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Exercise: 20 byte P2PKH witness program #27

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Exercise: 20 byte P2PKH witness program #27

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41 changes: 26 additions & 15 deletions src/script/interpreter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1215,23 +1215,34 @@ static bool VerifyWitnessProgram(const CScriptWitness& witness, int witversion,
CScript scriptPubKey;

if (witversion == 0) {
// Version 0 segregated witness program: CScript inside the program, inputs in witness
scriptPubKey = CScript(program.begin(), program.end());
stack = witness.stack;
} else if (witversion == 1) {
// Version 1 segregated witness program: SHA256(CScript) inside the program, CScript + inputs in witness
if (program.size() != 32) {
return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_WRONG_LENGTH);
if (program.size() == 32) {
// Version 0 segregated witness program: SHA256(CScript) inside the program, CScript + inputs in witness
if (witness.stack.size() == 0) {
return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_WITNESS_EMPTY);
}
scriptPubKey = CScript(witness.stack.back().begin(), witness.stack.back().end());
stack = std::vector<std::vector<unsigned char> >(witness.stack.begin(), witness.stack.end() - 1);
uint256 hashScriptPubKey;
CSHA256().Write(&scriptPubKey[0], scriptPubKey.size()).Finalize(hashScriptPubKey.begin());
if (memcmp(hashScriptPubKey.begin(), &program[0], 32)) {
return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_MISMATCH);
}
}
if (witness.stack.size() == 0) {
return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_WITNESS_EMPTY);
else if (program.size() == 20) {
if (witness.stack.size() != 2) {
return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_MISMATCH); // 2 items in witness
}
scriptPubKey = CScript(OP_CHECKSIG); // scriptPubKey is OP_CHECKSIG???
pubKey = CScript(witness.stack.back().begin(), witness.stack.back().end()); // last witness item is pubKey
stack = witness.stack; // stack is the whole witness.stack
uint256 hashPubKey;
CHASH160().Write(&pubKey[0], pubKey.size()).Finalize(hashPubKey.begin()); // hash160 of pubKey
if (memcmp(hashPubKey.begin(), &program[0], 20)) {
return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_MISMATCH); // compare with witness program
}
}
scriptPubKey = CScript(witness.stack.back().begin(), witness.stack.back().end());
stack = std::vector<std::vector<unsigned char> >(witness.stack.begin(), witness.stack.end() - 1);
uint256 hashScriptPubKey;
CSHA256().Write(&scriptPubKey[0], scriptPubKey.size()).Finalize(hashScriptPubKey.begin());
if (memcmp(hashScriptPubKey.begin(), &program[0], 32)) {
return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_MISMATCH);
else {
return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_WRONG_LENGTH);
}
} else if (flags & SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_WITNESS_PROGRAM) {
return set_error(serror, SCRIPT_ERR_DISCOURAGE_UPGRADABLE_WITNESS_PROGRAM);
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