challtools.py

#!/usr/bin/env python2
def xor(a,b):
    return chr(ord(a)^ord(b))

def xors(a,b):
    if len(a) < len(b):
        tmp = a
        a = b
        b = tmp
    return ''.join(xor(a[i], b[i % len(b)]) for i in range(len(a)))

if __name__ == "__main__" :
    c = "AZERTYUIOPMLKJHGFDSQWXCVBN"
    d = "098765"
    e = xors(c, d)
    print("e:" + str(e))
    e = xors(e, d)
    print("e:" + str(e))