BIP143: Signing logic

2016-03-31 14:54:58 +02:00
parent c86a1cb86e
commit 157a5d0d9c
13 changed files with 391 additions and 175 deletions
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -19,7 +19,7 @@ typedef vector<unsigned char> valtype;

 TransactionSignatureCreator::TransactionSignatureCreator(const CKeyStore* keystoreIn, const CTransaction* txToIn, unsigned int nInIn, const CAmount& amountIn, int nHashTypeIn) : BaseSignatureCreator(keystoreIn), txTo(txToIn), nIn(nInIn), nHashType(nHashTypeIn), amount(amountIn), checker(txTo, nIn, amountIn) {}

-bool TransactionSignatureCreator::CreateSig(std::vector<unsigned char>& vchSig, const CKeyID& address, const CScript& scriptCode) const
+bool TransactionSignatureCreator::CreateSig(std::vector<unsigned char>& vchSig, const CKeyID& address, const CScript& scriptCode, SigVersion sigversion) const
 {
    CKey key;
    if (!keystore->GetKey(address, key))
@@ -27,7 +27,7 @@ bool TransactionSignatureCreator::CreateSig(std::vector<unsigned char>& vchSig,

    uint256 hash;
    try {
-        hash = SignatureHash(scriptCode, *txTo, nIn, nHashType, amount, SIGVERSION_BASE);
+        hash = SignatureHash(scriptCode, *txTo, nIn, nHashType, amount, sigversion);
    } catch (logic_error ex) {
        return false;
    }
@@ -38,16 +38,16 @@ bool TransactionSignatureCreator::CreateSig(std::vector<unsigned char>& vchSig,
    return true;
 }

-static bool Sign1(const CKeyID& address, const BaseSignatureCreator& creator, const CScript& scriptCode, CScript& scriptSigRet)
+static bool Sign1(const CKeyID& address, const BaseSignatureCreator& creator, const CScript& scriptCode, std::vector<valtype>& ret, SigVersion sigversion)
 {
    vector<unsigned char> vchSig;
-    if (!creator.CreateSig(vchSig, address, scriptCode))
+    if (!creator.CreateSig(vchSig, address, scriptCode, sigversion))
        return false;
-    scriptSigRet << vchSig;
+    ret.push_back(vchSig);
    return true;
 }

-static bool SignN(const vector<valtype>& multisigdata, const BaseSignatureCreator& creator, const CScript& scriptCode, CScript& scriptSigRet)
+static bool SignN(const vector<valtype>& multisigdata, const BaseSignatureCreator& creator, const CScript& scriptCode, std::vector<valtype>& ret, SigVersion sigversion)
 {
    int nSigned = 0;
    int nRequired = multisigdata.front()[0];
@@ -55,7 +55,7 @@ static bool SignN(const vector<valtype>& multisigdata, const BaseSignatureCreato
    {
        const valtype& pubkey = multisigdata[i];
        CKeyID keyID = CPubKey(pubkey).GetID();
-        if (Sign1(keyID, creator, scriptCode, scriptSigRet))
+        if (Sign1(keyID, creator, scriptCode, ret, sigversion))
            ++nSigned;
    }
    return nSigned==nRequired;
@@ -68,9 +68,11 @@ static bool SignN(const vector<valtype>& multisigdata, const BaseSignatureCreato
 * Returns false if scriptPubKey could not be completely satisfied.
 */
 static bool SignStep(const BaseSignatureCreator& creator, const CScript& scriptPubKey,
-                     CScript& scriptSigRet, txnouttype& whichTypeRet)
+                     std::vector<valtype>& ret, txnouttype& whichTypeRet, SigVersion sigversion)
 {
-    scriptSigRet.clear();
+    CScript scriptRet;
+    uint160 h160;
+    ret.clear();

