Alpenhorn

Alpenhorn is the first system for initiating an encrypted connection between two users that provides strong privacy and forward secrecy guarantees for metadata. Alpenhorn does not require out-of-band communication other than knowing your friend's Alpenhorn username (usually their email address). Alpenhorn's design, threat model, and performance are described in our OSDI 2016 paper.

In short, Alpenhorn works well for bootstrapping conversations in Vuvuzela. Now users can start chatting on Vuvuzela without having to exchange keys in person or over some less secure channel.

A beta deployment of Alpenhorn and Vuvuzela is coming soon.