Paper 2026/1731
Generic Ring-Signature Transforms for Fiat-Shamir with Aborts and Hash-and-Sign with Retry
, NTT Social Informatics Laboratories, Toyohashi University of TechnologyAbstract
Ring signatures provide signer anonymity for ad hoc sets of public keys. Generic Abe-Ohkubo-Suzuki (AOS) transforms are well understood for plain Fiat--Shamir and hash-and-sign signatures, but not for their rejection-sampling variants: Fiat--Shamir with aborts (FSwA) and hash-and-sign with retry (HSwR). We formalize AOS ring transforms for FSwA and HSwR and analyze their security in the quantum random-oracle model. For unforgeability, we reduce security under adaptive ring-signing queries to security without signing queries using essentially the same assumptions as in security proofs for the corresponding ordinary signatures; handling adaptive corruption additionally requires the simulation property to remain valid after key exposure. Strong unforgeability additionally requires response uniqueness and special soundness for FSwA, or second-preimage resistance and non-invertibility for HSwR. The residual no-signing-query requirement admits generic reductions, but with loss exponential in the number of honest keys. Finally, an ML-DSA case study shows that augmented public keys achieve the required key-exposure simulation while identifying its limitations; we also identify conditions for candidate HSwR instantiations.
Metadata
- Available format(s)
-
PDF
- Category
- Public-key cryptography
- Publication info
- Preprint.
- Keywords
- ring signatureFiat-Shamir with abortshash-and-sign with retryquantum random oracle model
- Contact author(s)
-
hrhs kosuge @ ntt com
suzuki @ cs tut ac jp - History
- 2026-08-21: approved
- 2026-08-19: received
- See all versions
- Short URL
- https://ia.cr/2026/1731
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2026/1731,
author = {Haruhisa Kosuge and Koutarou Suzuki},
title = {Generic Ring-Signature Transforms for Fiat-Shamir with Aborts and Hash-and-Sign with Retry},
howpublished = {Cryptology {ePrint} Archive, Paper 2026/1731},
year = {2026},
url = {https://eprint.iacr.org/2026/1731}
}
