Compact e-cash from bounded accumulator

Abstract

Known compact e-cash schemes are constructed from signature schemes with efficient protocols and verifiable random functions. In this paper, we introduce a different approach. We construct compact e-cash schemes from bounded accumulators. A bounded accumulator is an accumulator with a limit on the number of accumulated values. We show a generic construction of compact e-cash schemes from bounded accumulators and signature schemes with certain properties and instan-tiate it using an existing pairing-based accumulator and a new signature scheme. Our scheme revokes the secret key of the double-spender directly and thus supports more efficient coin tracing. The new signature scheme has an interesting property that is has the message space of a cyclic group G1 equipped with a bilinear pairing, with efficient protocol to show possession of a signature without revealing the signature nor the message. We show that the new scheme is secure in the generic group model. The new signature scheme may be of independent interest.