Abstract

We introduce Ad hoc Anonymous Identification schemes, a new multi-user cryptographic primitive that allows participants from a user population to form ad-hoc groups, and then prove membership anonymously in such groups. Our schemes are based on the notion of accumulator with one-way domain, a natural extension of cryptographic accumulators we introduce in this work. We provide a formal model for Ad hoc Anonymous Identification schemes and design secure such schemes both generically (based on any accumulator with one-way domain) and for a specific e#cient implementation of such an accumulator based on the Strong RSA Assumption. A salient feature of our approach is that all the identification protocols take time independent of the size of the ad-hoc group. All our schemes and notions can be generally and efficiently amended so that they allow the recovery of the signer's identity by an authority, if the latter is desired. Using

Citations