Draft requirements for new hashing standard open for comment

The National Institute of Standards and Technology has kicked off an effort to upgrade the Federal Information Processing Standard for hashing algorithms, publishing for public comment a draft of minimum requirements for candidates.

The new standard would replace the current FIPS 180-2, which now specifies several versions of the Secure Hash Algorithm, SHA-1; and SHA-224, SHA-256, SHA-384 and SHA-512, known collectively as SHA-2. The decision to upgrade the standard comes in the wake of successful attacks developed against some unrelated algorithms, as well as a partial compromise of SHA-1.

The current hashing standard is reviewed every five years and is scheduled for review this year and again in 2012. NIST hopes to have the new standard in place by 2012. In the meantime, the agency last year advised federal users to migrate away from use of SHA-1 as quickly as possible and no later than 2010, except for limited functions.

A hashing algorithm is a formula for generating a unique numerical digest, or hash, of a message. Because the contents of the message cannot be derived from the digest, and because the digest is (to a high degree of probability) unique, the hash can be used to securely confirm that a document has not been altered. This can be used to effectively 'sign' a document and link the signature to the contents.

The numerical suffixes in the SHA algorithms refer to the length of the digest produced by each algorithm. SHA-1 has a 160-bit digest length. The longer the digest, the more likely it is to be unique to a given message.

The SHA algorithms now recognized in the federal standard were developed by the National Security Agency. Selection of a new standard will follow the process used in developing the Advanced Encryption Standard (FIPS 140-2). Rather than rely on a proprietary algorithm developed in-house, NIST will consider publicly disclosed formulas on the assumption that public scrutiny will result in a more rigorous evaluation process and a more robust product.

The technical requirements proposed for submitted algorithms are minimal. They must be:
  • Publicly disclosed and available without a royalty
  • Implementable in a wide range of hardware and software platforms
  • Support 224-, 256-, 384- and 512-bit message digests.
NIST also has published proposed submission requirements and evaluation criteria. Comments on draft requirements are due by April 27. Additional information is available from Shujen Chang at NIST, Stop 8930, Gaithersburg, MD, 20899; or (301) 975-2940; or at www.nist.gov/hash-function.

Written comments should be mailed to William Burr, attn: Hash Algorithm Requirements and Evaluation Criteria, NIST, 100 Bureau Drive, Stop 8930, Gaithersburg, MD, 20899, or e-mailed to hash-function@nist.gov with 'Hash Algorithm Requirements and Evaluation Criteria' in the subject line.

A tentative timeline for the process calls for submissions by the third calendar quarter of 2008 and selection of the first round of candidates the following quarter. The final round of evaluations would begin in the second quarter of 2010, with a final decision in the third quarter of 2012.

About the Author

William Jackson is a Maryland-based freelance writer.

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