Paper 2023/1064 Original: eprint.iacr.org/2023/1064 ↗

Decoding Quasi-Cyclic codes is NP-complete

Ernesto Dominguez Fiallo
Pablo Freyre Arrozarena
Luis Ramiro Piñeiro
Abstract

This paper establishes the computational complexity of the Quasi-Cyclic Syndrome Decoding Problem (QC-SDP). We introduce a novel characterization of Quasi-Cyclic (QC) codes that generalizes their structure and reveals connections to random codes. Building on this characterization, we prove that QC-SDP is NP-hard and that its decision variant is NP-complete. These results provide the first formal complexity treatment of QC-SDP in its general form, addressing a fundamental open question in code-based cryptography. We also discuss the practical implications and limitations of these theoretical findings for cryptographic applications.

Metadata
Available format(s)
PDF
Category
Foundations
Publication info
Preprint.
History
2025-11-04: last updated
2023-07-07: published
Short URL
https://ia.cr/2023/1064
License
https://creativecommons.org/publicdomain/zero/1.0/

BibTeX

@misc{cryptoeprint:2023/1064,
      author = {Ernesto Dominguez Fiallo and Pablo Freyre Arrozarena and Luis Ramiro Piñeiro},
      title = {Decoding Quasi-Cyclic codes is NP-complete},
      howpublished = {Cryptology {ePrint} Archive, Paper 2023/1064},
      year = {2023},
      url = {https://eprint.iacr.org/2023/1064}
}
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