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BIP143: Verification logic
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Includes simplifications by Eric Lombrozo.
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@sipa
sipa committed Jun 22, 2016
1 parent 0ef1dd3 commit 3dd4102
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Showing 11 changed files with 131 additions and 63 deletions.
2 changes: 1 addition & 1 deletion src/bitcoin-tx.cpp
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Expand Up @@ -471,7 +471,7 @@ static void MutateTxSign(CMutableTransaction& tx, const string& flagStr)

// ... and merge in other signatures:
BOOST_FOREACH(const CTransaction& txv, txVariants) {
txin.scriptSig = CombineSignatures(prevPubKey, mergedTx, i, txin.scriptSig, txv.vin[i].scriptSig);
txin.scriptSig = CombineSignatures(prevPubKey, mergedTx, i, amount, txin.scriptSig, txv.vin[i].scriptSig);
}
if (!VerifyScript(txin.scriptSig, prevPubKey, mergedTx.wit.vtxinwit.size() > i ? &mergedTx.wit.vtxinwit[i].scriptWitness : NULL, STANDARD_SCRIPT_VERIFY_FLAGS, MutableTransactionSignatureChecker(&mergedTx, i, amount)))
fComplete = false;
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2 changes: 1 addition & 1 deletion src/policy/policy.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -137,7 +137,7 @@ bool AreInputsStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs)
{
std::vector<std::vector<unsigned char> > stack;
// convert the scriptSig into a stack, so we can inspect the redeemScript
if (!EvalScript(stack, tx.vin[i].scriptSig, SCRIPT_VERIFY_NONE, BaseSignatureChecker(), 0))
if (!EvalScript(stack, tx.vin[i].scriptSig, SCRIPT_VERIFY_NONE, BaseSignatureChecker(), SIGVERSION_BASE))
return false;
if (stack.empty())
return false;
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2 changes: 1 addition & 1 deletion src/rpc/rawtransaction.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -787,7 +787,7 @@ UniValue signrawtransaction(const UniValue& params, bool fHelp)

// ... and merge in other signatures:
BOOST_FOREACH(const CMutableTransaction& txv, txVariants) {
txin.scriptSig = CombineSignatures(prevPubKey, txConst, i, txin.scriptSig, txv.vin[i].scriptSig);
txin.scriptSig = CombineSignatures(prevPubKey, txConst, i, amount, txin.scriptSig, txv.vin[i].scriptSig);
}
ScriptError serror = SCRIPT_ERR_OK;
if (!VerifyScript(txin.scriptSig, prevPubKey, mergedTx.wit.vtxinwit.size() > i ? &mergedTx.wit.vtxinwit[i].scriptWitness : NULL, STANDARD_SCRIPT_VERIFY_FLAGS, TransactionSignatureChecker(&txConst, i, amount), &serror)) {
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84 changes: 72 additions & 12 deletions src/script/interpreter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -229,7 +229,7 @@ bool static CheckMinimalPush(const valtype& data, opcodetype opcode) {
return true;
}

bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* serror)
bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker, SigVersion sigversion, ScriptError* serror)
{
static const CScriptNum bnZero(0);
static const CScriptNum bnOne(1);
Expand Down Expand Up @@ -869,13 +869,15 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
CScript scriptCode(pbegincodehash, pend);

// Drop the signature, since there's no way for a signature to sign itself
scriptCode.FindAndDelete(CScript(vchSig));
if (sigversion == SIGVERSION_BASE) {
scriptCode.FindAndDelete(CScript(vchSig));
}

if (!CheckSignatureEncoding(vchSig, flags, serror) || !CheckPubKeyEncoding(vchPubKey, flags, serror)) {
//serror is set
return false;
}
bool fSuccess = checker.CheckSig(vchSig, vchPubKey, scriptCode);
bool fSuccess = checker.CheckSig(vchSig, vchPubKey, scriptCode, sigversion);

popstack(stack);
popstack(stack);
Expand Down Expand Up @@ -925,7 +927,9 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
for (int k = 0; k < nSigsCount; k++)
{
valtype& vchSig = stacktop(-isig-k);
scriptCode.FindAndDelete(CScript(vchSig));
if (sigversion == SIGVERSION_BASE) {
scriptCode.FindAndDelete(CScript(vchSig));
}
}

bool fSuccess = true;
Expand All @@ -943,7 +947,7 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
}

