re keeping your mouth shut was hard drive security in article c k ce a sunfish usd edu vkub charlie usd edu vince kub writes now the original scheme as suggested here would be to have the key disappear if certain threatening conditions are met once the key is gone there is no question of contempt of court as there is nothing to compell the key is no longer there to be produced getting rid of the keys is actually pretty easy to do automatically on a communications link as opposed to storage where the keys have to be retained somehow as long as the owner wants to be able to retrieve the data the right way to do communications security is to generate a random session key with diffie hellman use it for a while and then destroy it once it s gone there s no getting it back and no way to decrypt recordings of the conversation to make sure you aren t being attacked by a man in the middle you have to authenticate your dh exchanges the at t secure phone does this by displaying the dh key so you can compare them verbally over the phone this is nice and simple but it relies on user awareness plus the inability of the man in the middle to duplicate the users voices a better way is to authenticate the exchanges with rsa since you d never use rsa for actual encryption compromising your rsa secret key would only allow someone to impersonate you in a future conversation and even that only until you revoke your public key they would still not be able to decrypt recordings of prior conversations for which the session keys have been destroyed i m convinced that this is how the government s own secure phones the stu iii must work neat eh phil
