The Security Analysis and Improvement of Some Novel Quantum Proxy Signature Schemes

In recent years, some quantum proxy signature schemes based on controlled teleportation are proposed by Cao et al.. In these schemes, the properties of quantum mechanics are directly applied to ensure the security. In this paper, we have summarized a general model from the quantum proxy signature schemes. Furthermore, it can be seen that there exist some loopholes which have not been considered in the previous analysis. Specifically, the receiver can forge a valid signature. And these schemes can not be immune to collusive attack. To overcome these loopholes, some improved ideas are presented in this paper.