    vector<valtype> vSolutions;
    if (!Solver(scriptPubKey, whichTypeRet, vSolutions))
@@ -84,62 +86,142 @@ static bool SignStep(const BaseSignatureCreator& creator, const CScript& scriptP
        return false;
    case TX_PUBKEY:
        keyID = CPubKey(vSolutions[0]).GetID();
-        return Sign1(keyID, creator, scriptPubKey, scriptSigRet);
+        return Sign1(keyID, creator, scriptPubKey, ret, sigversion);
    case TX_PUBKEYHASH:
        keyID = CKeyID(uint160(vSolutions[0]));
-        if (!Sign1(keyID, creator, scriptPubKey, scriptSigRet))
+        if (!Sign1(keyID, creator, scriptPubKey, ret, sigversion))
            return false;
        else
        {
            CPubKey vch;
            creator.KeyStore().GetPubKey(keyID, vch);
-            scriptSigRet << ToByteVector(vch);
+            ret.push_back(ToByteVector(vch));
        }
        return true;
    case TX_SCRIPTHASH:
-        return creator.KeyStore().GetCScript(uint160(vSolutions[0]), scriptSigRet);
-
-    case TX_MULTISIG:
-        scriptSigRet << OP_0; // workaround CHECKMULTISIG bug
-        return (SignN(vSolutions, creator, scriptPubKey, scriptSigRet));
-    }
-    return false;
-}
-
-bool ProduceSignature(const BaseSignatureCreator& creator, const CScript& fromPubKey, CScript& scriptSig)
-{
-    txnouttype whichType;
-    if (!SignStep(creator, fromPubKey, scriptSig, whichType))
+        if (creator.KeyStore().GetCScript(uint160(vSolutions[0]), scriptRet)) {
+            ret.push_back(std::vector<unsigned char>(scriptRet.begin(), scriptRet.end()));
+            return true;
+        }
        return false;

-    if (whichType == TX_SCRIPTHASH)
-    {
-        // Solver returns the subscript that need to be evaluated;
-        // the final scriptSig is the signatures from that
-        // and then the serialized subscript:
-        CScript subscript = scriptSig;
+    case TX_MULTISIG:
+        ret.push_back(valtype()); // workaround CHECKMULTISIG bug
+        return (SignN(vSolutions, creator, scriptPubKey, ret, sigversion));

-        txnouttype subType;
-        bool fSolved =
-            SignStep(creator, subscript, scriptSig, subType) && subType != TX_SCRIPTHASH;
-        // Append serialized subscript whether or not it is completely signed:
-        scriptSig << static_cast<valtype>(subscript);
-        if (!fSolved) return false;
+    case TX_WITNESS_V0_KEYHASH:
+        ret.push_back(vSolutions[0]);
+        return true;
+
+    case TX_WITNESS_V0_SCRIPTHASH:
+        CRIPEMD160().Write(&vSolutions[0][0], vSolutions[0].size()).Finalize(h160.begin());
+        if (creator.KeyStore().GetCScript(h160, scriptRet)) {
+            ret.push_back(std::vector<unsigned char>(scriptRet.begin(), scriptRet.end()));
+            return true;
+        }
+        return false;
+
+    default:
+        return false;
    }
-
-    // Test solution
-    return VerifyScript(scriptSig, fromPubKey, STANDARD_SCRIPT_VERIFY_FLAGS, creator.Checker());
 }

