Paper 2022/1725 Original: eprint.iacr.org/2022/1725 ↗

A note on SPHINCS+ parameter sets

Stefan Kölbl
Jade Philipoom
Abstract

In this note, we explore parameter sets for SPHINCS+ which support a smaller number of signatures than $2^{64}$, but are otherwise compatible with the SLH-DSA specification. In practice, use cases for which a low number of signatures per key pair suffice are common, and as we will show this allows a significant reduction in signature size and verification speed for SPHINCS+. For this we carry out a larger search through the SPHINCS+ parameter space, comparing it with the current parameter sets and further showing that for carefully chosen parameter the security degrades slowly if one exceeds the limits. Finally, we provide a case study for firmware signing on OpenTitan to demonstrate the efficiency of these alternative parameters.

Metadata
Available format(s)
PDF
Category
Public-key cryptography
Publication info
Preprint.
History
2024-01-09: last updated
2022-12-14: published
Short URL
https://ia.cr/2022/1725
License
https://creativecommons.org/publicdomain/zero/1.0/

BibTeX

@misc{cryptoeprint:2022/1725,
      author = {Stefan Kölbl and Jade Philipoom},
      title = {A note on SPHINCS+ parameter sets},
      howpublished = {Cryptology {ePrint} Archive, Paper 2022/1725},
      year = {2022},
      url = {https://eprint.iacr.org/2022/1725}
}
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