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Precompute sighashes

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Original version by Nicolas Dorier. Precomputing version by Pieter Wuille.

Edited for Zcash by Ariel Gabizon and Jack Grigg
This commit is contained in:
Pieter Wuille
2018-01-01 13:27:59 +02:00
committed by Jack Grigg
parent 722d811f89
commit f762d44973
10 changed files with 84 additions and 38 deletions
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54
src/script/interpreter.cpp
View File

@@ -1050,9 +1050,40 @@ public:
}
};
uint256 GetPrevoutHash(const CTransaction& txTo) {
CHashWriter ss(SER_GETHASH, 0);
for (unsigned int n = 0; n < txTo.vin.size(); n++) {
ss << txTo.vin[n].prevout;
}
return ss.GetHash();
}
uint256 GetSequenceHash(const CTransaction& txTo) {
CHashWriter ss(SER_GETHASH, 0);
for (unsigned int n = 0; n < txTo.vin.size(); n++) {
ss << txTo.vin[n].nSequence;
}
return ss.GetHash();
}
uint256 GetOutputsHash(const CTransaction& txTo) {
CHashWriter ss(SER_GETHASH, 0);
for (unsigned int n = 0; n < txTo.vout.size(); n++) {
ss << txTo.vout[n];
}
return ss.GetHash();
}
} // anon namespace
uint256 SignatureHash(const CScript& scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType, const CAmount& amount, SigVersion sigversion)
CachedHashes::CachedHashes(const CTransaction& txTo)
{
hashPrevouts = GetPrevoutHash(txTo);
hashSequence = GetSequenceHash(txTo);
hashOutputs = GetOutputsHash(txTo);
}
uint256 SignatureHash(const CScript& scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType, const CAmount& amount, SigVersion sigversion, const CachedHashes* cache)
{
if (nIn >= txTo.vin.size() && nIn != NOT_AN_INPUT) {
// nIn out of range
@@ -1065,27 +1096,16 @@ uint256 SignatureHash(const CScript& scriptCode, const CTransaction& txTo, unsig
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
hashPrevouts = cache ? cache->hashPrevouts : GetPrevoutHash(txTo);
}
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
hashSequence = cache ? cache->hashSequence : GetSequenceHash(txTo);
}
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
hashOutputs = cache ? cache->hashOutputs : GetOutputsHash(txTo);
} else if ((nHashType & 0x1f) == SIGHASH_SINGLE && nIn < txTo.vout.size()) {
CHashWriter ss(SER_GETHASH, 0);
ss << txTo.vout[nIn];
@@ -1154,7 +1174,7 @@ bool TransactionSignatureChecker::CheckSig(const vector<unsigned char>& vchSigIn
uint256 sighash;
try {
sighash = SignatureHash(scriptCode, *txTo, nIn, nHashType, amount, sigversion);
sighash = SignatureHash(scriptCode, *txTo, nIn, nHashType, amount, sigversion, this->cachedHashes);
} catch (logic_error ex) {
return false;
}

13
src/script/interpreter.h
View File

@@ -88,13 +88,20 @@ enum
SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY = (1U << 9),
};
struct CachedHashes
{
uint256 hashPrevouts, hashSequence, hashOutputs;
CachedHashes(const CTransaction& tx);
};
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);
uint256 SignatureHash(const CScript &scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType, const CAmount& amount, SigVersion sigversion, const CachedHashes* cache = NULL);
class BaseSignatureChecker
{
@@ -118,12 +125,14 @@ private:
const CTransaction* txTo;
unsigned int nIn;
const CAmount amount;
const CachedHashes* cachedHashes;
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& amountIn) : txTo(txToIn), nIn(nInIn), amount(amountIn) {}
TransactionSignatureChecker(const CTransaction* txToIn, unsigned int nInIn, const CAmount& amountIn) : txTo(txToIn), nIn(nInIn), amount(amountIn), cachedHashes(NULL) {}
TransactionSignatureChecker(const CTransaction* txToIn, unsigned int nInIn, const CAmount& amountIn, const CachedHashes& cachedHashesIn) : txTo(txToIn), nIn(nInIn), amount(amountIn), cachedHashes(&cachedHashesIn) {}
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;
};

2
src/script/sigcache.h
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@@ -18,7 +18,7 @@ private:
bool store;
public:
CachingTransactionSignatureChecker(const CTransaction* txToIn, unsigned int nInIn, const CAmount& amount, bool storeIn) : TransactionSignatureChecker(txToIn, nInIn, amount), store(storeIn) {}
CachingTransactionSignatureChecker(const CTransaction* txToIn, unsigned int nInIn, const CAmount& amount, bool storeIn, CachedHashes& cachedHashesIn) : TransactionSignatureChecker(txToIn, nInIn, amount, cachedHashesIn), store(storeIn) {}
bool VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& vchPubKey, const uint256& sighash) const;
};

4
src/script/zcashconsensus.cpp
View File

@@ -84,9 +84,9 @@ int zcashconsensus_verify_script(const unsigned char *scriptPubKey, unsigned int
// Regardless of the verification result, the tx did not error.
set_error(err, zcashconsensus_ERR_OK);
CachedHashes cachedHashes(tx);
CAmount am(0);
return VerifyScript(tx.vin[nIn].scriptSig, CScript(scriptPubKey, scriptPubKey + scriptPubKeyLen), flags, TransactionSignatureChecker(&tx, nIn, am), NULL);
return VerifyScript(tx.vin[nIn].scriptSig, CScript(scriptPubKey, scriptPubKey + scriptPubKeyLen), flags, TransactionSignatureChecker(&tx, nIn, am, cachedHashes), NULL);
} catch (const std::exception&) {
return set_error(err, zcashconsensus_ERR_TX_DESERIALIZE); // Error deserializing
}