15 files changed, 615 insertions, 1147 deletions
diff --git a/src/script/descriptor.cpp b/src/script/descriptor.cpp
index 96cd93df5a..8ae0460273 100644
--- a/src/script/descriptor.cpp
+++ b/src/script/descriptor.cpp
@@ -10,6 +10,7 @@
 #include <script/standard.h>
 
 #include <span.h>
+#include <util/bip32.h>
 #include <util/system.h>
 #include <util/strencodings.h>
 
@@ -20,21 +21,130 @@
 namespace {
 
 ////////////////////////////////////////////////////////////////////////////
-// Internal representation                                                //
+// Checksum                                                               //
 ////////////////////////////////////////////////////////////////////////////
 
-typedef std::vector<uint32_t> KeyPath;
+// This section implements a checksum algorithm for descriptors with the
+// following properties:
+// * Mistakes in a descriptor string are measured in "symbol errors". The higher
+//   the number of symbol errors, the harder it is to detect:
+//   * An error substituting a character from 0123456789()[],'/*abcdefgh@:$%{} for
+//     another in that set always counts as 1 symbol error.
+//     * Note that hex encoded keys are covered by these characters. Xprvs and
+//       xpubs use other characters too, but already have their own checksum
+//       mechanism.
+//     * Function names like "multi()" use other characters, but mistakes in
+//       these would generally result in an unparseable descriptor.
+//   * A case error always counts as 1 symbol error.
+//   * Any other 1 character substitution error counts as 1 or 2 symbol errors.
+// * Any 1 symbol error is always detected.
+// * Any 2 or 3 symbol error in a descriptor of up to 49154 characters is always detected.
+// * Any 4 symbol error in a descriptor of up to 507 characters is always detected.
+// * Any 5 symbol error in a descriptor of up to 77 characters is always detected.
+// * Is optimized to minimize the chance a 5 symbol error in a descriptor up to 387 characters is undetected
+// * Random errors have a chance of 1 in 2**40 of being undetected.
+//
+// These properties are achieved by expanding every group of 3 (non checksum) characters into
+// 4 GF(32) symbols, over which a cyclic code is defined.
+
+/*
+ * Interprets c as 8 groups of 5 bits which are the coefficients of a degree 8 polynomial over GF(32),
+ * multiplies that polynomial by x, computes its remainder modulo a generator, and adds the constant term val.
+ *
+ * This generator is G(x) = x^8 + {30}x^7 + {23}x^6 + {15}x^5 + {14}x^4 + {10}x^3 + {6}x^2 + {12}x + {9}.
+ * It is chosen to define an cyclic error detecting code which is selected by:
+ * - Starting from all BCH codes over GF(32) of degree 8 and below, which by construction guarantee detecting
+ *   3 errors in windows up to 19000 symbols.
+ * - Taking all those generators, and for degree 7 ones, extend them to degree 8 by adding all degree-1 factors.
+ * - Selecting just the set of generators that guarantee detecting 4 errors in a window of length 512.
+ * - Selecting one of those with best worst-case behavior for 5 errors in windows of length up to 512.
+ *
+ * The generator and the constants to implement it can be verified using this Sage code:
+ *   B = GF(2) # Binary field
+ *   BP.<b> = B[] # Polynomials over the binary field
+ *   F_mod = b**5 + b**3 + 1
+ *   F.<f> = GF(32, modulus=F_mod, repr='int') # GF(32) definition
+ *   FP.<x> = F[] # Polynomials over GF(32)
+ *   E_mod = x**3 + x + F.fetch_int(8)
+ *   E.<e> = F.extension(E_mod) # Extension field definition
+ *   alpha = e**2743 # Choice of an element in extension field
+ *   for p in divisors(E.order() - 1): # Verify alpha has order 32767.
+ *       assert((alpha**p == 1) == (p % 32767 == 0))
+ *   G = lcm([(alpha**i).minpoly() for i in [1056,1057,1058]] + [x + 1])
+ *   print(G) # Print out the generator
+ *   for i in [1,2,4,8,16]: # Print out {1,2,4,8,16}*(G mod x^8), packed in hex integers.
+ *       v = 0
+ *       for coef in reversed((F.fetch_int(i)*(G % x**8)).coefficients(sparse=True)):
+ *           v = v*32 + coef.integer_representation()
+ *       print("0x%x" % v)
+ */
+uint64_t PolyMod(uint64_t c, int val)
+{
+    uint8_t c0 = c >> 35;
+    c = ((c & 0x7ffffffff) << 5) ^ val;
+    if (c0 & 1) c ^= 0xf5dee51989;
+    if (c0 & 2) c ^= 0xa9fdca3312;
+    if (c0 & 4) c ^= 0x1bab10e32d;
+    if (c0 & 8) c ^= 0x3706b1677a;
+    if (c0 & 16) c ^= 0x644d626ffd;
+    return c;
+}
 
-std::string FormatKeyPath(const KeyPath& path)
+std::string DescriptorChecksum(const Span<const char>& span)
 {
-    std::string ret;
-    for (auto i : path) {
-        ret += strprintf("/%i", (i << 1) >> 1);
-        if (i >> 31) ret += '\'';
+    /** A character set designed such that:
+     *  - The most common 'unprotected' descriptor characters (hex, keypaths) are in the first group of 32.
+     *  - Case errors cause an offset that's a multiple of 32.
+     *  - As many alphabetic characters are in the same group (while following the above restrictions).
+     *
+     * If p(x) gives the position of a character c in this character set, every group of 3 characters
+     * (a,b,c) is encoded as the 4 symbols (p(a) & 31, p(b) & 31, p(c) & 31, (p(a) / 32) + 3 * (p(b) / 32) + 9 * (p(c) / 32).
+     * This means that changes that only affect the lower 5 bits of the position, or only the higher 2 bits, will just
+     * affect a single symbol.
+     *
+     * As a result, within-group-of-32 errors count as 1 symbol, as do cross-group errors that don't affect
+     * the position within the groups.
+     */
+    static std::string INPUT_CHARSET =
+        "0123456789()[],'/*abcdefgh@:$%{}"
+        "IJKLMNOPQRSTUVWXYZ&+-.;<=>?!^_|~"
+        "ijklmnopqrstuvwxyzABCDEFGH`#\"\\ ";
+
+    /** The character set for the checksum itself (same as bech32). */
+    static std::string CHECKSUM_CHARSET = "qpzry9x8gf2tvdw0s3jn54khce6mua7l";
+
+    uint64_t c = 1;
+    int cls = 0;
+    int clscount = 0;
+    for (auto ch : span) {
+        auto pos = INPUT_CHARSET.find(ch);
+        if (pos == std::string::npos) return "";
+        c = PolyMod(c, pos & 31); // Emit a symbol for the position inside the group, for every character.
+        cls = cls * 3 + (pos >> 5); // Accumulate the group numbers
+        if (++clscount == 3) {
+            // Emit an extra symbol representing the group numbers, for every 3 characters.
+            c = PolyMod(c, cls);
+            cls = 0;
+            clscount = 0;
+        }
     }
+    if (clscount > 0) c = PolyMod(c, cls);
+    for (int j = 0; j < 8; ++j) c = PolyMod(c, 0); // Shift further to determine the checksum.
+    c ^= 1; // Prevent appending zeroes from not affecting the checksum.
+
+    std::string ret(8, ' ');
+    for (int j = 0; j < 8; ++j) ret[j] = CHECKSUM_CHARSET[(c >> (5 * (7 - j))) & 31];
     return ret;
 }
 
+std::string AddChecksum(const std::string& str) { return str + "#" + DescriptorChecksum(MakeSpan(str)); }
+
+////////////////////////////////////////////////////////////////////////////
+// Internal representation                                                //
+////////////////////////////////////////////////////////////////////////////
+
+typedef std::vector<uint32_t> KeyPath;
+
 /** Interface for public key objects in descriptors. */
 struct PubkeyProvider
 {
@@ -54,6 +164,9 @@ struct PubkeyProvider
 
     /** Get the descriptor string form including private data (if available in arg). */
     virtual bool ToPrivateString(const SigningProvider& arg, std::string& out) const = 0;
+
+    /** Derive a private key, if private data is available in arg. */
+    virtual bool GetPrivKey(int pos, const SigningProvider& arg, CKey& key) const = 0;
 };
 
 class OriginPubkeyProvider final : public PubkeyProvider
@@ -63,7 +176,7 @@ class OriginPubkeyProvider final : public PubkeyProvider
 
     std::string OriginString() const
     {
-        return HexStr(std::begin(m_origin.fingerprint), std::end(m_origin.fingerprint)) + FormatKeyPath(m_origin.path);
+        return HexStr(std::begin(m_origin.fingerprint), std::end(m_origin.fingerprint)) + FormatHDKeypath(m_origin.path);
     }
 
 public:
@@ -85,6 +198,10 @@ public:
         ret = "[" + OriginString() + "]" + std::move(sub);
         return true;
     }
+    bool GetPrivKey(int pos, const SigningProvider& arg, CKey& key) const override
+    {
+        return m_provider->GetPrivKey(pos, arg, key);
+    }
 };
 
 /** An object representing a parsed constant public key in a descriptor. */
@@ -112,6 +229,10 @@ public:
         ret = EncodeSecret(key);
         return true;
     }
+    bool GetPrivKey(int pos, const SigningProvider& arg, CKey& key) const override
+    {
+        return arg.GetKey(m_pubkey.GetID(), key);
+    }
 };
 
 enum class DeriveType {
@@ -156,14 +277,9 @@ public:
     {
         if (key) {
             if (IsHardened()) {
-                CExtKey extkey;
-                if (!GetExtKey(arg, extkey)) return false;
-                for (auto entry : m_path) {
-                    extkey.Derive(extkey, entry);
-                }
-                if (m_derive == DeriveType::UNHARDENED) extkey.Derive(extkey, pos);
-                if (m_derive == DeriveType::HARDENED) extkey.Derive(extkey, pos | 0x80000000UL);
-                *key = extkey.Neuter().pubkey;
+                CKey priv_key;
+                if (!GetPrivKey(pos, arg, priv_key)) return false;
+                *key = priv_key.GetPubKey();
             } else {
                 // TODO: optimize by caching
                 CExtPubKey extkey = m_extkey;
@@ -184,7 +300,7 @@ public:
     }
     std::string ToString() const override
     {
-        std::string ret = EncodeExtPubKey(m_extkey) + FormatKeyPath(m_path);
+        std::string ret = EncodeExtPubKey(m_extkey) + FormatHDKeypath(m_path);
         if (IsRange()) {
             ret += "/*";
             if (m_derive == DeriveType::HARDENED) ret += '\'';
@@ -195,13 +311,25 @@ public:
     {
         CExtKey key;
         if (!GetExtKey(arg, key)) return false;
-        out = EncodeExtKey(key) + FormatKeyPath(m_path);
+        out = EncodeExtKey(key) + FormatHDKeypath(m_path);
         if (IsRange()) {
             out += "/*";
             if (m_derive == DeriveType::HARDENED) out += '\'';
         }
         return true;
     }
+    bool GetPrivKey(int pos, const SigningProvider& arg, CKey& key) const override
+    {
+        CExtKey extkey;
+        if (!GetExtKey(arg, extkey)) return false;
+        for (auto entry : m_path) {
+            extkey.Derive(extkey, entry);
+        }
+        if (m_derive == DeriveType::UNHARDENED) extkey.Derive(extkey, pos);
+        if (m_derive == DeriveType::HARDENED) extkey.Derive(extkey, pos | 0x80000000UL);
+        key = extkey.key;
+        return true;
+    }
 };
 
