Zero-Correlation Linear Cryptanalysis on SPARX-64

SPARX is a family of ARX-based block ciphers designed according to the long-trail strategy, which has 32-bit ARX-based SBoxes and has provable bounds against single-differential and single-linear cryptanalysis. Since its proposation, some third-party cryptanalysis methods have been presented. As far as we know, the best attacks against SPARX-64 covered 16 (out of 24) rounds. In this paper, we propose zero-correlation linear attacks on SPARX-64. At first, we construct some new zero-correlation linear distinguishers covering 14-round and 15-round SPARX-64. Then, 15,16,17 and 18-round versions can be attacked using multidimensional or multiple zero-correlation linear attack models, under DKP(distinct known plaintexts) settings. These are the best attacks against SPARX-64 up to now, regarding to the number of attacked rounds. Finally, we transform the zero-correlation distinguishers into integral ones using existing methods, which are also longer than the ones proposed by the designers.

Enhancing Security in Digital Data using various Function of S-box in Data Encryption Standard Method

Stage of networking is quintessential task in which security comes into play. Securing these networks which contains confidential digital data that needs to secured will be the agenda of cryptography. Many cryptographic algorithms increment their strengths over parameters like key size, increasing the rounds of iteration and finally using confusion box as S-box as it has best robustness. So, this paper mainly focusses over securing digital data with the help of S-box function over Data Encryption Standard (DES) algorithm. For this, a plain text and key will be given to this DES as it extracts 8x8(64) bit characters from the key and converting them into its corresponding ASCII value and are concatenating to form an 8 value by taking mod16. These will give to 8 S-box in order to generate its corresponding output to make even more secure and also shows dynamic DES gives much result than other crypto methods. The evaluation of this integrated s-box and DES shows much fruitful results over factors like non-linearity, Avalanche criterion, Balance, Robustness to linear cryptanalysis, Robustness to differential cryptanalysis.

Statistical Model of Correlation Difference and Related-Key Linear Cryptanalysis

The goal of this work is to propose a related-key model for linear cryptanalysis. We start by giving the mean and variance of the difference of sampled correlations of two Boolean functions when using the same sample of inputs to compute both correlations. This result is further extended to determine the mean and variance of the difference of correlations of a pair of Boolean functions taken over a random data sample of fixed size and over a random pair of Boolean functions. We use the properties of the multinomial distribution to achieve these results without independence assumptions. Using multivariate normal approximation of the multinomial distribution we obtain that the distribution of the difference of related-key correlations is approximately normal. This result is then applied to existing related-key cryptanalyses. We obtain more accurate right-key and wrong-key distributions and remove artificial assumptions about independence of sampled correlations. We extend this study to using multiple linear approximations and propose a Χ2-type statistic, which is proven to be Χ2 distributed if the linear approximations are independent. We further examine this statistic for multidimensional linear approximation and discuss why removing the assumption about independence of linear approximations does not work in the related-key setting the same way as in the single-key setting.

Improved Impossible Differentials and Zero-Correlation Linear Hulls of New Structure III

Impossible differential cryptanalysis and zero-correlation linear cryptanalysis are two kinds of most effective tools for evaluating the security of block ciphers. In those attacks, the core step is to construct a distinguisher as long as possible. In this paper, we focus on the security of New Structure III, which is a kind of block cipher structure with excellent resistance against differential and linear attacks. While the best previous result can only exploit one-round linear layer P to construct impossible differential and zero-correlation linear distinguishers, we try to exploit more rounds to find longer distinguishers. Combining the Miss-in-the-Middle strategy and the characteristic matrix method proposed at EUROCRYPT 2016, we could construct 23-round impossible differentials and zero-correlation linear hulls when the linear layer P satisfies some restricted conditions. To our knowledge, both of them are 1 round longer than the best previous works concerning the two cryptanalytical methods. Furthermore, to show the effectiveness of our distinguishers, the linear layer of the round function is specified to the permutation matrix of block cipher SKINNY which was proposed at CRYPTO 2016. Our results indicate that New Structure III has weaker resistance against impossible differential and zero-correlation linear attacks, though it possesses good differential and linear properties.

Multidimensional linear cryptanalysis with key difference invariant bias for block ciphers

For block ciphers, Bogdanov et al. found that there are some linear approximations satisfying that their biases are deterministically invariant under key difference. This property is called key difference invariant bias. Based on this property, Bogdanov et al. proposed a related-key statistical distinguisher and turned it into key-recovery attacks on LBlock and TWINE-128. In this paper, we propose a new related-key model by combining multidimensional linear cryptanalysis with key difference invariant bias. The main theoretical advantage is that our new model does not depend on statistical independence of linear approximations. We demonstrate our cryptanalysis technique by performing key recovery attacks on LBlock and TWINE-128. By using the relations of the involved round keys to reduce the number of guessed subkey bits. Moreover, the partial-compression technique is used to reduce the time complexity. We can recover the master key of LBlock up to 25 rounds with about 260.4 distinct known plaintexts, 278.85 time complexity and 261 bytes of memory requirements. Our attack can recover the master key of TWINE-128 up to 28 rounds with about 261.5 distinct known plaintexts, 2126.15 time complexity and 261 bytes of memory requirements. The results are the currently best ones on cryptanalysis of LBlock and TWINE-128.

