VoIP Encryption

This recently from wired news a review of Zfone, an open source VoIP encryption software.

Phil Zimmermann, yes the same guy that is credited with producing PGP, Is now working on a new thorn in the NSA's side, Zfone is currently still in beta versions and as such is not widely used/usable but it is definitely a start (and darn good one at that) at protecting internet phone calls. The review at wired covers many details (which I wont go into here) of Zfone and a few counterparts.

"The protocol is based on SRTP, a system that uses the 256-bit AES cipher and adds to that a 3,000-bit key exchange that produces the codes callers can read off to one another."