Comments on "Analysis and Improvement of a Secure and Efficient Handover Authentication Based on Bilinear Pairing Functions"

Usually the main primitive in building a secure wireless authentication is a cryptographic algorithm, such as digital signature scheme. He et al. proposed a handover authentication protocol in [1] (IEEE Trans. Wireless Commun., vol. 11, no. 1, 2011) and a distributed reprogramming protocol in [3] (IEEE Trans. Ind. Electron., vol. 59, no. 11, 2012) for wireless networks. Both protocols are based on an identity-based signature scheme which is claimed to be secure yet efficient. Very recently, He et al. pointed out that such a signature scheme is vulnerable to the key compromised problem. They proposed a simple modification to fix this problem without losing the efficiency and security of the scheme in both [2] (IEEE Commun. Lett., vol. 16, no. 8, 2012) and [4] (IEEE Trans. Ind. Electron., to appear). In this letter, we show that the proposed modification remains vulnerable to the key compromised problem.