Extended Signature Scheme Based On Group Signature

The digital signature technology is one of the main research fields in modern cryptology. As a kind of specific digital signature, group signature possesses the features of anonymity, traceability, non-relation and so on, which make it have some security attributes that the common digital signatures do not possess. With the rapid development of electronic commerce and electronic government, some application environment has many special requirements for group signature which the traditional group signature schemes cannot meet perfectly. Thus, many kinds of extended group signature schemes based on group signature are put forward and catching more and more attention in the researches of group signature.This paper has the following findings:1. Based on the proxy signature, this paper puts forward a group signature scheme with forward security which imitates the process in which the original signer qualifies the proxy signer to add group members so that the anonymity, forward security and traceability as well as the flexibility of the size of the group can be achieved.2. This paper puts forward a dynamic sub-group signature scheme with forward security which avoids effectively the same-mode attack to RSA public-key signature system and thus possesses anonymity, traceability, forward security, non-relation, and the ability to resist against the centralized attack of counterfeit groups, the forgery attack, member attack of counterfeit groups and collusive attack. This scheme can also add and revoke group members. Without signature of knowledge, this scheme is fairly efficient in the process of member joining and the revocation of membership because of Chinese remainder theorem.3. Inspired by the idea of ring signature, this paper puts forward an extended group signature scheme with forward security. Possessing comparatively perfect safety, the scheme also allows the signature recipient participate the opening stage of the signature and thus effectively limits the authority of the group manage. Besides, the group members can set flexibly the update frequency of the secret keys of the signature and choose freely the anonymous range of the signature in this scheme to reach a balance between the operation efficiency and security.