Notes on the CRTDH Group Key Agreement Protocol

Group key management (GKM) is one of the primary is-sues for secure group communication (SGC). Contributory group key agreement is crucial for SGC over wireless and mobile ad hoc networks (MANETs) when there is lack of a fixed infrastructure and it is difficult to have a central trusted entity. Recently, Balachandran et al. proposed a contributory key agreement protocol for MANETs, called CRTDH [5]. This protocol is based upon both the Chinese Remainder Theorem and the Diffie-Hellman key exchange scheme. CRTDH exhibits a very nice idea, but contains some problems that make it not very practical in terms of efficiency and security. We point out these problems and propose a solution to them. Analysis and experiments are also presented which show our improved protocol outper-forms the original CRTDH protocol in terms of both effi-ciency and security