FAQGLOBALFIPS hash-function evidence

FIPS 180-4 and FIPS 202 hash functions How should teams use them in FIPS-approved algorithm decisions?

Use FIPS 180-4 for SHA-1 and SHA-2, FIPS 202 for SHA-3 and SHAKE, and then verify the exact implementation and operating environment through the right CAVP and CMVP evidence.

This FAQ separates hash-function selection from higher-level algorithm approval and cryptographic module validation.

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Author
Sorena AI
Published
May 9, 2026
Updated
May 9, 2026
Questions
3

Structured answer sets in this page tree.

Primary sources
5

Cited legal and guidance references.

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Sorena AI
Published May 9, 2026
Updated May 9, 2026
Overview

Short answer: cite FIPS 180-4 or FIPS 202 to identify the approved hash family, but use CAVP evidence to verify the tested implementation and CMVP evidence to verify a FIPS 140-3 module claim.

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3 of 3 questions
Question 1

Which hash functions come from FIPS 180-4 and FIPS 202?

FIPS 180-4 is the Secure Hash Standard for SHA-1 and the SHA-2 family: SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224, and SHA-512/256. FIPS 202 adds the SHA-3 family: SHA3-224, SHA3-256, SHA3-384, SHA3-512, plus the SHAKE128 and SHAKE256 extendable-output functions.

For a FIPS-approved algorithm decision, start by naming the exact function and use case. A message digest for digital signatures, an HMAC construction, a KDF, a DRBG, a post-quantum algorithm component, and a standalone SHAKE use can have different validation evidence even when the same hash family appears in the design.

  • Use FIPS 180-4 when the decision is about SHA-1 or SHA-2 digest functions.
  • Use FIPS 202 when the decision is about SHA-3 hash functions or SHAKE extendable-output functions.
  • Do not treat the standard name alone as proof that a product, library, or module is validated.
Citations
Question 2

What evidence proves the hash implementation is approved?

The useful evidence is not a screenshot that says SHA-256 or SHA3-256 exists. Record the CAVP algorithm certificate or validation result for the exact implementation name, version, algorithm, parameters, and tested operational environment.

Keep that algorithm evidence separate from the module evidence. CAVP validates algorithm implementations; CMVP validates cryptographic modules under FIPS 140-3. A module claim needs the module certificate, approved-mode documentation, and security policy scope, not only a hash-algorithm certificate.

  • Capture the algorithm name, certificate number or validation entry, implementation version, vendor, and tested operating environment.
  • For software modules, compare the CAVP operating environment with the module operating environment before relying on the certificate.
  • For a FIPS 140-3 claim, tie the hash evidence to the validated module boundary and approved services shown in CMVP-facing documentation.
Citations
Recommended next step

Separate FIPS 180-4, FIPS 202, CAVP, and CMVP claims before review

Use this FAQ to align hash-function selection, algorithm validation evidence, module scope, and approved-mode service documentation.

Assessment workflow
Check the evidence boundary

Review whether hash, higher-level algorithm, and module validation claims point to the right records.

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Research workflow
Resolve a scoped FIPS question

Compare CAVP, CMVP, and NIST source support when a hash function is used inside a larger cryptographic claim.

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Talk to Sorena
Talk through implementation

Review the product boundary, operating environment, and validation evidence for the hash functions in scope.

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Question 3

Where do teams make mistakes with SHA-3 and SHAKE?

The main mistake is treating every FIPS 202 function as interchangeable. SHA-3 hash functions can appear as standalone functions or inside approved higher-level algorithms when the relevant testing path supports that use. CMVP implementation guidance is more restrictive for SHAKE128 and SHAKE256: outside algorithm standards that explicitly allow them, SHAKE functions are used as standalone algorithms.

A second mistake is importing a hash certificate into a higher-level claim without checking whether the higher-level algorithm has its own CAVP testing requirement or vendor-affirmed path. That matters for signatures, KDFs, DRBGs, and module approved-service listings.

  • Do not substitute SHAKE for a fixed-length hash unless the higher-level algorithm standard or NIST guidance supports that use.
  • Do not list a higher-level algorithm as approved merely because one internal hash function has a CAVP certificate.
  • Do not reuse a hash validation across a changed implementation or operating environment without checking the certificate scope.
Citations
NIST FIPS 202 SHA-3 Standard

Explains that SHA-3 functions supplement FIPS 180-4 hash functions and that SHAKE output length is application-dependent.

Primary sources

References and citations

NIST FIPS 180-4 Secure Hash Standard
csrc.nist.gov
Referenced sections
  • Identifies the SHA-1 and SHA-2 algorithms covered by the Secure Hash Standard.
"SHA-1, SHA-224, SHA-256, SHA-384, SHA-512"
NIST FIPS 202 SHA-3 Standard
csrc.nist.gov
Referenced sections
  • Explains that SHA-3 functions supplement FIPS 180-4 hash functions and that SHAKE output length is application-dependent.
"the length of the output can be chosen"
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