.size() == b.size() && std::equal(a.begin(), a.end(), b.begin()); }
+    friend constexpr bool operator!=(const Span& a, const Span& b) noexcept { return !(a == b); }
+    friend constexpr bool operator<(const Span& a, const Span& b) noexcept { return std::lexicographical_compare(a.begin(), a.end(), b.begin(), b.end()); }
+    friend constexpr bool operator<=(const Span& a, const Span& b) noexcept { return !(b < a); }
+    friend constexpr bool operator>(const Span& a, const Span& b) noexcept { return (b < a); }
+    friend constexpr bool operator>=(const Span& a, const Span& b) noexcept { return !(a < b); }
 };
 
 /** Create a span to a container exposing data() and size().
@@ -34,6 +51,9 @@ public:
  *
  * std::span will have a constructor that implements this functionality directly.
  */
+template<typename A, int N>
+constexpr Span<A> MakeSpan(A (&a)[N]) { return Span<A>(a, N); }
+
 template<typename V>
 constexpr Span<typename std::remove_pointer<decltype(std::declval<V>().data())>::type> MakeSpan(V& v) { return Span<typename std::remove_pointer<decltype(std::declval<V>().data())>::type>(v.data(), v.size()); }
 
diff --git a/src/test/blockencodings_tests.cpp b/src/test/blockencodings_tests.cpp
index 3dd5356164..df839884fe 100644
--- a/src/test/blockencodings_tests.cpp
+++ b/src/test/blockencodings_tests.cpp
@@ -62,8 +62,8 @@ BOOST_AUTO_TEST_CASE(SimpleRoundTripTest)
     TestMemPoolEntryHelper entry;
     CBlock block(BuildBlockTestCase());
 
-    pool.addUnchecked(block.vtx[2]->GetHash(), entry.FromTx(block.vtx[2]));
     LOCK(pool.cs);
+    pool.addUnchecked(block.vtx[2]->GetHash(), entry.FromTx(block.vtx[2]));
     BOOST_CHECK_EQUAL(pool.mapTx.find(block.vtx[2]->GetHash())->GetSharedTx().use_count(), SHARED_TX_OFFSET + 0);
 
     // Do a simple ShortTxIDs RT
@@ -162,8 +162,8 @@ BOOST_AUTO_TEST_CASE(NonCoinbasePreforwardRTTest)
     TestMemPoolEntryHelper entry;
     CBlock block(BuildBlockTestCase());
 
-    pool.addUnchecked(block.vtx[2]->GetHash(), entry.FromTx(block.vtx[2]));
     LOCK(pool.cs);
+    pool.addUnchecked(block.vtx[2]->GetHash(), entry.FromTx(block.vtx[2]));
     BOOST_CHECK_EQUAL(pool.mapTx.find(block.vtx[2]->GetHash())->GetSharedTx().use_count(), SHARED_TX_OFFSET + 0);
 
     uint256 txhash;
@@ -232,8 +232,8 @@ BOOST_AUTO_TEST_CASE(SufficientPreforwardRTTest)
     TestMemPoolEntryHelper entry;
     CBlock block(BuildBlockTestCase());
 
-    pool.addUnchecked(block.vtx[1]->GetHash(), entry.FromTx(block.vtx[1]));
     LOCK(pool.cs);
+    pool.addUnchecked(block.vtx[1]->GetHash(), entry.FromTx(block.vtx[1]));
     BOOST_CHECK_EQUAL(pool.mapTx.find(block.vtx[1]->GetHash())->GetSharedTx().use_count(), SHARED_TX_OFFSET + 0);
 