-bool SignSignature(const CKeyStore &keystore, const CScript& fromPubKey, CMutableTransaction& txTo, unsigned int nIn, int nHashType)
+static CScript PushAll(const vector<valtype>& values)
+{
+    CScript result;
+    BOOST_FOREACH(const valtype& v, values) {
+        if (v.size() == 0) {
+            result << OP_0;
+        } else if (v.size() == 1 && v[0] >= 1 && v[0] <= 16) {
+            result << CScript::EncodeOP_N(v[0]);
+        } else {
+            result << v;
+        }
+    }
+    return result;
+}
+
+bool ProduceSignature(const BaseSignatureCreator& creator, const CScript& fromPubKey, SignatureData& sigdata)
+{
+    CScript script = fromPubKey;
+    bool solved = true;
+    std::vector<valtype> result;
+    txnouttype whichType;
+    solved = SignStep(creator, script, result, whichType, SIGVERSION_BASE);
+    bool P2SH = false;
+    CScript subscript;
+    sigdata.scriptWitness.stack.clear();
+
+    if (solved && whichType == TX_SCRIPTHASH)
+    {
+        // Solver returns the subscript that needs to be evaluated;
+        // the final scriptSig is the signatures from that
+        // and then the serialized subscript:
+        script = subscript = CScript(result[0].begin(), result[0].end());
+        solved = solved && SignStep(creator, script, result, whichType, SIGVERSION_BASE) && whichType != TX_SCRIPTHASH;
+        P2SH = true;
+    }
+
+    if (solved && whichType == TX_WITNESS_V0_KEYHASH)
+    {
+        CScript witnessscript;
+        witnessscript << OP_DUP << OP_HASH160 << ToByteVector(result[0]) << OP_EQUALVERIFY << OP_CHECKSIG;
+        txnouttype subType;
+        solved = solved && SignStep(creator, witnessscript, result, subType, SIGVERSION_WITNESS_V0);
+        sigdata.scriptWitness.stack = result;
+        result.clear();
+    }
+    else if (solved && whichType == TX_WITNESS_V0_SCRIPTHASH)
+    {
+        CScript witnessscript(result[0].begin(), result[0].end());
+        txnouttype subType;
+        solved = solved && SignStep(creator, witnessscript, result, subType, SIGVERSION_WITNESS_V0) && subType != TX_SCRIPTHASH && subType != TX_WITNESS_V0_SCRIPTHASH && subType != TX_WITNESS_V0_KEYHASH;
+        result.push_back(std::vector<unsigned char>(witnessscript.begin(), witnessscript.end()));
+        sigdata.scriptWitness.stack = result;
+        result.clear();
+    }
+
+    if (P2SH) {
+        result.push_back(std::vector<unsigned char>(subscript.begin(), subscript.end()));
+    }
+    sigdata.scriptSig = PushAll(result);
+
+    // Test solution
+    return solved && VerifyScript(sigdata.scriptSig, fromPubKey, STANDARD_SCRIPT_VERIFY_FLAGS, creator.Checker());
+}
+
+SignatureData DataFromTransaction(const CMutableTransaction& tx, unsigned int nIn)
+{
+    SignatureData data;
+    assert(tx.vin.size() > nIn);
+    data.scriptSig = tx.vin[nIn].scriptSig;
+    if (tx.wit.vtxinwit.size() > nIn) {
+        data.scriptWitness = tx.wit.vtxinwit[nIn].scriptWitness;
+    }
+    return data;
+}
+
+void UpdateTransaction(CMutableTransaction& tx, unsigned int nIn, const SignatureData& data)
+{
+    assert(tx.vin.size() > nIn);
+    tx.vin[nIn].scriptSig = data.scriptSig;
+    if (!data.scriptWitness.IsNull() || tx.wit.vtxinwit.size() > nIn) {
+        tx.wit.vtxinwit.resize(tx.vin.size());
+        tx.wit.vtxinwit[nIn].scriptWitness = data.scriptWitness;
+    }
+}
+
+bool SignSignature(const CKeyStore &keystore, const CScript& fromPubKey, CMutableTransaction& txTo, unsigned int nIn, const CAmount& amount, int nHashType)
 {
    assert(nIn < txTo.vin.size());
-    CTxIn& txin = txTo.vin[nIn];

    CTransaction txToConst(txTo);
-    TransactionSignatureCreator creator(&keystore, &txToConst, nIn, nHashType);
+    TransactionSignatureCreator creator(&keystore, &txToConst, nIn, amount, nHashType);

-    return ProduceSignature(creator, fromPubKey, txin.scriptSig);
+    SignatureData sigdata;
+    bool ret = ProduceSignature(creator, fromPubKey, sigdata);
+    UpdateTransaction(txTo, nIn, sigdata);
+    return ret;
 }

 bool SignSignature(const CKeyStore &keystore, const CTransaction& txFrom, CMutableTransaction& txTo, unsigned int nIn, int nHashType)
@@ -149,20 +231,12 @@ bool SignSignature(const CKeyStore &keystore, const CTransaction& txFrom, CMutab
    assert(txin.prevout.n < txFrom.vout.size());
    const CTxOut& txout = txFrom.vout[txin.prevout.n];

-    return SignSignature(keystore, txout.scriptPubKey, txTo, nIn, nHashType);
+    return SignSignature(keystore, txout.scriptPubKey, txTo, nIn, txout.nValue, nHashType);
 }

