Amplified Boomerang Attacks Against Reduced-Round MARS and Serpent

J. Kelsey, T. Kohno, and B. Schneier

Seventh Fast Software Encryption Workshop, Springer-Verlag, 2000, to appear.

ABSTRACT: We introduce a new cryptanalytic technique based on Wagner's boomerang and inside-out attacks. We first describe this new attack in terms of the original boomerang attack, and then demonstrate its use on reduced-round variants of the MARS core and Serpent. Our attack breaks eleven rounds of the MARS core with 265 chosen plaintexts, 270 memory, and 2229 partial decryptions. Our attack breaks eight rounds of Serpent with 2114 chosen plaintexts, 2119 memory, and 2179 partial decryptions.

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