VoIP Encryption in a Surveillance Society

In one of my previous articles, I touched upon the basics of VoIP security. Recently I came across this YouTube video covering a seminar given by Phillip Zimmermann (the Father of PGP) talking about VoIP encryption for the Stanford University Computer Systems Colloquium. Basically, Zimmermann talks about ephemeral encryption of VoIP traffic using Diffie-Hellman key exchange. Its a lengthy video (1 hour 15 mins) but quite an interesting watch.