-static CScript PushAll(const vector<valtype>& values)
-{
-    CScript result;
-    BOOST_FOREACH(const valtype& v, values)
-        result << v;
-    return result;
-}
-
-static CScript CombineMultisig(const CScript& scriptPubKey, const BaseSignatureChecker& checker,
+static vector<valtype> CombineMultisig(const CScript& scriptPubKey, const BaseSignatureChecker& checker,
                               const vector<valtype>& vSolutions,
-                               const vector<valtype>& sigs1, const vector<valtype>& sigs2)
+                               const vector<valtype>& sigs1, const vector<valtype>& sigs2, SigVersion sigversion)
 {
    // Combine all the signatures we've got:
    set<valtype> allsigs;
@@ -190,7 +264,7 @@ static CScript CombineMultisig(const CScript& scriptPubKey, const BaseSignatureC
            if (sigs.count(pubkey))
                continue; // Already got a sig for this pubkey

-            if (checker.CheckSig(sig, pubkey, scriptPubKey, SIGVERSION_BASE))
+            if (checker.CheckSig(sig, pubkey, scriptPubKey, sigversion))
            {
                sigs[pubkey] = sig;
                break;
@@ -199,87 +273,126 @@ static CScript CombineMultisig(const CScript& scriptPubKey, const BaseSignatureC
    }
    // Now build a merged CScript:
    unsigned int nSigsHave = 0;
-    CScript result; result << OP_0; // pop-one-too-many workaround
+    std::vector<valtype> result; result.push_back(valtype()); // pop-one-too-many workaround
    for (unsigned int i = 0; i < nPubKeys && nSigsHave < nSigsRequired; i++)
    {
        if (sigs.count(vSolutions[i+1]))
        {
-            result << sigs[vSolutions[i+1]];
+            result.push_back(sigs[vSolutions[i+1]]);
            ++nSigsHave;
        }
    }
    // Fill any missing with OP_0:
    for (unsigned int i = nSigsHave; i < nSigsRequired; i++)
-        result << OP_0;
+        result.push_back(valtype());

    return result;
 }

-static CScript CombineSignatures(const CScript& scriptPubKey, const BaseSignatureChecker& checker,
+namespace
+{
+struct Stacks
+{
+    std::vector<valtype> script;
+    std::vector<valtype> witness;
+
+    Stacks() {}
+    explicit Stacks(const std::vector<valtype>& scriptSigStack_) : script(scriptSigStack_), witness() {}
+    explicit Stacks(const SignatureData& data) : witness(data.scriptWitness.stack) {
+        EvalScript(script, data.scriptSig, SCRIPT_VERIFY_STRICTENC, BaseSignatureChecker(), SIGVERSION_BASE);
+    }
+
+    SignatureData Output() const {
+        SignatureData result;
+        result.scriptSig = PushAll(script);
+        result.scriptWitness.stack = witness;
+        return result;
+    }
+};
+}
+
+static Stacks CombineSignatures(const CScript& scriptPubKey, const BaseSignatureChecker& checker,
                                 const txnouttype txType, const vector<valtype>& vSolutions,
-                                 vector<valtype>& sigs1, vector<valtype>& sigs2)
+                                 Stacks sigs1, Stacks sigs2, SigVersion sigversion)
 {
    switch (txType)
    {
    case TX_NONSTANDARD:
    case TX_NULL_DATA:
        // Don't know anything about this, assume bigger one is correct:
-        if (sigs1.size() >= sigs2.size())
-            return PushAll(sigs1);
-        return PushAll(sigs2);
+        if (sigs1.script.size() >= sigs2.script.size())
+            return sigs1;
+        return sigs2;
    case TX_PUBKEY:
    case TX_PUBKEYHASH:
        // Signatures are bigger than placeholders or empty scripts:
-        if (sigs1.empty() || sigs1[0].empty())
-            return PushAll(sigs2);
-        return PushAll(sigs1);
+        if (sigs1.script.empty() || sigs1.script[0].empty())
+            return sigs2;
+        return sigs1;
+    case TX_WITNESS_V0_KEYHASH:
+        // Signatures are bigger than placeholders or empty scripts:
+        if (sigs1.witness.empty() || sigs1.witness[0].empty())
+            return sigs2;
+        return sigs1;
    case TX_SCRIPTHASH:
-        if (sigs1.empty() || sigs1.back().empty())
-            return PushAll(sigs2);
-        else if (sigs2.empty() || sigs2.back().empty())
-            return PushAll(sigs1);
+        if (sigs1.script.empty() || sigs1.script.back().empty())
+            return sigs2;
+        else if (sigs2.script.empty() || sigs2.script.back().empty())
+            return sigs1;
        else
        {
            // Recur to combine:
-            valtype spk = sigs1.back();
+            valtype spk = sigs1.script.back();
            CScript pubKey2(spk.begin(), spk.end());

