Identity-based partially blind signature in the standard model for electronic cash

Partially blind signature allows a signer to explicitly include a piece of common information in a blind signature under some agreement with a receiver. Partially blind signature is a crucial component of electronic cash systems. Recently, some identity-based partially blind signature schemes were proposed. However, all of these schemes are provably secure in the random oracle model. In this paper, we propose an identity-based partially blind signature scheme in the standard model. Our scheme is based on Paterson and Schuldt’s identity-based signature scheme. We prove that our scheme has existential unforgeability under the computational Diffie–Hellman assumption and partial blindness. To the best of our knowledge, the proposed scheme is the first identity-based partially blind signature scheme that is secure in the standard model. We give an example of potential application to electronic cash systems using our scheme.