// Check signature
bool fOk = checker.CheckSig(vchSig, vchPubKey, scriptCode);
bool fOk = checker.CheckSig(vchSig, vchPubKey, scriptCode, sigversion);

if (fOk) {
isig++;
Expand Down Expand Up @@ -1106,8 +1110,64 @@ class CTransactionSignatureSerializer {

} // anon namespace

uint256 SignatureHash(const CScript& scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType)
uint256 SignatureHash(const CScript& scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType, const CAmount& amount, SigVersion sigversion)
{
if (sigversion == SIGVERSION_WITNESS_V0) {
uint256 hashPrevouts;
uint256 hashSequence;
uint256 hashOutputs;

if (!(nHashType & SIGHASH_ANYONECANPAY)) {
CHashWriter ss(SER_GETHASH, 0);
for (unsigned int n = 0; n < txTo.vin.size(); n++) {
ss << txTo.vin[n].prevout;
}
hashPrevouts = ss.GetHash(); // TODO: cache this value for all signatures in a transaction
}

if (!(nHashType & SIGHASH_ANYONECANPAY) && (nHashType & 0x1f) != SIGHASH_SINGLE && (nHashType & 0x1f) != SIGHASH_NONE) {
CHashWriter ss(SER_GETHASH, 0);
for (unsigned int n = 0; n < txTo.vin.size(); n++) {
ss << txTo.vin[n].nSequence;
}
hashSequence = ss.GetHash(); // TODO: cache this value for all signatures in a transaction
}

if ((nHashType & 0x1f) != SIGHASH_SINGLE && (nHashType & 0x1f) != SIGHASH_NONE) {
CHashWriter ss(SER_GETHASH, 0);
for (unsigned int n = 0; n < txTo.vout.size(); n++) {
ss << txTo.vout[n];
}
hashOutputs = ss.GetHash(); // TODO: cache this value for all signatures in a transaction
} else if ((nHashType & 0x1f) == SIGHASH_SINGLE && nIn < txTo.vout.size()) {
CHashWriter ss(SER_GETHASH, 0);
ss << txTo.vout[nIn];
hashOutputs = ss.GetHash();
}

CHashWriter ss(SER_GETHASH, 0);
// Version
ss << txTo.nVersion;
// Input prevouts/nSequence (none/all, depending on flags)
ss << hashPrevouts;
ss << hashSequence;
// The input being signed (replacing the scriptSig with scriptCode + amount)
// The prevout may already be contained in hashPrevout, and the nSequence
// may already be contain in hashSequence.
ss << txTo.vin[nIn].prevout;
ss << static_cast<const CScriptBase&>(scriptCode);
ss << amount;
ss << txTo.vin[nIn].nSequence;
// Outputs (none/one/all, depending on flags)
ss << hashOutputs;
// Locktime
ss << txTo.nLockTime;
// Sighash type
ss << nHashType;

return ss.GetHash();
}

static const uint256 one(uint256S("0000000000000000000000000000000000000000000000000000000000000001"));
if (nIn >= txTo.vin.size()) {
// nIn out of range
Expand Down Expand Up @@ -1136,7 +1196,7 @@ bool TransactionSignatureChecker::VerifySignature(const std::vector<unsigned cha
return pubkey.Verify(sighash, vchSig);
}

bool TransactionSignatureChecker::CheckSig(const vector<unsigned char>& vchSigIn, const vector<unsigned char>& vchPubKey, const CScript& scriptCode) const
bool TransactionSignatureChecker::CheckSig(const vector<unsigned char>& vchSigIn, const vector<unsigned char>& vchPubKey, const CScript& scriptCode, SigVersion sigversion) const
{
CPubKey pubkey(vchPubKey);
if (!pubkey.IsValid())
Expand All @@ -1149,7 +1209,7 @@ bool TransactionSignatureChecker::CheckSig(const vector<unsigned char>& vchSigIn
int nHashType = vchSig.back();
vchSig.pop_back();

uint256 sighash = SignatureHash(scriptCode, *txTo, nIn, nHashType);
uint256 sighash = SignatureHash(scriptCode, *txTo, nIn, nHashType, amount, sigversion);

if (!VerifySignature(vchSig, pubkey, sighash))
return false;
Expand Down Expand Up @@ -1280,7 +1340,7 @@ static bool VerifyWitnessProgram(const CScriptWitness& witness, int witversion,
return set_error(serror, SCRIPT_ERR_PUSH_SIZE);
}

if (!EvalScript(stack, scriptPubKey, flags, checker, serror)) {
if (!EvalScript(stack, scriptPubKey, flags, checker, SIGVERSION_WITNESS_V0, serror)) {
return false;
}

