Vaudenay's privacy model in the universal composability framework: A case study

Abstract

At ASIACCS'09, Bringer et al. introduced different Zero-Knowledge (ZK) identification protocols which respect privacy. To do so, they give a generic technique to increase the privacy of existing ZK schemes. As an application, they transform the Girault-Poupard-Stern (GPS) scheme to get new protocols. Their proofs rely on the privacy model of Vaudenay. We here want to examine the validity of their results in the more general framework of the Universal Composability (UC). This is relevant considering that Contactless Devices (CLDs) seem to be the first target for implementing these protocols. More precisely, we here transpose Vaudenay's privacy model in the UC framework, and we show how to modify the Randomized Hashed GPS scheme in order to obtain a secure protocol in the UC framework. © 2011 Springer-Verlag.