 /** Base class for all Descriptor implementations. */
@@ -228,7 +356,7 @@ protected:
      *  @param pubkeys The evaluations of the m_pubkey_args field.
      *  @param script The evaluation of m_subdescriptor_arg (or nullptr when m_subdescriptor_arg is nullptr).
      *  @param out A FlatSigningProvider to put scripts or public keys in that are necessary to the solver.
-     *             The script and pubkeys argument to this function are automatically added.
+     *             The script arguments to this function are automatically added, as is the origin info of the provided pubkeys.
      *  @return A vector with scriptPubKeys for this descriptor.
      */
     virtual std::vector<CScript> MakeScripts(const std::vector<CPubKey>& pubkeys, const CScript* script, FlatSigningProvider& out) const = 0;
@@ -284,10 +412,15 @@ public:
     {
         std::string ret;
         ToStringHelper(nullptr, ret, false);
-        return ret;
+        return AddChecksum(ret);
     }
 
-    bool ToPrivateString(const SigningProvider& arg, std::string& out) const override final { return ToStringHelper(&arg, out, true); }
+    bool ToPrivateString(const SigningProvider& arg, std::string& out) const override final
+    {
+        bool ret = ToStringHelper(&arg, out, true);
+        out = AddChecksum(out);
+        return ret;
+    }
 
     bool ExpandHelper(int pos, const SigningProvider& arg, Span<const unsigned char>* cache_read, std::vector<CScript>& output_scripts, FlatSigningProvider& out, std::vector<unsigned char>* cache_write) const
     {
@@ -325,8 +458,7 @@ public:
         pubkeys.reserve(entries.size());
         for (auto& entry : entries) {
             pubkeys.push_back(entry.first);
-            out.origins.emplace(entry.first.GetID(), std::move(entry.second));
-            out.pubkeys.emplace(entry.first.GetID(), entry.first);
+            out.origins.emplace(entry.first.GetID(), std::make_pair<CPubKey, KeyOriginInfo>(CPubKey(entry.first), std::move(entry.second)));
         }
         if (m_subdescriptor_arg) {
             for (const auto& subscript : subscripts) {
@@ -352,6 +484,20 @@ public:
         Span<const unsigned char> span = MakeSpan(cache);
         return ExpandHelper(pos, DUMMY_SIGNING_PROVIDER, &span, output_scripts, out, nullptr) && span.size() == 0;
     }
+
+    void ExpandPrivate(int pos, const SigningProvider& provider, FlatSigningProvider& out) const final
+    {
+        for (const auto& p : m_pubkey_args) {
+            CKey key;
+            if (!p->GetPrivKey(pos, provider, key)) continue;
+            out.keys.emplace(key.GetPubKey().GetID(), key);
+        }
+        if (m_script_arg) {
+            FlatSigningProvider subprovider;
+            m_script_arg->ExpandPrivate(pos, provider, subprovider);
+            out = Merge(out, subprovider);
+        }
+    }
 };
 
 /** Construct a vector with one element, which is moved into it. */
@@ -400,7 +546,12 @@ public:
 class PKHDescriptor final : public DescriptorImpl
 {
 protected:
-    std::vector<CScript> MakeScripts(const std::vector<CPubKey>& keys, const CScript*, FlatSigningProvider&) const override { return Singleton(GetScriptForDestination(keys[0].GetID())); }
+    std::vector<CScript> MakeScripts(const std::vector<CPubKey>& keys, const CScript*, FlatSigningProvider& out) const override
+    {
+        CKeyID id = keys[0].GetID();
+        out.pubkeys.emplace(id, keys[0]);
+        return Singleton(GetScriptForDestination(PKHash(id)));
+    }
 public:
     PKHDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Singleton(std::move(prov)), {}, "pkh") {}
 };
@@ -409,7 +560,12 @@ public:
 class WPKHDescriptor final : public DescriptorImpl
 {
 protected:
-    std::vector<CScript> MakeScripts(const std::vector<CPubKey>& keys, const CScript*, FlatSigningProvider&) const override { return Singleton(GetScriptForDestination(WitnessV0KeyHash(keys[0].GetID()))); }
+    std::vector<CScript> MakeScripts(const std::vector<CPubKey>& keys, const CScript*, FlatSigningProvider& out) const override
+    {
+        CKeyID id = keys[0].GetID();
+        out.pubkeys.emplace(id, keys[0]);
+        return Singleton(GetScriptForDestination(WitnessV0KeyHash(id)));
+    }
 public:
     WPKHDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Singleton(std::move(prov)), {}, "wpkh") {}
 };
@@ -422,13 +578,14 @@ protected:
     {
         std::vector<CScript> ret;
         CKeyID id = keys[0].GetID();
+        out.pubkeys.emplace(id, keys[0]);
         ret.emplace_back(GetScriptForRawPubKey(keys[0])); // P2PK
-        ret.emplace_back(GetScriptForDestination(id)); // P2PKH
+        ret.emplace_back(GetScriptForDestination(PKHash(id))); // P2PKH
         if (keys[0].IsCompressed()) {
             CScript p2wpkh = GetScriptForDestination(WitnessV0KeyHash(id));
             out.scripts.emplace(CScriptID(p2wpkh), p2wpkh);
             ret.emplace_back(p2wpkh);
-            ret.emplace_back(GetScriptForDestination(CScriptID(p2wpkh))); // P2SH-P2WPKH
+            ret.emplace_back(GetScriptForDestination(ScriptHash(p2wpkh))); // P2SH-P2WPKH
         }
         return ret;
     }
@@ -451,7 +608,7 @@ public:
 class SHDescriptor final : public DescriptorImpl
 {
 protected:
-    std::vector<CScript> MakeScripts(const std::vector<CPubKey>&, const CScript* script, FlatSigningProvider&) const override { return Singleton(GetScriptForDestination(CScriptID(*script))); }
+    std::vector<CScript> MakeScripts(const std::vector<CPubKey>&, const CScript* script, FlatSigningProvider&) const override { return Singleton(GetScriptForDestination(ScriptHash(*script))); }
 public:
     SHDescriptor(std::unique_ptr<DescriptorImpl> desc) : DescriptorImpl({}, std::move(desc), "sh") {}
 };
@@ -754,11 +911,25 @@ std::unique_ptr<DescriptorImpl> InferScript(const CScript& script, ParseScriptCo
     return MakeUnique<RawDescriptor>(script);
 }
 
+
 } // namespace
 
-std::unique_ptr<Descriptor> Parse(const std::string& descriptor, FlatSigningProvider& out)
+std::unique_ptr<Descriptor> Parse(const std::string& descriptor, FlatSigningProvider& out, bool require_checksum)
 {
     Span<const char> sp(descriptor.data(), descriptor.size());
+
+    // Checksum checks
+    auto check_split = Split(sp, '#');
+    if (check_split.size() > 2) return nullptr; // Multiple '#' symbols
+    if (check_split.size() == 1 && require_checksum) return nullptr; // Missing checksum
+    if (check_split.size() == 2) {
+        if (check_split[1].size() != 8) return nullptr; // Unexpected length for checksum
+        auto checksum = DescriptorChecksum(check_split[0]);
+        if (checksum.empty()) return nullptr; // Invalid characters in payload
+        if (!std::equal(checksum.begin(), checksum.end(), check_split[1].begin())) return nullptr; // Checksum mismatch
+    }
+    sp = check_split[0];
+
     auto ret = ParseScript(sp, ParseScriptContext::TOP, out);
     if (sp.size() == 0 && ret) return std::unique_ptr<Descriptor>(std::move(ret));
     return nullptr;
diff --git a/src/script/descriptor.h b/src/script/descriptor.h
index 2be157b861..a34e9f0d8a 100644
--- a/src/script/descriptor.h
+++ b/src/script/descriptor.h
@@ -7,6 +7,7 @@
 
 #include <script/script.h>
 #include <script/sign.h>
+#include <script/signingprovider.h>
 
 #include <vector>
 
@@ -60,10 +61,25 @@ struct Descriptor {
      * out: scripts and public keys necessary for solving the expanded scriptPubKeys will be put here (may be equal to provider).
      */
     virtual bool ExpandFromCache(int pos, const std::vector<unsigned char>& cache, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const = 0;
+
+    /** Expand the private key for a descriptor at a specified position, if possible.
+     *
+     * pos: the position at which to expand the descriptor. If IsRange() is false, this is ignored.
+     * provider: the provider to query for the private keys.
+     * out: any private keys available for the specified pos will be placed here.
+     */
+    virtual void ExpandPrivate(int pos, const SigningProvider& provider, 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);
+/** Parse a descriptor string. Included private keys are put in out.
+ *
+ * If the descriptor has a checksum, it must be valid. If require_checksum
+ * is set, the checksum is mandatory - otherwise it is optional.
+ *
+ * If a parse error occurs, or the checksum is missing/invalid, or anything
+ * else is wrong, nullptr is returned.
+ */
+std::unique_ptr<Descriptor> Parse(const std::string& descriptor, FlatSigningProvider& out, bool require_checksum = false);
 
 /** Find a descriptor for the specified script, using information from provider where possible.
  *
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
index 95b25b4911..f8701b6d01 100644
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -926,7 +926,7 @@ bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript&
 