     uint256 txhash;
diff --git a/src/test/descriptor_tests.cpp b/src/test/descriptor_tests.cpp
new file mode 100644
index 0000000000..f189222be8
--- /dev/null
+++ b/src/test/descriptor_tests.cpp
@@ -0,0 +1,163 @@
+// Copyright (c) 2018 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 <vector>
+#include <string>
+#include <script/sign.h>
+#include <script/standard.h>
+#include <test/test_bitcoin.h>
+#include <boost/test/unit_test.hpp>
+#include <script/descriptor.h>
+#include <utilstrencodings.h>
+
+namespace {
+
+void CheckUnparsable(const std::string& prv, const std::string& pub)
+{
+    FlatSigningProvider keys_priv, keys_pub;
+    auto parse_priv = Parse(prv, keys_priv);
+    auto parse_pub = Parse(pub, keys_pub);
+    BOOST_CHECK(!parse_priv);
+    BOOST_CHECK(!parse_pub);
+}
+
+constexpr int DEFAULT = 0;
+constexpr int RANGE = 1; // Expected to be ranged descriptor
+constexpr int HARDENED = 2; // Derivation needs access to private keys
+constexpr int UNSOLVABLE = 4; // This descriptor is not expected to be solvable
+constexpr int SIGNABLE = 8; // We can sign with this descriptor (this is not true when actual BIP32 derivation is used, as that's not integrated in our signing code)
+
+std::string MaybeUseHInsteadOfApostrophy(std::string ret)
+{
+    if (InsecureRandBool()) {
+        while (true) {
+            auto it = ret.find("'");
+            if (it != std::string::npos) {
+                ret[it] = 'h';
+            } else {
+                break;
+            }
+        }
+    }
+    return ret;
+}
+
+void Check(const std::string& prv, const std::string& pub, int flags, const std::vector<std::vector<std::string>>& scripts)
+{
+    FlatSigningProvider keys_priv, keys_pub;
+
+    // Check that parsing succeeds.
+    auto parse_priv = Parse(MaybeUseHInsteadOfApostrophy(prv), keys_priv);
+    auto parse_pub = Parse(MaybeUseHInsteadOfApostrophy(pub), keys_pub);
+    BOOST_CHECK(parse_priv);
+    BOOST_CHECK(parse_pub);
+
+    // Check private keys are extracted from the private version but not the public one.
+    BOOST_CHECK(keys_priv.keys.size());
+    BOOST_CHECK(!keys_pub.keys.size());
+
+    // Check that both versions serialize back to the public version.
+    std::string pub1 = parse_priv->ToString();
+    std::string pub2 = parse_priv->ToString();
+    BOOST_CHECK_EQUAL(pub, pub1);
+    BOOST_CHECK_EQUAL(pub, pub2);
+
+    // Check that both can be serialized with private key back to the private version, but not without private key.
+    std::string prv1, prv2;
+    BOOST_CHECK(parse_priv->ToPrivateString(keys_priv, prv1));
+    BOOST_CHECK_EQUAL(prv, prv1);
+    BOOST_CHECK(!parse_priv->ToPrivateString(keys_pub, prv1));
+    BOOST_CHECK(parse_pub->ToPrivateString(keys_priv, prv1));
+    BOOST_CHECK_EQUAL(prv, prv1);
+    BOOST_CHECK(!parse_pub->ToPrivateString(keys_pub, prv1));
+
+    // Check whether IsRange on both returns the expected result
+    BOOST_CHECK_EQUAL(parse_pub->IsRange(), (flags & RANGE) != 0);
+    BOOST_CHECK_EQUAL(parse_priv->IsRange(), (flags & RANGE) != 0);
+
+
+    // Is not ranged descriptor, only a single result is expected.
+    if (!(flags & RANGE)) assert(scripts.size() == 1);
+
+    size_t max = (flags & RANGE) ? scripts.size() : 3;
+    for (size_t i = 0; i < max; ++i) {
+        const auto& ref = scripts[(flags & RANGE) ? i : 0];
+        for (int t = 0; t < 2; ++t) {
+            FlatSigningProvider key_provider = (flags & HARDENED) ? keys_priv : keys_pub;
+            FlatSigningProvider script_provider;
+            std::vector<CScript> spks;
+            BOOST_CHECK((t ? parse_priv : parse_pub)->Expand(i, key_provider, spks, script_provider));
+            BOOST_CHECK_EQUAL(spks.size(), ref.size());
+            for (size_t n = 0; n < spks.size(); ++n) {
+                BOOST_CHECK_EQUAL(ref[n], HexStr(spks[n].begin(), spks[n].end()));
+                BOOST_CHECK_EQUAL(IsSolvable(Merge(key_provider, script_provider), spks[n]), (flags & UNSOLVABLE) == 0);
+
+                if (flags & SIGNABLE) {
+                    CMutableTransaction spend;
+                    spend.vin.resize(1);
+                    spend.vout.resize(1);
+                    BOOST_CHECK_MESSAGE(SignSignature(Merge(keys_priv, script_provider), spks[n], spend, 0, 1, SIGHASH_ALL), prv);
+                }
+            }
+
+        }
+    }
+}
+
+}
+
+BOOST_FIXTURE_TEST_SUITE(descriptor_tests, BasicTestingSetup)
+
+BOOST_AUTO_TEST_CASE(descriptor_test)
+{
+    // Basic single-key compressed
+    Check("combo(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1)", "combo(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)", SIGNABLE, {{"2103a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bdac","76a9149a1c78a507689f6f54b847ad1cef1e614ee23f1e88ac","00149a1c78a507689f6f54b847ad1cef1e614ee23f1e","a91484ab21b1b2fd065d4504ff693d832434b6108d7b87"}});
