ZRTP - Third party reviews

Ten Risks of PKI: What You’re not Being Told about Public Key Infrastructuresss by Carl Ellison, Bruce Schneier, 2000

Security is a chain; it’s only as strong as the weakest link. The security of any CA-based system is based on many links and they’re not all cryptographic.

Zfone: A New Approach for Securing VoIP Communication by Samuel Sotillo, 2006 (Abstract)

This paper reviews some security challenges currently faced by VoIP systems as well as their potential solutions. Particularly, it focuses on Zfone, a vendor-neutral security solution developed by PGP’s creator, Phil Zimmermann.

Information Security Issues in Voice Over Internet Protocol, 2006

A team of researchers from the University of Pisa in Italy and the Ecole d'Ingénieurs et de Gestion du Canton de Vaud in Switzerland have proposed what many have called the first intrusion detection system for VoIP.

The ZRTP Protocol Security Considerations by Riccardo Bresciani, 2007

This is an analysis of the protocol performed with AVISPA and ProVerif, which tests security properties of ZRTP; in order to perform the analysis, the protocol has been modeled in HLPSL (for AVISPA) and in the applied pi-calculus (for Proverif). An improvement to gather some extra resistance against Man-in-the-Middle attacks is also proposed.

Forensic Analysis – Zfone by Livingstone, 2008

This document outlines the results of an analysis of Zfone-encrypted network traffic and a forensic analysis of a PC that has used the Zfone software to perform some VoIP calls.

Security and Usability Aspects of Man-in-the-Middle Attacks on ZRTP, 2008

Despite measures a Relay Attack (also known as Mafia Fraud Attack or Chess Grandmaster Attack) is still possible. We present a practical implementation of such an attack and discuss its characteristics and limitations, and show that the attack works only in certain scenarios.

ZRTP - Analysis of the Diffie-Hellman mode by Riccardo Bresciani, 2009

This paper analyze with ProVerif that the security model of ZRTP protocol formally proven to be secure. It's a formal verification of ZRTP security properties related to Diffie-Hellman Key Exchange.