| Attribute-based group signature (ABGS) is a combination of attribute-based primitive and group signatures. Different from traditional group signature, in ABGS, group members do not share the same signing privilege; instead, privileges are determined by their own attributes. A verifier can request a signature with certain predicate requirements from a group member. Only members that satisfy these requirements can generate the signature. Therefore, an ABGS signature can be a proof for the predicated requirement of the signer. In ABGS, only predicate-satisfied group members can generate the signature. Any forging tools, such as forge from existing signatures or attribute collusion, are invalid. ABGS also protects attributes privacy of group members, since signatures reveal nothing but whether certain predicates are met or not by the signers. Besides the above, ABGS possesses the full anonymity and full traceability as required in group signatures.The paper gives a detailed analysis on related works done in this area, points out the deficiencies and security issues of existing schema. The existing ABGS protocals are exposed to defects, such as security based on random oracle, disclosure of user's attribute privacy and over-responsibility of group manager; While ABS scheme which uses threshold to protect attribute privacy will bring deficiencies as excessive computation, variance of signature size with attribute size and the cumbersome updating procedure of adding new attribute keys. The paper studies the weakness mentioned above and proposes enhanced designs and algorithms, respectively. Thus, a strongly unforgeable ABGS schema is constructed which is the first proposed ABGS schema with proved security in standard model. Compared with existing schemes, the new construction ensures higher security and provides better efficiency. Finally, the proposed ABGS schema is applied to realize attribute-based access control in distributed system. |
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