The Commercial National Security Algorithm Suite (CNSA) is a set of cryptographic algorithms promulgated by the National Security Agency as a replacement for NSA Suite B Cryptography algorithms. It serves as the cryptographic base to protect US National Security Systems information up to the top secret level, while the NSA plans for a transition to quantum-resistant cryptography.[1][2][3][4][5][6]
The suite includes:
- Advanced Encryption Standard with 256 bit keys
- Elliptic-curve Diffie–Hellman and Elliptic Curve Digital Signature Algorithm with curve P-384
- SHA-2 with 384 bits, Diffie–Hellman key exchange with a minimum 3072-bit modulus, and
- RSA with a minimum modulus size of 3072.[2]
The CNSA transition is notable for moving RSA from a temporary legacy status, as it appeared in Suite B, to supported status. It also did not include the Digital Signature Algorithm. This, and the overall delivery and timing of the announcement, in the absence of post-quantum standards, raised considerable speculation about whether NSA had found weaknesses e.g. in elliptic-curve algorithms or others, or was trying to distance itself from an exclusive focus on ECC for non-technical reasons.[7][8][9]
In September 2022, the NSA announced CNSA 2.0, which includes its first recommendations for post-quantum cryptographic algorithms.[10]
CNSA 2.0 includes:[2]
- Advanced Encryption Standard with 256 bit keys
- Module-Lattice-Based Key-Encapsulation Mechanism Standard (ML-KEM aka CRYSTALS-Kyber) with parameter set ML-KEM-1024
- Module-Lattice-Based Digital Signature Standard (ML-DSA aka CRYSTALS-Dilithium) with parameter set ML-DSA-87
- SHA-2 with 384 or 512 bits
- eXtended Merkle Signature Scheme (XMSS) and Leighton-Micali Signatures (LMS) with all parameters approved, with SHA256/192 recommended
Note that compared to CNSA 1.0, CNSA 2.0:
- Suggests separate post-quantum algorithms (XMSS/LMS) for software/firmware signing for use immediately
- Allows SHA-512
- Announced the selection of CRYSTALS-Kyber and CRYSTALS-Dilithium early, with the expectation that they will be mandated only when the final standards and FIPS-validated implementations are released.
- RSA, Diffie-Hellman, and elliptic curve cryptography will be deprecated at that time.
The CNSA 2.0 and CNSA 1.0 algorithms, detailed functions descriptions, specifications, and parameters are below:[11]
CNSA 2.0
| Algorithm | Function | Specification | Parameters |
|---|---|---|---|
| Advanced Encryption Standard (AES) | Symmetric block cipher for information protection | FIPS PUB 197 | Use 256-bit keys for all classification levels. |
| Module-Lattice-Based Key-Encapsulation Mechanism Standard (ML-KEM aka CRYSTALS-Kyber) | Asymmetric algorithm for key establishment | FIPS PUB 203 | Use ML-KEM-1024 parameter set for all classification levels. |
| Module-Lattice-Based Digital Signature Standard (aka CRYSTALS-Dilithium) | Asymmetric algorithm for digital signatures | FIPS PUB 204 | Use ML-DSA-87 parameter set for all classification levels. |
| Secure Hash Algorithm (SHA) | Algorithm for computing a condensed representation of information | FIPS PUB 180-4 | Use SHA-384 or SHA-512 for all classification levels. |
| Leighton-Micali Signature (LMS) | Asymmetric algorithm for digitally signing firmware and software | NIST SP 800-208 | All parameters approved for all classification levels. SHA256/192 recommended. |
| Xtended Merkle Signature Scheme (XMSS) | Asymmetric algorithm for digitally signing firmware and software | NIST SP 800-208 | All parameters approved for all classification levels. |
CNSA 1.0
| Algorithm | Function | Specification | Parameters |
|---|---|---|---|
| Advanced Encryption Standard (AES) | Symmetric block cipher for information protection | FIPS PUB 197 | Use 256-bit keys for all classification levels. |
| Elliptic Curve Diffie-Hellman (ECDH) Key Exchange | Asymmetric algorithm for key establishment | NIST SP 800-56A | Use Curve P-384 for all classification levels. |
| Elliptic Curve Digital Signature Algorithm (ECDSA) | Asymmetric algorithm for digital signatures | FIPS PUB 186-4 | Use Curve P-384 for all classification levels. |
| Secure Hash Algorithm (SHA) | Algorithm for computing a condensed representation of information | FIPS PUB 180-4 | Use SHA-384 for all classification levels. |
| Diffie-Hellman (DH) Key Exchange | Asymmetric algorithm for key establishment | IETF RFC 3526 | Minimum 3072-bit modulus for all classification levels |
| [Rivest-Shamir-Adleman] RSA | Asymmetric algorithm for key establishment | FIPS SP 800-56B | Minimum 3072-bit modulus for all classification levels |
| [Rivest-Shamir-Adleman] RSA | Asymmetric algorithm for digital signatures | FIPS PUB 186-4 | Minimum 3072-bit modulus for all classification levels |
- ^ Cook, John (2019-05-23). "NSA recommendations | algorithms to use until PQC". www.johndcook.com. Retrieved 2020-02-28.
- ^ a b c "Announcing the Commercial National Security Algorithm Suite 2.0" (PDF). media.defense.gov. 2022-09-07. Retrieved 2024-06-10.
- ^ "CNSA Suite and Quantum Computing FAQ" (PDF). cryptome.org. January 2016. Retrieved 24 July 2023.
- ^ "Use of public standards for the secure sharing of information among national security systems, Advisory Memorandum 02-15 CNSS Advisory Memorandum Information Assurance 02-15". Committee on National Security Systems. 2015-07-31. Archived from the original on 2020-02-28. Retrieved 2020-02-28.
- ^ "Commercial National Security Algorithm Suite". apps.nsa.gov. 19 August 2015. Archived from the original on 2022-02-18. Retrieved 2020-02-28.
- ^ Housley, Russ; Zieglar, Lydia (July 2018). "RFC 8423 - Reclassification of Suite B Documents to Historic Status". tools.ietf.org. Retrieved 2020-02-28.
- ^ "NSA's FAQs Demystify the Demise of Suite B, but Fail to Explain One Important Detail – Pomcor". 9 February 2016. Retrieved 2020-02-28.
- ^ "A riddle wrapped in a curve". A Few Thoughts on Cryptographic Engineering. 2015-10-22. Retrieved 2020-02-28.
- ^ Koblitz, Neal; Menezes, Alfred J. (2018-05-19). "A Riddle Wrapped in an Enigma". Cryptology ePrint Archive.
- ^ "Post-Quantum Cybersecurity Resources". www.nsa.gov. Retrieved 2023-03-03.
- ^ "Announcing the Commercial National Security Algorithm Suite 2.0, U/OO/194427-22, PP-22-1338, Ver. 1.0" (PDF). media.defense.gov. National Security Agency. September 2022. Table IV: CNSA 2.0 algorithms, p. 9.; Table V: CNSA 1.0 algorithms, p. 10. Retrieved 2024-04-14.