Why two time pads are a BadThing™

otp.py

#!/usr/bin/env python

def xor_int_tuple(tup):
    return reduce(lambda a,b:a^b, tup)

def xor_tuple(tup):
    return ord(tup[0]) ^ ord(tup[1])

def encrypt(m, k, op=xor_tuple):
    return map(op, zip(m, k))

k = "abcdefg"
c1 = encrypt("Stephen", k)
c2 = encrypt("Joanna", k)

print c1
print c2
print encrypt(c1, c2, op=xor_int_tuple)
print encrypt("Stephen", "Joanna")

[50, 22, 6, 20, 13, 3, 9]
[43, 13, 2, 10, 11, 7]
[25, 27, 4, 30, 6, 4]
[25, 27, 4, 30, 6, 4]