Abstract. In this paper we analyse the security of two authenticated group key agreement schemes based on the group key agreement protocol of Burmester and Desmedt. One scheme was proposed by Burmester and Desmedt, and uses a separate authentication scheme to achieve authentication among the participants. We show that this scheme suffers from a number of security vulnerabilities. The other scheme was generated using the general protocol compiler of Katz and Yung. We show that in some circumstances, even if key confirmation is implemented, this scheme still suffers from insider attacks (which are not covered by the security model used by Katz and Yung). 1
In order to ensure authenticity of the information for conference key negotiation, the information which each party sends should be authenticated. Digital signature and share secret are two methods for authentication. Identity-based public key cryptosystems from the Weil pairing on elliptic curve are introduced. Two authenticated conference key agreement protocols are designed using identitybased signature scheme and identity-based Diffie-Hellman shared key. The protocols are secure and efficient. They can be applied to all kinds of environment in which multi-parties negotiate session keys.