高效可证安全的无证书代理签名方案的安全性分析

摘要

Recently ,S-H .Seo et al proposed a certificateless signature scheme and used it to construct a certificateless proxy signature with provable security .They demonstrated that their schemes are provable security in the random oracle model under the computational Diffie-Hellman assumption .Unfortunately ,by given concrete attack ,the paper demonstrated that their schemes were not secure against the Type Ⅱ adversary .A Type Ⅱ adversary could forge a legal proxy signature of any message .The paper analyzed the root cause of attack and gave some suggestions for modifications in the end .%对于 S-H ．Seo 等提出的无证书代理签名方案进行了密码分析，给出了一个有效的伪造攻击算法，指出此方案不能抵抗第二种类型敌手的攻击，敌手Ⅱ可以伪造任意消息的合法代理签名。最后分析了此方案遭受攻击的主要原因，并给出了相应的改进措施。