Zfone - Encrypt your VoIP calls
Phil Zimmerman, the guy behind PGP, is working on a new product; Zfone . Zfone encrypts voice traffic on the fly and works with VoIP clients like X-Lite and Gizmo that use the SIP protocol. The software uses a simple voice authentication system so there is no need to agree on encryption keys in advance or to type in long passwords.
In the future, the ZRTP protocol will be integrated into standalone secure VoIP clients, but today we have a software product that lets you turn your existing VoIP client into a secure phone. The current Zfone software runs in the Internet Protocol stack on any Windows XP, Mac OS X, or Linux PC, and intercepts and filters all the VoIP packets as they go in and out of the machine, and secures the call on the fly. You can use a variety of different software VoIP clients to make a VoIP call. The Zfone software detects when the call starts, and initiates a cryptographic key agreement between the two parties, and then proceeds to encrypt and decrypt the voice packets on the fly. It has its own little separate GUI, telling the user if the call is secure. It's as if Zfone were a "bump on the cord", sitting between the VoIP client and the Internet. Think of it as a software bump-on-the-cord. Maybe a bump in the protocol stack.