Paper 2010/473

Two Attacks on Dutta’s Dynamic Group Key Agreement Protocol

Hui Zhang, Chunxiang Xu, and Abdur Rashid Sangi

Abstract

Ratna Dutta and Rana Barua proposed a dynamic group key agreement protocol with constant round referred to as DGKA protocol. They claimed that the DGKA protocol is dynamic, efficient and provably secure under DDH assumption. In this paper, we analyze the security of the DGKA protocol and discovered its vulnerable nature towards two attacks. The first attack relates to the fact that this protocol does not satisfy the key independence property which is crucial for dynamic group key agreement protocol. The second one is an impersonation attack which demonstrates that the DGKA protocol is vulnerable to replay attacks.