Quantum differential and linear cryptanalysis

Рассматриваются квантовые версии разностного и линейного методов криптоанализа, основанные на комбинации квантового алгоритма поиска минимума/максимума и квантового алгоритма перечисления. Получены оценки трудоемкости и необходимого количества ресурсов для квантовых разностного и линейного методов криптоанализа блочных шифров. Показано, что реализация квантового линейного метода требует меньше логических кубитов, чем реализация квантового разностного метода. Отмечено, что ускорение вычислений за счет «квантового параллелизма» в квантовых разностном и линейном методах криптоанализа, основанных на комбинации квантовых алгоритмов Гровера и квантового перечисления, видимо, отсутствует.

Linear Cryptanalyses of Three AEADs with GIFT-128 as Underlying Primitives

This paper considers the linear cryptanalyses of Authenticated Encryptions with Associated Data (AEADs) GIFT-COFB, SUNDAE-GIFT, and HyENA. All of these proposals take GIFT-128 as underlying primitives. The automatic search with the Boolean satisfiability problem (SAT) method is implemented to search for linear approximations that match the attack settings concerning these primitives. With the newly identified approximations, we launch key-recovery attacks on GIFT-COFB, SUNDAE-GIFT, and HyENA when the underlying primitives are replaced with 16-round, 17-round, and 16-round versions of GIFT-128. The resistance of GIFT-128 against linear cryptanalysis is also evaluated. We present a 24-round key-recovery attack on GIFT-128 with a newly obtained 19-round linear approximation. We note that the attack results in this paper are far from threatening the security of GIFT-COFB, SUNDAE-GIFT, HyENA, and GIFT-128.

Improving Highest Security Lightweight block cipher (HISEC) Algorithm Using Key Dependent S-box

Information security is considered as a very critical issue in the transmission of information. Therforelossing or threatening the information transmission will therefore be a great loss in the process of transmitting the information. Recently, Lightweight block cipher Algorithms have gained wide acceptance and it is used in restricted applications, such as electronic passport, smart card, etc. In this study, a modified HISEC algorithm is proposed to enhance and improve the original HISEC algorithm by introducing the concept of a key dependent S-box. This proposal algorithm aims to generate a safer block of code and solve the problem of the fixed structure of the used S-box that was a vulnerability for the attacker. It was an impenetrable barrier facing the attacks of the (Linear cryptanalysis) and (Differential Cryptanalysis). The proposed algorithm showed some improvements when comparing it to the orginal algorithm.

Generalized differential-linear cryptanalysis of block cipher

Differential-linear cryptanalysis of block ciphers was proposed in 1994. It turns out to be more efficient in comparison with (separately) differential and linear cryptanalytic methods, but its scientific substantiation remains the subject of further research. There are several publications devoted to formalization of differential-linear cryptanalysis and clarification of the conditions under which its complexity can be mathematically accurately assessed. However, the problem of the differential-linear cryptanalytic method substantiation remains completely unresolved. This paper presents first results obtained by the author in the direction of solving this problem. The class of differential-linear attacks on block ciphers is expanded. Namely, both distinguishing attacks and attacks aimed at recovering one bit of information about a key are considered. In this case, no assumptions are made (as in well-known publications) about the possibility of representing the cipher in the form of some two components. Lower bounds of information complexity of these attacks are obtained. The expressions of these bounds depend on the averaged (by keys) values of the elements’ squares of the generalized autocorrelation table of the encryption transformation. In contrast to the known ones, the obtained bounds are not based on any heuristic assumptions about the investigated block ciphers and are valid for a wider class of attacks as compared to the traditional differential-linear attack. Relations between, respectively, differential, linear and differential-linear properties of bijective Boolean mappings are given. In contrast to the well-known works, the matrix form of the relations is used that makes it possible to clarify better their essence and simplify the proofs. A new relation is derived for the elements of the generalized autocorrelation table of the encryption transformation of the product of two block ciphers, which may be useful in further research.

Towards Key-recovery-attack Friendly Distinguishers: Application to GIFT-128

When analyzing a block cipher, the first step is to search for some valid distinguishers, for example, the differential trails in the differential cryptanalysis and the linear trails in the linear cryptanalysis. A distinguisher is advantageous if it can be utilized to attack more rounds and the amount of the involved key bits during the key-recovery process is small, as this leads to a long attack with a low complexity. In this article, we propose a two-step strategy to search for such advantageous distinguishers. This strategy is inspired by the intuition that if a differential is advantageous only when some properties are satisfied, then we can predefine some constraints describing these properties and search for the differentials in the small set.As applications, our strategy is used to analyze GIFT-128, which was proposed in CHES 2017. Based on some 20-round differentials, we give the first 27-round differential attack on GIFT-128, which covers one more round than the best previous result. Also, based on two 17-round linear trails, we give the first linear hull attack on GIFT-128, which covers 22 rounds. In addition, we also give some results on two GIFT-128 based AEADs GIFT-COFB and SUNDAE-GIFT.