Expand All @@ -1307,12 +1367,12 @@ bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, const C
}

vector<vector<unsigned char> > stack, stackCopy;
if (!EvalScript(stack, scriptSig, flags, checker, serror))
if (!EvalScript(stack, scriptSig, flags, checker, SIGVERSION_BASE, serror))
// serror is set
return false;
if (flags & SCRIPT_VERIFY_P2SH)
stackCopy = stack;
if (!EvalScript(stack, scriptPubKey, flags, checker, serror))
if (!EvalScript(stack, scriptPubKey, flags, checker, SIGVERSION_BASE, serror))
// serror is set
return false;
if (stack.empty())
Expand Down Expand Up @@ -1358,7 +1418,7 @@ bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, const C
CScript pubKey2(pubKeySerialized.begin(), pubKeySerialized.end());
popstack(stack);

if (!EvalScript(stack, pubKey2, flags, checker, serror))
if (!EvalScript(stack, pubKey2, flags, checker, SIGVERSION_BASE, serror))
// serror is set
return false;
if (stack.empty())
Expand Down
17 changes: 12 additions & 5 deletions src/script/interpreter.h
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Original file line number Diff line number Diff line change
Expand Up @@ -98,12 +98,18 @@ enum

bool CheckSignatureEncoding(const std::vector<unsigned char> &vchSig, unsigned int flags, ScriptError* serror);

uint256 SignatureHash(const CScript &scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType);
enum SigVersion
{
SIGVERSION_BASE = 0,
SIGVERSION_WITNESS_V0 = 1,
};

uint256 SignatureHash(const CScript &scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType, const CAmount& amount, SigVersion sigversion);

class BaseSignatureChecker
{
public:
virtual bool CheckSig(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode) const
virtual bool CheckSig(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode, SigVersion sigversion) const
{
return false;
}
Expand All @@ -126,13 +132,14 @@ class TransactionSignatureChecker : public BaseSignatureChecker
private:
const CTransaction* txTo;
unsigned int nIn;
const CAmount amount;

protected:
virtual bool VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& vchPubKey, const uint256& sighash) const;

public:
TransactionSignatureChecker(const CTransaction* txToIn, unsigned int nInIn, const CAmount& amount) : txTo(txToIn), nIn(nInIn) {}
bool CheckSig(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode) const;
TransactionSignatureChecker(const CTransaction* txToIn, unsigned int nInIn, const CAmount& amountIn) : txTo(txToIn), nIn(nInIn), amount(amountIn) {}
bool CheckSig(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode, SigVersion sigversion) const;
bool CheckLockTime(const CScriptNum& nLockTime) const;
bool CheckSequence(const CScriptNum& nSequence) const;
};
Expand All @@ -146,7 +153,7 @@ class MutableTransactionSignatureChecker : public TransactionSignatureChecker
MutableTransactionSignatureChecker(const CMutableTransaction* txToIn, unsigned int nInIn, const CAmount& amount) : TransactionSignatureChecker(&txTo, nInIn, amount), txTo(*txToIn) {}
};

bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* error = NULL);
bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker, SigVersion sigversion, ScriptError* error = NULL);
bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, const CScriptWitness* witness, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* serror = NULL);

#endif // BITCOIN_SCRIPT_INTERPRETER_H
17 changes: 8 additions & 9 deletions src/script/sign.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -18,16 +18,15 @@ using namespace std;

typedef std::vector<unsigned char> valtype;

static const CAmount amountZero = 0;
TransactionSignatureCreator::TransactionSignatureCreator(const CKeyStore* keystoreIn, const CTransaction* txToIn, unsigned int nInIn, int nHashTypeIn) : BaseSignatureCreator(keystoreIn), txTo(txToIn), nIn(nInIn), nHashType(nHashTypeIn), checker(txTo, nIn, amountZero) {}
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
{
CKey key;
if (!keystore->GetKey(address, key))
return false;

uint256 hash = SignatureHash(scriptCode, *txTo, nIn, nHashType);
uint256 hash = SignatureHash(scriptCode, *txTo, nIn, nHashType, amount, SIGVERSION_BASE);
if (!key.Sign(hash, vchSig))
return false;
vchSig.push_back((unsigned char)nHashType);
Expand Down Expand Up @@ -186,7 +185,7 @@ 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))
if (checker.CheckSig(sig, pubkey, scriptPubKey, SIGVERSION_BASE))
{
sigs[pubkey] = sig;
break;
Expand Down Expand Up @@ -256,10 +255,10 @@ static CScript CombineSignatures(const CScript& scriptPubKey, const BaseSignatur
return CScript();
}

