insecurity_of_XOR.sf

#!/usr/bin/ruby

# XOR can be insecure!

var key1 = "a"*64       # Alice key
var key2 = "z"*64       # Bob key

var msg = "Hello world! How are you doing?"

var c1 = (msg ^ key1)       # Alice encrypts the message with her private key and sends it to Bob
var c2 = ( c1 ^ key2)       # Bob encrypts the encrypted message with his private key and sends the message back to Alice
var c3 = ( c2 ^ key1)       # Alice removes her encryption layer and sends the message back to Bob

say (c3 ^ key2)             # Bob can now remove his layer of encryption and read the message

# However, this is insecure!
# Someone that intercepts the encrypted messages, can decrypt them!

say (c2 ^ c3)               # Alice's private key
say (c1 ^ c2)               # Bob's private key
say (c1 ^ c2 ^ c3)          # The original message decrypted from the encrypted messages