void checkCanonicalSignature(const valtype &vchSig) {
// See https://bitcointalk.org/index.php?topic=8392.msg127623#msg127623
// A canonical signature exists of: <30> <total len> <02> <len R> <R> <02> <len S> <S> <hashtype>
// Where R and S are not negative (their first byte has its highest bit not set), and not
// excessively padded (do not start with a 0 byte, unless an otherwise negative number follows,
// in which case a single 0 byte is necessary and even required).
if (vchSig.size() < 9)
throw runtime_error("Non-canonical signature: too short");
if (vchSig.size() > 73)
throw runtime_error("Non-canonical signature: too long");
unsigned char nHashType = vchSig[vchSig.size() - 1] & (~(SIGHASH_ANYONECANPAY));
if (nHashType < SIGHASH_ALL || nHashType > SIGHASH_SINGLE)
throw runtime_error("Non-canonical signature: unknown hashtype byte");
if (vchSig[0] != 0x30)
throw runtime_error("Non-canonical signature: wrong type");
if (vchSig[1] != vchSig.size()-3)
throw runtime_error("Non-canonical signature: wrong length marker");
unsigned int nLenR = vchSig[3];
if (5 + nLenR >= vchSig.size())
throw runtime_error("Non-canonical signature: S length misplaced");
unsigned int nLenS = vchSig[5+nLenR];
if ((unsigned long)(nLenR+nLenS+7) != vchSig.size())
throw runtime_error("Non-canonical signature: R+S length mismatch");
const unsigned char *R = &vchSig[4];
if (R[-2] != 0x02)
throw runtime_error("Non-canonical signature: R value type mismatch");
if (nLenR == 0)
throw runtime_error("Non-canonical signature: R length is zero");
if (R[0] & 0x80)
throw runtime_error("Non-canonical signature: R value negative");
if (nLenR > 1 && (R[0] == 0x00) && !(R[1] & 0x80))
throw runtime_error("Non-canonical signature: R value excessively padded");
const unsigned char *S = &vchSig[6+nLenR];
if (S[-2] != 0x02)
throw runtime_error("Non-canonical signature: S value type mismatch");
if (nLenS == 0)
throw runtime_error("Non-canonical signature: S length is zero");
if (S[0] & 0x80)
throw runtime_error("Non-canonical signature: S value negative");
if (nLenS > 1 && (S[0] == 0x00) && !(S[1] & 0x80))
throw runtime_error("Non-canonical signature: S value excessively padded");
}
bool static CheckMinimalPush(const valtype& data, opcodetype opcode) {
if (data.size() == 0) {
// Could have used OP_0.
return opcode == OP_0;
} else if (data.size() == 1 && data[0] >= 1 && data[0] <= 16) {
// Could have used OP_1 .. OP_16.
return opcode == OP_1 + (data[0] - 1);
} else if (data.size() == 1 && data[0] == 0x81) {
// Could have used OP_1NEGATE.
return opcode == OP_1NEGATE;
} else if (data.size() <= 75) {
// Could have used a direct push (opcode indicating number of bytes pushed + those bytes).
return opcode == data.size();
} else if (data.size() <= 255) {
// Could have used OP_PUSHDATA.
return opcode == OP_PUSHDATA1;
} else if (data.size() <= 65535) {
// Could have used OP_PUSHDATA2.
return opcode == OP_PUSHDATA2;
}
return true;
}
/**
* A canonical signature exists of: <30> <total len> <02> <len R> <R> <02> <len S> <S> <hashtype>
* Where R and S are not negative (their first byte has its highest bit not set), and not
* excessively padded (do not start with a 0 byte, unless an otherwise negative number follows,
* in which case a single 0 byte is necessary and even required).
*
* See https://bitcredittalk.org/index.php?topic=8392.msg127623#msg127623
*/
bool static IsDERSignature(const valtype &vchSig) {
if (vchSig.size() < 9) {
// Non-canonical signature: too short
return false;
}
if (vchSig.size() > 73) {
// Non-canonical signature: too long
return false;
}
if (vchSig[0] != 0x30) {
// Non-canonical signature: wrong type
return false;
}
if (vchSig[1] != vchSig.size()-3) {
// Non-canonical signature: wrong length marker
return false;
}
unsigned int nLenR = vchSig[3];
if (5 + nLenR >= vchSig.size()) {
// Non-canonical signature: S length misplaced
return false;
}
unsigned int nLenS = vchSig[5+nLenR];
if ((unsigned long)(nLenR+nLenS+7) != vchSig.size()) {
// Non-canonical signature: R+S length mismatch
return false;
}
const unsigned char *R = &vchSig[4];
if (R[-2] != 0x02) {
// Non-canonical signature: R value type mismatch
return false;
}
if (nLenR == 0) {
// Non-canonical signature: R length is zero
return false;
}
if (R[0] & 0x80) {
// Non-canonical signature: R value negative
return false;
}
if (nLenR > 1 && (R[0] == 0x00) && !(R[1] & 0x80)) {
// Non-canonical signature: R value excessively padded
return false;
}
const unsigned char *S = &vchSig[6+nLenR];
if (S[-2] != 0x02) {
// Non-canonical signature: S value type mismatch
return false;
}
if (nLenS == 0) {
// Non-canonical signature: S length is zero
return false;
}
if (S[0] & 0x80) {
// Non-canonical signature: S value negative
return false;
}
if (nLenS > 1 && (S[0] == 0x00) && !(S[1] & 0x80)) {
// Non-canonical signature: S value excessively padded
return false;
}
return true;
}