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Herding, second preimage and Trojan message attacks beyond Merkle-Damgård. (English) Zbl 1267.94029
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, 393-414 (2009).
Summary: In this paper we present new attack techniques to analyze the structure of hash functions that are not based on the classical Merkle-Damgård construction. We extend the herding attack to concatenated hashes, and to certain hash functions that process each message block several times. Using this technique, we show a second preimage attack on the folklore “hash-twice” construction which process two concatenated copies of the message. We follow with showing how to apply the herding attack to tree hashes. Finally, we present a new type of attack – the trojan message attack, which allows for producing second preimages of unknown messages (from a small known space) when they are appended with a fixed suffix.
For the entire collection see [Zbl 1177.94012].

94A60 Cryptography
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