Welcome to the resource topic for 2025/985
Title:
Tighter Quantum Security for Fiat-Shamir-with-Aborts and Hash-and-Sign-with-Retry Signatures
Authors: Pouria Fallahpour, Serge Fehr, Yu-Hsuan Huang
Abstract:We revisit the quantum security (in the QROM) of digital signature schemes that follow the Fiat-Shamir-with-aborts (FSwA) or the probabilistic hash-and-sign with retry/abort (HSwA) design paradigm. Important examples of such signature schemes are Dilithium, SeaSign, Falcon+ and UOV. In particular, we are interested in the UF-CMA-to-UF-NMA reduction for such schemes. We observe that previous such reductions have a reduction loss that is larger than what one would hope for, or require a more stringent notion of zero-knowledge than one would hope for.
We resolve this matter here by means of a novel UF-CMA-to-UF-NMA reduction that applies to FSwA and HSwA signature schemes simultaneously, and that offers an improved reduction loss (without making the zero-knowledge assumption more stringent).
ePrint: https://eprint.iacr.org/2025/985
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