+    Check("pk(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1)", "pk(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)", SIGNABLE, {{"2103a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bdac"}});
+    Check("pkh(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1)", "pkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)", SIGNABLE, {{"76a9149a1c78a507689f6f54b847ad1cef1e614ee23f1e88ac"}});
+    Check("wpkh(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1)", "wpkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)", SIGNABLE, {{"00149a1c78a507689f6f54b847ad1cef1e614ee23f1e"}});
+    Check("sh(wpkh(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1))", "sh(wpkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))", SIGNABLE, {{"a91484ab21b1b2fd065d4504ff693d832434b6108d7b87"}});
+
+    // Basic single-key uncompressed
+    Check("combo(5KYZdUEo39z3FPrtuX2QbbwGnNP5zTd7yyr2SC1j299sBCnWjss)", "combo(04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235)", SIGNABLE, {{"4104a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235ac","76a914b5bd079c4d57cc7fc28ecf8213a6b791625b818388ac"}});
+    Check("pk(5KYZdUEo39z3FPrtuX2QbbwGnNP5zTd7yyr2SC1j299sBCnWjss)", "pk(04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235)", SIGNABLE, {{"4104a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235ac"}});
+    Check("pkh(5KYZdUEo39z3FPrtuX2QbbwGnNP5zTd7yyr2SC1j299sBCnWjss)", "pkh(04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235)", SIGNABLE, {{"76a914b5bd079c4d57cc7fc28ecf8213a6b791625b818388ac"}});
+    CheckUnparsable("wpkh(5KYZdUEo39z3FPrtuX2QbbwGnNP5zTd7yyr2SC1j299sBCnWjss)", "wpkh(04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235)"); // No uncompressed keys in witness
+    CheckUnparsable("wsh(pk(5KYZdUEo39z3FPrtuX2QbbwGnNP5zTd7yyr2SC1j299sBCnWjss))", "wsh(pk(04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235))"); // No uncompressed keys in witness
+    CheckUnparsable("sh(wpkh(5KYZdUEo39z3FPrtuX2QbbwGnNP5zTd7yyr2SC1j299sBCnWjss))", "sh(wpkh(04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235))"); // No uncompressed keys in witness
+
+    // Some unconventional single-key constructions
+    Check("sh(pk(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1))", "sh(pk(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))", SIGNABLE, {{"a9141857af51a5e516552b3086430fd8ce55f7c1a52487"}});
+    Check("sh(pkh(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1))", "sh(pkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))", SIGNABLE, {{"a9141a31ad23bf49c247dd531a623c2ef57da3c400c587"}});
+    Check("wsh(pk(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1))", "wsh(pk(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))", SIGNABLE, {{"00202e271faa2325c199d25d22e1ead982e45b64eeb4f31e73dbdf41bd4b5fec23fa"}});
+    Check("wsh(pkh(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1))", "wsh(pkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))", SIGNABLE, {{"0020338e023079b91c58571b20e602d7805fb808c22473cbc391a41b1bd3a192e75b"}});
+    Check("sh(wsh(pk(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1)))", "sh(wsh(pk(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)))", SIGNABLE, {{"a91472d0c5a3bfad8c3e7bd5303a72b94240e80b6f1787"}});
+    Check("sh(wsh(pkh(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1)))", "sh(wsh(pkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)))", SIGNABLE, {{"a914b61b92e2ca21bac1e72a3ab859a742982bea960a87"}});
+
+    // Versions with BIP32 derivations
+    Check("combo(xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc)", "combo(xpub6ERApfZwUNrhLCkDtcHTcxd75RbzS1ed54G1LkBUHQVHQKqhMkhgbmJbZRkrgZw4koxb5JaHWkY4ALHY2grBGRjaDMzQLcgJvLJuZZvRcEL)", SIGNABLE, {{"2102d2b36900396c9282fa14628566582f206a5dd0bcc8d5e892611806cafb0301f0ac","76a91431a507b815593dfc51ffc7245ae7e5aee304246e88ac","001431a507b815593dfc51ffc7245ae7e5aee304246e","a9142aafb926eb247cb18240a7f4c07983ad1f37922687"}});
+    Check("pk(xprv9uPDJpEQgRQfDcW7BkF7eTya6RPxXeJCqCJGHuCJ4GiRVLzkTXBAJMu2qaMWPrS7AANYqdq6vcBcBUdJCVVFceUvJFjaPdGZ2y9WACViL4L/0)", "pk(xpub68NZiKmJWnxxS6aaHmn81bvJeTESw724CRDs6HbuccFQN9Ku14VQrADWgqbhhTHBaohPX4CjNLf9fq9MYo6oDaPPLPxSb7gwQN3ih19Zm4Y/0)", DEFAULT, {{"210379e45b3cf75f9c5f9befd8e9506fb962f6a9d185ac87001ec44a8d3df8d4a9e3ac"}});
+    Check("pkh(xprv9s21ZrQH143K31xYSDQpPDxsXRTUcvj2iNHm5NUtrGiGG5e2DtALGdso3pGz6ssrdK4PFmM8NSpSBHNqPqm55Qn3LqFtT2emdEXVYsCzC2U/2147483647'/0)", "pkh(xpub661MyMwAqRbcFW31YEwpkMuc5THy2PSt5bDMsktWQcFF8syAmRUapSCGu8ED9W6oDMSgv6Zz8idoc4a6mr8BDzTJY47LJhkJ8UB7WEGuduB/2147483647'/0)", HARDENED, {{"76a914ebdc90806a9c4356c1c88e42216611e1cb4c1c1788ac"}});
