Combinatorics on words in information security: Unavoidable regularities in the construction of multicollision attacks on iterated hash functions

Juha Kortelainen
(Department of Information Processing Science, University of Oulu, Finland)

Classically in combinatorics on words one studies unavoidable regularities that appear in sufficiently long strings of symbols over a fixed size alphabet. In this paper we take another viewpoint and focus on combinatorial properties of long words in which the number of occurrences of any symbol is restritced by a fixed constant. We then demonstrate the connection of these properties to constructing multicollision attacks on so called generalized iterated hash functions.

Invited Presentation in Petr Ambrož, Štěpán Holub and Zuzana Masáková: Proceedings 8th International Conference Words 2011 (WORDS 2011), Prague, Czech Republic, 12-16th September 2011, Electronic Proceedings in Theoretical Computer Science 63, pp. 22–29.
Published: 17th August 2011.

ArXived at: http://dx.doi.org/10.4204/EPTCS.63.4 bibtex PDF
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