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Cryptanalysis of dynamic SHA(2). (English) Zbl 1267.94035
Jacobson, Michael J. jun. (ed.) et al., Selected areas in cryptography. 16th annual international workshop, SAC 2009, Calgary, Alberta, Canada, August 13–14, 2009. Revised selected papers. Berlin: Springer (ISBN 978-3-642-05443-3/pbk). Lecture Notes in Computer Science 5867, 415-432 (2009).
Summary: In this paper, we analyze the hash functions dynamic SHA and dynamic SHA2, which have been selected as first round candidates in the NIST hash function competition. These hash functions rely heavily on data-dependent rotations, similar to certain block ciphers, e.g., RC5. Our analysis suggests that in the case of hash functions, where the attacker has more control over the rotations, this approach is less favorable than in block ciphers. We present practical, or close to practical, collision attacks on both dynamic SHA and dynamic SHA2. Moreover, we present a preimage attack on dynamic SHA that is faster than exhaustive search.
For the entire collection see [Zbl 1177.94012].
MSC:
94A60 Cryptography
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