HQC

• Algorithm type: Key encapsulation mechanism.
• Main cryptographic assumption: Syndrome decoding of structure codes (Hamming Quasi-Cyclic).
• Principal submitters: Carlos Aguilar Melchor, Nicolas Aragon, Slim Bettaieb, Loïc Bidoux, Olivier Blazy, Jurjen Bos, Jean-Christophe Deneuville, Arnaud Dion, Philippe Gaborit, Jérôme Lacan, Edoardo Persichetti, Jean-Marc Robert, Pascal Véron, Gilles Zémor.
• Authors' website: https://pqc-hqc.org/
• Specification version: 2023-04-30.
• Primary Source:
  • Source: https://github.com/PQClean/PQClean/commit/8e221ae797b229858a0b0d784577a8cb149d5789
  • Implementation license (SPDX-Identifier): Public domain
• Ancestors of primary source:
  • https://github.com/SWilson4/package-pqclean/tree/8db1b24b/hqc, which takes it from:
  • submission 2023-04-30 at https://pqc-hqc.org/implementation.html

Parameter set summary

Parameter set	Parameter set alias	Security model	Claimed NIST Level	Public key size (bytes)	Secret key size (bytes)	Ciphertext size (bytes)	Shared secret size (bytes)
HQC-128	NA	IND-CCA2	1	2249	2305	4433	64
HQC-192	NA	IND-CCA2	3	4522	4586	8978	64
HQC-256	NA	IND-CCA2	5	7245	7317	14421	64

HQC-128 implementation characteristics

Implementation source	Identifier in upstream	Supported architecture(s)	Supported operating system(s)	CPU extension(s) used	No branching-on-secrets claimed?	No branching-on-secrets checked by valgrind?	Large stack usage?‡
Primary Source	clean	All	All	None	True	True	False

Are implementations chosen based on runtime CPU feature detection? Yes.

‡For an explanation of what this denotes, consult the Explanation of Terms section at the end of this file.

HQC-192 implementation characteristics

Implementation source	Identifier in upstream	Supported architecture(s)	Supported operating system(s)	CPU extension(s) used	No branching-on-secrets claimed?	No branching-on-secrets checked by valgrind?	Large stack usage?
Primary Source	clean	All	All	None	True	True	False

Are implementations chosen based on runtime CPU feature detection? Yes.

HQC-256 implementation characteristics

Implementation source	Identifier in upstream	Supported architecture(s)	Supported operating system(s)	CPU extension(s) used	No branching-on-secrets claimed?	No branching-on-secrets checked by valgrind?	Large stack usage?
Primary Source	clean	All	All	None	True	True	False

Are implementations chosen based on runtime CPU feature detection? Yes.

Explanation of Terms

• Large Stack Usage: Implementations identified as having such may cause failures when running in threads or in constrained environments.