+    Check("wpkh(xprv9vHkqa6EV4sPZHYqZznhT2NPtPCjKuDKGY38FBWLvgaDx45zo9WQRUT3dKYnjwih2yJD9mkrocEZXo1ex8G81dwSM1fwqWpWkeS3v86pgKt/1/2/*)", "wpkh(xpub69H7F5d8KSRgmmdJg2KhpAK8SR3DjMwAdkxj3ZuxV27CprR9LgpeyGmXUbC6wb7ERfvrnKZjXoUmmDznezpbZb7ap6r1D3tgFxHmwMkQTPH/1/2/*)", RANGE, {{"0014326b2249e3a25d5dc60935f044ee835d090ba859"},{"0014af0bd98abc2f2cae66e36896a39ffe2d32984fb7"},{"00141fa798efd1cbf95cebf912c031b8a4a6e9fb9f27"}});
+    Check("sh(wpkh(xprv9s21ZrQH143K3QTDL4LXw2F7HEK3wJUD2nW2nRk4stbPy6cq3jPPqjiChkVvvNKmPGJxWUtg6LnF5kejMRNNU3TGtRBeJgk33yuGBxrMPHi/10/20/30/40/*'))", "sh(wpkh(xpub661MyMwAqRbcFtXgS5sYJABqqG9YLmC4Q1Rdap9gSE8NqtwybGhePY2gZ29ESFjqJoCu1Rupje8YtGqsefD265TMg7usUDFdp6W1EGMcet8/10/20/30/40/*'))", RANGE | HARDENED, {{"a9149a4d9901d6af519b2a23d4a2f51650fcba87ce7b87"},{"a914bed59fc0024fae941d6e20a3b44a109ae740129287"},{"a9148483aa1116eb9c05c482a72bada4b1db24af654387"}});
+    Check("combo(xprvA2JDeKCSNNZky6uBCviVfJSKyQ1mDYahRjijr5idH2WwLsEd4Hsb2Tyh8RfQMuPh7f7RtyzTtdrbdqqsunu5Mm3wDvUAKRHSC34sJ7in334/*)", "combo(xpub6FHa3pjLCk84BayeJxFW2SP4XRrFd1JYnxeLeU8EqN3vDfZmbqBqaGJAyiLjTAwm6ZLRQUMv1ZACTj37sR62cfN7fe5JnJ7dh8zL4fiyLHV/*)", RANGE, {{"2102df12b7035bdac8e3bab862a3a83d06ea6b17b6753d52edecba9be46f5d09e076ac","76a914f90e3178ca25f2c808dc76624032d352fdbdfaf288ac","0014f90e3178ca25f2c808dc76624032d352fdbdfaf2","a91408f3ea8c68d4a7585bf9e8bda226723f70e445f087"},{"21032869a233c9adff9a994e4966e5b821fd5bac066da6c3112488dc52383b4a98ecac","76a914a8409d1b6dfb1ed2a3e8aa5e0ef2ff26b15b75b788ac","0014a8409d1b6dfb1ed2a3e8aa5e0ef2ff26b15b75b7","a91473e39884cb71ae4e5ac9739e9225026c99763e6687"}});
+    CheckUnparsable("pkh(xprv9s21ZrQH143K31xYSDQpPDxsXRTUcvj2iNHm5NUtrGiGG5e2DtALGdso3pGz6ssrdK4PFmM8NSpSBHNqPqm55Qn3LqFtT2emdEXVYsCzC2U/2147483648)", "pkh(xpub661MyMwAqRbcFW31YEwpkMuc5THy2PSt5bDMsktWQcFF8syAmRUapSCGu8ED9W6oDMSgv6Zz8idoc4a6mr8BDzTJY47LJhkJ8UB7WEGuduB/2147483648)"); // BIP 32 path element overflow
+
+    // Multisig constructions
+    Check("multi(1,L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1,5KYZdUEo39z3FPrtuX2QbbwGnNP5zTd7yyr2SC1j299sBCnWjss)", "multi(1,03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd,04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235)", SIGNABLE, {{"512103a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd4104a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea23552ae"}});
+    Check("sh(multi(2,xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc,xprv9uPDJpEQgRQfDcW7BkF7eTya6RPxXeJCqCJGHuCJ4GiRVLzkTXBAJMu2qaMWPrS7AANYqdq6vcBcBUdJCVVFceUvJFjaPdGZ2y9WACViL4L/0))", "sh(multi(2,xpub6ERApfZwUNrhLCkDtcHTcxd75RbzS1ed54G1LkBUHQVHQKqhMkhgbmJbZRkrgZw4koxb5JaHWkY4ALHY2grBGRjaDMzQLcgJvLJuZZvRcEL,xpub68NZiKmJWnxxS6aaHmn81bvJeTESw724CRDs6HbuccFQN9Ku14VQrADWgqbhhTHBaohPX4CjNLf9fq9MYo6oDaPPLPxSb7gwQN3ih19Zm4Y/0))", DEFAULT, {{"a91445a9a622a8b0a1269944be477640eedc447bbd8487"}});
+    Check("wsh(multi(2,xprv9s21ZrQH143K31xYSDQpPDxsXRTUcvj2iNHm5NUtrGiGG5e2DtALGdso3pGz6ssrdK4PFmM8NSpSBHNqPqm55Qn3LqFtT2emdEXVYsCzC2U/2147483647'/0,xprv9vHkqa6EV4sPZHYqZznhT2NPtPCjKuDKGY38FBWLvgaDx45zo9WQRUT3dKYnjwih2yJD9mkrocEZXo1ex8G81dwSM1fwqWpWkeS3v86pgKt/1/2/*,xprv9s21ZrQH143K3QTDL4LXw2F7HEK3wJUD2nW2nRk4stbPy6cq3jPPqjiChkVvvNKmPGJxWUtg6LnF5kejMRNNU3TGtRBeJgk33yuGBxrMPHi/10/20/30/40/*'))", "wsh(multi(2,xpub661MyMwAqRbcFW31YEwpkMuc5THy2PSt5bDMsktWQcFF8syAmRUapSCGu8ED9W6oDMSgv6Zz8idoc4a6mr8BDzTJY47LJhkJ8UB7WEGuduB/2147483647'/0,xpub69H7F5d8KSRgmmdJg2KhpAK8SR3DjMwAdkxj3ZuxV27CprR9LgpeyGmXUbC6wb7ERfvrnKZjXoUmmDznezpbZb7ap6r1D3tgFxHmwMkQTPH/1/2/*,xpub661MyMwAqRbcFtXgS5sYJABqqG9YLmC4Q1Rdap9gSE8NqtwybGhePY2gZ29ESFjqJoCu1Rupje8YtGqsefD265TMg7usUDFdp6W1EGMcet8/10/20/30/40/*'))", HARDENED | RANGE, {{"0020b92623201f3bb7c3771d45b2ad1d0351ea8fbf8cfe0a0e570264e1075fa1948f"},{"002036a08bbe4923af41cf4316817c93b8d37e2f635dd25cfff06bd50df6ae7ea203"},{"0020a96e7ab4607ca6b261bfe3245ffda9c746b28d3f59e83d34820ec0e2b36c139c"}});
+    Check("sh(wsh(multi(16,KzoAz5CanayRKex3fSLQ2BwJpN7U52gZvxMyk78nDMHuqrUxuSJy,KwGNz6YCCQtYvFzMtrC6D3tKTKdBBboMrLTsjr2NYVBwapCkn7Mr,KxogYhiNfwxuswvXV66eFyKcCpm7dZ7TqHVqujHAVUjJxyivxQ9X,L2BUNduTSyZwZjwNHynQTF14mv2uz2NRq5n5sYWTb4FkkmqgEE9f,L1okJGHGn1kFjdXHKxXjwVVtmCMR2JA5QsbKCSpSb7ReQjezKeoD,KxDCNSST75HFPaW5QKpzHtAyaCQC7p9Vo3FYfi2u4dXD1vgMiboK,L5edQjFtnkcf5UWURn6UuuoFrabgDQUHdheKCziwN42aLwS3KizU,KzF8UWFcEC7BYTq8Go1xVimMkDmyNYVmXV5PV7RuDicvAocoPB8i,L3nHUboKG2w4VSJ5jYZ5CBM97oeK6YuKvfZxrefdShECcjEYKMWZ,KyjHo36dWkYhimKmVVmQTq3gERv3pnqA4xFCpvUgbGDJad7eS8WE,KwsfyHKRUTZPQtysN7M3tZ4GXTnuov5XRgjdF2XCG8faAPmFruRF,KzCUbGhN9LJhdeFfL9zQgTJMjqxdBKEekRGZX24hXdgCNCijkkap,KzgpMBwwsDLwkaC5UrmBgCYaBD2WgZ7PBoGYXR8KT7gCA9UTN5a3,KyBXTPy4T7YG4q9tcAM3LkvfRpD1ybHMvcJ2ehaWXaSqeGUxEdkP,KzJDe9iwJRPtKP2F2AoN6zBgzS7uiuAwhWCfGdNeYJ3PC1HNJ8M8,L1xbHrxynrqLKkoYc4qtoQPx6uy5qYXR5ZDYVYBSRmCV5piU3JG9)))","sh(wsh(multi(16,03669b8afcec803a0d323e9a17f3ea8e68e8