Efficient ring signatures without random oracles

Abstract

We describe the first efficient ring signature scheme secure, without random oracles, based on standard assumptions. Our ring signatures are based in bilinear groups. For l members of a ring our signatures consist of 2l + 2 group elements and require 2l + 3 pairings to verify. We prove our scheme secure in the strongest security model proposed by Bender, Katz, and Morselli: namely, we show our scheme to be anonymous against full key exposure and unforgeable with respect to insider corruption. A shortcoming of our approach is that all the users' keys must be defined in the same group. © International Association for Cryptologic Research 2007.