Protecting IM From Big Brother

holden writes "Ian Goldberg, leading security researcher, professor at the University of Waterloo, and co-creator of the Off-the-Record Messaging (OTR) protocol recently gave a talk on protecting your IM conversations. He discusses OTR and its importance in today's world of warrant-less wire tapping. OTR users benefit from being able to have truly private conversations over IM by using encryption to obtain authentication, deniability, and perfect forward secrecy, while working within their existing IM infrastructure. With the recent NSA wiretapping activities and increasing Big Brother presence, security and OTR are increasingly important. An avi of the talk is available by http as well as by bittorrent and a bunch of other formats."

Comments

Encrypted RAM and HDD Storage

[EmagGeek]

You can't have perfect secrecy unless your RAM contents are also encrypted. Wasn't there some case recently where the RAM contents of some server were subpoenaed in a court case? If your RAM is unencrypted, then your IM conversation is stored in plain text SOMEWHERE, even if it is encrypted on the network stack. Of course, having encrypted RAM would be a HUMONGOUS performance hit, but it could be done. Hmmm..

Off to the patent office I go..

Re:Encryption

[thegrassyknowl]

The beauty of OTR messaging is that it claims to guarantee perfect forward secrecy. In other words, if you lose control of your private keys no previous conversation is compromised. This is a big plus, because even if they force you to turn over the keys they can't see the previous conversations.

It works (as I understand) by using your key pair to derive and exchange public session keys. The session keys then are used to do actual encryption and are changed frequently. The private key at each end is only ever stored in RAM and is discarded when the session ends or after a timeout.

It's neat because even listening in to the whole session and obtaining the public session keys isn't enough to compromise the session. Of course, having the public keys and obtaining the master private key may go a long way to helping with a mathematical attack of the algorithm.