abe5a278020a929adbec52421adbd0,0260b2003c386519fc9eadf2b5cf124dd8eea4c4e68d5e154050a9346ea98ce600,0362a74e399c39ed5593852a30147f2959b56bb827dfa3e60e464b02ccf87dc5e8,0261345b53de74a4d721ef877c255429961b7e43714171ac06168d7e08c542a8b8,02da72e8b46901a65d4374fe6315538d8f368557dda3a1dcf9ea903f3afe7314c8,0318c82dd0b53fd3a932d16e0ba9e278fcc937c582d5781be626ff16e201f72286,0297ccef1ef99f9d73dec9ad37476ddb232f1238aff877af19e72ba04493361009,02e502cfd5c3f972fe9a3e2a18827820638f96b6f347e54d63deb839011fd5765d,03e687710f0e3ebe81c1037074da939d409c0025f17eb86adb9427d28f0f7ae0e9,02c04d3a5274952acdbc76987f3184b346a483d43be40874624b29e3692c1df5af,02ed06e0f418b5b43a7ec01d1d7d27290fa15f75771cb69b642a51471c29c84acd,036d46073cbb9ffee90473f3da429abc8de7f8751199da44485682a989a4bebb24,02f5d1ff7c9029a80a4e36b9a5497027ef7f3e73384a4a94fbfe7c4e9164eec8bc,02e41deffd1b7cce11cde209a781adcffdabd1b91c0ba0375857a2bfd9302419f3,02d76625f7956a7fc505ab02556c23ee72d832f1bac391bcd2d3abce5710a13d06,0399eb0a5487515802dc14544cf10b3666623762fbed2ec38a3975716e2c29c232)))", SIGNABLE, {{"a9147fc63e13dc25e8a95a3cee3d9a714ac3afd96f1e87"}});
+    CheckUnparsable("sh(multi(16,KzoAz5CanayRKex3fSLQ2BwJpN7U52gZvxMyk78nDMHuqrUxuSJy,KwGNz6YCCQtYvFzMtrC6D3tKTKdBBboMrLTsjr2NYVBwapCkn7Mr,KxogYhiNfwxuswvXV66eFyKcCpm7dZ7TqHVqujHAVUjJxyivxQ9X,L2BUNduTSyZwZjwNHynQTF14mv2uz2NRq5n5sYWTb4FkkmqgEE9f,L1okJGHGn1kFjdXHKxXjwVVtmCMR2JA5QsbKCSpSb7ReQjezKeoD,KxDCNSST75HFPaW5QKpzHtAyaCQC7p9Vo3FYfi2u4dXD1vgMiboK,L5edQjFtnkcf5UWURn6UuuoFrabgDQUHdheKCziwN42aLwS3KizU,KzF8UWFcEC7BYTq8Go1xVimMkDmyNYVmXV5PV7RuDicvAocoPB8i,L3nHUboKG2w4VSJ5jYZ5CBM97oeK6YuKvfZxrefdShECcjEYKMWZ,KyjHo36dWkYhimKmVVmQTq3gERv3pnqA4xFCpvUgbGDJad7eS8WE,KwsfyHKRUTZPQtysN7M3tZ4GXTnuov5XRgjdF2XCG8faAPmFruRF,KzCUbGhN9LJhdeFfL9zQgTJMjqxdBKEekRGZX24hXdgCNCijkkap,KzgpMBwwsDLwkaC5UrmBgCYaBD2WgZ7PBoGYXR8KT7gCA9UTN5a3,KyBXTPy4T7YG4q9tcAM3LkvfRpD1ybHMvcJ2ehaWXaSqeGUxEdkP,KzJDe9iwJRPtKP2F2AoN6zBgzS7uiuAwhWCfGdNeYJ3PC1HNJ8M8,L1xbHrxynrqLKkoYc4qtoQPx6uy5qYXR5ZDYVYBSRmCV5piU3JG9))","sh(multi(16,03669b8afcec803a0d323e9a17f3ea8e68e8abe5a278020a929adbec52421adbd0,0260b2003c386519fc9eadf2b5cf124dd8eea4c4e68d5e154050a9346ea98ce600,0362a74e399c39ed5593852a30147f2959b56bb827dfa3e60e464b02ccf87dc5e8,0261345b53de74a4d721ef877c255429961b7e43714171ac06168d7e08c542a8b8,02da72e8b46901a65d4374fe6315538d8f368557dda3a1dcf9ea903f3afe7314c8,0318c82dd0b53fd3a932d16e0ba9e278fcc937c582d5781be626ff16e201f72286,0297ccef1ef99f9d73dec9ad37476ddb232f1238aff877af19e72ba04493361009,02e502cfd5c3f972fe9a3e2a18827820638f96b6f347e54d63deb839011fd5765d,03e687710f0e3ebe81c1037074da939d409c0025f17eb86adb9427d28f0f7ae0e9,02c04d3a5274952acdbc76987f3184b346a483d43be40874624b29e3692c1df5af,02ed06e0f418b5b43a7ec01d1d7d27290fa15f75771cb69b642a51471c29c84acd,036d46073cbb9ffee90473f3da429abc8de7f8751199da44485682a989a4bebb24,02f5d1ff7c9029a80a4e36b9a5497027ef7f3e73384a4a94fbfe7c4e9164eec8bc,02e41deffd1b7cce11cde209a781adcffdabd1b91c0ba0375857a2bfd9302419f3,02d76625f7956a7fc505ab02556c23ee72d832f1bac391bcd2d3abce5710a13d06,0399eb0a5487515802dc14544cf10b3666623762fbed2ec38a3975716e2c29c232))"); // P2SH does not fit 16 compressed pubkeys in a redeemscript
+
+    // Check for invalid nesting of structures
+    CheckUnparsable("sh(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1)", "sh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)"); // P2SH needs a script, not a key
+    CheckUnparsable("sh(combo(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1))", "sh(combo(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))"); // Old must be top level
+    CheckUnparsable("wsh(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1)", "wsh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)"); // P2WSH needs a script, not a key
+    CheckUnparsable("wsh(wpkh(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1))", "wsh(wpkh(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))"); // Cannot embed witness inside witness
+    CheckUnparsable("wsh(sh(pk(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1)))", "wsh(sh(pk(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)))"); // Cannot embed P2SH inside P2WSH
+    CheckUnparsable("sh(sh(pk(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1)))", "sh(sh(pk(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)))"); // Cannot embed P2SH inside P2SH
+    CheckUnparsable("wsh(wsh(pk(L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1)))", "wsh(wsh(pk(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)))"); // Cannot embed P2WSH inside P2WSH
+}
+
+BOOST_AUTO_TEST_SUITE_END()
diff --git a/src/test/mempool_tests.cpp b/src/test/mempool_tests.cpp
index e2d76dc293..fb80599af7 100644
--- a/src/test/mempool_tests.cpp
+++ b/src/test/mempool_tests.cpp
@@ -55,6 +55,7 @@ BOOST_AUTO_TEST_CASE(MempoolRemoveTest)
 
