Philip Zimmerman, creator of PGP, has released new software for Linux, MacOS and Windows called Zfone which encrypts VoIP telephony. Here is how Zimmerman describes it:
Zfone is my new secure VoIP phone software, which lets you make secure phone calls over the Internet. It encrypts your call so that only the other person can hear you speak. Zfone lets you whisper in someone’s ear, even if their ear is a thousand miles away.
In the future, the Zfone 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.
Zfone is still in beta and versions are available for download for Linux and MacOS. A Windows version is due out in mid-April.
Read more at the Zfone website