Q3b.py

from sys import exit
from bitcoin.core.script import *

from lib.utils import *
from lib.config import (my_private_key, my_public_key, my_address,
                    faucet_address, network_type)
from Q1 import P2PKH_scriptPubKey
from Q3a import (Q3a_txout_scriptPubKey, cust1_private_key, cust2_private_key,
                  cust3_private_key)


def multisig_scriptSig(txin, txout, txin_scriptPubKey):
    bank_sig = create_OP_CHECKSIG_signature(txin, txout, txin_scriptPubKey,
                                             my_private_key)
    cust1_sig = create_OP_CHECKSIG_signature(txin, txout, txin_scriptPubKey,
                                             cust1_private_key)
    cust2_sig = create_OP_CHECKSIG_signature(txin, txout, txin_scriptPubKey,
                                             cust2_private_key)
    cust3_sig = create_OP_CHECKSIG_signature(txin, txout, txin_scriptPubKey,
                                             cust3_private_key)
    ######################################################################
    # TODO: Complete this script to unlock the BTC that was locked in the
    # multisig transaction created in Exercise 3a.
    # For 2-of-3 multisig, we need OP_0 (due to CHECKMULTISIG bug) and 2 signatures
    return [
        OP_0,
        cust1_sig,
        cust2_sig,
    ]
    ######################################################################


def send_from_multisig_transaction(amount_to_send, txid_to_spend, utxo_index,
                                   txin_scriptPubKey, txout_scriptPubKey, network):
    txout = create_txout(amount_to_send, txout_scriptPubKey)

    txin = create_txin(txid_to_spend, utxo_index)
    txin_scriptSig = multisig_scriptSig(txin, txout, txin_scriptPubKey)

    new_tx = create_signed_transaction(txin, txout, txin_scriptPubKey,
                                       txin_scriptSig)

    return broadcast_transaction(new_tx, network)

if __name__ == '__main__':
    ######################################################################
    # TODO: set these parameters correctly
    amount_to_send = None # amount of BTC in the output you're sending minus fee
    txid_to_spend = (
        'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX')
    utxo_index = None # index of the output you are spending, indices start at 0
    ######################################################################

    txin_scriptPubKey = Q3a_txout_scriptPubKey
    txout_scriptPubKey = P2PKH_scriptPubKey(faucet_address)

    response = send_from_multisig_transaction(
        amount_to_send, txid_to_spend, utxo_index,
        txin_scriptPubKey, txout_scriptPubKey, network_type)
    print(response.status_code, response.reason)
    print(response.text)