PGP complete lacks perfect forward secrecy. Suppose an eavesdropper is recording your email, even though they can't understand it. If your private key is ever compromised (say by torture or subpoena), then all your previous messages can be immediately decrypted.
> You could say that Bob losing control of his private key
was the problem. But with today’s easily-compromised personal computers, this is an all-too-likely occurence. We
would really prefer to be able to handle such failures gracefully, and not simply give away the farm.
> You could say that Bob losing control of his private key was the problem. But with today’s easily-compromised personal computers, this is an all-too-likely occurence. We would really prefer to be able to handle such failures gracefully, and not simply give away the farm.
http://www.cypherpunks.ca/otr/otr-wpes.pdf