Overview. Off-the-Record (OTR) Messaging allows you to have private conversations over instant messaging by providing Encryption, Authentication, Deniability and Perfect forward secrecy.

Availability. It is available for Adium, Pidgin, Miranda, Trillian and a few other instant messaging clients. There are implementations of OTR available for users running Windows, OS X and Unix/Linux.

Competition. Compared to the pidgin-encryption plugin OTR also provides deniability and perfect forward secrecy. OTR is an easy choice over Trillian’s SecureIM which doesn’t provide authentication. Primary reason for OTR from my point of view is that it’s available for multiple clients and can be used under any of the usual operatives.

My weapon of choice. Quite obviously I’m vouching for OTR. Having tried around with a bunch of multi protocol instant messaging clients I’ve settled down with Pidgin as my favourite. You don’t have to use the same but I would like you to use some client that supports OTR.

Links for downloading.

All three mentioned clients support quite a few protocols. OSCAR, WLM/MSNP, XMPP and IRC which should be enough for most users but the list goes on.

Havn’t you installed OTR yet? If you need more convincing here’s some reading for you: 1 2 3 4 5 6 7 …

Update. Video capture of a lecture on useful security and privacy technologies. and OTR in particular.