Silent Circle Instant Messaging Protocol
The Silent Circle Instant Messaging Protocol is one of the encrypted protocols supported by the Silent Circle service, which offers the ability to exchange messages with others privately without anybody (including the operators of the service) knowing their contents, and with the added feature that the messages can be made to self-destruct after a particular time interval (like the messages in Mission Impossible).
(Of course, messages that have self-destructed, assuming that the protocol works as intended without any way of defeating it, will be unavailable for the archivists of the future at whom this site is aimed!)
The protocol is able to work with a number of data formats including JSON and XML, and currently the Silent Circle service uses JSON (wrapped in an encrypted layer). The messages can then be transmitted over a message transport such as XMPP (Jabber).