 
     CTxMemPool testPool;
+    LOCK(testPool.cs);
 
     // Nothing in pool, remove should do nothing:
     unsigned int poolSize = testPool.size();
@@ -119,6 +120,7 @@ static void CheckSort(CTxMemPool &pool, std::vector<std::string> &sortedOrder) E
 BOOST_AUTO_TEST_CASE(MempoolIndexingTest)
 {
     CTxMemPool pool;
+    LOCK(pool.cs);
     TestMemPoolEntryHelper entry;
 
     /* 3rd highest fee */
@@ -165,7 +167,6 @@ BOOST_AUTO_TEST_CASE(MempoolIndexingTest)
     sortedOrder[2] = tx1.GetHash().ToString(); // 10000
     sortedOrder[3] = tx4.GetHash().ToString(); // 15000
     sortedOrder[4] = tx2.GetHash().ToString(); // 20000
-    LOCK(pool.cs);
     CheckSort<descendant_score>(pool, sortedOrder);
 
     /* low fee but with high fee child */
@@ -292,6 +293,7 @@ BOOST_AUTO_TEST_CASE(MempoolIndexingTest)
 BOOST_AUTO_TEST_CASE(MempoolAncestorIndexingTest)
 {
     CTxMemPool pool;
+    LOCK(pool.cs);
     TestMemPoolEntryHelper entry;
 
     /* 3rd highest fee */
@@ -347,7 +349,6 @@ BOOST_AUTO_TEST_CASE(MempoolAncestorIndexingTest)
     }
     sortedOrder[4] = tx3.GetHash().ToString(); // 0
 
-    LOCK(pool.cs);
     CheckSort<ancestor_score>(pool, sortedOrder);
 
     /* low fee parent with high fee child */
@@ -421,6 +422,7 @@ BOOST_AUTO_TEST_CASE(MempoolAncestorIndexingTest)
 BOOST_AUTO_TEST_CASE(MempoolSizeLimitTest)
 {
     CTxMemPool pool;
+    LOCK(pool.cs);
     TestMemPoolEntryHelper entry;
 
     CMutableTransaction tx1 = CMutableTransaction();
@@ -593,6 +595,7 @@ BOOST_AUTO_TEST_CASE(MempoolAncestryTests)
     size_t ancestors, descendants;
 
     CTxMemPool pool;
+    LOCK(pool.cs);
     TestMemPoolEntryHelper entry;
 
     /* Base transaction */
diff --git a/src/test/miner_tests.cpp b/src/test/miner_tests.cpp
index 10c7fd00e8..e2424f012d 100644
--- a/src/test/miner_tests.cpp
+++ b/src/test/miner_tests.cpp
@@ -99,7 +99,7 @@ static bool TestSequenceLocks(const CTransaction &tx, int flags)
 // Test suite for ancestor feerate transaction selection.
 // Implemented as an additional function, rather than a separate test case,
 // to allow reusing the blockchain created in CreateNewBlock_validity.
-static void TestPackageSelection(const CChainParams& chainparams, CScript scriptPubKey, std::vector<CTransactionRef>& txFirst)
+static void TestPackageSelection(const CChainParams& chainparams, const CScript& scriptPubKey, const std::vector<CTransactionRef>& txFirst) EXCLUSIVE_LOCKS_REQUIRED(::mempool.cs)
 {
     // Test the ancestor feerate transaction selection.
     TestMemPoolEntryHelper entry;
@@ -253,6 +253,7 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
     }
 