            txnouttype txType2;
            vector<vector<unsigned char> > vSolutions2;
            Solver(pubKey2, txType2, vSolutions2);
-            sigs1.pop_back();
-            sigs2.pop_back();
-            CScript result = CombineSignatures(pubKey2, checker, txType2, vSolutions2, sigs1, sigs2);
-            result << spk;
+            sigs1.script.pop_back();
+            sigs2.script.pop_back();
+            Stacks result = CombineSignatures(pubKey2, checker, txType2, vSolutions2, sigs1, sigs2, sigversion);
+            result.script.push_back(spk);
            return result;
        }
    case TX_MULTISIG:
-        return CombineMultisig(scriptPubKey, checker, vSolutions, sigs1, sigs2);
+        return Stacks(CombineMultisig(scriptPubKey, checker, vSolutions, sigs1.script, sigs2.script, sigversion));
+    case TX_WITNESS_V0_SCRIPTHASH:
+        if (sigs1.witness.empty() || sigs1.witness.back().empty())
+            return sigs2;
+        else if (sigs2.witness.empty() || sigs2.witness.back().empty())
+            return sigs1;
+        else
+        {
+            // Recur to combine:
+            CScript pubKey2(sigs1.witness.back().begin(), sigs1.witness.back().end());
+            txnouttype txType2;
+            vector<valtype> vSolutions2;
+            Solver(pubKey2, txType2, vSolutions2);
+            sigs1.witness.pop_back();
+            sigs1.script = sigs1.witness;
+            sigs1.witness.clear();
+            sigs2.witness.pop_back();
+            sigs2.script = sigs2.witness;
+            sigs2.witness.clear();
+            Stacks result = CombineSignatures(pubKey2, checker, txType2, vSolutions2, sigs1, sigs2, SIGVERSION_WITNESS_V0);
+            result.witness = result.script;
+            result.script.clear();
+            result.witness.push_back(valtype(pubKey2.begin(), pubKey2.end()));
+            return result;
+        }
+    default:
+        return Stacks();
    }
-
-    return CScript();
 }

-CScript CombineSignatures(const CScript& scriptPubKey, const CTransaction& txTo, unsigned int nIn, const CAmount& amount,
-                          const CScript& scriptSig1, const CScript& scriptSig2)
-{
-    TransactionSignatureChecker checker(&txTo, nIn, amount);
-    return CombineSignatures(scriptPubKey, checker, scriptSig1, scriptSig2);
-}
-
-CScript CombineSignatures(const CScript& scriptPubKey, const BaseSignatureChecker& checker,
-                          const CScript& scriptSig1, const CScript& scriptSig2)
+SignatureData CombineSignatures(const CScript& scriptPubKey, const BaseSignatureChecker& checker,
+                          const SignatureData& scriptSig1, const SignatureData& scriptSig2)
 {
    txnouttype txType;
    vector<vector<unsigned char> > vSolutions;
    Solver(scriptPubKey, txType, vSolutions);

-    vector<valtype> stack1;
-    EvalScript(stack1, scriptSig1, SCRIPT_VERIFY_STRICTENC, BaseSignatureChecker(), SIGVERSION_BASE);
-    vector<valtype> stack2;
-    EvalScript(stack2, scriptSig2, SCRIPT_VERIFY_STRICTENC, BaseSignatureChecker(), SIGVERSION_BASE);
-
-    return CombineSignatures(scriptPubKey, checker, txType, vSolutions, stack1, stack2);
+    return CombineSignatures(scriptPubKey, checker, txType, vSolutions, Stacks(scriptSig1), Stacks(scriptSig2), SIGVERSION_BASE).Output();
 }

 namespace {
@@ -302,7 +415,7 @@ const BaseSignatureChecker& DummySignatureCreator::Checker() const
    return dummyChecker;
 }

