Impossible differential attacks are among the most powerful forms of cryptanalysis against block ciphers. We present in this paper an in-depth complexity analysis of these attacks. We show an unified way to mount such attacks and provide generic formulas for estimating their time and data complexities. LBlock is a well studied lightweight block cipher with respect to impossible differential att...

A well-recognized open conceptual problem in relativistic quantum field theory concerns the relation between measurement and causality. Naive generalizations of rules can allow for superluminal signaling (``impossible measurements''). This raises delineating physically allowed measurements operations. We analyze this issue a recently proposed framework which local (in possibly curved spacetime)...

We introduce subspace trail cryptanalysis, a generalization of invariant subspace cryptanalysis. With this more generic treatment of subspaces we do no longer rely on specific choices of round constants or subkeys, and the resulting method is as such a potentially more powerful attack vector. Interestingly, subspace trail cryptanalysis in fact includes techniques based on impossible or truncate...

Impossible boomerang attack [5] (IBA) is a new variant of differential cryptanalysis against block ciphers. Evident from its name, it combines the ideas of both impossible differential cryptanalysis and boomerang attack. Though such an attack might not be the best attack available, its complexity is still less than that of the exhaustive search. In impossible boomerang attack, impossible boomer...

Standard differential cryptanalysis uses statistical dependencies between the difference of two plaintexts and the difference of the respective two ciphertexts to attack a cipher. Here we introduce polytopic cryptanalysis which considers interdependencies between larger sets of texts as they traverse through the cipher. We prove that the methodology of standard differential cryptanalysis can un...

CLEFIA is a 128-bit block cipher proposed by Sony Corporation in 2007. Our paper introduces a new chosen text attack, impossible differential-linear attack, on iterated cryptosystems. The attack is efficient for 16-round CLEFIA with whitening keys. In the paper, we construct a 13-round impossible differential-linear distinguisher. Based on the distinguisher, we present an effective attack on 16...

SPARX-64/128 is an ARX-based block cipher with 64-bit block size and 128-bit key. It was published in Asiacrypt 2016 as one of the instantiations of a family of ARX-based block ciphers with provable security against single-characteristic differential and linear cryptanalysis. In this work, we present 12 and 13-round impossible distinguishers on SPARX-64/128 that can be used to attack 15 and 16-...

CLEFIA is a 128-bit block cipher proposed by Sony Corporation in 2007. Our paper introduces a new chosen text attack, the impossible differential-linear attack, on iterated cryptosystems. The attack is efficient for 16-round CLEFIA with whitening keys. In the paper, we construct a 13-round impossible differential-linear distinguisher. Based on the distinguisher, we present an effective attack o...

In this paper, a new tool searching for impossible differentials against symmetric-key primitives is presented. Compared to the previous tools, our tool can detect any contradiction between input and output differences, and it can take into account the property inside the S-box when its size is small e.g. 4 bits. In addition, several techniques are proposed to evaluate 8-bit S-box. With this to...

SAFER+ was a candidate block cipher for AES with 128-bit block size and a variable key sizes of 128, 192 or 256 bits. Bluetooth uses customized versions of SAFER+ for security. The numbers of rounds for SAFER+ with key sizes of 128, 192 and 256 are 8, 12 and 16, respectively. SAFER++, a variant of SAFER+, was among the cryptographic primitives selected for the second phase of the NESSIE project...