Paper 2013/804

Group Signature with relaxed-privacy and revocability for VANET

Mohammad Saiful Islam Mamun and Atsuko Miyaji

Abstract

This paper adapts a new group signature (GS) scheme to the specific needs of certain application e.g., a vehicular adhoc network (VANET). Groth GS is the first efficient GS scheme in the BSZ-model with security proofs in the standard model. We modify the Groth GS in order to meet a restricted, but arguably sufficient set of privacy proper-ties. Although there are some authentication schemes using GS none of them satisfy all the desirable security and privacy properties. Either they follow GSs that rely on Random Oracle Model, or unable to satisfy potential application requirements. In particular, link management which allows any designated entities to link messages, whether they are coming from the same member or a certain group of members without revealing their identities; opening soundness that prevents malicious accusations by the opener against some honest member of the group; revocation system that privileges from fraudulent member like the traditional Public Key infrastructure (PKI). In order to achieve the aforementioned security properties together, we propose a new GS model where linkability, sound opening and revocability properties are assembled in a single scheme. The novelty of our proposal stems from extending the Groth GS by relaxing strong privacy properties to a scheme with a lightly lesser privacy in order to fit an existing VANET application requirements. In addition, we partially minimize the Groth GS scheme to expedite efficiency.