-bool DummySignatureCreator::CreateSig(std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode) const
+bool DummySignatureCreator::CreateSig(std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode, SigVersion sigversion) const
 {
    // Create a dummy signature that is a valid DER-encoding
    vchSig.assign(72, '\000');
--- a/src/script/sign.h
+++ b/src/script/sign.h
@@ -27,7 +27,7 @@ public:
    virtual const BaseSignatureChecker& Checker() const =0;

    /** Create a singular (non-script) signature. */
-    virtual bool CreateSig(std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode) const =0;
+    virtual bool CreateSig(std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode, SigVersion sigversion) const =0;
 };

 /** A signature creator for transactions. */
@@ -41,7 +41,14 @@ class TransactionSignatureCreator : public BaseSignatureCreator {
 public:
    TransactionSignatureCreator(const CKeyStore* keystoreIn, const CTransaction* txToIn, unsigned int nInIn, const CAmount& amountIn, int nHashTypeIn=SIGHASH_ALL);
    const BaseSignatureChecker& Checker() const { return checker; }
-    bool CreateSig(std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode) const;
+    bool CreateSig(std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode, SigVersion sigversion) const;
+};
+
+class MutableTransactionSignatureCreator : public TransactionSignatureCreator {
+    CTransaction tx;
+
+public:
+    MutableTransactionSignatureCreator(const CKeyStore* keystoreIn, const CMutableTransaction* txToIn, unsigned int nInIn, const CAmount& amount, int nHashTypeIn) : TransactionSignatureCreator(keystoreIn, &tx, nInIn, amount, nHashTypeIn), tx(*txToIn) {}
 };

 /** A signature creator that just produces 72-byte empty signatyres. */
@@ -49,20 +56,29 @@ class DummySignatureCreator : public BaseSignatureCreator {
 public:
    DummySignatureCreator(const CKeyStore* keystoreIn) : BaseSignatureCreator(keystoreIn) {}
    const BaseSignatureChecker& Checker() const;
-    bool CreateSig(std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode) const;
+    bool CreateSig(std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode, SigVersion sigversion) const;
+};
+
+struct SignatureData {
+    CScript scriptSig;
+    CScriptWitness scriptWitness;
+
+    SignatureData() {}
+    explicit SignatureData(const CScript& script) : scriptSig(script) {}
 };

 /** Produce a script signature using a generic signature creator. */
-bool ProduceSignature(const BaseSignatureCreator& creator, const CScript& scriptPubKey, CScript& scriptSig);
+bool ProduceSignature(const BaseSignatureCreator& creator, const CScript& scriptPubKey, SignatureData& sigdata);

 /** Produce a script signature for a transaction. */
-bool SignSignature(const CKeyStore& keystore, const CScript& fromPubKey, CMutableTransaction& txTo, unsigned int nIn, int nHashType=SIGHASH_ALL);
-bool SignSignature(const CKeyStore& keystore, const CTransaction& txFrom, CMutableTransaction& txTo, unsigned int nIn, int nHashType=SIGHASH_ALL);
+bool SignSignature(const CKeyStore &keystore, const CScript& fromPubKey, CMutableTransaction& txTo, unsigned int nIn, const CAmount& amount, int nHashType);
+bool SignSignature(const CKeyStore& keystore, const CTransaction& txFrom, CMutableTransaction& txTo, unsigned int nIn, int nHashType);

 /** Combine two script signatures using a generic signature checker, intelligently, possibly with OP_0 placeholders. */
-CScript CombineSignatures(const CScript& scriptPubKey, const BaseSignatureChecker& checker, const CScript& scriptSig1, const CScript& scriptSig2);
+SignatureData CombineSignatures(const CScript& scriptPubKey, const BaseSignatureChecker& checker, const SignatureData& scriptSig1, const SignatureData& scriptSig2);