     LOCK(cs_main);
+    LOCK(::mempool.cs);
 
     // Just to make sure we can still make simple blocks
     BOOST_CHECK(pblocktemplate = AssemblerForTest(chainparams).CreateNewBlock(scriptPubKey));
diff --git a/src/test/policyestimator_tests.cpp b/src/test/policyestimator_tests.cpp
index 8d288ec993..e45fb6d17e 100644
--- a/src/test/policyestimator_tests.cpp
+++ b/src/test/policyestimator_tests.cpp
@@ -18,6 +18,7 @@ BOOST_AUTO_TEST_CASE(BlockPolicyEstimates)
 {
     CBlockPolicyEstimator feeEst;
     CTxMemPool mpool(&feeEst);
+    LOCK(mpool.cs);
     TestMemPoolEntryHelper entry;
     CAmount basefee(2000);
     CAmount deltaFee(100);
diff --git a/src/test/scheduler_tests.cpp b/src/test/scheduler_tests.cpp
index 179df7dd38..b1ea4b6fab 100644
--- a/src/test/scheduler_tests.cpp
+++ b/src/test/scheduler_tests.cpp
@@ -65,7 +65,7 @@ BOOST_AUTO_TEST_CASE(manythreads)
     size_t nTasks = microTasks.getQueueInfo(first, last);
     BOOST_CHECK(nTasks == 0);
 
-    for (int i = 0; i < 100; i++) {
+    for (int i = 0; i < 100; ++i) {
         boost::chrono::system_clock::time_point t = now + boost::chrono::microseconds(randomMsec(rng));
         boost::chrono::system_clock::time_point tReschedule = now + boost::chrono::microseconds(500 + randomMsec(rng));
         int whichCounter = zeroToNine(rng);
@@ -112,4 +112,46 @@ BOOST_AUTO_TEST_CASE(manythreads)
     BOOST_CHECK_EQUAL(counterSum, 200);
 }
 
+BOOST_AUTO_TEST_CASE(singlethreadedscheduler_ordered)
+{
+    CScheduler scheduler;
+
+    // each queue should be well ordered with respect to itself but not other queues
+    SingleThreadedSchedulerClient queue1(&scheduler);
+    SingleThreadedSchedulerClient queue2(&scheduler);
+
+    // create more threads than queues
+    // if the queues only permit execution of one task at once then
+    // the extra threads should effectively be doing nothing
+    // if they don't we'll get out of order behaviour
+    boost::thread_group threads;
+    for (int i = 0; i < 5; ++i) {
+        threads.create_thread(boost::bind(&CScheduler::serviceQueue, &scheduler));
+    }
+
+    // these are not atomic, if SinglethreadedSchedulerClient prevents
+    // parallel execution at the queue level no synchronization should be required here
+    int counter1 = 0;
+    int counter2 = 0;
+
+    // just simply count up on each queue - if execution is properly ordered then
+    // the callbacks should run in exactly the order in which they were enqueued
+    for (int i = 0; i < 100; ++i) {
+        queue1.AddToProcessQueue([i, &counter1]() {
+            BOOST_CHECK_EQUAL(i, counter1++);
+        });
+
+        queue2.AddToProcessQueue([i, &counter2]() {
+            BOOST_CHECK_EQUAL(i, counter2++);
+        });
+    }
+
+    // finish up
+    scheduler.stop(true);
+    threads.join_all();
+
+    BOOST_CHECK_EQUAL(counter1, 100);
+    BOOST_CHECK_EQUAL(counter2, 100);
+}
+
 BOOST_AUTO_TEST_SUITE_END()
diff --git a/src/txmempool.cpp b/src/txmempool.cpp
index 9d705e3d23..d68c38ad4e 100644
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -151,8 +151,6 @@ void CTxMemPool::UpdateTransactionsFromBlock(const std::vector<uint256> &vHashes
 
 bool CTxMemPool::CalculateMemPoolAncestors(const CTxMemPoolEntry &entry, setEntries &setAncestors, uint64_t limitAncestorCount, uint64_t limitAncestorSize, uint64_t limitDescendantCount, uint64_t limitDescendantSize, std::string &errString, bool fSearchForParents /* = true */) const
 {
-    LOCK(cs);
-
     setEntries parentHashes;
     const CTransaction &tx = entry.GetTx();
 
@@ -363,7 +361,6 @@ void CTxMemPool::addUnchecked(const uint256& hash, const CTxMemPoolEntry &entry,
     // Add to memory pool without checking anything.
     // Used by AcceptToMemoryPool(), which DOES do
     // all the appropriate checks.
-    LOCK(cs);
     indexed_transaction_set::iterator newit = mapTx.insert(entry).first;
     mapLinks.insert(make_pair(newit, TxLinks()));
 