CScript CombineSignatures(const CScript& scriptPubKey, const CTransaction& txTo, unsigned int nIn,
CScript CombineSignatures(const CScript& scriptPubKey, const CTransaction& txTo, unsigned int nIn, const CAmount& amount,
const CScript& scriptSig1, const CScript& scriptSig2)
{
TransactionSignatureChecker checker(&txTo, nIn, amountZero);
TransactionSignatureChecker checker(&txTo, nIn, amount);
return CombineSignatures(scriptPubKey, checker, scriptSig1, scriptSig2);
}

Expand All @@ -271,9 +270,9 @@ CScript CombineSignatures(const CScript& scriptPubKey, const BaseSignatureChecke
Solver(scriptPubKey, txType, vSolutions);

vector<valtype> stack1;
EvalScript(stack1, scriptSig1, SCRIPT_VERIFY_STRICTENC, BaseSignatureChecker());
EvalScript(stack1, scriptSig1, SCRIPT_VERIFY_STRICTENC, BaseSignatureChecker(), SIGVERSION_BASE);
vector<valtype> stack2;
EvalScript(stack2, scriptSig2, SCRIPT_VERIFY_STRICTENC, BaseSignatureChecker());
EvalScript(stack2, scriptSig2, SCRIPT_VERIFY_STRICTENC, BaseSignatureChecker(), SIGVERSION_BASE);

return CombineSignatures(scriptPubKey, checker, txType, vSolutions, stack1, stack2);
}
Expand All @@ -285,7 +284,7 @@ class DummySignatureChecker : public BaseSignatureChecker
public:
DummySignatureChecker() {}

bool CheckSig(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode) const
bool CheckSig(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode, SigVersion sigversion) const
{
return true;
}
Expand Down
5 changes: 3 additions & 2 deletions src/script/sign.h
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Original file line number Diff line number Diff line change
Expand Up @@ -35,10 +35,11 @@ class TransactionSignatureCreator : public BaseSignatureCreator {
const CTransaction* txTo;
unsigned int nIn;
int nHashType;
CAmount amount;
const TransactionSignatureChecker checker;

public:
TransactionSignatureCreator(const CKeyStore* keystoreIn, const CTransaction* txToIn, unsigned int nInIn, int nHashTypeIn=SIGHASH_ALL);
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;
};
Expand All @@ -62,6 +63,6 @@ bool SignSignature(const CKeyStore& keystore, const CTransaction& txFrom, CMutab
CScript CombineSignatures(const CScript& scriptPubKey, const BaseSignatureChecker& checker, const CScript& scriptSig1, const CScript& scriptSig2);

/** Combine two script signatures on transactions. */
CScript CombineSignatures(const CScript& scriptPubKey, const CTransaction& txTo, unsigned int nIn, const CScript& scriptSig1, const CScript& scriptSig2);
CScript CombineSignatures(const CScript& scriptPubKey, const CTransaction& txTo, unsigned int nIn, const CAmount& amount, const CScript& scriptSig1, const CScript& scriptSig2);

#endif // BITCOIN_SCRIPT_SIGN_H
2 changes: 1 addition & 1 deletion src/test/multisig_tests.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,7 @@ BOOST_FIXTURE_TEST_SUITE(multisig_tests, BasicTestingSetup)
CScript
sign_multisig(CScript scriptPubKey, vector<CKey> keys, CTransaction transaction, int whichIn)
{
uint256 hash = SignatureHash(scriptPubKey, transaction, whichIn, SIGHASH_ALL);
uint256 hash = SignatureHash(scriptPubKey, transaction, whichIn, SIGHASH_ALL, 0, SIGVERSION_BASE);

CScript result;
result << OP_0; // CHECKMULTISIG bug workaround
Expand Down
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