Deoxys is a final-round candidate of the CAESAR competition. Deoxys is built upon an internal tweakable block cipher Deoxys-BC, where in addition to the plaintext and key, it takes an extra non-secret input called a tweak. This paper presents the first impossible differential cryptanalysis of Deoxys-BC-256 which is used in Deoxys as an internal tweakable block cipher. First, we find a 4.5-round...

Impossible differential cryptanalysis, the extension of differential cryptanalysis, is one of the most efficient attacks against block ciphers. This cryptanalysis method has been applied to most of the block ciphers and has shown significant results. Using structures, key schedule considerations, early abort, and pre-computation are some common methods to reduce complexities of this attack. In ...

1 Evaluation of security 1.1. Differential cryptanalysis In extending differential cryptanalysis, Aoki , Kobayashi, and Moriai [1] greatly reduced the computational amount needed [2]. They determined that differential cryptanalysis could not be applied to FEAL with more than 32 rounds. Biham et al. [3] proposed a new cyptanalysis of Skipjack [4] using impossible differentials. Although regular ...

In this paper, we improve the impossible differential attack on 20-round LBlock given in the design paper of the LBlock cipher. Using relations between the round keys we attack on 21-round and 22-round LBlock with a complexity of 2 and 2 encryptions respectively. We use the same 14-round impossible differential characteristic observed by the designers to attack on 21 rounds and another 14-round...

This paper studies the security of ARIA against impossible differential cryptanalysis. Firstly an algorithm is given to find many new 4-round impossible differentials of ARIA. Followed by such impossible differentials, we improve the previous impossible differential attack on 5/6-round ARIA. We also point out that the existence of such impossible differentials are due to the bad properties of t...

Since its introduction, impossible differential cryptanalysis has been applied to many ciphers. Besides the specific application of the technique in various instances, there are some very basic results which apply to generic structures of ciphers, e.g., the well known 5-round impossible differential of Feistel ciphers with bijective round functions. In this paper we present a new approach for t...

Impossible differential cryptanalysis is one of the cryptanalysis methods that are applicable to the new Advanced Encryption Standard (AES). In this paper, we present an introduction to the method by applying it on Mini-AES, the mini version of the AES published in Cryptologia recently.

Impossible differential is a useful method for cryptanalysis. SIMON is a light weight block cipher that has attracted lots of attention ever since its publication in 2013. In this paper we propose impossible differential attack on five versions of SIMON, using bit conditions to minimize key bits guessed. We calculate keybits and give the exact attack results.