liboqs/docs/algorithms/kem/hqc.md

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, Olivier Blazy, Jurjen Bos, Jean-Christophe Deneuville, Philippe Gaborit, Edoardo Persichetti, Jean-Marc Robert, Pascal Véron, Gilles Zémor, Loïc Bidoux.
• Authors' website: https://pqc-hqc.org/
• Specification version: NIST Round 3 submission.
• Primary Source:
  • Source: 33bceb17eb
  • Implementation license (SPDX-Identifier): Public domain
• Ancestors of primary source:
  • https://github.com/jschanck/package-pqclean/tree/29f79e72/hqc, which takes it from:
  • submission 2020-10-01 at https://pqc-hqc.org/implementation.html

Advisories

• The implementations for all parameter sets DO NOT provide constant time execution properties. See: https://github.com/open-quantum-safe/liboqs/issues/995.

Parameter set summary

Parameter set	Security model	Claimed NIST Level	Public key size (bytes)	Secret key size (bytes)	Ciphertext size (bytes)	Shared secret size (bytes)
HQC-128	IND-CCA2	1	2249	2289	4481	64
HQC-192	IND-CCA2	3	4522	4562	9026	64
HQC-256	IND-CCA2	5	7245	7285	14469	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
Primary Source	avx2	x86_64	Linux,Darwin	AVX2,BMI1,PCLMULQDQ	False	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
Primary Source	avx2	x86_64	Linux,Darwin	AVX2,BMI1,PCLMULQDQ	False	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
Primary Source	avx2	x86_64	Linux,Darwin	AVX2,BMI1,PCLMULQDQ	False	True	True

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.