Nymbler: Privacy-enhanced Protection from Abuses of Anonymity

摘要: Anonymous communications networks help to solve the real and important problem of enabling users communicate privately over Internet. However, by doing so, they also introduce an entirely new problem: How can service providers on Internet—such as websites, IRC mail servers—allow anonymous access while protecting themselves against abuse misbehaving users? Recent research efforts have focused using blacklisting systems (also known revocation systems) this problem. As opposed revocable anonymity systems, which enable some trusted third party deanonymize users, provide a way for authenticate anonymously with provider, provider revoke from individual without revealing their identities. The literature contains several many are impractical real-world deployment. In 2006, however, Tsang et al. proposed Nymble, solves very efficiently parties. Nymble has inspired number subsequent systems. Some these use fundamentally different approaches accomplish what does parties at all; so far, proposals all suffered serious performance scalability problems. Other build framework reduce Nymble’s trust assumptions maintaining its highly efficient design. primary contribution thesis is system built framework—a nimbler version Nymble—called Nymbler. We propose enhancements that facilitate construction scheme minimizes in then set security privacy properties should possess protect: 1) users’ malicious (including other users), 2) users. requirements meet maximize potential adoption, formally define optional features literature. present Nymbler, improves existing Nymble-like reducing level placed parties, simultaneously providing stronger guarantees functionality. It avoids dependence hardware unreasonable about non-collusion between implemented key components our measurements indicate practical. Our open problems literature, makes cryptographic constructions likely be independent theoretical interest.