                     // Drop the signature in pre-segwit scripts but not segwit scripts
                     if (sigversion == SigVersion::BASE) {
-                        int found = FindAndDelete(scriptCode, CScript(vchSig));
+                        int found = FindAndDelete(scriptCode, CScript() << vchSig);
                         if (found > 0 && (flags & SCRIPT_VERIFY_CONST_SCRIPTCODE))
                             return set_error(serror, SCRIPT_ERR_SIG_FINDANDDELETE);
                     }
@@ -992,7 +992,7 @@ bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript&
                     {
                         valtype& vchSig = stacktop(-isig-k);
                         if (sigversion == SigVersion::BASE) {
-                            int found = FindAndDelete(scriptCode, CScript(vchSig));
+                            int found = FindAndDelete(scriptCode, CScript() << vchSig);
                             if (found > 0 && (flags & SCRIPT_VERIFY_CONST_SCRIPTCODE))
                                 return set_error(serror, SCRIPT_ERR_SIG_FINDANDDELETE);
                         }
diff --git a/src/script/ismine.cpp b/src/script/ismine.cpp
deleted file mode 100644
index 51bd2d6e9f..0000000000
--- a/src/script/ismine.cpp
+++ /dev/null
@@ -1,193 +0,0 @@
-// Copyright (c) 2009-2010 Satoshi Nakamoto
-// Copyright (c) 2009-2018 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/ismine.h>
-
-#include <key.h>
-#include <keystore.h>
-#include <script/script.h>
-#include <script/sign.h>
-
-
-typedef std::vector<unsigned char> valtype;
-
-namespace {
-
-/**
- * This is an enum that tracks the execution context of a script, similar to
- * SigVersion in script/interpreter. It is separate however because we want to
- * distinguish between top-level scriptPubKey execution and P2SH redeemScript
- * execution (a distinction that has no impact on consensus rules).
- */
-enum class IsMineSigVersion
-{
-    TOP = 0,        //!< scriptPubKey execution
-    P2SH = 1,       //!< P2SH redeemScript
-    WITNESS_V0 = 2, //!< P2WSH witness script execution
-};
-
-/**
- * This is an internal representation of isminetype + invalidity.
- * Its order is significant, as we return the max of all explored
- * possibilities.
- */
-enum class IsMineResult
-{
-    NO = 0,         //!< Not ours
-    WATCH_ONLY = 1, //!< Included in watch-only balance
-    SPENDABLE = 2,  //!< Included in all balances
-    INVALID = 3,    //!< Not spendable by anyone (uncompressed pubkey in segwit, P2SH inside P2SH or witness, witness inside witness)
-};
-
-bool PermitsUncompressed(IsMineSigVersion sigversion)
-{
-    return sigversion == IsMineSigVersion::TOP || sigversion == IsMineSigVersion::P2SH;
-}
-
-bool HaveKeys(const std::vector<valtype>& pubkeys, const CKeyStore& keystore)
-{
-    for (const valtype& pubkey : pubkeys) {
-        CKeyID keyID = CPubKey(pubkey).GetID();
-        if (!keystore.HaveKey(keyID)) return false;
-    }
-    return true;
-}
-
-IsMineResult IsMineInner(const CKeyStore& keystore, const CScript& scriptPubKey, IsMineSigVersion sigversion)
-{
-    IsMineResult ret = IsMineResult::NO;
-
-    std::vector<valtype> vSolutions;
-    txnouttype whichType = Solver(scriptPubKey, vSolutions);
-
-    CKeyID keyID;
-    switch (whichType)
-    {
-    case TX_NONSTANDARD:
-    case TX_NULL_DATA:
-    case TX_WITNESS_UNKNOWN:
-        break;
-    case TX_PUBKEY:
-        keyID = CPubKey(vSolutions[0]).GetID();
-        if (!PermitsUncompressed(sigversion) && vSolutions[0].size() != 33) {
-            return IsMineResult::INVALID;
-        }
-        if (keystore.HaveKey(keyID)) {
-            ret = std::max(ret, IsMineResult::SPENDABLE);
-        }
-        break;
-    case TX_WITNESS_V0_KEYHASH:
-    {
-        if (sigversion == IsMineSigVersion::WITNESS_V0) {
-            // P2WPKH inside P2WSH is invalid.
-            return IsMineResult::INVALID;
-        }
-        if (sigversion == IsMineSigVersion::TOP && !keystore.HaveCScript(CScriptID(CScript() << OP_0 << vSolutions[0]))) {
-            // We do not support bare witness outputs unless the P2SH version of it would be
-            // acceptable as well. This protects against matching before segwit activates.
-            // This also applies to the P2WSH case.
-            break;
-        }
-        ret = std::max(ret, IsMineInner(keystore, GetScriptForDestination(CKeyID(uint160(vSolutions[0]))), IsMineSigVersion::WITNESS_V0));
-        break;
-    }
-    case TX_PUBKEYHASH:
-        keyID = CKeyID(uint160(vSolutions[0]));
-        if (!PermitsUncompressed(sigversion)) {
-            CPubKey pubkey;
-            if (keystore.GetPubKey(keyID, pubkey) && !pubkey.IsCompressed()) {
-                return IsMineResult::INVALID;
-            }
-        }
-        if (keystore.HaveKey(keyID)) {
-            ret = std::max(ret, IsMineResult::SPENDABLE);
-        }
-        break;
-    case TX_SCRIPTHASH:
-    {
-        if (sigversion != IsMineSigVersion::TOP) {
-            // P2SH inside P2WSH or P2SH is invalid.
-            return IsMineResult::INVALID;
-        }
-        CScriptID scriptID = CScriptID(uint160(vSolutions[0]));
-        CScript subscript;
-        if (keystore.GetCScript(scriptID, subscript)) {
-            ret = std::max(ret, IsMineInner(keystore, subscript, IsMineSigVersion::P2SH));
-        }
-        break;
-    }
-    case TX_WITNESS_V0_SCRIPTHASH:
-    {
-        if (sigversion == IsMineSigVersion::WITNESS_V0) {
-            // P2WSH inside P2WSH is invalid.
-            return IsMineResult::INVALID;
-        }
-        if (sigversion == IsMineSigVersion::TOP && !keystore.HaveCScript(CScriptID(CScript() << OP_0 << vSolutions[0]))) {
-            break;
-        }
-        uint160 hash;
-        CRIPEMD160().Write(&vSolutions[0][0], vSolutions[0].size()).Finalize(hash.begin());
-        CScriptID scriptID = CScriptID(hash);
-        CScript subscript;
-        if (keystore.GetCScript(scriptID, subscript)) {
-            ret = std::max(ret, IsMineInner(keystore, subscript, IsMineSigVersion::WITNESS_V0));
-        }
-        break;
-    }
-
-    case TX_MULTISIG:
-    {
-        // Never treat bare multisig outputs as ours (they can still be made watchonly-though)
-        if (sigversion == IsMineSigVersion::TOP) {
-            break;
-        }
-
-        // Only consider transactions "mine" if we own ALL the
-        // keys involved. Multi-signature transactions that are
-        // partially owned (somebody else has a key that can spend
-        // them) enable spend-out-from-under-you attacks, especially
-        // in shared-wallet situations.
-        std::vector<valtype> keys(vSolutions.begin()+1, vSolutions.begin()+vSolutions.size()-1);
-        if (!PermitsUncompressed(sigversion)) {
-            for (size_t i = 0; i < keys.size(); i++) {
-                if (keys[i].size() != 33) {
-                    return IsMineResult::INVALID;
-                }
-            }
-        }
-        if (HaveKeys(keys, keystore)) {
-            ret = std::max(ret, IsMineResult::SPENDABLE);
-        }
-        break;
-    }
-    }
-
-    if (ret == IsMineResult::NO && keystore.HaveWatchOnly(scriptPubKey)) {
-        ret = std::max(ret, IsMineResult::WATCH_ONLY);
-    }
-    return ret;
-}
-
-} // namespace
-
-isminetype IsMine(const CKeyStore& keystore, const CScript& scriptPubKey)
-{
-    switch (IsMineInner(keystore, scriptPubKey, IsMineSigVersion::TOP)) {
-    case IsMineResult::INVALID:
-    case IsMineResult::NO:
-        return ISMINE_NO;
-    case IsMineResult::WATCH_ONLY:
-        return ISMINE_WATCH_ONLY;
-    case IsMineResult::SPENDABLE:
-        return ISMINE_SPENDABLE;
-    }
-    assert(false);
-}
-
-isminetype IsMine(const CKeyStore& keystore, const CTxDestination& dest)
-{
-    CScript script = GetScriptForDestination(dest);
-    return IsMine(keystore, script);
-}
diff --git a/src/script/ismine.h b/src/script/ismine.h
deleted file mode 100644
index 601e70f709..0000000000
--- a/src/script/ismine.h
+++ /dev/null
@@ -1,30 +0,0 @@
-// Copyright (c) 2009-2010 Satoshi Nakamoto
-// Copyright (c) 2009-2018 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_ISMINE_H
-#define BITCOIN_SCRIPT_ISMINE_H
-
-#include <script/standard.h>
-
-#include <stdint.h>
-
-class CKeyStore;
-class CScript;
-
-/** IsMine() return codes */
-enum isminetype
-{
-    ISMINE_NO = 0,
-    ISMINE_WATCH_ONLY = 1,
-    ISMINE_SPENDABLE = 2,
-    ISMINE_ALL = ISMINE_WATCH_ONLY | ISMINE_SPENDABLE
-};
-/** used for bitflags of isminetype */
-typedef uint8_t isminefilter;
-
-isminetype IsMine(const CKeyStore& keystore, const CScript& scriptPubKey);
-isminetype IsMine(const CKeyStore& keystore, const CTxDestination& dest);
-
-#endif // BITCOIN_SCRIPT_ISMINE_H
diff --git a/src/script/keyorigin.h b/src/script/keyorigin.h
new file mode 100644
index 0000000000..610f233500
--- /dev/null
+++ b/src/script/keyorigin.h
@@ -0,0 +1,37 @@
+// Copyright (c) 2019 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_KEYORIGIN_H
+#define BITCOIN_SCRIPT_KEYORIGIN_H
+
+#include <serialize.h>
+#include <streams.h>
+#include <vector>
+
+struct KeyOriginInfo
+{
+    unsigned char fingerprint[4]; //!< First 32 bits of the Hash160 of the public key at the root of the path
+    std::vector<uint32_t> path;
+
+    friend bool operator==(const KeyOriginInfo& a, const KeyOriginInfo& b)
+    {
+        return std::equal(std::begin(a.fingerprint), std::end(a.fingerprint), std::begin(b.fingerprint)) && a.path == b.path;
+    }
+
+    ADD_SERIALIZE_METHODS;
+    template <typename Stream, typename Operation>
+    inline void SerializationOp(Stream& s, Operation ser_action)
+    {
+        READWRITE(fingerprint);
+        READWRITE(path);
+    }
+
+    void clear()
+    {
+        memset(fingerprint, 0, 4);
+        path.clear();
+    }
+};
+
+#endif // BITCOIN_SCRIPT_KEYORIGIN_H
diff --git a/src/script/script.cpp b/src/script/script.cpp
index 982aa241e7..0666a385d1 100644
--- a/src/script/script.cpp
+++ b/src/script/script.cpp
@@ -5,7 +5,6 @@
 
 #include <script/script.h>
 
-#include <tinyformat.h>
 #include <util/strencodings.h>
 
 const char* GetOpName(opcodetype opcode)
diff --git a/src/script/script.h b/src/script/script.h
index 1d8ddba2f2..6355b8a704 100644
--- a/src/script/script.h
+++ b/src/script/script.h
@@ -437,7 +437,9 @@ public:
 
     explicit CScript(opcodetype b)     { operator<<(b); }
     explicit CScript(const CScriptNum& b) { operator<<(b); }
-    explicit CScript(const std::vector<unsigned char>& b) { operator<<(b); }
+    // delete non-existent constructor to defend against future introduction
+    // e.g. via prevector
+    explicit CScript(const std::vector<unsigned char>& b) = delete;
 
 
     CScript& operator<<(int64_t b) { return push_int64(b); }
@@ -581,13 +583,4 @@ struct CScriptWitness
     std::string ToString() const;
 };
 
-class CReserveScript
-{
-public:
-    CScript reserveScript;
-    virtual void KeepScript() {}
-    CReserveScript() {}
-    virtual ~CReserveScript() {}
-};
-
 #endif // BITCOIN_SCRIPT_SCRIPT_H
diff --git a/src/script/sigcache.cpp b/src/script/sigcache.cpp
index 94005cf6f3..eaf5363bd7 100644
--- a/src/script/sigcache.cpp
+++ b/src/script/sigcache.cpp
@@ -5,7 +5,6 @@
 
