New truncated differential cryptanalysis on 3D block cipher

Abstract

This paper presents 11- and 13-round key-recovery attacks on block cipher 3D with the truncated differential cryptanalysis, while the previous best key-recovery attack broke only 10 rounds with the impossible differential attack. 3D is an AES-based block cipher proposed at CANS 2008, which operates on 512-bit blocks and a 512-bit key, and consists of 22 rounds. It was previously believed that the truncated differential cryptanalysis could not extend the attack more than 5 rounds. However, by carefully analyzing the data processing part and key schedule function simultaneously, we show the attack to 11-round 3D with 2 251 chosen plaintext (CP), 2 288 computations, and 2 128 memory. Additionally, the time complexity is improved up to 2 113 by applying the early aborting technique. By utilizing the idea of neutral bit, we attack 13-round 3D with 2 469 CP, 2 308 computations, and 2 128 memory. © 2012 Springer-Verlag.