Security Analysis of an Identity-Based Signature From Factorization Problem

Many sensitive data are generated by resource-limitation devices in the Vehicular ad hoc network (VANET). When these data are divulged, people 's life and property will be threatened. To solve these problems, Wei et al. proposed a lightweight privacy-preserving protocol based on RSA assumption for VANET and they claimed that their protocol was secure and low overhead. In this paper, first of all, we show that the basic signature scheme to be used in Wei et al.'s protocol is not secure, i.e., the user's private key will be revealed from the pairs of message-signatures, which causes the protocol to be insecure. We also show that our security analysis is feasible and effective in practice from the theory and experiments. Then we construct a new identity-based signature scheme based RSA assumption and prove it is existentially unforgeable under the chosen message attack without random oracle. Finally, we update the Wei et al.'s protocol and do some experiments to evaluate the efficiency of our scheme in the updated protocol.