OTR can be trivially faked. So if you have a transcript of me saying "I did not ...

pnathan · on July 20, 2011

So... OTR provides a way out from the PKI trap of requiring a private key to encrypt (which in turn demonstrates access to the private key).

Perhaps I'm thinking about it narrowly, but that's all OTR is said to do, yes?

eru · on July 20, 2011

If you have a cipher that produces a stream of good pseudorandom numbers, you can use that as a one time pad. Forging is trivial.

If I remember correctly: For the individual messages OTR uses Diffie-Hellman to exchange the key. That means your dialog partner knows the same key, and could have produced the message, too.

But if you want the details, look up http://www.cypherpunks.ca/otr/Protocol-v2-3.1.0.html