 #include <script/sigcache.h>
 
-#include <memusage.h>
 #include <pubkey.h>
 #include <random.h>
 #include <uint256.h>
diff --git a/src/script/sign.cpp b/src/script/sign.cpp
index 792fb2997f..13481af9c5 100644
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -8,6 +8,7 @@
 #include <key.h>
 #include <policy/policy.h>
 #include <primitives/transaction.h>
+#include <script/signingprovider.h>
 #include <script/standard.h>
 #include <uint256.h>
 
@@ -83,6 +84,8 @@ static bool CreateSig(const BaseSignatureCreator& creator, SignatureData& sigdat
         assert(i.second);
         return true;
     }
+    // Could not make signature or signature not found, add keyid to missing
+    sigdata.missing_sigs.push_back(keyid);
     return false;
 }
 
@@ -116,17 +119,24 @@ static bool SignStep(const SigningProvider& provider, const BaseSignatureCreator
     case TX_PUBKEYHASH: {
         CKeyID keyID = CKeyID(uint160(vSolutions[0]));
         CPubKey pubkey;
-        if (!GetPubKey(provider, sigdata, keyID, pubkey)) return false;
+        if (!GetPubKey(provider, sigdata, keyID, pubkey)) {
+            // Pubkey could not be found, add to missing
+            sigdata.missing_pubkeys.push_back(keyID);
+            return false;
+        }
         if (!CreateSig(creator, sigdata, provider, sig, pubkey, scriptPubKey, sigversion)) return false;
         ret.push_back(std::move(sig));
         ret.push_back(ToByteVector(pubkey));
         return true;
     }
     case TX_SCRIPTHASH:
-        if (GetCScript(provider, sigdata, uint160(vSolutions[0]), scriptRet)) {
+        h160 = uint160(vSolutions[0]);
+        if (GetCScript(provider, sigdata, h160, scriptRet)) {
             ret.push_back(std::vector<unsigned char>(scriptRet.begin(), scriptRet.end()));
             return true;
         }
+        // Could not find redeemScript, add to missing
+        sigdata.missing_redeem_script = h160;
         return false;
 
     case TX_MULTISIG: {
@@ -154,6 +164,8 @@ static bool SignStep(const SigningProvider& provider, const BaseSignatureCreator
             ret.push_back(std::vector<unsigned char>(scriptRet.begin(), scriptRet.end()));
             return true;
         }
+        // Could not find witnessScript, add to missing
+        sigdata.missing_witness_script = uint256(vSolutions[0]);
         return false;
 
     default:
@@ -232,67 +244,6 @@ bool ProduceSignature(const SigningProvider& provider, const BaseSignatureCreato
     return sigdata.complete;
 }
 
-bool PSBTInputSigned(PSBTInput& input)
-{
-    return !input.final_script_sig.empty() || !input.final_script_witness.IsNull();
-}
-
-bool SignPSBTInput(const SigningProvider& provider, PartiallySignedTransaction& psbt, int index, int sighash)
-{
-    PSBTInput& input = psbt.inputs.at(index);
-    const CMutableTransaction& tx = *psbt.tx;
-
-    if (PSBTInputSigned(input)) {
-        return true;
-    }
-
-    // Fill SignatureData with input info
-    SignatureData sigdata;
-    input.FillSignatureData(sigdata);
-
-    // Get UTXO
-    bool require_witness_sig = false;
-    CTxOut utxo;
-
-    // Verify input sanity, which checks that at most one of witness or non-witness utxos is provided.
-    if (!input.IsSane()) {
-        return false;
-    }
-
-    if (input.non_witness_utxo) {
-        // If we're taking our information from a non-witness UTXO, verify that it matches the prevout.
-        COutPoint prevout = tx.vin[index].prevout;
-        if (input.non_witness_utxo->GetHash() != prevout.hash) {
-            return false;
-        }
-        utxo = input.non_witness_utxo->vout[prevout.n];
-    } else if (!input.witness_utxo.IsNull()) {
-        utxo = input.witness_utxo;
-        // When we're taking our information from a witness UTXO, we can't verify it is actually data from
-        // the output being spent. This is safe in case a witness signature is produced (which includes this
-        // information directly in the hash), but not for non-witness signatures. Remember that we require
-        // a witness signature in this situation.
-        require_witness_sig = true;
-    } else {
-        return false;
-    }
-
-    MutableTransactionSignatureCreator creator(&tx, index, utxo.nValue, sighash);
-    sigdata.witness = false;
-    bool sig_complete = ProduceSignature(provider, creator, utxo.scriptPubKey, sigdata);
-    // Verify that a witness signature was produced in case one was required.
-    if (require_witness_sig && !sigdata.witness) return false;
-    input.FromSignatureData(sigdata);
-
-    // If we have a witness signature, use the smaller witness UTXO.
-    if (sigdata.witness) {
-        input.witness_utxo = utxo;
-        input.non_witness_utxo = nullptr;
-    }
-
-    return sig_complete;
-}
-
 class SignatureExtractorChecker final : public BaseSignatureChecker
 {
 private:
@@ -473,22 +424,10 @@ public:
     }
 };
 
-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(32, 32);
 const BaseSignatureCreator& DUMMY_MAXIMUM_SIGNATURE_CREATOR = DummySignatureCreator(33, 32);
-const SigningProvider& DUMMY_SIGNING_PROVIDER = SigningProvider();
 
 bool IsSolvable(const SigningProvider& provider, const CScript& script)
 {
@@ -509,203 +448,18 @@ bool IsSolvable(const SigningProvider& provider, const CScript& script)
     return false;
 }
 
-PartiallySignedTransaction::PartiallySignedTransaction(const CMutableTransaction& tx) : tx(tx)
+bool IsSegWitOutput(const SigningProvider& provider, const CScript& script)
 {
-    inputs.resize(tx.vin.size());
-    outputs.resize(tx.vout.size());
-}
-
-bool PartiallySignedTransaction::IsNull() const
-{
-    return !tx && inputs.empty() && outputs.empty() && unknown.empty();
-}
-
-void PartiallySignedTransaction::Merge(const PartiallySignedTransaction& psbt)
-{
-    for (unsigned int i = 0; i < inputs.size(); ++i) {
-        inputs[i].Merge(psbt.inputs[i]);
-    }
-    for (unsigned int i = 0; i < outputs.size(); ++i) {
-        outputs[i].Merge(psbt.outputs[i]);
-    }
-    unknown.insert(psbt.unknown.begin(), psbt.unknown.end());
-}
-
-bool PartiallySignedTransaction::IsSane() const
-{
-    for (PSBTInput input : inputs) {
-        if (!input.IsSane()) return false;
-    }
-    return true;
-}
-
-bool PSBTInput::IsNull() const
-{
-    return !non_witness_utxo && witness_utxo.IsNull() && partial_sigs.empty() && unknown.empty() && hd_keypaths.empty() && redeem_script.empty() && witness_script.empty();
-}
-
-void PSBTInput::FillSignatureData(SignatureData& sigdata) const
-{
-    if (!final_script_sig.empty()) {
-        sigdata.scriptSig = final_script_sig;
-        sigdata.complete = true;
-    }
-    if (!final_script_witness.IsNull()) {
-        sigdata.scriptWitness = final_script_witness;
-        sigdata.complete = true;
-    }
-    if (sigdata.complete) {
-        return;
-    }
-
-    sigdata.signatures.insert(partial_sigs.begin(), partial_sigs.end());
-    if (!redeem_script.empty()) {
-        sigdata.redeem_script = redeem_script;
-    }
-    if (!witness_script.empty()) {
-        sigdata.witness_script = witness_script;
-    }
-    for (const auto& key_pair : hd_keypaths) {
-        sigdata.misc_pubkeys.emplace(key_pair.first.GetID(), key_pair);
-    }
-}
-
-void PSBTInput::FromSignatureData(const SignatureData& sigdata)
-{
-    if (sigdata.complete) {
-        partial_sigs.clear();
-        hd_keypaths.clear();
-        redeem_script.clear();
-        witness_script.clear();
-
-        if (!sigdata.scriptSig.empty()) {
-            final_script_sig = sigdata.scriptSig;
-        }
-        if (!sigdata.scriptWitness.IsNull()) {
-            final_script_witness = sigdata.scriptWitness;
+    std::vector<valtype> solutions;
+    auto whichtype = Solver(script, solutions);
+    if (whichtype == TX_WITNESS_V0_SCRIPTHASH || whichtype == TX_WITNESS_V0_KEYHASH || whichtype == TX_WITNESS_UNKNOWN) return true;
+    if (whichtype == TX_SCRIPTHASH) {
+        auto h160 = uint160(solutions[0]);
+        CScript subscript;
+        if (provider.GetCScript(h160, subscript)) {
+            whichtype = Solver(subscript, solutions);
+            if (whichtype == TX_WITNESS_V0_SCRIPTHASH || whichtype == TX_WITNESS_V0_KEYHASH || whichtype == TX_WITNESS_UNKNOWN) return true;
         }
-        return;
-    }
-
-    partial_sigs.insert(sigdata.signatures.begin(), sigdata.signatures.end());
-    if (redeem_script.empty() && !sigdata.redeem_script.empty()) {
-        redeem_script = sigdata.redeem_script;
-    }
-    if (witness_script.empty() && !sigdata.witness_script.empty()) {
-        witness_script = sigdata.witness_script;
-    }
-    for (const auto& entry : sigdata.misc_pubkeys) {
-        hd_keypaths.emplace(entry.second);
-    }
-}
-
-void PSBTInput::Merge(const PSBTInput& input)
-{
-    if (!non_witness_utxo && input.non_witness_utxo) non_witness_utxo = input.non_witness_utxo;
-    if (witness_utxo.IsNull() && !input.witness_utxo.IsNull()) {
-        witness_utxo = input.witness_utxo;
-        non_witness_utxo = nullptr; // Clear out any non-witness utxo when we set a witness one.
-    }
-
-    partial_sigs.insert(input.partial_sigs.begin(), input.partial_sigs.end());
-    hd_keypaths.insert(input.hd_keypaths.begin(), input.hd_keypaths.end());
-    unknown.insert(input.unknown.begin(), input.unknown.end());
-
-    if (redeem_script.empty() && !input.redeem_script.empty()) redeem_script = input.redeem_script;
-    if (witness_script.empty() && !input.witness_script.empty()) witness_script = input.witness_script;
-    if (final_script_sig.empty() && !input.final_script_sig.empty()) final_script_sig = input.final_script_sig;
-    if (final_script_witness.IsNull() && !input.final_script_witness.IsNull()) final_script_witness = input.final_script_witness;
-}
-
-bool PSBTInput::IsSane() const
-{
-    // Cannot have both witness and non-witness utxos
-    if (!witness_utxo.IsNull() && non_witness_utxo) return false;
-
-    // If we have a witness_script or a scriptWitness, we must also have a witness utxo
-    if (!witness_script.empty() && witness_utxo.IsNull()) return false;
-    if (!final_script_witness.IsNull() && witness_utxo.IsNull()) return false;
-
-    return true;
-}
-
-void PSBTOutput::FillSignatureData(SignatureData& sigdata) const
-{
-    if (!redeem_script.empty()) {
-        sigdata.redeem_script = redeem_script;
-    }
-    if (!witness_script.empty()) {
-        sigdata.witness_script = witness_script;
-    }
-    for (const auto& key_pair : hd_keypaths) {
-        sigdata.misc_pubkeys.emplace(key_pair.first.GetID(), key_pair);
-    }
-}
-
-void PSBTOutput::FromSignatureData(const SignatureData& sigdata)
-{
-    if (redeem_script.empty() && !sigdata.redeem_script.empty()) {
-        redeem_script = sigdata.redeem_script;
-    }
-    if (witness_script.empty() && !sigdata.witness_script.empty()) {
-        witness_script = sigdata.witness_script;
     }
-    for (const auto& entry : sigdata.misc_pubkeys) {
-        hd_keypaths.emplace(entry.second);
-    }
-}
-
-bool PSBTOutput::IsNull() const
-{
-    return redeem_script.empty() && witness_script.empty() && hd_keypaths.empty() && unknown.empty();
-}
-
-void PSBTOutput::Merge(const PSBTOutput& output)
-{
-    hd_keypaths.insert(output.hd_keypaths.begin(), output.hd_keypaths.end());
-    unknown.insert(output.unknown.begin(), output.unknown.end());
-
-    if (redeem_script.empty() && !output.redeem_script.empty()) redeem_script = output.redeem_script;
-    if (witness_script.empty() && !output.witness_script.empty()) witness_script = output.witness_script;
-}
-
-bool HidingSigningProvider::GetCScript(const CScriptID& scriptid, CScript& script) const
-{
-    return m_provider->GetCScript(scriptid, script);
-}
-
-bool HidingSigningProvider::GetPubKey(const CKeyID& keyid, CPubKey& pubkey) const
-{
-    return m_provider->GetPubKey(keyid, pubkey);
-}
-
-bool HidingSigningProvider::GetKey(const CKeyID& keyid, CKey& key) const
-{
-    if (m_hide_secret) return false;
-    return m_provider->GetKey(keyid, key);
-}
-
-bool HidingSigningProvider::GetKeyOrigin(const CKeyID& keyid, KeyOriginInfo& info) const
-{
-    if (m_hide_origin) return false;
-    return m_provider->GetKeyOrigin(keyid, info);
-}
-
-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::GetKeyOrigin(const CKeyID& keyid, KeyOriginInfo& info) const { return LookupHelper(origins, keyid, info); }
-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());
-    ret.origins = a.origins;
-    ret.origins.insert(b.origins.begin(), b.origins.end());
-    return ret;
+    return false;
 }
diff --git a/src/script/sign.h b/src/script/sign.h
index e884f4c480..0e751afd3b 100644
--- a/src/script/sign.h
+++ b/src/script/sign.h
@@ -10,6 +10,7 @@
 #include <hash.h>
 #include <pubkey.h>
 #include <script/interpreter.h>
+#include <script/keyorigin.h>
 #include <streams.h>
 
