liboqs/docs/algorithms/kem/ntru.md

NTRU

• Algorithm type: Key encapsulation mechanism.
• Main cryptographic assumption: NTRU in Z[x]/(q, x^n-1) with prime n and power-of-two q.
• Principal submitters: John M. Schanck.
• Auxiliary submitters: Cong Chen, Oussama Danba, Jeffrey Hoffstein, Andreas Hülsing, Joost Rijneveld, Tsunekazu Saito, Peter Schwabe, William Whyte, Keita Xagawa, Takashi Yamakawa, Zhenfei Zhang.
• Authors' website: https://ntru.org/
• Specification version: NIST Round 3 submission.
• Primary Source:
  • Source: 6a32796212
  • Implementation license (SPDX-Identifier): CC0-1.0 , which takes it from:
  • https://github.com/jschanck/ntru/tree/a43a4457

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)
NTRU-HPS-2048-509	IND-CCA2	1	699	935	699	32
NTRU-HPS-2048-677	IND-CCA2	3	930	1234	930	32
NTRU-HPS-4096-821	IND-CCA2	5	1230	1590	1230	32
NTRU-HPS-4096-1229	IND-CCA2	5	1842	2366	1842	32
NTRU-HRSS-701	IND-CCA2	3	1138	1450	1138	32
NTRU-HRSS-1373	IND-CCA2	5	2401	2983	2401	32

NTRU-HPS-2048-509 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,BMI2	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.

NTRU-HPS-2048-677 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,BMI2	True	True	False

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

NTRU-HPS-4096-821 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,BMI2	True	True	False

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

NTRU-HPS-4096-1229 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.

NTRU-HRSS-701 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,BMI2	True	True	False

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

NTRU-HRSS-1373 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.