Tripartite Key Agreement Protocols and Insider Impersonation Attack

三方式認證金鑰及內部偽造攻擊

Even though several certificate-based tripartite key agreement protocols with pairings have been proposed, the insider impersonation attack was not noticed. This specific threat applies to those key agreement protocols where there are more than two communicating parties. This paper re-examines the previous protocols. We find that both Shim’s scheme and the LHL scheme are not secure. The Shim scheme is weak in key-compromise impersonation attack, insider impersonation attack, and replay attack. The LHL tripartite key scheme is vulnerable to insider attack, outsider impersonation attack, and key-compromise impersonation attack.Furthemore, we propose two approaches to improve the security. Our schemes are moreefficient than Al-Riyami-Paterson’s tripartite key confirmation protocol, which is the mostsecure one among the referenced works.