Pythonで文字列をXORする関数 ref: http://qiita.com/items/dc60edfed7afc1d302e7

xor.py

# coding:utf-8
import base64
from itertools import cycle,izip

def xor_enc_base64(ss, key):
    key = cycle(key)
    return base64.b64encode(''.join(chr(ord(x) ^ ord(y)) for (x,y) in izip(ss, key)))

def xor_dec_base64(ss, key):
    key = cycle(key)
    return ''.join(chr(ord(x) ^ ord(y)) for (x,y) in izip(base64.b64decode(ss), key))

def main():
    mes = 'hello! can you understand this message?'
    key = 'world'
    e = xor_enc_base64(mes,key)
    d = xor_dec_base64(e,key)
    print d

if __name__ in '__main__':
    main()