中文摘要：

前向安全门限签名是一种重要的分布式签名，它继承了前向安全签名和门限签名的优点，通过每个成员持有的份额周期性地更新密钥，而公钥在整个时间周期中保持不变．这种签名技术可以使得敌手更难危及签名的安全性：如果敌手不能在一个时间段中攻击法定数量的成员就不能伪造任何签名，即使能够在某个时间段内攻击法定数量的成员得到他们的密钥份额，也不能伪造以前时间段的签名．2007年，彭华熹等人提出了一个基于双向性映射的前向安全门限签名方案．对此方案的安全性进行了分析，给出了几种安全性攻击的方法，指出了该方案是不安全的，同时也给出了一些改进的方法．

英文摘要：

The secret key exposure is a serious problem for the security of the digital signature. Unfortunately, for a regular digital signature, if the secret key is exposed, all the signatures previously signed are invalid because the verifier cannot identify whether a signature is produced before key exposure or not. Therefore, how to deal with the problem of secret key exposure in signatures is very important. Forward secure threshold signature is an important distributed signature to deal with this problem. ＂It inb.erits the advantages of forward secure signature and threshold signature. The secret key is renewed periodically through the shares that the players hold, while the public key is fixed during the whole time periods. This kind of signature makes it more difficult for an adversary to compromise the security of the signature, if an adversary cannot attack a quorum number of players, he can＇t forge any signature; if an adversary can attack a quorum number of players in a certain time period, he can＇t forge any signature of previous time periods. In 2007, Peng et al. proposed a forward secure threshold signature scheme from bilinear pairing. Analyzed in this paper is the security of Peng et al. ＇s scheme. Several techniques of security attack are given and it is pointed out that their scheme is insecure. At the same time, some improvement methods are also given.