-/** Combine two script signatures on transactions. */
-CScript CombineSignatures(const CScript& scriptPubKey, const CTransaction& txTo, unsigned int nIn, const CAmount& amount, const CScript& scriptSig1, const CScript& scriptSig2);
+/** Extract signature data from a transaction, and insert it. */
+SignatureData DataFromTransaction(const CMutableTransaction& tx, unsigned int nIn);
+void UpdateTransaction(CMutableTransaction& tx, unsigned int nIn, const SignatureData& data);

 #endif // BITCOIN_SCRIPT_SIGN_H
--- a/src/script/standard.cpp
+++ b/src/script/standard.cpp
@@ -30,6 +30,8 @@ const char* GetTxnOutputType(txnouttype t)
    case TX_SCRIPTHASH: return "scripthash";
    case TX_MULTISIG: return "multisig";
    case TX_NULL_DATA: return "nulldata";
+    case TX_WITNESS_V0_KEYHASH: return "witness_v0_keyhash";
+    case TX_WITNESS_V0_SCRIPTHASH: return "witness_v0_scripthash";
    }
    return NULL;
 }
@@ -68,6 +70,22 @@ bool Solver(const CScript& scriptPubKey, txnouttype& typeRet, vector<vector<unsi
        return true;
    }

+    int witnessversion;
+    std::vector<unsigned char> witnessprogram;
+    if (scriptPubKey.IsWitnessProgram(witnessversion, witnessprogram)) {
+        if (witnessversion == 0 && witnessprogram.size() == 20) {
+            typeRet = TX_WITNESS_V0_KEYHASH;
+            vSolutionsRet.push_back(witnessprogram);
+            return true;
+        }
+        if (witnessversion == 0 && witnessprogram.size() == 32) {
+            typeRet = TX_WITNESS_V0_SCRIPTHASH;
+            vSolutionsRet.push_back(witnessprogram);
+            return true;
+        }
+        return false;
+    }
+
    // Scan templates
    const CScript& script1 = scriptPubKey;
    BOOST_FOREACH(const PAIRTYPE(txnouttype, CScript)& tplate, mTemplates)
@@ -316,3 +334,26 @@ CScript GetScriptForMultisig(int nRequired, const std::vector<CPubKey>& keys)
    script << CScript::EncodeOP_N(keys.size()) << OP_CHECKMULTISIG;
    return script;
 }
+
+CScript GetScriptForWitness(const CScript& redeemscript)
+{
+    CScript ret;
+
+    txnouttype typ;
+    std::vector<std::vector<unsigned char> > vSolutions;
+    if (Solver(redeemscript, typ, vSolutions)) {
+        if (typ == TX_PUBKEY) {
+            unsigned char h160[20];
+            CHash160().Write(&vSolutions[0][0], vSolutions[0].size()).Finalize(h160);
+            ret << OP_0 << std::vector<unsigned char>(&h160[0], &h160[20]);
+            return ret;
+        } else if (typ == TX_PUBKEYHASH) {
+           ret << OP_0 << vSolutions[0];
+           return ret;
+        }
+    }
+    uint256 hash;
+    CSHA256().Write(&redeemscript[0], redeemscript.size()).Finalize(hash.begin());
+    ret << OP_0 << ToByteVector(hash);
+    return ret;
+}
--- a/src/script/standard.h
+++ b/src/script/standard.h
@@ -65,6 +65,8 @@ enum txnouttype
    TX_SCRIPTHASH,
    TX_MULTISIG,
    TX_NULL_DATA,
+    TX_WITNESS_V0_SCRIPTHASH,
+    TX_WITNESS_V0_KEYHASH,
 };

 class CNoDestination {
@@ -92,5 +94,6 @@ bool ExtractDestinations(const CScript& scriptPubKey, txnouttype& typeRet, std::

 CScript GetScriptForDestination(const CTxDestination& dest);
 CScript GetScriptForMultisig(int nRequired, const std::vector<CPubKey>& keys);
+CScript GetScriptForWitness(const CScript& redeemscript);

 #endif // BITCOIN_SCRIPT_STANDARD_H