Research On The Forward Secure Group Signature

A Group Signature allows any member of a group to digitally sign a document in a manner such that a verifier can confirm that it came from the group ,but does not know which individual in the group signed the document. The protocol allows for the identity of the signer to be discovered, in case of disputes, by a designated group authority who has some auxiliary information .Because of those characteristics, Let its respect of auctioning the systems, electronic lottery ticket system in electronic . payment system , electron etc. have extensive application prospects because of one group of this kind of characteristics of signing. So Group Signature always focus that field of the digital signature. Originally we provide the group signature scheme formalization defining and structure method in common use in the article, the scheme of one group of signatures of understanding making us clearer is how to realize their two important characteristics: Anonymous and Traceable.The Forward Secure Digital Signature can not prevent the key from letting out. But it can be the key losses after letting out are reduced, controlled by a kind of risk. It to through keep common key change , realize evolving private key according to definite period with one-way function mainly, after guaranteeing that the present private key is let out, will not influence the signature before this period. The forward secure Group Signature Schemes introduce forward secure to the Group Signature, improved the security of the Group Signatures, make its can be suitable for some specific application. In addition, the revocation on the basis of the forward secure is getting higher in efficiency compared with general Group Signature, give to introduction of security how is it delete one groups of member each this is it disclose a kind of new train of thought of problem to sign effectively to solve we before we can saying. But the existing one must confirm the term of validity of group public key at first to the forward secure Group Signature Scheme, that is to say this forward secure is in limit period. Deletion movements of the revocation to combine to the forward secure can only be done within specific time(two transition period in time slots), so the apparent one is stiff in the existing scheme is in practical application.In this paper, we introduce a new Forward Secure Group Signature Scheme, itsadvantage lies in that the valid deadline of group manger's public key is not needed to be established when realizing the forward property, and thus it has the forward secure of no-limited time. A so-called no limited time mean that it do not confirm the validity of group manager public key when initialize systematically, and group manager can notify groups of member evolve their private key at any time according to concrete conditions, finish the transition to another time slots for one time slot. Can be finished on the basis of no limited forward secure from to deletion movement of method at any moment, we have given the concrete revocation scheme here. In addition, we provide another revocation scheme which isn't base on the forward secure. In this way, users have constructed a dynamic forward secure Group Signature Schemes in revocation method that can choose oneself to be suitable for in practical application.