AESConnection offers unauthenticated encryption

[rraval]

Specifically, once a connection is established, any new message is simply decrypted and shoved into the clipboard.

A MitM can observe the client handshake and then proceed to inject garbage into the receiver's clipboard. MAC'ing the individual messages (after encryption!) and verifying the MAC before decryption should do the right thing here.

A more sophisticated attacker can exploit mallaebility to alter known plaintexts. I'm struggling to come up with a good threat model for this specific scenario though :P

[christophebiocca]

Ok. Todo list for this one:

• Split HMAC into a module.
• MAC the ciphertext on its way out, MAC-check it on its way in.