Phil Zimmermann, the founder of Pretty Good Privacy (PGP), has joined forces with security firm BorderWare Technologies in a bid to make internet telephony more secure.

On Tuesday, BorderWare became the first commercial licensee of Zfone, Zimmerman’s secure VoIP encryption software. The agreement means BorderWare can integrate Zfone with its own SIPassure VoIP Security Gateway to lock down internet telephony systems.

Through the partnership, BorderWare promises to extend the level of VoIP security to protect organisations from such threats as spam, Denial of Service (DoS) attacks, eavesdropping, spying and wiretapping.

“As VoIP grows into a replacement for the PSTN, we will absolutely need to protect it, or organised crime will be attacking it as intensively as they attack the rest of the internet today,” said Zimmerman. “VoIP is far more vulnerable to interception than the PSTN. Corporate VoIP calls can be captured and organised on disk for convenient point-and-click wiretapping by criminals half a world away.”

Zfone uses a protocol called ZRTP, which achieves security without the reliance on PKI (Public Key Infrastructure), key certification, trust models, certificate authorities or key management as email encryption does. Nor does it rely on SIP signalling or servers for the key management.

The technology performs its key agreements and key management in a pure peer to peer (P2P) manner over the RTP packet stream. ZRTP is also interoperable with any standard SIP phone, but only encrypts the call if you are calling another ZRTP enabled device or phone.

The protocol has been submitted to the IETF as a proposal for a public standard, to enable interoperability of SIP endpoints from different vendors.