Function _CheckMultiSig

bitcoin/core/scripteval.py:149–224

(opcode, script, stack, txTo, inIdx, flags, err_raiser, nOpCount)

def _CheckMultiSig(opcode, script, stack, txTo, inIdx, flags, err_raiser, nOpCount):
    i = 1
    if len(stack) < i:
        err_raiser(MissingOpArgumentsError, opcode, stack, i)

    keys_count = _CastToBigNum(stack[-i], err_raiser)
    if keys_count < 0 or keys_count > 20:
        err_raiser(ArgumentsInvalidError, opcode, "keys count invalid")
    i += 1
    ikey = i
    i += keys_count
    nOpCount[0] += keys_count
    if nOpCount[0] > MAX_SCRIPT_OPCODES:
        err_raiser(MaxOpCountError)
    if len(stack) < i:
        err_raiser(ArgumentsInvalidError, opcode, "not enough keys on stack")

    sigs_count = _CastToBigNum(stack[-i], err_raiser)
    if sigs_count < 0 or sigs_count > keys_count:
        err_raiser(ArgumentsInvalidError, opcode, "sigs count invalid")

    i += 1
    isig = i
    i += sigs_count
    if len(stack) < i-1:
        raise err_raiser(ArgumentsInvalidError, opcode, "not enough sigs on stack")
    elif len(stack) < i:
        raise err_raiser(ArgumentsInvalidError, opcode, "missing dummy value")

    # Drop the signature, since there's no way for a signature to sign itself
    #
    # Of course, this can only come up in very contrived cases now that
    # scriptSig and scriptPubKey are processed separately.
    for k in range(sigs_count):
        sig = stack[-isig - k]
        script = FindAndDelete(script, CScript([sig]))

    success = True

    while success and sigs_count > 0:
        sig = stack[-isig]
        pubkey = stack[-ikey]

        if _CheckSig(sig, pubkey, script, txTo, inIdx, err_raiser):
            isig += 1
            sigs_count -= 1

        ikey += 1
        keys_count -= 1

        if sigs_count > keys_count:
            success = False

            # with VERIFY bail now before we modify the stack
            if opcode == OP_CHECKMULTISIGVERIFY:
                err_raiser(VerifyOpFailedError, opcode)

    while i > 1: