Abstract:Recently, Wu et al. pointed out that the identity-based public key systems proposed by Nyberg and Rueppel cannot prevent from the impersonation attack. They also gave an improvement to withstand the security weakness appeared in the Nyberg-Rueppel’s systems. However, this paper will show that the improvement is still vulnerable to the impersonation attack. Furthermore, we will propose new identity-based public key recovery systems to eliminate the security leak. As compared with Wu et al.’s systems, the proposed ones have better performance in terms of computation complexity.