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Inline signature serializer

Instead of building a full copy of a CTransaction being signed, and
then modifying bits and pieces until its fits the form necessary
for computing the signature hash, use a wrapper serializer that
only serializes the necessary bits on-the-fly.

This makes it easier to see which data is actually being hash,
reduces load on the heap, and also marginally improves performances
(around 3-4us/sigcheck here). The performance improvements are much
larger for large transactions, though.

The old implementation of SignatureHash is moved to a unit tests,
to test whether the old and new algorithm result in the same value
for randomly-constructed transactions.
pull/1/head
Pieter Wuille 9 years ago
parent
commit
f5857e5cb5
  1. 146
      src/script.cpp
  2. 2
      src/test/Makefile.am
  3. 2
      src/test/multisig_tests.cpp
  4. 2
      src/test/script_tests.cpp
  5. 120
      src/test/sighash_tests.cpp

146
src/script.cpp

@ -971,62 +971,118 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, co @@ -971,62 +971,118 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, co
namespace {
/** Wrapper that serializes like CTransaction, but with the modifications
* required for the signature hash done in-place
*/
class CTransactionSignatureSerializer {
private:
const CTransaction &txTo; // reference to the spending transaction (the one being serialized)
const CScript &scriptCode; // output script being consumed
const unsigned int nIn; // input index of txTo being signed
const bool fAnyoneCanPay; // whether the hashtype has the SIGHASH_ANYONECANPAY flag set
const bool fHashSingle; // whether the hashtype is SIGHASH_SINGLE
const bool fHashNone; // whether the hashtype is SIGHASH_NONE
uint256 SignatureHash(CScript scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType)
{
if (nIn >= txTo.vin.size())
{
LogPrintf("ERROR: SignatureHash() : nIn=%d out of range\n", nIn);
return 1;
public:
CTransactionSignatureSerializer(const CTransaction &txToIn, const CScript &scriptCodeIn, unsigned int nInIn, int nHashTypeIn) :
txTo(txToIn), scriptCode(scriptCodeIn), nIn(nInIn),
fAnyoneCanPay(!!(nHashTypeIn & SIGHASH_ANYONECANPAY)),
fHashSingle((nHashTypeIn & 0x1f) == SIGHASH_SINGLE),
fHashNone((nHashTypeIn & 0x1f) == SIGHASH_NONE) {}
/** Serialize the passed scriptCode, skipping OP_CODESEPARATORs */
template<typename S>
void SerializeScriptCode(S &s, int nType, int nVersion) const {
CScript::const_iterator it = scriptCode.begin();
CScript::const_iterator itBegin = it;
opcodetype opcode;
unsigned int nCodeSeparators = 0;
while (scriptCode.GetOp(it, opcode)) {
if (opcode == OP_CODESEPARATOR)
nCodeSeparators++;
}
::WriteCompactSize(s, scriptCode.size() - nCodeSeparators);
it = itBegin;
while (scriptCode.GetOp(it, opcode)) {
if (opcode == OP_CODESEPARATOR) {
s.write((char*)&itBegin[0], it-itBegin-1);
itBegin = it;
}
}
s.write((char*)&itBegin[0], it-itBegin);
}
CTransaction txTmp(txTo);
// In case concatenating two scripts ends up with two codeseparators,
// or an extra one at the end, this prevents all those possible incompatibilities.
scriptCode.FindAndDelete(CScript(OP_CODESEPARATOR));
/** Serialize an input of txTo */
template<typename S>
void SerializeInput(S &s, unsigned int nInput, int nType, int nVersion) const {
// In case of SIGHASH_ANYONECANPAY, only the input being signed is serialized
if (fAnyoneCanPay)
nInput = nIn;
// Serialize the prevout
::Serialize(s, txTo.vin[nInput].prevout, nType, nVersion);
// Serialize the script
if (nInput != nIn)
// Blank out other inputs' signatures
::Serialize(s, CScript(), nType, nVersion);
else
SerializeScriptCode(s, nType, nVersion);
// Serialize the nSequence
if (nInput != nIn && (fHashSingle || fHashNone))
// let the others update at will
::Serialize(s, (int)0, nType, nVersion);
else
::Serialize(s, txTo.vin[nInput].nSequence, nType, nVersion);
}
// Blank out other inputs' signatures
for (unsigned int i = 0; i < txTmp.vin.size(); i++)
txTmp.vin[i].scriptSig = CScript();
txTmp.vin[nIn].scriptSig = scriptCode;
/** Serialize an output of txTo */
template<typename S>
void SerializeOutput(S &s, unsigned int nOutput, int nType, int nVersion) const {
if (fHashSingle && nOutput != nIn)
// Do not lock-in the txout payee at other indices as txin
::Serialize(s, CTxOut(), nType, nVersion);
else
::Serialize(s, txTo.vout[nOutput], nType, nVersion);
}
// Blank out some of the outputs
if ((nHashType & 0x1f) == SIGHASH_NONE)
{
// Wildcard payee
txTmp.vout.clear();
/** Serialize txTo */
template<typename S>
void Serialize(S &s, int nType, int nVersion) const {
// Serialize nVersion
::Serialize(s, txTo.nVersion, nType, nVersion);
// Serialize vin
unsigned int nInputs = fAnyoneCanPay ? 1 : txTo.vin.size();
::WriteCompactSize(s, nInputs);
for (unsigned int nInput = 0; nInput < nInputs; nInput++)
SerializeInput(s, nInput, nType, nVersion);
// Serialize vout
unsigned int nOutputs = fHashNone ? 0 : (fHashSingle ? nIn+1 : txTo.vout.size());
::WriteCompactSize(s, nOutputs);
for (unsigned int nOutput = 0; nOutput < nOutputs; nOutput++)
SerializeOutput(s, nOutput, nType, nVersion);
// Serialie nLockTime
::Serialize(s, txTo.nLockTime, nType, nVersion);
}
};
}
// Let the others update at will
for (unsigned int i = 0; i < txTmp.vin.size(); i++)
if (i != nIn)
txTmp.vin[i].nSequence = 0;
uint256 SignatureHash(const CScript &scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType)
{
if (nIn >= txTo.vin.size()) {
LogPrintf("ERROR: SignatureHash() : nIn=%d out of range\n", nIn);
return 1;
}
else if ((nHashType & 0x1f) == SIGHASH_SINGLE)
{
// Only lock-in the txout payee at same index as txin
unsigned int nOut = nIn;
if (nOut >= txTmp.vout.size())
{
LogPrintf("ERROR: SignatureHash() : nOut=%d out of range\n", nOut);
// Check for invalid use of SIGHASH_SINGLE
if ((nHashType & 0x1f) == SIGHASH_SINGLE) {
if (nIn >= txTo.vout.size()) {
LogPrintf("ERROR: SignatureHash() : nOut=%d out of range\n", nIn);
return 1;
}
txTmp.vout.resize(nOut+1);
for (unsigned int i = 0; i < nOut; i++)
txTmp.vout[i].SetNull();
// Let the others update at will
for (unsigned int i = 0; i < txTmp.vin.size(); i++)
if (i != nIn)
txTmp.vin[i].nSequence = 0;
}
// Blank out other inputs completely, not recommended for open transactions
if (nHashType & SIGHASH_ANYONECANPAY)
{
txTmp.vin[0] = txTmp.vin[nIn];
txTmp.vin.resize(1);
}
// Wrapper to serialize only the necessary parts of the transaction being signed
CTransactionSignatureSerializer txTmp(txTo, scriptCode, nIn, nHashType);
// Serialize and hash
CHashWriter ss(SER_GETHASH, 0);

