Many group-orientedapplications in distributedsystems, such as teleconferencing andcooperati ve works, involve dynamic peer groups. In order to secure communications in dynamic peer groups, authenticatedk ey agreement protocols are required. In this paper, we propose a new authenticatedk ey
agreement protocol, composedof a basic protocol anda dynamic protocol, for dynamic peer groups. With the basic protocol, a secret group key can be achievedin a peer group via group handshake, secret broadcast, key derivation and key confirmation phases. By the dynamic protocol, a new secret group key can be reachedwhen member or mass join, group mergence, group division, member or mass quit occurs in a dynamic peer group. Security analysis shows that our protocol offers explicit group key authentication andpre vents from both passive andacti ve attacks. In our basic protocol, each group member equally contributes to the secret group key in parallel andguarantees key freshness.