Paper 2026/2134
ANSA-IBS: Identity-Based Signatures from Annular NTRU Trapdoors and Bimodal Fiat-Shamir with Aborts
Abstract
We give a lattice identity-based signature scheme from annular NTRU trapdoors and Fiat--Shamir with aborts (FSwA). Countered hashing maps each identity to its first invertible DLP/NTRU syndrome $a$. Extraction returns a short witness to $s_0+s_1h=a\bmod q$, and signing normalizes this relation to a fixed-target two-response equation with public commitment recovery. Gärtner's iterative rejection method fits naturally into this signing layer: processing the challenge monomials separately reduces the Gaussian mask width and expected signing attempts, yielding shorter signatures. We report three parameter sets whose signing layer is calibrated against NIST security categories 2, 3, and 5, with fixed signature sizes of $8486$, $11309$, and $12727$ bytes, respectively.
Note: This is the full version of a paper presented at CANS 2026. It includes more security analysis details and a fixed-point realization of the scheme.
Metadata
- Available format(s)
-
PDF
- Category
- Public-key cryptography
- Publication info
- Published elsewhere. Major revision. CANS 2026
- Keywords
- identity-based signaturelattice cryptographyNTRU trapdoorsbimodal signaturesFiat- Shamir with aborts
- Contact author(s)
-
mzhcheng @ gmail com
hengfuyang @ hnfnu edu cn
xiongxk @ myibc net - History
- 2026-09-22: approved
- 2026-09-21: received
- See all versions
- Short URL
- https://ia.cr/2026/2134
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2026/2134,
author = {Zhaohui Cheng and Hengfu Yang and Kaixin Xiong},
title = {{ANSA}-{IBS}: Identity-Based Signatures from Annular {NTRU} Trapdoors and Bimodal Fiat-Shamir with Aborts},
howpublished = {Cryptology {ePrint} Archive, Paper 2026/2134},
year = {2026},
url = {https://eprint.iacr.org/2026/2134}
}