 class CKey;
@@ -17,63 +18,10 @@ class CKeyID;
 class CScript;
 class CScriptID;
 class CTransaction;
+class SigningProvider;
 
 struct CMutableTransaction;
 
-struct KeyOriginInfo
-{
-    unsigned char fingerprint[4];
-    std::vector<uint32_t> path;
-
-    friend bool operator==(const KeyOriginInfo& a, const KeyOriginInfo& b)
-    {
-        return std::equal(std::begin(a.fingerprint), std::end(a.fingerprint), std::begin(b.fingerprint)) && a.path == b.path;
-    }
-};
-
-/** An interface to be implemented by keystores that support signing. */
-class SigningProvider
-{
-public:
-    virtual ~SigningProvider() {}
-    virtual bool GetCScript(const CScriptID &scriptid, CScript& script) const { return false; }
-    virtual bool GetPubKey(const CKeyID &address, CPubKey& pubkey) const { return false; }
-    virtual bool GetKey(const CKeyID &address, CKey& key) const { return false; }
-    virtual bool GetKeyOrigin(const CKeyID& keyid, KeyOriginInfo& info) const { return false; }
-};
-
-extern const SigningProvider& DUMMY_SIGNING_PROVIDER;
-
-class HidingSigningProvider : public SigningProvider
-{
-private:
-    const bool m_hide_secret;
-    const bool m_hide_origin;
-    const SigningProvider* m_provider;
-
-public:
-    HidingSigningProvider(const SigningProvider* provider, bool hide_secret, bool hide_origin) : m_hide_secret(hide_secret), m_hide_origin(hide_origin), m_provider(provider) {}
-    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;
-    bool GetKeyOrigin(const CKeyID& keyid, KeyOriginInfo& info) const override;
-};
-
-struct FlatSigningProvider final : public SigningProvider
-{
-    std::map<CScriptID, CScript> scripts;
-    std::map<CKeyID, CPubKey> pubkeys;
-    std::map<CKeyID, KeyOriginInfo> origins;
-    std::map<CKeyID, CKey> keys;
-
-    bool GetCScript(const CScriptID& scriptid, CScript& script) const override;
-    bool GetPubKey(const CKeyID& keyid, CPubKey& pubkey) const override;
-    bool GetKeyOrigin(const CKeyID& keyid, KeyOriginInfo& info) 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:
@@ -117,38 +65,16 @@ struct SignatureData {
     CScriptWitness scriptWitness; ///< The scriptWitness of an input. Contains complete signatures or the traditional partial signatures format. scriptWitness is part of a transaction input per BIP 144.
     std::map<CKeyID, SigPair> signatures; ///< BIP 174 style partial signatures for the input. May contain all signatures necessary for producing a final scriptSig or scriptWitness.
     std::map<CKeyID, std::pair<CPubKey, KeyOriginInfo>> misc_pubkeys;
+    std::vector<CKeyID> missing_pubkeys; ///< KeyIDs of pubkeys which could not be found
+    std::vector<CKeyID> missing_sigs; ///< KeyIDs of pubkeys for signatures which could not be found
+    uint160 missing_redeem_script; ///< ScriptID of the missing redeemScript (if any)
+    uint256 missing_witness_script; ///< SHA256 of the missing witnessScript (if any)
 
     SignatureData() {}
     explicit SignatureData(const CScript& script) : scriptSig(script) {}
     void MergeSignatureData(SignatureData sigdata);
 };
 
-// Magic bytes
-static constexpr uint8_t PSBT_MAGIC_BYTES[5] = {'p', 's', 'b', 't', 0xff};
-
-// Global types
-static constexpr uint8_t PSBT_GLOBAL_UNSIGNED_TX = 0x00;
-
-// Input types
-static constexpr uint8_t PSBT_IN_NON_WITNESS_UTXO = 0x00;
-static constexpr uint8_t PSBT_IN_WITNESS_UTXO = 0x01;
-static constexpr uint8_t PSBT_IN_PARTIAL_SIG = 0x02;
-static constexpr uint8_t PSBT_IN_SIGHASH = 0x03;
-static constexpr uint8_t PSBT_IN_REDEEMSCRIPT = 0x04;
-static constexpr uint8_t PSBT_IN_WITNESSSCRIPT = 0x05;
-static constexpr uint8_t PSBT_IN_BIP32_DERIVATION = 0x06;
-static constexpr uint8_t PSBT_IN_SCRIPTSIG = 0x07;
-static constexpr uint8_t PSBT_IN_SCRIPTWITNESS = 0x08;
-
-// Output types
-static constexpr uint8_t PSBT_OUT_REDEEMSCRIPT = 0x00;
-static constexpr uint8_t PSBT_OUT_WITNESSSCRIPT = 0x01;
-static constexpr uint8_t PSBT_OUT_BIP32_DERIVATION = 0x02;
-
-// The separator is 0x00. Reading this in means that the unserializer can interpret it
-// as a 0 length key which indicates that this is the separator. The separator has no value.
-static constexpr uint8_t PSBT_SEPARATOR = 0x00;
-
 // Takes a stream and multiple arguments and serializes them as if first serialized into a vector and then into the stream
 // The resulting output into the stream has the total serialized length of all of the objects followed by all objects concatenated with each other.
 template<typename Stream, typename... X>
@@ -223,514 +149,6 @@ void SerializeHDKeypaths(Stream& s, const std::map<CPubKey, KeyOriginInfo>& hd_k
     }
 }
 
