patch.py

import os
import sys
import hashlib
import binascii

def change_pw(path, hash, password):
    # build hash for new password
    new_pw_hash = hashlib.sha1(password.encode())

    # read program file bytes
    s = open(path, 'rb').read()

    # replace old hash with new hash in file bytes
    s = s.replace(binascii.unhexlify(hash), binascii.unhexlify(new_pw_hash.hexdigest()))

    # write the bytes to a new file
    f = open(path + ".patched", 'wb')
    f.write(s)

path = sys.argv[1]
pw_hash = sys.argv[2]
new_pw = sys.argv[3]

change_pw(path, pw_hash, new_pw)

print("program patched!")