Threshold Proxy Signature Scheme with Specified Signature Folder

A scheme called threshold proxy signature with a specified signature folder is proposed based on ElGamal signature.In this scheme,when the participants are joining or quitting,the sub-key of participants do not require to be update and the system do not need to maintain a secure channel between the signature participants to specify the signature.After finishing the part signature,the signature folder verifies them and combine it.The security of the scheme is ensured by the difficulty of solving discrete logarithm.Compared with scheme proposed by threshold proxy signature scheme of ElGamal signature scheme,it has smaller quantity of computation and communication during the proxy signature stage.So it is more safe and more efficient.