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Announcement of Proposal to Convert FIPS 198-1, "The Keyed-Hash Message Authentication Code (HMAC)," to a NIST Special Publication
September 20, 2022

As a part of the periodic review of NIST’s cryptographic standards and guidelines, NIST's Crypto Publication Review Board announced the review of FIPS 198-1 The Keyed-Hash Message Authentication Code (HMAC) in August 2021. In response, NIST received public comments.

NIST proposes to convert FIPS 198-1 to a NIST Special Publication (SP), and apply the following changes:

  • Update the HMAC specification to include block sizes for the SHA-3 family of hash functions
  • Include a discussion on truncation
  • Improve the editorial quality and update references

Conversion to an SP: NIST typically specifies fundamental cryptographic primitives—block ciphers, digital signatures algorithms, and hash functions—as FIPS publications, whereas other cryptographic schemes—modes of operation, message authentication codes, etc.—are published as a part of the NIST SP 800 series. (For more information, see Section 3 of NISTIR 7977.) To be consistent with that approach, NIST proposes to convert FIPS 198-1 to an SP.

In particular, NIST proposes to develop a draft SP for the HMAC specification, updated as described above, which would be released for public comment. When the SP is finalized and published, FIPS 198-1 would be withdrawn simultaneously.

Send comments on the decision proposal by October 20, 2022 to with “Comments on FIPS 198-1 decision proposal” in the subject line.  

Comments received in response to this request will be posted on the Crypto Publication Review Project site after the due date. Submitters’ names and affiliations (when provided) will be included, while contact information will be removed. See the project site for additional information about the review process.

Created September 19, 2022, Updated September 20, 2022