Generic code to do a multi-byte XOR encoding

multibyte_xor.py

# Python 2
def multibyte_xor(data, key):
  from itertools import izip, cycle
  return ''.join(chr(ord(x) ^ ord(y)) for (x,y) in izip(data, cycle(key)))

# Python 3
def multibyte_xor(data, key):
    from itertools import cycle
    return bytes([b ^ k for b, k in zip(data, cycle(key))])