Linkable Group Signature for Auditing Anonymous Communication

Abusing anonymity has become a severe threat for anonymous communication system. Auditing and further tracing the identity of illegal users become an urgent requirement. Although a large body of anonymous communication mechanisms have been proposed, there is almost no research on auditing and supervising. In this paper, we propose a general construction of linkable group signature to achieve the anonymity, auditing and tracing functions for communication sender simultaneously. The general framework is constructed by using basic cryptography modules of blind signature, public key encryption, trapdoor indicative commitment and signature of knowledge. Furthermore, we first formally define a new concept called trapdoor indicative commitment, which helps to determine whether two given signatures are signed by the same member without opening signatures. Finally, we present an efficient linkable group signature instance. Performance analysis shows that our instance requires less computation and shorter signature length, compared with related works, making it suitable for practical applications.