2
src/test/Makefile.am

@ -34,7 +34,7 @@ test_bitcoin_SOURCES = accounting_tests.cpp alert_tests.cpp \ @@ -34,7 +34,7 @@ test_bitcoin_SOURCES = accounting_tests.cpp alert_tests.cpp \
netbase_tests.cpp pmt_tests.cpp rpc_tests.cpp script_P2SH_tests.cpp \
script_tests.cpp serialize_tests.cpp sigopcount_tests.cpp test_bitcoin.cpp \
transaction_tests.cpp uint160_tests.cpp uint256_tests.cpp util_tests.cpp \
wallet_tests.cpp $(JSON_TEST_FILES) $(RAW_TEST_FILES)
wallet_tests.cpp sighash_tests.cpp $(JSON_TEST_FILES) $(RAW_TEST_FILES)
nodist_test_bitcoin_SOURCES = $(BUILT_SOURCES)

2
src/test/multisig_tests.cpp

@ -19,7 +19,7 @@ using namespace boost::assign; @@ -19,7 +19,7 @@ using namespace boost::assign;
typedef vector<unsigned char> valtype;
extern uint256 SignatureHash(CScript scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType);
extern uint256 SignatureHash(const CScript &scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType);
BOOST_AUTO_TEST_SUITE(multisig_tests)

2
src/test/script_tests.cpp

@ -21,7 +21,7 @@ using namespace std; @@ -21,7 +21,7 @@ using namespace std;
using namespace json_spirit;
using namespace boost::algorithm;
extern uint256 SignatureHash(CScript scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType);
extern uint256 SignatureHash(const CScript &scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType);
static const unsigned int flags = SCRIPT_VERIFY_P2SH | SCRIPT_VERIFY_STRICTENC;