-/** A structure for PSBTs which contain per-input information */
-struct PSBTInput
-{
-    CTransactionRef non_witness_utxo;
-    CTxOut witness_utxo;
-    CScript redeem_script;
-    CScript witness_script;
-    CScript final_script_sig;
-    CScriptWitness final_script_witness;
-    std::map<CPubKey, KeyOriginInfo> hd_keypaths;
-    std::map<CKeyID, SigPair> partial_sigs;
-    std::map<std::vector<unsigned char>, std::vector<unsigned char>> unknown;
-    int sighash_type = 0;
-
-    bool IsNull() const;
-    void FillSignatureData(SignatureData& sigdata) const;
-    void FromSignatureData(const SignatureData& sigdata);
-    void Merge(const PSBTInput& input);
-    bool IsSane() const;
-    PSBTInput() {}
-
-    template <typename Stream>
-    inline void Serialize(Stream& s) const {
-        // Write the utxo
-        // If there is a non-witness utxo, then don't add the witness one.
-        if (non_witness_utxo) {
-            SerializeToVector(s, PSBT_IN_NON_WITNESS_UTXO);
-            OverrideStream<Stream> os(&s, s.GetType(), s.GetVersion() | SERIALIZE_TRANSACTION_NO_WITNESS);
-            SerializeToVector(os, non_witness_utxo);
-        } else if (!witness_utxo.IsNull()) {
-            SerializeToVector(s, PSBT_IN_WITNESS_UTXO);
-            SerializeToVector(s, witness_utxo);
-        }
-
-        if (final_script_sig.empty() && final_script_witness.IsNull()) {
-            // Write any partial signatures
-            for (auto sig_pair : partial_sigs) {
-                SerializeToVector(s, PSBT_IN_PARTIAL_SIG, MakeSpan(sig_pair.second.first));
-                s << sig_pair.second.second;
-            }
-
-            // Write the sighash type
-            if (sighash_type > 0) {
-                SerializeToVector(s, PSBT_IN_SIGHASH);
-                SerializeToVector(s, sighash_type);
-            }
-
-            // Write the redeem script
-            if (!redeem_script.empty()) {
-                SerializeToVector(s, PSBT_IN_REDEEMSCRIPT);
-                s << redeem_script;
-            }
-
-            // Write the witness script
-            if (!witness_script.empty()) {
-                SerializeToVector(s, PSBT_IN_WITNESSSCRIPT);
-                s << witness_script;
-            }
-
-            // Write any hd keypaths
-            SerializeHDKeypaths(s, hd_keypaths, PSBT_IN_BIP32_DERIVATION);
-        }
-
-        // Write script sig
-        if (!final_script_sig.empty()) {
-            SerializeToVector(s, PSBT_IN_SCRIPTSIG);
-            s << final_script_sig;
-        }
-        // write script witness
-        if (!final_script_witness.IsNull()) {
-            SerializeToVector(s, PSBT_IN_SCRIPTWITNESS);
-            SerializeToVector(s, final_script_witness.stack);
-        }
-
-        // Write unknown things
-        for (auto& entry : unknown) {
-            s << entry.first;
-            s << entry.second;
-        }
-
-        s << PSBT_SEPARATOR;
-    }
-
-
-    template <typename Stream>
-    inline void Unserialize(Stream& s) {
-        // Read loop
-        bool found_sep = false;
-        while(!s.empty()) {
-            // Read
-            std::vector<unsigned char> key;
-            s >> key;
-
-            // the key is empty if that was actually a separator byte
-            // This is a special case for key lengths 0 as those are not allowed (except for separator)
-            if (key.empty()) {
-                found_sep = true;
-                break;
-            }
-
-            // First byte of key is the type
-            unsigned char type = key[0];
-
-            // Do stuff based on type
-            switch(type) {
-                case PSBT_IN_NON_WITNESS_UTXO:
-                {
-                    if (non_witness_utxo) {
-                        throw std::ios_base::failure("Duplicate Key, input non-witness utxo already provided");
-                    } else if (key.size() != 1) {
-                        throw std::ios_base::failure("Non-witness utxo key is more than one byte type");
-                    }
-                    // Set the stream to unserialize with witness since this is always a valid network transaction
-                    OverrideStream<Stream> os(&s, s.GetType(), s.GetVersion() & ~SERIALIZE_TRANSACTION_NO_WITNESS);
-                    UnserializeFromVector(os, non_witness_utxo);
-                    break;
-                }
-                case PSBT_IN_WITNESS_UTXO:
-                    if (!witness_utxo.IsNull()) {
-                        throw std::ios_base::failure("Duplicate Key, input witness utxo already provided");
-                    } else if (key.size() != 1) {
-                        throw std::ios_base::failure("Witness utxo key is more than one byte type");
-                    }
-                    UnserializeFromVector(s, witness_utxo);
-                    break;
-                case PSBT_IN_PARTIAL_SIG:
-                {
-                    // Make sure that the key is the size of pubkey + 1
-                    if (key.size() != CPubKey::PUBLIC_KEY_SIZE + 1 && key.size() != CPubKey::COMPRESSED_PUBLIC_KEY_SIZE + 1) {
-                        throw std::ios_base::failure("Size of key was not the expected size for the type partial signature pubkey");
-                    }
-                    // Read in the pubkey from key
-                    CPubKey pubkey(key.begin() + 1, key.end());
-                    if (!pubkey.IsFullyValid()) {
-                       throw std::ios_base::failure("Invalid pubkey");
-                    }
-                    if (partial_sigs.count(pubkey.GetID()) > 0) {
-                        throw std::ios_base::failure("Duplicate Key, input partial signature for pubkey already provided");
-                    }
-
-                    // Read in the signature from value
-                    std::vector<unsigned char> sig;
-                    s >> sig;
-
-                    // Add to list
-                    partial_sigs.emplace(pubkey.GetID(), SigPair(pubkey, std::move(sig)));
-                    break;
-                }
-                case PSBT_IN_SIGHASH:
-                    if (sighash_type > 0) {
-                        throw std::ios_base::failure("Duplicate Key, input sighash type already provided");
-                    } else if (key.size() != 1) {
-                        throw std::ios_base::failure("Sighash type key is more than one byte type");
-                    }
-                    UnserializeFromVector(s, sighash_type);
-                    break;
-                case PSBT_IN_REDEEMSCRIPT:
-                {
-                    if (!redeem_script.empty()) {
-                        throw std::ios_base::failure("Duplicate Key, input redeemScript already provided");
-                    } else if (key.size() != 1) {
-                        throw std::ios_base::failure("Input redeemScript key is more than one byte type");
-                    }
-                    s >> redeem_script;
-                    break;
-                }
-                case PSBT_IN_WITNESSSCRIPT:
-                {
-                    if (!witness_script.empty()) {
-                        throw std::ios_base::failure("Duplicate Key, input witnessScript already provided");
-                    } else if (key.size() != 1) {
-                        throw std::ios_base::failure("Input witnessScript key is more than one byte type");
-                    }
-                    s >> witness_script;
-                    break;
-                }
-                case PSBT_IN_BIP32_DERIVATION:
-                {
-                    DeserializeHDKeypaths(s, key, hd_keypaths);
-                    break;
-                }
-                case PSBT_IN_SCRIPTSIG:
-                {
-                    if (!final_script_sig.empty()) {
-                        throw std::ios_base::failure("Duplicate Key, input final scriptSig already provided");
-                    } else if (key.size() != 1) {
-                        throw std::ios_base::failure("Final scriptSig key is more than one byte type");
-                    }
-                    s >> final_script_sig;
-                    break;
-                }
-                case PSBT_IN_SCRIPTWITNESS:
-                {
-                    if (!final_script_witness.IsNull()) {
-                        throw std::ios_base::failure("Duplicate Key, input final scriptWitness already provided");
-                    } else if (key.size() != 1) {
-                        throw std::ios_base::failure("Final scriptWitness key is more than one byte type");
-                    }
-                    UnserializeFromVector(s, final_script_witness.stack);
-                    break;
-                }
-                // Unknown stuff
-                default:
-                    if (unknown.count(key) > 0) {
-                        throw std::ios_base::failure("Duplicate Key, key for unknown value already provided");
-                    }
-                    // Read in the value
-                    std::vector<unsigned char> val_bytes;
-                    s >> val_bytes;
-                    unknown.emplace(std::move(key), std::move(val_bytes));
-                    break;
-            }
-        }
-
-        if (!found_sep) {
-            throw std::ios_base::failure("Separator is missing at the end of an input map");
-        }
-    }
-
-    template <typename Stream>
-    PSBTInput(deserialize_type, Stream& s) {
-        Unserialize(s);
-    }
-};
-
-/** A structure for PSBTs which contains per output information */
-struct PSBTOutput
-{
-    CScript redeem_script;
-    CScript witness_script;
-    std::map<CPubKey, KeyOriginInfo> hd_keypaths;
-    std::map<std::vector<unsigned char>, std::vector<unsigned char>> unknown;
-
-    bool IsNull() const;
-    void FillSignatureData(SignatureData& sigdata) const;
-    void FromSignatureData(const SignatureData& sigdata);
-    void Merge(const PSBTOutput& output);
-    bool IsSane() const;
-    PSBTOutput() {}
-
-    template <typename Stream>
-    inline void Serialize(Stream& s) const {
-        // Write the redeem script
-        if (!redeem_script.empty()) {
-            SerializeToVector(s, PSBT_OUT_REDEEMSCRIPT);
-            s << redeem_script;
-        }
-
-        // Write the witness script
-        if (!witness_script.empty()) {
-            SerializeToVector(s, PSBT_OUT_WITNESSSCRIPT);
-            s << witness_script;
-        }
-
-        // Write any hd keypaths
-        SerializeHDKeypaths(s, hd_keypaths, PSBT_OUT_BIP32_DERIVATION);
-
-        // Write unknown things
-        for (auto& entry : unknown) {
-            s << entry.first;
-            s << entry.second;
-        }
-
-        s << PSBT_SEPARATOR;
-    }
-
-
-    template <typename Stream>
-    inline void Unserialize(Stream& s) {
-        // Read loop
-        bool found_sep = false;
-        while(!s.empty()) {
-            // Read
-            std::vector<unsigned char> key;
-            s >> key;
-
-            // the key is empty if that was actually a separator byte
-            // This is a special case for key lengths 0 as those are not allowed (except for separator)
-            if (key.empty()) {
-                found_sep = true;
-                break;
-            }
-
-            // First byte of key is the type
-            unsigned char type = key[0];
-
-            // Do stuff based on type
-            switch(type) {
-                case PSBT_OUT_REDEEMSCRIPT:
-                {
-                    if (!redeem_script.empty()) {
-                        throw std::ios_base::failure("Duplicate Key, output redeemScript already provided");
-                    } else if (key.size() != 1) {
-                        throw std::ios_base::failure("Output redeemScript key is more than one byte type");
-                    }
-                    s >> redeem_script;
-                    break;
-                }
-                case PSBT_OUT_WITNESSSCRIPT:
-                {
-                    if (!witness_script.empty()) {
-                        throw std::ios_base::failure("Duplicate Key, output witnessScript already provided");
-                    } else if (key.size() != 1) {
-                        throw std::ios_base::failure("Output witnessScript key is more than one byte type");
-                    }
-                    s >> witness_script;
-                    break;
-                }
-                case PSBT_OUT_BIP32_DERIVATION:
-                {
-                    DeserializeHDKeypaths(s, key, hd_keypaths);
-                    break;
-                }
-                // Unknown stuff
-                default: {
-                    if (unknown.count(key) > 0) {
-                        throw std::ios_base::failure("Duplicate Key, key for unknown value already provided");
-                    }
-                    // Read in the value
-                    std::vector<unsigned char> val_bytes;
-                    s >> val_bytes;
-                    unknown.emplace(std::move(key), std::move(val_bytes));
-                    break;
-                }
-            }
-        }
-
-        if (!found_sep) {
-            throw std::ios_base::failure("Separator is missing at the end of an output map");
-        }
-    }
-
-    template <typename Stream>
-    PSBTOutput(deserialize_type, Stream& s) {
-        Unserialize(s);
-    }
-};
-
-/** A version of CTransaction with the PSBT format*/
-struct PartiallySignedTransaction
-{
-    boost::optional<CMutableTransaction> tx;
-    std::vector<PSBTInput> inputs;
-    std::vector<PSBTOutput> outputs;
-    std::map<std::vector<unsigned char>, std::vector<unsigned char>> unknown;
-
-    bool IsNull() const;
-    void Merge(const PartiallySignedTransaction& psbt);
-    bool IsSane() const;
-    PartiallySignedTransaction() {}
-    PartiallySignedTransaction(const PartiallySignedTransaction& psbt_in) : tx(psbt_in.tx), inputs(psbt_in.inputs), outputs(psbt_in.outputs), unknown(psbt_in.unknown) {}
-    explicit PartiallySignedTransaction(const CMutableTransaction& tx);
-
-    // Only checks if they refer to the same transaction
-    friend bool operator==(const PartiallySignedTransaction& a, const PartiallySignedTransaction &b)
-    {
-        return a.tx->GetHash() == b.tx->GetHash();
-    }
-    friend bool operator!=(const PartiallySignedTransaction& a, const PartiallySignedTransaction &b)
-    {
-        return !(a == b);
-    }
-
-    template <typename Stream>
-    inline void Serialize(Stream& s) const {
-
-        // magic bytes
-        s << PSBT_MAGIC_BYTES;
-
-        // unsigned tx flag
-        SerializeToVector(s, PSBT_GLOBAL_UNSIGNED_TX);
-
-        // Write serialized tx to a stream
-        OverrideStream<Stream> os(&s, s.GetType(), s.GetVersion() | SERIALIZE_TRANSACTION_NO_WITNESS);
-        SerializeToVector(os, *tx);
-
-        // Write the unknown things
-        for (auto& entry : unknown) {
-            s << entry.first;
-            s << entry.second;
-        }
-
-        // Separator
-        s << PSBT_SEPARATOR;
-
-        // Write inputs
-        for (const PSBTInput& input : inputs) {
-            s << input;
-        }
-        // Write outputs
-        for (const PSBTOutput& output : outputs) {
-            s << output;
-        }
-    }
-
-
-    template <typename Stream>
-    inline void Unserialize(Stream& s) {
-        // Read the magic bytes
-        uint8_t magic[5];
-        s >> magic;
-        if (!std::equal(magic, magic + 5, PSBT_MAGIC_BYTES)) {
-            throw std::ios_base::failure("Invalid PSBT magic bytes");
-        }
-
-        // Read global data
-        bool found_sep = false;
-        while(!s.empty()) {
-            // Read
-            std::vector<unsigned char> key;
-            s >> key;
-
-            // the key is empty if that was actually a separator byte
-            // This is a special case for key lengths 0 as those are not allowed (except for separator)
-            if (key.empty()) {
-                found_sep = true;
-                break;
-            }
-
-            // First byte of key is the type
-            unsigned char type = key[0];
-
-            // Do stuff based on type
-            switch(type) {
-                case PSBT_GLOBAL_UNSIGNED_TX:
-                {
-                    if (tx) {
-                        throw std::ios_base::failure("Duplicate Key, unsigned tx already provided");
-                    } else if (key.size() != 1) {
-                        throw std::ios_base::failure("Global unsigned tx key is more than one byte type");
-                    }
-                    CMutableTransaction mtx;
-                    // Set the stream to serialize with non-witness since this should always be non-witness
-                    OverrideStream<Stream> os(&s, s.GetType(), s.GetVersion() | SERIALIZE_TRANSACTION_NO_WITNESS);
-                    UnserializeFromVector(os, mtx);
-                    tx = std::move(mtx);
-                    // Make sure that all scriptSigs and scriptWitnesses are empty
-                    for (const CTxIn& txin : tx->vin) {
-                        if (!txin.scriptSig.empty() || !txin.scriptWitness.IsNull()) {
-                            throw std::ios_base::failure("Unsigned tx does not have empty scriptSigs and scriptWitnesses.");
-                        }
-                    }
-                    break;
-                }
-                // Unknown stuff
-                default: {
-                    if (unknown.count(key) > 0) {
-                        throw std::ios_base::failure("Duplicate Key, key for unknown value already provided");
-                    }
-                    // Read in the value
-                    std::vector<unsigned char> val_bytes;
-                    s >> val_bytes;
-                    unknown.emplace(std::move(key), std::move(val_bytes));
-                }
-            }
-        }
-
-        if (!found_sep) {
-            throw std::ios_base::failure("Separator is missing at the end of the global map");
-        }
-
-        // Make sure that we got an unsigned tx
-        if (!tx) {
-            throw std::ios_base::failure("No unsigned transcation was provided");
-        }
-
-        // Read input data
-        unsigned int i = 0;
-        while (!s.empty() && i < tx->vin.size()) {
-            PSBTInput input;
-            s >> input;
-            inputs.push_back(input);
-
-            // Make sure the non-witness utxo matches the outpoint
-            if (input.non_witness_utxo && input.non_witness_utxo->GetHash() != tx->vin[i].prevout.hash) {
-                throw std::ios_base::failure("Non-witness UTXO does not match outpoint hash");
-            }
-            ++i;
-        }
-        // Make sure that the number of inputs matches the number of inputs in the transaction
-        if (inputs.size() != tx->vin.size()) {
-            throw std::ios_base::failure("Inputs provided does not match the number of inputs in transaction.");
-        }
-
-        // Read output data
-        i = 0;
-        while (!s.empty() && i < tx->vout.size()) {
-            PSBTOutput output;
-            s >> output;
-            outputs.push_back(output);
-            ++i;
-        }
-        // Make sure that the number of outputs matches the number of outputs in the transaction
-        if (outputs.size() != tx->vout.size()) {
-            throw std::ios_base::failure("Outputs provided does not match the number of outputs in transaction.");
-        }
-        // Sanity check
-        if (!IsSane()) {
-            throw std::ios_base::failure("PSBT is not sane.");
-        }
-    }
-
-    template <typename Stream>
-    PartiallySignedTransaction(deserialize_type, Stream& s) {
-        Unserialize(s);
-    }
-};
-
 /** Produce a script signature using a generic signature creator. */
 bool ProduceSignature(const SigningProvider& provider, const BaseSignatureCreator& creator, const CScript& scriptPubKey, SignatureData& sigdata);
 
