Abstract: Present a security analysis of an efficient forward secure short threshold proxy signature scheme，which does not possess the strong unforgeability property，anyone including proxy signer can forge a valid proxy-delegate process，at the same time，this scheme can’t withstand conspiracy attack，any threshold（or more） proxy signers can conspire to gain the private keys of other proxy signers，and can forge their valid signatures.An improved forward secure short threshold proxy signature scheme is proposed，which can resolve the security problem existing in the original scheme，and there is backward security in the improved scheme.

Key words: forward secure, threshold proxy signature, backward security

摘要： 通过对一种高效前向安全短门限代理签名方案分析，发现该方案不能抵抗伪造攻击，任何人包括代理签名者都可以伪造原始签名者委托代理签名团体进行代理签名，同时该方案也不能抵御内部合谋攻击，任意门限个代理签名者可以合谋获取其他代理签名者的私钥，进而可以伪造他们的签名。对这种门限代理签名方案进行了改进，改进方案克服了原方案的缺陷的同时还具有后向安全性。

关键词: 前向安全, 门限代理签名, 后向安全性