Abstract
Abstract Secure group communication over an untrusted open network is a continuing problem, especially in mobile environments. With the development of 3G networks and mobile computing technology, the number of group-oriented applications is increasing rapidly. Although these applications are convenient, achieving secure group communication to protect user privacy is a major concern. This study presents an authenticated group key agreement protocol for mobile environments. By using certificateless public key cryptography, the protocol reduces the cost of managing the certificates and avoids the key escrow problem. Instead of a fully-trusted server, the protocol uses a semi-trusted server, which helps users communicate but does not learn about the group key. The analytical results indicate that the proposed protocol provides good security in mobile environments. © 2015 Elsevier Inc.