@@ -738,12 +156,6 @@ bool ProduceSignature(const SigningProvider& provider, const BaseSignatureCreato
 bool SignSignature(const SigningProvider &provider, const CScript& fromPubKey, CMutableTransaction& txTo, unsigned int nIn, const CAmount& amount, int nHashType);
 bool SignSignature(const SigningProvider &provider, const CTransaction& txFrom, CMutableTransaction& txTo, unsigned int nIn, int nHashType);
 
-/** Checks whether a PSBTInput is already signed. */
-bool PSBTInputSigned(PSBTInput& input);
-
-/** Signs a PSBTInput, verifying that all provided data matches what is being signed. */
-bool SignPSBTInput(const SigningProvider& provider, PartiallySignedTransaction& psbt, int index, int sighash = SIGHASH_ALL);
-
 /** Extract signature data from a transaction input, and insert it. */
 SignatureData DataFromTransaction(const CMutableTransaction& tx, unsigned int nIn, const CTxOut& txout);
 void UpdateInput(CTxIn& input, const SignatureData& data);
@@ -754,4 +166,7 @@ void UpdateInput(CTxIn& input, const SignatureData& data);
  * Solvability is unrelated to whether we consider this output to be ours. */
 bool IsSolvable(const SigningProvider& provider, const CScript& script);
 
