NSA Cryptographic Standards

Here’s a summary of the main cryptographic standard sets devised or endorsed by the National Security Agency (NSA) for U.S. Government usage, including the current-state status.

1. Suite A

• Suite A is a set of classified/unpublished cryptographic algorithms used by the NSA for the most highly-sensitive (e.g., SCI) communications. Wikipedia+2Wikipedia+2
• Because the algorithms are not publicly disclosed, their details are not available to the general public.
• It is used where publicly‐documented algorithms (e.g., Suite B) may not be appropriate. Wikipedia

2. Suite B

• Announced by the NSA on 16 February 2005 as part of its Cryptographic Modernization Program. Wikipedia+1
• Its goal: provide a common set of cryptographic algorithms to support both unclassified information and most classified information (up to a certain level). Wikipedia
• Components (publicly documented) of Suite B include:

• • Symmetric encryption: AES (with key sizes 128 / 256) Wikipedia+1
  • Digital signatures: ECDSA (elliptic curve digital signature algorithm) using P-256 and P-384 curves. Wikipedia+1
  • Key agreement: ECDH (elliptic curve Diffie–Hellman) with 256/384‐bit parameters. Wikipedia+1
  • Hashing/digests: SHA‑2 family (e.g., SHA-256, SHA-384) Wikipedia

• For example, RFC 6380 (“Suite B Profile for IPsec”) specifies using AES + ECDSA/ECDH curves etc. IETF Datatracker
• Important caveat: In 2015 the NSA indicated it would transition away from Suite B toward quantum-resilient algorithms; Suite B algorithms were reclassified as “historic” by IETF in 2018. Wikipedia+1

3. Commercial National Security Algorithm (CNSA) Suite

• As part of preparing for quantum threats and moving beyond Suite B, the NSA introduced the CNSA Suite (original in 2015) which defines algorithm sets for Government use protecting classified information and “future environments.” Wikipedia+2U.S. Department of War+2
• For instance, the document “CNSA 2.0” (2022) provides FAQ and guidance for the next generation algorithm set. U.S. Department of War
• These are currently the baseline for U.S. Government cryptographic use in many contexts, especially as quantum resistance becomes a focus. U.S. Department of War+1

4. Other relevant definitions & standards

• “FIPS 140” (Federal Information Processing Standard 140) and its successor FIPS 140-3 define security requirements for cryptographic modules—hardware or software—that handle sensitive data. While not solely NSA cryptographic algorithm standards, they go hand-in-hand with NSA requirements for “NSA-approved cryptography.” Wikipedia+1
• Definition: “NSA-approved cryptography” means: (i) an approved algorithm; (ii) an implementation approved for protection of classified or controlled unclassified information; (iii) a supporting key-management infrastructure. NIST Computer Security Resource Center

5. Key take-aways for application / compliance

• If your environment requires NSA-approved cryptography (e.g., for classified or national-security systems), you must ensure you’re using an algorithm from a suite recognized by the NSA (Suite A or Suite B or CNSA), with an approved implementation and proper key-management.
• Legacy systems using Suite B algorithms should transition to the CNSA Suite in light of evolving threats (especially quantum).
• Selection of algorithm among the suite depends on classification level, performance, interoperability, and lifecycle considerations.
• Implementation matters: using a strong algorithm isn’t sufficient unless the module and key-management are also approved and validated. Side-channel resistance, tamper-resistance, etc become critical especially for high‐assurance systems. Rambus+1