Falcon

• Algorithm type: Digital signature scheme.
• Main cryptographic assumption: hardness of NTRU lattice problems.
• Principal submitters: Thomas Prest.
• Auxiliary submitters: Pierre-Alain Fouque, Jeffrey Hoffstein, Paul Kirchner, Vadim Lyubashevsky, Thomas Pornin, Thomas Prest, Thomas Ricosset, Gregor Seiler, William Whyte, Zhenfei Zhang.
• Authors' website: https://falcon-sign.info
• Specification version: 20211101.
• Primary Source:
  • Source: https://github.com/PQClean/PQClean/commit/8e221ae797b229858a0b0d784577a8cb149d5789
  • Implementation license (SPDX-Identifier): MIT
• Optimized Implementation sources: https://github.com/PQClean/PQClean/commit/8e221ae797b229858a0b0d784577a8cb149d5789
  • pqclean-aarch64:
    • Source: https://github.com/PQClean/PQClean/commit/7707d1bcc8ae7f9ffd296dd13b1d76d2767d14f8
    • Implementation license (SPDX-Identifier): Apache-2.0

Parameter set summary

Parameter set	Parameter set alias	Security model	Claimed NIST Level	Public key size (bytes)	Secret key size (bytes)	Signature size (bytes)
Falcon-512	NA	EUF-CMA	1	897	1281	752
Falcon-1024	NA	EUF-CMA	5	1793	2305	1462
Falcon-padded-512	NA	EUF-CMA	1	897	1281	666
Falcon-padded-1024	NA	EUF-CMA	5	1793	2305	1280

Falcon-512 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	All	AVX2	False	False	False
pqclean-aarch64	aarch64	ARM64_V8	Linux,Darwin	None	False	False	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.

Falcon-1024 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	All	AVX2	False	False	False
pqclean-aarch64	aarch64	ARM64_V8	Linux,Darwin	None	False	False	False

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

Falcon-padded-512 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	All	AVX2	False	False	False
pqclean-aarch64	aarch64	ARM64_V8	Linux,Darwin	None	False	False	False

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

Falcon-padded-1024 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	All	AVX2	False	False	False
pqclean-aarch64	aarch64	ARM64_V8	Linux,Darwin	None	False	False	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.