OpenPGP is an encryption technology that is primarily used to secure email, although sadly it is not as widely used as one might like.
Doing my bit to counter the “Summer of Surveillance”, and in a bid to make encryption more omnipresent (and because I had a need for this for a client), I quickly put together a plugin that adds OpenPGP support to Elgg.
The plugin does two main things; provide a mechanism where by a user can upload the public key for their registered email address, and secondly, provide an email handler that will attempt to encrypt any outgoing messages using that key (where possible).
Enjoy!