Showing papers by "Tadayoshi Kohno published in 2000"

Amplified Boomerang Attacks Against Reduced-Round MARS and Serpent

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.

Preliminary Cryptanalysis of Reduced-Round Serpent

Abstract: Serpent is a 32-round AES block cipher nalist. In this paper we present several attacks on reduced-round variants of Serpent that re- quire less work than exhaustive search. We attack six-round 256-bit Ser- pent using the meet-in-the-middle technique, 512 known plaintexts, 2 246 bytes of memory, and approximately 2 247 trial encryptions. For all key sizes, we attack six-round Serpent using standard dierential cryptanaly- sis, 2 83 chosen plaintexts, 2 40 bytes of memory, and 2 90 trial encryptions. We present boomerang and amplied boomerang attacks on seven- and eight-round Serpent, and show how to break nine-round 256-bit Serpent using the amplied boomerang technique, 2 110 chosen plaintexts, 2 212 bytes of memory, and approximately 2 252 trial encryptions.