Cognitive radio (CR) can improve the utilization of the spectrum by making use of licensed spectrum in an opportunistic manner. However, the security aspects of cognitive radio networks have garnered little attention. In this paper, we identify a threat to cognitive radio networks, which we call the spectrum sensing data falsification (SSDF) attack. SSDF attack can hugely degrade the achievable detection accuracy. To counter this threat, we proposed a new method to confront the SSDF attacks by excluding malicious users is cognitive radio. In detail, the proposed scheme defense the SSDF attacks by calculating and updating the credit value of the Secondary Users (SUs), malicious users are excluded to avoid the attacks affect in cooperative spectrum sensing. Simulations results show that both the detection probability and the false alarm probability are significantly improved compared to the case when all users are by default trusted to be normal users.

We construct an efficient and novel identity-based strong designated verifier signature (IBSDVS) scheme based on bilinear pairings, and provide the security proofs and efficiency analysis for the proposed scheme. Our IBSDVS scheme achieves higher efficiency and satisfies all the security requirements of the designated verifier signatures in identity-based cryptography.