Abstract: There are more security threats in cognitive radio networks than traditional wireless networks due to the strategy of opening spectrum. Switching spectrum brings time delay and interferes with network efficiency. The question also adversely effects on key-exchange protocol which is an important part of key agreement, and gives malicious nodes the attack chance. So this paper put forward a new method, firstly cognitive radio network was divided into multiple clusters, secondly used protocol the time delay of switching channel to select the optimal path with traveling salesman problem in cluster and built the optimal multicast routing tree among clusters; at last different key-exchange protocols based on self-certified were used in cluster and among clusters, which can prevent active attack and passive attack, authentication and key agreement can also simultaneously carried out. The efficiency of protocol is O(2m),m is the number of cluster.

Key words: Cognitive radio, Security, Key exchange, Cluster, Ad hoc, Self-certified