Zfone

Zfone is a secure VoIP software that uses a new protocol called ZRTP. This protocol is superior to other encryption approaches because it achieves security without relying on a PKI, key certification, trust models, certificate authorities, or key management complexity. Unlike other encryption solutions, Zfone does not rely on SIP signaling for key management, nor does it rely on any servers at all. Instead, it performs key agreements and management in a purely peer-to-peer manner over the RTP packet stream.

Further, Zfone works with any standard SIP phone, although the call will only be encrypted if both parties are using a ZRTP client. This new protocol has been submitted to the IETF as a proposal for a public standard to enable interoperability of SIP endpoints from different vendors. In the future, ZRTP will be integrated into standalone secure VoIP clients. For now, Zfone lets you turn your existing VoIP client into a secure phone.

The Zfone software runs in the Internet Protocol stack on any Windows XP, Mac OS X, or Linux PC. It intercepts and filters all VoIP packets as they go in and out of the machine, securing the call on the fly. The 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 GUI that informs the user if the call is secure, much like a "bump on the cord" between the VoIP client and the Internet.

There is also a ZRTP SDK for VoIP client developers to integrate this protocol into their VoIP clients, both software and hardware. In addition, the software is implemented in C for easy integration. In conclusion, Zfone is a highly reliable and secure VoIP software that provides encryption without the need for complex and cumbersome key management schemes. It is a must-have for anyone looking to protect their VoIP communication.