MPCitH Signature from Restricted Syndrome Decoding

Michele Battagliola; Ethan Y. Chen; Hugo Sauerbier Couvée; Violetta Weger

Paper 2025/1908 Original: eprint.iacr.org/2025/1908 ↗

MPCitH Signature from Restricted Syndrome Decoding

Michele Battagliola

Ethan Y. Chen

Hugo Sauerbier Couvée

Violetta Weger

Abstract

Abstract. CROSS is a code-based signature based on the Restricted Syndrome Decoding Problem (R-SDP) that is currently among the fourteen candidates in the NIST standardization process. While CROSS enjoys a very competitive verification time, its primary drawback is its significantly large signature size. In this work, we introduce a new Multi-Party Computation in the Head (MPCitH) protocol for the R-SDP with the primary goal of reducing CROSS signature size. To do so, we design a publicly verifiable secret sharing scheme tailored for restricted vectors and a new multiplicative-to-additive conversion for it. These new cryptographic gadgets may be of independent interest as they can serve as building blocks for future research in multi-party computation, such as a threshold version of CROSS.

Metadata

Available format(s): PDF
Category: Public-key cryptography
Publication info: Preprint.
History: 2025-11-10: last updated; 2025-10-13: published
Short URL: https://ia.cr/2025/1908
License: https://creativecommons.org/licenses/by-sa/4.0/

BibTeX

@misc{cryptoeprint:2025/1908,
      author = {Michele Battagliola and Ethan Y. Chen and Hugo Sauerbier Couvée and Violetta Weger},
      title = {MPCitH Signature from Restricted Syndrome Decoding},
      howpublished = {Cryptology {ePrint} Archive, Paper 2025/1908},
      year = {2025},
      url = {https://eprint.iacr.org/2025/1908}
}