Leak-free Mediated Group Signatures

Group signatures are an interesting and appealing cryptographic construct with many promising potential applications. This paper is motivated by attractive features of group signatures, particularly, the potential to serve as foundation for anonymous credential systems. We re-examine the whole notion of group signatures from a systems perspective and propose two new requirements: leak-freedom and immediate-revocation, which are crucial for a large class of enterprise-centric applications. We then present a new group signature scheme that achieves all identified properties. Our scheme is based on the so-called systems architecture approach. It is appreciably more efficient than the stateof- the-art, easy to implement and reflects the well-known separation-of-duty principle. Another benefit of our scheme is the obviated reliance on underlying anonymous communication channels, which has been a requirement in all previous group signature schemes.