@@ -933,7 +930,6 @@ int CTxMemPool::Expire(int64_t time) {
 
 void CTxMemPool::addUnchecked(const uint256&hash, const CTxMemPoolEntry &entry, bool validFeeEstimate)
 {
-    LOCK(cs);
     setEntries setAncestors;
     uint64_t nNoLimit = std::numeric_limits<uint64_t>::max();
     std::string dummy;
diff --git a/src/txmempool.h b/src/txmempool.h
index bb676cf05d..0feea08f0b 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -539,8 +539,8 @@ public:
     // Note that addUnchecked is ONLY called from ATMP outside of tests
     // and any other callers may break wallet's in-mempool tracking (due to
     // lack of CValidationInterface::TransactionAddedToMempool callbacks).
-    void addUnchecked(const uint256& hash, const CTxMemPoolEntry &entry, bool validFeeEstimate = true);
-    void addUnchecked(const uint256& hash, const CTxMemPoolEntry &entry, setEntries &setAncestors, bool validFeeEstimate = true);
+    void addUnchecked(const uint256& hash, const CTxMemPoolEntry& entry, bool validFeeEstimate = true) EXCLUSIVE_LOCKS_REQUIRED(cs);
+    void addUnchecked(const uint256& hash, const CTxMemPoolEntry& entry, setEntries& setAncestors, bool validFeeEstimate = true) EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     void removeRecursive(const CTransaction &tx, MemPoolRemovalReason reason = MemPoolRemovalReason::UNKNOWN);
     void removeForReorg(const CCoinsViewCache *pcoins, unsigned int nMemPoolHeight, int flags);
@@ -596,7 +596,7 @@ public:
      *  fSearchForParents = whether to search a tx's vin for in-mempool parents, or
      *    look up parents from mapLinks. Must be true for entries not in the mempool
      */
-    bool CalculateMemPoolAncestors(const CTxMemPoolEntry &entry, setEntries &setAncestors, uint64_t limitAncestorCount, uint64_t limitAncestorSize, uint64_t limitDescendantCount, uint64_t limitDescendantSize, std::string &errString, bool fSearchForParents = true) const;
+    bool CalculateMemPoolAncestors(const CTxMemPoolEntry& entry, setEntries& setAncestors, uint64_t limitAncestorCount, uint64_t limitAncestorSize, uint64_t limitDescendantCount, uint64_t limitDescendantSize, std::string& errString, bool fSearchForParents = true) const EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     /** Populate setDescendants with all in-mempool descendants of hash.
      *  Assumes that setDescendants includes all in-mempool descendants of anything
diff --git a/src/util.cpp b/src/util.cpp
index 2f81f50a71..238554ee4a 100644
--- a/src/util.cpp
+++ b/src/util.cpp
@@ -859,9 +859,13 @@ bool ArgsManager::ReadConfigStream(std::istream& stream, std::string& error, boo
         }
 
         // Check that the arg is known
-        if (!IsArgKnown(strKey) && !ignore_invalid_keys) {
-            error = strprintf("Invalid configuration value %s", option.first.c_str());
-            return false;
+        if (!IsArgKnown(strKey)) {
+            if (!ignore_invalid_keys) {
+                error = strprintf("Invalid configuration value %s", option.first.c_str());
+                return false;
+            } else {
+                LogPrintf("Ignoring unknown configuration value %s\n", option.first);
+            }
         }
     }
     return true;
diff --git a/src/validationinterface.h b/src/validationinterface.h
index 42cc2e9a20..bddc28d24a 100644
--- a/src/validationinterface.h
+++ b/src/validationinterface.h
@@ -53,6 +53,21 @@ void CallFunctionInValidationInterfaceQueue(std::function<void ()> func);
  */
 void SyncWithValidationInterfaceQueue();
 
+/**
+ * Implement this to subscribe to events generated in validation
+ *
+ * Each CValidationInterface() subscriber will receive event callbacks
+ * in the order in which the events were generated by validation.
+ * Furthermore, each ValidationInterface() subscriber may assume that
+ * callbacks effectively run in a single thread with single-threaded
+ * memory consistency. That is, for a given ValidationInterface()
+ * instantiation, each callback will complete before the next one is
+ * invoked. This means, for example when a block is connected that the
+ * UpdatedBlockTip() callback may depend on an operation performed in
+ * the BlockConnected() callback without worrying about explicit
+ * synchronization. No ordering should be assumed across
+ * ValidationInterface() subscribers.
+ */
 class CValidationInterface {
 protected:
     /**
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 4918100b30..218684fdf1 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -3018,7 +3018,8 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CTransac
         size_t nLimitDescendants = gArgs.GetArg("-limitdescendantcount", DEFAULT_DESCENDANT_LIMIT);
         size_t nLimitDescendantSize = gArgs.GetArg("-limitdescendantsize", DEFAULT_DESCENDANT_SIZE_LIMIT)*1000;
         std::string errString;
-        if (!mempool.CalculateMemPoolAncestors(entry, setAncestors, nLimitAncestors, nLimitAncestorSize, nLimitDescendants, nLimitDescendantSize, errString)) {
+        LOCK(::mempool.cs);
+        if (!::mempool.CalculateMemPoolAncestors(entry, setAncestors, nLimitAncestors, nLimitAncestorSize, nLimitDescendants, nLimitDescendantSize, errString)) {
             strFailReason = _("Transaction has too long of a mempool chain");
             return false;
         }
@@ -4423,7 +4424,10 @@ std::vector<OutputGroup> CWallet::GroupOutputs(const std::vector<COutput>& outpu
             size_t ancestors, descendants;
             mempool.GetTransactionAncestry(output.tx->GetHash(), ancestors, descendants);
             if (!single_coin && ExtractDestination(output.tx->tx->vout[output.i].scriptPubKey, dst)) {
-                if (gmap.count(dst) == 10) {
+                // Limit output groups to no more than 10 entries, to protect
+                // against inadvertently creating a too-large transaction
+                // when using -avoidpartialspends
+                if (gmap[dst].m_outputs.size() >= 10) {
                     groups.push_back(gmap[dst]);
                     gmap.erase(dst);
                 }