Blind Signatures are a useful primitive for privacy preserving applications such as electronic payments, e-voting, anonymous credentials, and more. However, existing practical blind signature schemes based on standard assumptions require either pairings or lattices. We present the first practical construction of a round-optimal blind signature in the random oracle model based on standard assumptions without resorting to pairings or lattices. In particular, our construction is secure under the strong RSA assumption and DDH (in pairing-free groups). For our construction, we provide a NIZK-friendly signature based on strong RSA, and efficiently instantiate a variant of Fischlin’s generic framework (CRYPTO’06). Our Blind Signature scheme has signatures of size 4.28 KB and communication cost 10.98 KB. On the way, we develop techniques that might be of independent interest. In particular, we provide efficient relaxed range-proofs for large ranges with subversion zero-knowledge and compact commitments to elements of arbitrary groups.

doi.org/10.1007/978-3-031-68376-3_7
Lecture Notes in Computer Science , Annual International Cryptology Conference
44th Annual International Cryptology Conference
Centrum Wiskunde & Informatica, Amsterdam (CWI), The Netherlands

Kastner, J., Nguyen, K., Reichle, M., & Kastner, J. (2024). Pairing-free blind signatures from standard assumptions in the ROM. In Annual Cryptology Conference (pp. 210–245). doi:10.1007/978-3-031-68376-3_7