120
src/test/sighash_tests.cpp

@ -0,0 +1,120 @@ @@ -0,0 +1,120 @@
#include <boost/test/unit_test.hpp>
#include "main.h"
#include "util.h"
extern uint256 SignatureHash(const CScript &scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType);
// Old script.cpp SignatureHash function
uint256 static SignatureHashOld(CScript scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType)
{
if (nIn >= txTo.vin.size())
{
printf("ERROR: SignatureHash() : nIn=%d out of range\n", nIn);
return 1;
}
CTransaction txTmp(txTo);
// In case concatenating two scripts ends up with two codeseparators,
// or an extra one at the end, this prevents all those possible incompatibilities.
scriptCode.FindAndDelete(CScript(OP_CODESEPARATOR));
// Blank out other inputs' signatures
for (unsigned int i = 0; i < txTmp.vin.size(); i++)
txTmp.vin[i].scriptSig = CScript();
txTmp.vin[nIn].scriptSig = scriptCode;
// Blank out some of the outputs
if ((nHashType & 0x1f) == SIGHASH_NONE)
{
// Wildcard payee
txTmp.vout.clear();
// Let the others update at will
for (unsigned int i = 0; i < txTmp.vin.size(); i++)
if (i != nIn)
txTmp.vin[i].nSequence = 0;
}
else if ((nHashType & 0x1f) == SIGHASH_SINGLE)
{
// Only lock-in the txout payee at same index as txin
unsigned int nOut = nIn;
if (nOut >= txTmp.vout.size())
{
printf("ERROR: SignatureHash() : nOut=%d out of range\n", nOut);
return 1;
}
txTmp.vout.resize(nOut+1);
for (unsigned int i = 0; i < nOut; i++)
txTmp.vout[i].SetNull();
// Let the others update at will
for (unsigned int i = 0; i < txTmp.vin.size(); i++)
if (i != nIn)
txTmp.vin[i].nSequence = 0;
}
// Blank out other inputs completely, not recommended for open transactions
if (nHashType & SIGHASH_ANYONECANPAY)
{
txTmp.vin[0] = txTmp.vin[nIn];
txTmp.vin.resize(1);
}
// Serialize and hash
CHashWriter ss(SER_GETHASH, 0);
ss << txTmp << nHashType;
return ss.GetHash();
}
void static RandomScript(CScript &script) {
static const opcodetype oplist[] = {OP_FALSE, OP_1, OP_2, OP_3, OP_CHECKSIG, OP_IF, OP_VERIF, OP_RETURN, OP_CODESEPARATOR};
script = CScript();
int ops = (insecure_rand() % 10);
for (int i=0; i<ops; i++)
script << oplist[insecure_rand() % (sizeof(oplist)/sizeof(oplist[0]))];
}
void static RandomTransaction(CTransaction &tx, bool fSingle) {
tx.nVersion = insecure_rand();
tx.vin.clear();
tx.vout.clear();
tx.nLockTime = (insecure_rand() % 2) ? insecure_rand() : 0;
int ins = (insecure_rand() % 4) + 1;
int outs = fSingle ? ins : (insecure_rand() % 4) + 1;
for (int in = 0; in < ins; in++) {
tx.vin.push_back(CTxIn());
CTxIn &txin = tx.vin.back();
txin.prevout.hash = GetRandHash();
txin.prevout.n = insecure_rand() % 4;
RandomScript(txin.scriptSig);
txin.nSequence = (insecure_rand() % 2) ? insecure_rand() : (unsigned int)-1;
}
for (int out = 0; out < outs; out++) {
tx.vout.push_back(CTxOut());
CTxOut &txout = tx.vout.back();
txout.nValue = insecure_rand() % 100000000;
RandomScript(txout.scriptPubKey);
}
}
BOOST_AUTO_TEST_SUITE(sighash_tests)
BOOST_AUTO_TEST_CASE(sighash_test)
{
seed_insecure_rand(false);
for (int i=0; i<50000; i++) {
int nHashType = insecure_rand();
CTransaction txTo;
RandomTransaction(txTo, (nHashType & 0x1f) == SIGHASH_SINGLE);
CScript scriptCode;
RandomScript(scriptCode);
int nIn = insecure_rand() % txTo.vin.size();
BOOST_CHECK(SignatureHash(scriptCode, txTo, nIn, nHashType) ==
SignatureHashOld(scriptCode, txTo, nIn, nHashType));
}
}
BOOST_AUTO_TEST_SUITE_END()
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