+/** Check whether a scriptPubKey is known to be segwit. */
+bool IsSegWitOutput(const SigningProvider& provider, const CScript& script);
+
 #endif // BITCOIN_SCRIPT_SIGN_H
diff --git a/src/script/signingprovider.cpp b/src/script/signingprovider.cpp
new file mode 100644
index 0000000000..01757e2f65
--- /dev/null
+++ b/src/script/signingprovider.cpp
@@ -0,0 +1,199 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2019 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/keyorigin.h>
+#include <script/signingprovider.h>
+#include <script/standard.h>
+
+#include <util/system.h>
+
+const SigningProvider& DUMMY_SIGNING_PROVIDER = SigningProvider();
+
+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;
+}
+
+bool HidingSigningProvider::GetCScript(const CScriptID& scriptid, CScript& script) const
+{
+    return m_provider->GetCScript(scriptid, script);
+}
+
+bool HidingSigningProvider::GetPubKey(const CKeyID& keyid, CPubKey& pubkey) const
+{
+    return m_provider->GetPubKey(keyid, pubkey);
+}
+
+bool HidingSigningProvider::GetKey(const CKeyID& keyid, CKey& key) const
+{
+    if (m_hide_secret) return false;
+    return m_provider->GetKey(keyid, key);
+}
+
+bool HidingSigningProvider::GetKeyOrigin(const CKeyID& keyid, KeyOriginInfo& info) const
+{
+    if (m_hide_origin) return false;
+    return m_provider->GetKeyOrigin(keyid, info);
+}
+
+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::GetKeyOrigin(const CKeyID& keyid, KeyOriginInfo& info) const
+{
+    std::pair<CPubKey, KeyOriginInfo> out;
+    bool ret = LookupHelper(origins, keyid, out);
+    if (ret) info = std::move(out.second);
+    return ret;
+}
+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());
+    ret.origins = a.origins;
+    ret.origins.insert(b.origins.begin(), b.origins.end());
+    return ret;
+}
+
+void FillableSigningProvider::ImplicitlyLearnRelatedKeyScripts(const CPubKey& pubkey)
+{
+    AssertLockHeld(cs_KeyStore);
+    CKeyID key_id = pubkey.GetID();
+    // This adds the redeemscripts necessary to detect P2WPKH and P2SH-P2WPKH
+    // outputs. Technically P2WPKH outputs don't have a redeemscript to be
+    // spent. However, our current IsMine logic requires the corresponding
+    // P2SH-P2WPKH redeemscript to be present in the wallet in order to accept
+    // payment even to P2WPKH outputs.
+    // Also note that having superfluous scripts in the keystore never hurts.
+    // They're only used to guide recursion in signing and IsMine logic - if
+    // a script is present but we can't do anything with it, it has no effect.
+    // "Implicitly" refers to fact that scripts are derived automatically from
+    // existing keys, and are present in memory, even without being explicitly
+    // loaded (e.g. from a file).
+    if (pubkey.IsCompressed()) {
+        CScript script = GetScriptForDestination(WitnessV0KeyHash(key_id));
+        // This does not use AddCScript, as it may be overridden.
+        CScriptID id(script);
+        mapScripts[id] = std::move(script);
+    }
+}
+
+bool FillableSigningProvider::GetPubKey(const CKeyID &address, CPubKey &vchPubKeyOut) const
+{
+    CKey key;
+    if (!GetKey(address, key)) {
+        return false;
+    }
+    vchPubKeyOut = key.GetPubKey();
+    return true;
+}
+
+bool FillableSigningProvider::AddKeyPubKey(const CKey& key, const CPubKey &pubkey)
+{
+    LOCK(cs_KeyStore);
+    mapKeys[pubkey.GetID()] = key;
+    ImplicitlyLearnRelatedKeyScripts(pubkey);
+    return true;
+}
+
+bool FillableSigningProvider::HaveKey(const CKeyID &address) const
+{
+    LOCK(cs_KeyStore);
+    return mapKeys.count(address) > 0;
+}
+
+std::set<CKeyID> FillableSigningProvider::GetKeys() const
+{
+    LOCK(cs_KeyStore);
+    std::set<CKeyID> set_address;
+    for (const auto& mi : mapKeys) {
+        set_address.insert(mi.first);
+    }
+    return set_address;
+}
+
+bool FillableSigningProvider::GetKey(const CKeyID &address, CKey &keyOut) const
+{
+    LOCK(cs_KeyStore);
+    KeyMap::const_iterator mi = mapKeys.find(address);
+    if (mi != mapKeys.end()) {
+        keyOut = mi->second;
+        return true;
+    }
+    return false;
+}
+
+bool FillableSigningProvider::AddCScript(const CScript& redeemScript)
+{
+    if (redeemScript.size() > MAX_SCRIPT_ELEMENT_SIZE)
+        return error("FillableSigningProvider::AddCScript(): redeemScripts > %i bytes are invalid", MAX_SCRIPT_ELEMENT_SIZE);
+
+    LOCK(cs_KeyStore);
+    mapScripts[CScriptID(redeemScript)] = redeemScript;
+    return true;
+}
+
+bool FillableSigningProvider::HaveCScript(const CScriptID& hash) const
+{
+    LOCK(cs_KeyStore);
+    return mapScripts.count(hash) > 0;
+}
+
+std::set<CScriptID> FillableSigningProvider::GetCScripts() const
+{
+    LOCK(cs_KeyStore);
+    std::set<CScriptID> set_script;
+    for (const auto& mi : mapScripts) {
+        set_script.insert(mi.first);
+    }
+    return set_script;
+}
+
+bool FillableSigningProvider::GetCScript(const CScriptID &hash, CScript& redeemScriptOut) const
+{
+    LOCK(cs_KeyStore);
+    ScriptMap::const_iterator mi = mapScripts.find(hash);
+    if (mi != mapScripts.end())
+    {
+        redeemScriptOut = (*mi).second;
+        return true;
+    }
+    return false;
+}
+
+CKeyID GetKeyForDestination(const SigningProvider& store, const CTxDestination& dest)
+{
+    // Only supports destinations which map to single public keys, i.e. P2PKH,
+    // P2WPKH, and P2SH-P2WPKH.
+    if (auto id = boost::get<PKHash>(&dest)) {
+        return CKeyID(*id);
+    }
+    if (auto witness_id = boost::get<WitnessV0KeyHash>(&dest)) {
+        return CKeyID(*witness_id);
+    }
+    if (auto script_hash = boost::get<ScriptHash>(&dest)) {
+        CScript script;
+        CScriptID script_id(*script_hash);
+        CTxDestination inner_dest;
+        if (store.GetCScript(script_id, script) && ExtractDestination(script, inner_dest)) {
+            if (auto inner_witness_id = boost::get<WitnessV0KeyHash>(&inner_dest)) {
+                return CKeyID(*inner_witness_id);
+            }
+        }
+    }
+    return CKeyID();
+}
diff --git a/src/script/signingprovider.h b/src/script/signingprovider.h
new file mode 100644
index 0000000000..4eec2311d4
--- /dev/null
+++ b/src/script/signingprovider.h
@@ -0,0 +1,92 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2019 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_SIGNINGPROVIDER_H
+#define BITCOIN_SCRIPT_SIGNINGPROVIDER_H
+
+#include <key.h>
+#include <pubkey.h>
+#include <script/script.h>
+#include <script/standard.h>
+#include <sync.h>
+
+struct KeyOriginInfo;
+
+/** An interface to be implemented by keystores that support signing. */
+class SigningProvider
+{
+public:
+    virtual ~SigningProvider() {}
+    virtual bool GetCScript(const CScriptID &scriptid, CScript& script) const { return false; }
+    virtual bool HaveCScript(const CScriptID &scriptid) const { return false; }
+    virtual bool GetPubKey(const CKeyID &address, CPubKey& pubkey) const { return false; }
+    virtual bool GetKey(const CKeyID &address, CKey& key) const { return false; }
+    virtual bool HaveKey(const CKeyID &address) const { return false; }
+    virtual bool GetKeyOrigin(const CKeyID& keyid, KeyOriginInfo& info) const { return false; }
+};
+
+extern const SigningProvider& DUMMY_SIGNING_PROVIDER;
+
+class HidingSigningProvider : public SigningProvider
+{
+private:
+    const bool m_hide_secret;
+    const bool m_hide_origin;
+    const SigningProvider* m_provider;
+
+public:
+    HidingSigningProvider(const SigningProvider* provider, bool hide_secret, bool hide_origin) : m_hide_secret(hide_secret), m_hide_origin(hide_origin), m_provider(provider) {}
+    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;
+    bool GetKeyOrigin(const CKeyID& keyid, KeyOriginInfo& info) const override;
+};
+
+struct FlatSigningProvider final : public SigningProvider
+{
+    std::map<CScriptID, CScript> scripts;
+    std::map<CKeyID, CPubKey> pubkeys;
+    std::map<CKeyID, std::pair<CPubKey, KeyOriginInfo>> origins;
+    std::map<CKeyID, CKey> keys;
+
+    bool GetCScript(const CScriptID& scriptid, CScript& script) const override;
+    bool GetPubKey(const CKeyID& keyid, CPubKey& pubkey) const override;
+    bool GetKeyOrigin(const CKeyID& keyid, KeyOriginInfo& info) const override;
+    bool GetKey(const CKeyID& keyid, CKey& key) const override;
+};
+
+FlatSigningProvider Merge(const FlatSigningProvider& a, const FlatSigningProvider& b);
+
+/** Fillable signing provider that keeps keys in an address->secret map */
+class FillableSigningProvider : public SigningProvider
+{
+protected:
+    mutable CCriticalSection cs_KeyStore;
+
+    using KeyMap = std::map<CKeyID, CKey>;
+    using ScriptMap = std::map<CScriptID, CScript>;
+
+    KeyMap mapKeys GUARDED_BY(cs_KeyStore);
+    ScriptMap mapScripts GUARDED_BY(cs_KeyStore);
+
+    void ImplicitlyLearnRelatedKeyScripts(const CPubKey& pubkey) EXCLUSIVE_LOCKS_REQUIRED(cs_KeyStore);
+
+public:
+    virtual bool AddKeyPubKey(const CKey& key, const CPubKey &pubkey);
+    virtual bool AddKey(const CKey &key) { return AddKeyPubKey(key, key.GetPubKey()); }
+    virtual bool GetPubKey(const CKeyID &address, CPubKey& vchPubKeyOut) const override;
+    virtual bool HaveKey(const CKeyID &address) const override;
+    virtual std::set<CKeyID> GetKeys() const;
+    virtual bool GetKey(const CKeyID &address, CKey &keyOut) const override;
+    virtual bool AddCScript(const CScript& redeemScript);
+    virtual bool HaveCScript(const CScriptID &hash) const override;
+    virtual std::set<CScriptID> GetCScripts() const;
+    virtual bool GetCScript(const CScriptID &hash, CScript& redeemScriptOut) const override;
+};
+
+/** Return the CKeyID of the key involved in a script (if there is a unique one). */
+CKeyID GetKeyForDestination(const SigningProvider& store, const CTxDestination& dest);
+
+#endif // BITCOIN_SCRIPT_SIGNINGPROVIDER_H
diff --git a/src/script/standard.cpp b/src/script/standard.cpp
index 31bfd04b0f..fc6898f444 100644
--- a/src/script/standard.cpp
+++ b/src/script/standard.cpp
@@ -8,9 +8,6 @@
 #include <crypto/sha256.h>
 #include <pubkey.h>
 #include <script/script.h>
-#include <util/system.h>
-#include <util/strencodings.h>
-
 
 typedef std::vector<unsigned char> valtype;
 
@@ -19,6 +16,10 @@ unsigned nMaxDatacarrierBytes = MAX_OP_RETURN_RELAY;
 
 CScriptID::CScriptID(const CScript& in) : uint160(Hash160(in.begin(), in.end())) {}
 
+ScriptHash::ScriptHash(const CScript& in) : uint160(Hash160(in.begin(), in.end())) {}
+
+PKHash::PKHash(const CPubKey& pubkey) : uint160(pubkey.GetID()) {}
+
 WitnessV0ScriptHash::WitnessV0ScriptHash(const CScript& in)
 {
     CSHA256().Write(in.data(), in.size()).Finalize(begin());
@@ -162,17 +163,17 @@ bool ExtractDestination(const CScript& scriptPubKey, CTxDestination& addressRet)
         if (!pubKey.IsValid())
             return false;
 
-        addressRet = pubKey.GetID();
+        addressRet = PKHash(pubKey);
         return true;
     }
     else if (whichType == TX_PUBKEYHASH)
     {
-        addressRet = CKeyID(uint160(vSolutions[0]));
+        addressRet = PKHash(uint160(vSolutions[0]));
         return true;
     }
     else if (whichType == TX_SCRIPTHASH)
     {
-        addressRet = CScriptID(uint160(vSolutions[0]));
+        addressRet = ScriptHash(uint160(vSolutions[0]));
         return true;
     } else if (whichType == TX_WITNESS_V0_KEYHASH) {
         WitnessV0KeyHash hash;
@@ -217,7 +218,7 @@ bool ExtractDestinations(const CScript& scriptPubKey, txnouttype& typeRet, std::
             if (!pubKey.IsValid())
                 continue;
 
-            CTxDestination address = pubKey.GetID();
+            CTxDestination address = PKHash(pubKey);
             addressRet.push_back(address);
         }
 
@@ -250,13 +251,13 @@ public:
         return false;
     }
 
-    bool operator()(const CKeyID &keyID) const {
+    bool operator()(const PKHash &keyID) const {
         script->clear();
         *script << OP_DUP << OP_HASH160 << ToByteVector(keyID) << OP_EQUALVERIFY << OP_CHECKSIG;
         return true;
     }
 
-    bool operator()(const CScriptID &scriptID) const {
+    bool operator()(const ScriptHash &scriptID) const {
         script->clear();
         *script << OP_HASH160 << ToByteVector(scriptID) << OP_EQUAL;
         return true;
diff --git a/src/script/standard.h b/src/script/standard.h
index fc20fb6a08..e45e2d92cc 100644
--- a/src/script/standard.h
+++ b/src/script/standard.h
@@ -73,6 +73,22 @@ public:
     friend bool operator<(const CNoDestination &a, const CNoDestination &b) { return true; }
 };
 
+struct PKHash : public uint160
+{
+    PKHash() : uint160() {}
+    explicit PKHash(const uint160& hash) : uint160(hash) {}
+    explicit PKHash(const CPubKey& pubkey);
+    using uint160::uint160;
+};
+
+struct ScriptHash : public uint160
+{
+    ScriptHash() : uint160() {}
+    explicit ScriptHash(const uint160& hash) : uint160(hash) {}
+    explicit ScriptHash(const CScript& script);
+    using uint160::uint160;
+};
+
 struct WitnessV0ScriptHash : public uint256
 {
     WitnessV0ScriptHash() : uint256() {}
@@ -113,14 +129,14 @@ struct WitnessUnknown
 /**
  * A txout script template with a specific destination. It is either:
  *  * CNoDestination: no destination set
- *  * CKeyID: TX_PUBKEYHASH destination (P2PKH)
- *  * CScriptID: TX_SCRIPTHASH destination (P2SH)
+ *  * PKHash: TX_PUBKEYHASH destination (P2PKH)
+ *  * ScriptHash: TX_SCRIPTHASH destination (P2SH)
  *  * WitnessV0ScriptHash: TX_WITNESS_V0_SCRIPTHASH destination (P2WSH)
  *  * WitnessV0KeyHash: TX_WITNESS_V0_KEYHASH destination (P2WPKH)
  *  * WitnessUnknown: TX_WITNESS_UNKNOWN destination (P2W???)
  *  A CTxDestination is the internal data type encoded in a bitcoin address
  */
-typedef boost::variant<CNoDestination, CKeyID, CScriptID, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessUnknown> CTxDestination;
+typedef boost::variant<CNoDestination, PKHash, ScriptHash, WitnessV0ScriptHash, WitnessV0KeyHash, WitnessUnknown> CTxDestination;
 
 /** Check whether a CTxDestination is a CNoDestination. */
 bool IsValidDestination(const CTxDestination& dest);
@@ -153,8 +169,7 @@ bool ExtractDestination(const CScript& scriptPubKey, CTxDestination& addressRet)
  * multisig scripts, this populates the addressRet vector with the pubkey IDs
  * and nRequiredRet with the n required to spend. For other destinations,
  * addressRet is populated with a single value and nRequiredRet is set to 1.
- * Returns true if successful. Currently does not extract address from
- * pay-to-witness scripts.
+ * Returns true if successful.
  *
  * Note: this function confuses destinations (a subset of CScripts that are
  * encodable as an address) with key identifiers (of keys involved in a