HashWires: Hyperefficient Credential-Based Range Proofs

• Main Authors: Chalkias Konstantinos, Cohen Shir, Lewi Kevin, Moezinia Fredric, Romailler Yolan
• Format: Article
• Language: English
• Published: Sciendo 2021-10-01
• Series: Proceedings on Privacy Enhancing Technologies
• Subjects: range proofs; credentials; hash-chains; accumulators; cryptographic commitments; malleability; micro-payments; location privacy
• Online Access: https://doi.org/10.2478/popets-2021-0061

This paper presents HashWires, a hash-based range proof protocol that is applicable in settings for which there is a trusted third party (typically a credential issuer) that can generate commitments. We refer to these as “credential-based” range proofs (CBRPs). HashWires improves upon hashchain solutions that are typically restricted to micro-payments for small interval ranges, achieving an exponential speedup in proof generation and verification time. Under reasonable assumptions and performance considerations, a Hash-Wires proof can be as small as 305 bytes for 64-bit integers. Although CBRPs are not zero-knowledge and are inherently less flexible than general zero-knowledge range proofs, we provide a number of applications in which a credential issuer can leverage HashWires to provide range proofs for private values, without having to rely on heavyweight cryptographic tools and assumptions.