Plan-execute-verify on OWASP vs NIST on password hashing

Based on my research, I need to correct my previous answer because it made claims not supported by the sources. Let me provide an accurate answer based only on what these sources actually state.

Corrected Answer

When a team must satisfy both OWASP password storage guidance and NIST SP 800-63B-4 requirements while maintaining US federal FIPS compliance, the two sources address the requirement differently.

OWASP Password Storage Guidance

OWASP recommends a clear hierarchy. For systems without FIPS requirements, the primary recommendation is Argon2id: "Use Argon2id with a minimum configuration of 19 MiB of memory, an iteration count of 2, and 1 degree of parallelism." For FIPS-140 compliance specifically, OWASP states: "If FIPS-140 compliance is required, use PBKDF2 with a work factor of 600,000 or more and set with an internal hash function of HMAC-SHA-256."

Later in the OWASP guidance, when discussing PBKDF2, it states: "Since PBKDF2 is permitted by NIST SP 800-63B-4 and has FIPS-140 validated implementations, it should be the preferred algorithm when these are required."

NIST SP 800-63B-4 Requirements

NIST SP 800-63B-4 requires password hashing but does not mandate specific algorithms by name. The standard states: "Passwords SHALL be salted and hashed using a suitable password hashing scheme. Password hashing schemes take a password, a salt, and a cost factor as inputs and generate a password hash." It further specifies: "An approved password hashing scheme published in the latest revision of [SP800-132] or updated NIST guidelines on password hashing schemes SHOULD be used."

NIST SP 800-63B-4 defines "approved cryptography" as: "An encryption algorithm, hash function, random bit generator, or similar technique that is Federal Information Processing Standards (FIPS)-approved or NIST-recommended. Approved algorithms and techniques are either specified or adopted in a FIPS or NIST recommendation."

Reconciliation

The reconciliation depends on interpreting what constitutes "approved" algorithms under NIST SP 800-63B-4. NIST's definition includes both FIPS-approved and NIST-recommended algorithms. However, NIST SP 800-63B-4 itself does not name specific password hashing algorithms, instead referring to SP800-132 (which specifies PBKDF2) and "updated NIST guidelines."

For systems requiring FIPS-140 compliance, both sources effectively converge on PBKDF2: OWASP explicitly requires it for FIPS-140, and OWASP notes that PBKDF2 is "permitted by NIST SP 800-63B-4." PBKDF2 with HMAC-SHA-256 at 600,000 iterations (per OWASP) satisfies the requirement for an "approved" algorithm under NIST's definition, as it is FIPS-approved.

For systems without FIPS requirements, OWASP's recommendation of Argon2id differs from what NIST SP 800-63B-4 explicitly names, since NIST SP 800-63B-4 does not mention Argon2 by name. The reconciliation requires understanding that NIST defers to "updated NIST guidelines on password hashing schemes" beyond what is explicitly stated in the document.

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