[Federal Register Volume 73, Number 146 (Tuesday, July 29, 2008)]
[Notices]
[Page 43914]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-17363]


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DEPARTMENT OF COMMERCE

National Institute of Standards and Technology

[Docket No.: 070413089-8493-02]


Announcing Approval of Federal Information Processing Standard 
(FIPS) Publication 198-1, The Keyed-Hash Message Authentication Code 
(HMAC), a Revision of FIPS 198

AGENCY: National Institute of Standards and Technology (NIST), 
Commerce.

ACTION: Notice.

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SUMMARY: The National Institute of Standards and Technology (NIST) 
announces approval of Federal Information Processing Standard (FIPS) 
Publication 198-1, The Keyed-Hash Message Authentication Code (HMAC), a 
revision of FIPS 198. The FIPS specifies a mechanism for message 
authentication using cryptographic hash functions in federal 
information systems. The technical information about the security 
provided by the HMAC algorithm, and the length limit and security 
implications of truncated HMAC outputs have been removed from the 
revised standard. This information may need frequent updating, and its 
removal from the specification will enable NIST to employ a more 
effective process for keeping the information current. NIST will 
provide specific guidelines about the security provided by the HMAC and 
the use of truncation techniques for it in Special Publication (SP) 
800-17, which can be updated in a timely manner as the technical 
conditions change.

DATES: The approval changes are effective as of July 29, 2008.

FOR FURTHER INFORMATION CONTACT: Elaine Barker, Telephone (301)975-
2911, or via e-mail at [email protected] or Quynh Dang, (301) 975-
3610, e-mail: [email protected], National Institute of Standards and 
Technology, 100 Bureau Drive, Mailstop 8930, Gaithersburg, MD 20899. 
FIPS 198-1 is available electronically from the NIST Web site at: 
http://csrc.nist.gov/publications/PubsFIPS.html. NIST Special 
Publications (SPs) are available electronically from the NIST Web site 
at: http://csrc.nist.gov/publications/PubsFIPS.html.

SUPPLEMENTARY INFORMATION: On June 12, 2007, NIST published a notice in 
the Federal Register (72 FR 32281), announcing draft FIPS 198-1, and 
soliciting comments on draft standard from the public, research 
communities, manufacturers, voluntary standards organizations and 
federal, state and local government organizations. In addition, to 
being published in the Federal Register, the notice was posted on the 
NIST web pages. Information was provided about the submission of 
electronic comments and an electronic template for the submission of 
comments was made available.
    NIST received comments, responses, and questions from three federal 
government organizations and two from the public. The comments received 
asked for clarification of the text of the standard or recommended 
editorial and formatting changes. None of the comments opposed the 
approval of the revised standard. All of the suggestions and 
recommendations were carefully reviewed, and changes were made to the 
standard where appropriate. The following is the summary of the 
specific comments and NIST's responses to them:
    Comment: What are the changes between FIPS 198 and FIPS 198-1?
    Response: The length specifications for the truncated HMAC outputs 
and their security implications are no longer discussed in this 
Standard; instead, they are included in SP 800-107. The discussion 
about the limitations of MAC algorithms has been moved to SP 800-107. 
Examples and OIDs have been removed from the standards and are now 
posted on a NIST Web site that is identified in the Standard. This list 
of changes has been provided in Appendix A.
    Comment: ``K'' in the last sentence of Section 3 should be changed 
``K0'' to be consistent with Section 4.
    Response: NIST revised the text in Section 3 to improve the clarity 
of the meaning of the text.
    Comment: The first paragraph of Section 5 talks about replacing one 
of the hashes with a different hash. The need for this paragraph is not 
clearly understood.
    Response: NIST revised Section 5 to improve the clarity of the 
intended meaning of the text.
    Comment: Why has truncation been removed from the algorithm 
specification?
    Response: Truncation is still addressed in FIPS 198-1. However, the 
length of the truncated HMAC outputs and the security implications of 
truncation are not discussed in this Standard; instead, they are 
discussed in SP 800-107. A pointer to SP 800-107 has been provided in 
FIPS 198-1.
    Comment: Why is the security of the HMAC not mentioned in the FIPS 
198-1?
    Response: The discussion on the limitations of the MAC algorithms 
(i.e., the security discussion) has been moved to SP 800-107. A pointer 
to SP 800-107 has been provided in FIPS 198-1.
    Comment: A number of editorial and legal text changes were 
suggested.
    Response: NIST made the suggested changes.
    Comment: Change 0x00 to x`00' in Step 3 of Table 1 to make it 
consistent with the definition in Section 2.3.
    Response: NIST made the suggested change.
    Comment: Figure 1 does not accurately represent the steps in the 
HMAC algorithm.
    Response: NIST reviewed Figure 1 and determined that it is 
accurate.
    Security issues related to the HMAC algorithm, its applications and 
truncation limitations are addressed in draft NIST Special Publication 
800-107, Recommendation for Using Approved Hash Algorithms. Draft NIST 
Special Publication 800-107 will become NIST Special Publication 800-
107 in the near future.

    Authority: In accordance with the Information Technology 
Management Reform Act of 1996 (Pub. L. 104-106) and the Federal 
Information Security Management Act (FISMA) of 2002 (Pub. L. 107-
347), the Secretary of Commerce is authorized to approve Federal 
Information Processing Standards (FIPS). NIST activities to develop 
computer security standards to protect Federal sensitive 
(unclassified) information systems are undertaken pursuant to 
specific responsibilities assigned to NIST by section 20 of the 
National Institute of Standards and Technology Act (5 U.S.C. 278g-3) 
as amended by section 303 of the Federal Information Security 
Management Act of 2002.

    E.O. 12866: This notice has been determined not be significant for 
the purpose of E.O.12866.

    Dated: July 21, 2008.
James M. Turner,
Deputy Director.
[FR Doc. E8-17363 Filed 7-28-08; 8:45 am]
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