Decrypt/Encrypt Fallout Shelter save files

fshack.py

#!/usr/bin/python
from __future__ import print_function,division
from Crypto.Protocol.KDF import PBKDF2
from Crypto.Cipher import AES
from base64 import decodestring,encodestring
from sys import stdout,stdin
from json import loads,dumps
from math import ceil

# fshack.py <Vault1.sav >Vault2.sav
# cp Vault2.sav Vault2.sav.bpk

INITIALIZATION_VECTOR = b'tu89geji340t89u2'
PASSWORD = b'UGxheWVy'
KEY_SIZE = 32

# Derive the key from our password and IV
key = PBKDF2(PASSWORD, INITIALIZATION_VECTOR, KEY_SIZE)

def decode(s):
  # Use AES in Block cipher mode with our key and IV 
  aes = AES.new(key, AES.MODE_CBC, INITIALIZATION_VECTOR)

  message = decodestring(encrypted_data)
  decrypted_data = aes.decrypt(message)
  decrypted_data = decrypted_data[:decrypted_data.rindex("}")+1]
  
  return loads(decrypted_data)

def encode(d):
  aes = AES.new(key, AES.MODE_CBC, INITIALIZATION_VECTOR)
  
  message = dumps(d, separators=(',',':'))
  pad = int(ceil(len(message)/16))*16-len(message)
  pad = chr(pad) * pad
  message += pad
  
  encrypted_data = aes.encrypt(message)
  
  return encodestring(encrypted_data).translate(None,"\n")

encrypted_data = stdin.readline()
decrypted_data = decode(encrypted_data)

#decrypted_data["vault"]["storage"]["resources"]["Nuka"] = 999999.00 # caps
decrypted_data["vault"]["storage"]["resources"]["NukaColaQuantum"] = 9999.00

encrypted_data = encode(decrypted_data)
stdout.write(encrypted_data)