Paper 2009/198

DAA: Fixing the pairing based protocols

L Chen and P. Morrissey and N.P. Smart

Abstract

Previously we presented a pairing based DAA protocol in the asymmetric setting, along with a ``security proof''. Jiangtao Li has pointed out to us an attack against this published protocol, thus our prior work should not be considered sound. In this paper we give a repaired version, along with a highly detailed security proof. A full paper will be made available shortly. However in the meantime we present this paper for the community to check and comment on.

Note: The model in the paper contains a major flaw. Indeed no protocol can be proved secure in this model (for any protocol there is a trivial distinguisher between the real and ideal worlds). The protocol we propose has issues related to linking, and the "ZK proof" in the Join protocol is the wrong way around. These latter two points can be fixed (which will be done in a soon to be posted paper to e-print)