Impossible Differential Cryptanalysis(IDC) [4] uses impossible differential characteristics to retrieve a subkey material for the first or the last several rounds of block ciphers. Thus, the security of a block cipher against IDC can be evaluated by impossible differential characteristics. In this paper, we study impossible differential characteristics of block cipher structures whose round fun...

Many attacks on iterated block ciphers rely on statistical considerations using plaintext/ciphertext pairs to distinguish some part of the cipher from a random permutation. We provide here a simple formula for estimating the amount of plaintext/ciphertext pairs which is needed for such distinguishers and which applies to a lot of different scenarios (linear cryptanalysis, differentiallinear cry...

This paper describes truncated and impossible differential cryptanalysis of the 128-bit block cipher Camellia, which was proposed by NTT and Mitsubishi Electric Corporation. Our work improves on the best known truncated and impossible differential cryptanalysis. As a result, we show a nontrivial 9-round byte characteristic, which may lead to a possible attack of reduced-round version of Camelli...

This paper studies the security of the block ciphers ARIA and Camellia against impossible differential cryptanalysis. Our work improves the best impossible differential cryptanalysis of ARIA and Camellia known so far. The designers of ARIA expected no impossible differentials exist for 4-round ARIA. However, we found some nontrivial 4-round impossible differentials, which may lead to a possible...

In this paper, we analyze the security claims of Extended Generalized Feistel Networks (EGFNs) schemes proposed by Berger et al [1]. We provide impossible differentials for 10 rounds of EGFNs with 16 branches which add up one round to the claim of 9 rounds in the impossible differential trail. Therefore, impossible differential trail covers 10 rounds for the EGFNs scheme, which is the best resu...

We introduce commutative diagram cryptanalysis, a framework for expressing certain kinds of attacks on product ciphers. We show that many familiar attacks, including linear cryptanalysis, differential cryptanalysis, differential-linear cryptanalysis, mod n attacks, truncated differential cryptanalysis, impossible differential cryptanalysis, higherorder differential cryptanalysis, and interpolat...

© 2014 ETRI Journal, Volume 36, Number 6, December 2014 http://dx.doi.org/10.4218/etrij.14.0113.1335 The Lai-Massey scheme, proposed by Vaudenay, is a modified structure in the International Data Encryption Algorithm cipher. A family of block ciphers, named FOX, were built on the Lai-Massey scheme. Impossible differential cryptanalysis is a powerful technique used to recover the secret key of b...

Midori128 is a lightweight block cipher proposed at ASIACRYPT 2015 to achieve low energy consumption per bit. Currently, the best published impossible differential attack on Midori128 covers 10 rounds without the pre-whitening key. By exploiting the special structure of the S-boxes and the binary linear transformation layer in Midori128, we present impossible differential distinguishers that co...

Camellia and MISTY1 are Feistel block ciphers. In this paper, we observe that, when conducting impossible differential cryptanalysis on Camellia and MISTY1, their round structures allow us to partially determine whether a candidate pair is right by guessing only a small fraction of the unknown required subkey bits of a relevant round at a time, instead of all of them. This reduces the computati...