关键词: 前向安全, 门限代理签名, 后向安全性

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