Group signature Scheme resistant against Colluding Attack

Abstract

Group signature is an extension of digital signature, which allows a group member to sign anonymously a document on behalf of the group. Any client can verify the authenticity of the document by using the public parameters of the group. The identity of the group member cannot be revealed from the group signature. In case of a legal dispute, an authorized group member can disclose the identity of the group member from the signed document. Group signature can have wide application to corporate world, banks, and e-commerce applications. In this thesis, we designed a group signature protocol based upon hard computational assumptions such as, Discrete Logarithm Problem (DLP), Integer Factorization Problem (IFP), and Computational Diffie Hellmann (CDH) problem. The proposed scheme is proved to be resistant against colluding attack. Moreover, the group signature remains valid, if some members leave the group or some new members join the group. Full traceability feature is confirmed in the proposed scheme. The scheme can have wide applications in real life scenarios such as e-banking, e-voting, and e-commerce applications.