def _sign_simple_signature_fulfillment()

in resdb_driver/transaction.py [0:0]

• 20 lines of code
• 4 McCabe index (conditional complexity)

    def _sign_simple_signature_fulfillment(cls, input_, message, key_pairs):
        """! Signs a Ed25519Fulfillment.

        @param input_ (:class:`~resdb.transaction.Input`) The Input to be signed.
        @param message (str): The message to be signed
        @param key_pairs (dict): The keys to sign the Transaction with.
        """
        # NOTE: To eliminate the dangers of accidentally signing a condition by
        #       reference, we remove the reference of input_ here
        #       intentionally. If the user of this class knows how to use it,
        #       this should never happen, but then again, never say never.
        input_ = deepcopy(input_)
        public_key = input_.owners_before[0]
        message = sha3_256(message.encode())
        if input_.fulfills:
            message.update(
                "{}{}".format(input_.fulfills.txid,
                              input_.fulfills.output).encode()
            )

        try:
            # cryptoconditions makes no assumptions of the encoding of the
            # message to sign or verify. It only accepts bytestrings
            input_.fulfillment.sign(
                message.digest(), base58.b58decode(
                    key_pairs[public_key].encode())
            )
        except KeyError:
            raise KeypairMismatchException(
                "Public key {} is not a pair to "
                "any of the private keys".format(public_key)
            )
        return input_