12 Mart 2012 Pazartesi

NIST hash function competition SHA-3


The NIST hash function competition is an open competition held by the US National Institute of Standards and Technology for a new SHA-3 function to replace the older SHA-1 and SHA-2, which was formally announced in the Federal Register on November 2, 2007. "NIST is initiating an effort to develop one or more additional hash algorithms through a public competition, similar to the development process for the Advanced Encryption Standard (AES)."

Submissions were due October 31, 2008, with a list of candidates accepted for the first round published December 9, 2008. NIST held a conference in late February 2009 where submitters gave presentations on their algorithms and NIST officials discussed criteria for narrowing down the field of candidates for Round 2. The list of 14 candidates accepted to Round 2 was published on July 24, 2009. Another conference was held August 23-24, 2010 (after CRYPTO 2010) at the University of California, Santa Barbara, where the second-round candidates were discussed. The announcement of the final round candidates occurred on December 10, 2010 and the proclamation of a winner and publication of the new standard are scheduled to take place in 2012.


NIST has selected five SHA-3 candidate algorithms to advance to the third (and final) round:
Grøstl (Knudsen et al.)
Keccak (Keccak team, Daemen et al.)
Skein (Schneier et al.)

NIST noted some factors that figured into its selection as it announced the finalists:

Performance: "A couple of algorithms were wounded or eliminated by very large [hardware gate] area requirement – it seemed that the area they required precluded their use in too much of the potential application space."

Security: "We preferred to be conservative about security, and in some cases did not select algorithms with exceptional performance, largely because something about them made us 'nervous,' even though we knew of no clear attack against the full algorithm."

Analysis: "NIST eliminated several algorithms because of the extent of their second-round tweaks or because of a relative lack of reported cryptanalysis – either tended to create the suspicion that the design might not yet be fully tested and mature."

Diversity: The finalists included hashes based on different modes of operation, including the HAIFA and sponge hash constructions, and with different internal structures, including ones based on AES, bitslicing, and alternating XOR with addition.

NIST has released a report explaining its evaluation algorithm-by-algorithm.

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