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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/145/head
Pieter Wuille
11 years ago
5 changed files with 224 additions and 48 deletions
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#include <boost/test/unit_test.hpp> |
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#include "main.h" |
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#include "util.h" |
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extern uint256 SignatureHash(const CScript &scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType); |
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// Old script.cpp SignatureHash function
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uint256 static SignatureHashOld(CScript scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType) |
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{ |
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if (nIn >= txTo.vin.size()) |
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{ |
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printf("ERROR: SignatureHash() : nIn=%d out of range\n", nIn); |
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return 1; |
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} |
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CTransaction txTmp(txTo); |
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// In case concatenating two scripts ends up with two codeseparators,
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// or an extra one at the end, this prevents all those possible incompatibilities.
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scriptCode.FindAndDelete(CScript(OP_CODESEPARATOR)); |
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// Blank out other inputs' signatures
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for (unsigned int i = 0; i < txTmp.vin.size(); i++) |
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txTmp.vin[i].scriptSig = CScript(); |
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txTmp.vin[nIn].scriptSig = scriptCode; |
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// Blank out some of the outputs
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if ((nHashType & 0x1f) == SIGHASH_NONE) |
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{ |
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// Wildcard payee
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txTmp.vout.clear(); |
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// Let the others update at will
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for (unsigned int i = 0; i < txTmp.vin.size(); i++) |
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if (i != nIn) |
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txTmp.vin[i].nSequence = 0; |
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} |
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else if ((nHashType & 0x1f) == SIGHASH_SINGLE) |
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{ |
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// Only lock-in the txout payee at same index as txin
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unsigned int nOut = nIn; |
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if (nOut >= txTmp.vout.size()) |
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{ |
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printf("ERROR: SignatureHash() : nOut=%d out of range\n", nOut); |
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return 1; |
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} |
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txTmp.vout.resize(nOut+1); |
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for (unsigned int i = 0; i < nOut; i++) |
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txTmp.vout[i].SetNull(); |
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// Let the others update at will
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for (unsigned int i = 0; i < txTmp.vin.size(); i++) |
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if (i != nIn) |
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txTmp.vin[i].nSequence = 0; |
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} |
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// Blank out other inputs completely, not recommended for open transactions
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if (nHashType & SIGHASH_ANYONECANPAY) |
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{ |
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txTmp.vin[0] = txTmp.vin[nIn]; |
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txTmp.vin.resize(1); |
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} |
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// Serialize and hash
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CHashWriter ss(SER_GETHASH, 0); |
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ss << txTmp << nHashType; |
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return ss.GetHash(); |
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} |
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void static RandomScript(CScript &script) { |
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static const opcodetype oplist[] = {OP_FALSE, OP_1, OP_2, OP_3, OP_CHECKSIG, OP_IF, OP_VERIF, OP_RETURN, OP_CODESEPARATOR}; |
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script = CScript(); |
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int ops = (insecure_rand() % 10); |
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for (int i=0; i<ops; i++) |
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script << oplist[insecure_rand() % (sizeof(oplist)/sizeof(oplist[0]))]; |
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} |
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void static RandomTransaction(CTransaction &tx, bool fSingle) { |
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tx.nVersion = insecure_rand(); |
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tx.vin.clear(); |
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tx.vout.clear(); |
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tx.nLockTime = (insecure_rand() % 2) ? insecure_rand() : 0; |
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int ins = (insecure_rand() % 4) + 1; |
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int outs = fSingle ? ins : (insecure_rand() % 4) + 1; |
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for (int in = 0; in < ins; in++) { |
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tx.vin.push_back(CTxIn()); |
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CTxIn &txin = tx.vin.back(); |
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txin.prevout.hash = GetRandHash(); |
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txin.prevout.n = insecure_rand() % 4; |
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RandomScript(txin.scriptSig); |
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txin.nSequence = (insecure_rand() % 2) ? insecure_rand() : (unsigned int)-1; |
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} |
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for (int out = 0; out < outs; out++) { |
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tx.vout.push_back(CTxOut()); |
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CTxOut &txout = tx.vout.back(); |
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txout.nValue = insecure_rand() % 100000000; |
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RandomScript(txout.scriptPubKey); |
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} |
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} |
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BOOST_AUTO_TEST_SUITE(sighash_tests) |
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BOOST_AUTO_TEST_CASE(sighash_test) |
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{ |
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seed_insecure_rand(false); |
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for (int i=0; i<50000; i++) { |
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int nHashType = insecure_rand(); |
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CTransaction txTo; |
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RandomTransaction(txTo, (nHashType & 0x1f) == SIGHASH_SINGLE); |
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CScript scriptCode; |
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RandomScript(scriptCode); |
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int nIn = insecure_rand() % txTo.vin.size(); |
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BOOST_CHECK(SignatureHash(scriptCode, txTo, nIn, nHashType) == |
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SignatureHashOld(scriptCode, txTo, nIn, nHashType)); |
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} |
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} |
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BOOST_AUTO_TEST_SUITE_END() |
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