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. Two versions of CNSA exist: the pre-quantum 1.0 of 2015 and the quantum-resistant 2.0 of 2022.

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CNSA 1.0 A singular parameter length is provided for protection up to TOP SECRET level.

+Components of CNSA 1.0 Purpose Algorithm Standard Parameter Length Bits of Security Notes Symmetric encryption AES FIPS 197 256 256 Digital SignatureElliptic Curve Digital Signature Algorithm (ECDSA) FIPS 186-4 384 192 Use curve P-384 only. RSA FIPS 186-4 3072 128 Minimum modulus size, can be larger.Key agreementElliptic-curve Diffie–Hellman (ECDH) NIST SP 800-56Ar3 384 192 Use curve P-384 only. Diffie–Hellman key exchange 3072 128 Minimum modulus size, can be larger. RSA FIPS SP 800-56Br2 3072 128 Minimum modulus size, can be larger.Message digestSHA-2 FIPS 180-4 384 192 Use exactly SHA-384.

The CNSA 1.0 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.

Documents describing the integration of CNSA 1.0 with Internet protocols include: RFC 9151 Commercial National Security Algorithm (CNSA) Suite Profile for TLS and DTLS 1.2 and 1.3 RFC 9206 Commercial National Security Algorithm (CNSA) Suite Cryptography for Internet Protocol RFC 9212 Commercial National Security Algorithm (CNSA) Suite Cryptography for Secure Shell (SSH) RFC 8755 Using Commercial National Security Algorithm Suite Algorithms in Secure/Multipurpose RFC 8756 Commercial National Security Algorithm (CNSA) Suite Profile of Certificate Management over CMS RFC 8603 Commercial National Security Algorithm (CNSA) Suite Certificate and Certificate Revocation List (CRL) Profile

CNSA 2.0 In September 2022, the NSA announced CNSA 2.0, which includes its first recommendations for post-quantum cryptographic algorithms. Again, all parameters are provided for classified information up to TOP SECRET level.

+Components of CNSA 2.0 Purpose Algorithm Standard Parameter Length Bits of Security Notes Symmetric encryption AES FIPS 197-upd1 256 256 Key agreement ML-KEM FIPS 203 ML-KEM-1024 256 Digital signature ML-DSA FIPS 204 ML-DSA-87 256 Message digest of data SHA-2 FIPS 180-4 384 or 512 192 or 256 Digital signature of firmware and software Leighton-Micali NIST SP 800-208 192 or 256 192 or 256 All standard parameter sets are approved, the minimum being SHA256/192. SHA256/192 is the recommended choice. Xtended Merkle NIST SP 800-208 192 or 256 192 or 256 All standard parameter sets are approved, the minimum being SHA256/192.

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.

Documents describing the integration of CNSA 2.0 with Internet protocols include: draft-becker-cnsa2-smime-profile-01 Commercial National Security Algorithm (CNSA) Suite Profile for Secure/Multipurpose Internet Mail Extensions (S/MIME) draft-becker-cnsa2-ssh-profile-02 Commercial National Security Algorithm (CNSA) Suite Profile for SSH draft-becker-cnsa2-tls-profile-02 Commercial National Security Algorithm (CNSA) Suite Profile for TLS 1.3 draft-guthrie-cnsa2-ipsec-profile-01 Commercial National Security Algorithm (CNSA) Suite 2.0 Profile for IPsec draft-jenkins-cnsa2-cmc-profile-01 Commercial National Security Algorithm (CNSA) Suite Profile of Certificate Management over CMS draft-jenkins-cnsa2-pkix-profile-03 Commercial National Security Algorithm Suite Certificate and Certificate Revocation List Profile

References