Jun Ao

Password-based Dynamic Group Key Agreement

A password-based dynamic group key agreement protocol from tripartite Diffie-Hellman using pairing on elliptic curve is presented in this paper. In this scheme, due to all users share a common pre-distributed password, the setup of the key agreement is simplified and the performance is improved. In addition, each user establishes a relation between his left and right neighbors respectively in order to implement the fast joining and leaving operations. Under the DDH assumption, proofs are given to show that the proposed key agreement protocol is secure against passive attack.

A Novel Verifier-Based Authenticated Key Agreement Protocol

Lee et al.’s presented a Verifier-based key agreement protocol in 2004. They claimed that their protocol was secure against Stolen-verifier attack in the case of server compromise. However, it is not really a secure protocol. In this paper, we briefly review this scheme and demonstrate the flaw, which once was pointed out by Shim and Seo. Subsequently, we propose a novel Verifier-based authenticated key agreement protocol and show that it withstands Stolen-verifier attack, Dictionary attack, and man-in-middle attack.