Towards a combined Rotational-Differential Cryptanalytic Framework

In this report, we suggest a new cryptanalytic framework of constructing distinguishers which can be eventually extended to full attacks in the related-key scenario. We name this new paradigm as ”Relational Cryptanalysis”. The main idea is to exhibit the non-randomness of a given encryption algorithm by observing the propagation of specific sets of plaintexts of the form (P,P′) such that these pairs satisfy some rotational and differential properties of the form R1(P) = P′ and P ⊕ P′ ∈ ∆P, for some rotational symmetry R1 and fixed set of differences ∆P . Except of rotational and differential properties, we can add any other relation which seems to hold for a reduced number of rounds of the cryptographic primitive we study. Intuitively, we expect that by adding more relations we increase the observed probability of the propagation and this result to stronger statistical distinguishers

Advanced truncated differential cryptanalysis of GOST block cipher

n this paper, we use the ideas presented by Courtois and Mourouzis to study the security of two variants of GOST, which are considered as the simpler and most secure variants [9]; the one with the S-boxes replaced by the Identity Map and the ISO version which is assumed to be the strongest one. The advanced differential attacks we present are of the form of Depth-First Key search, which uses a 20 round distinguisher in the middle (or equivalently 26-round distinguisher for the simpler version of GOST with Identity Map) [11]. The main idea is that we consider a partition of the 32 rounds by placing in the middle the constructed distinguisher. Then, based on the weak diffusion we can extend these very strong statistical distinguishers to efficiently good filters for some external rounds. Then, by guessing some key bits for external rounds and determining some plaintext and ciphertext pairs of specified input-output differences we can extend the construction to an attack against the full block cipher. Thus, the technique we apply is a generic cryptanalytic framework of First-Search key search type which involves several optimization tasks obtained from the specific structure of the given encryption algorithm

Fast, parallel and secure cryptography algorithm using Lorenz's attractor

A novel cryptography method based on the Lorenz's attractor chaotic system is presented. The proposed algorithm is secure and fast, making it practical for general use. We introduce the chaotic operation mode, which provides an interaction among the password, message and a chaotic system. It ensures that the algorithm yields a secure codification, even if the nature of the chaotic system is known. The algorithm has been implemented in two versions: one sequential and slow and the other, parallel and fast. Our algorithm assures the integrity of the ciphertext (we know if it has been altered, which is not assured by traditional algorithms) and consequently its authenticity. Numerical experiments are presented, discussed and show the behavior of the method in terms of security and performance. The fast version of the algorithm has a performance comparable to AES, a popular cryptography program used commercially nowadays, but it is more secure, which makes it immediately suitable for general purpose cryptography applications. An internet page has been set up, which enables the readers to test the algorithm and also to try to break into the cipher in

RAZOR A Lightweight Block Cipher for Security in IoT

Rapid technological developments prompted a need to do everything from anywhere and that is growing due to modern lifestyle. The Internet of Things (IoT) technology is helping to provide the solutions by inter-connecting the smart devices. Lightweight block ciphers are deployed to enable the security in such devices. In this paper, a new lightweight block cipher RAZOR is proposed that is based on a hybrid design technique. The round function of RAZOR is designed by mixing the Feistel and substitution permutation network techniques. The rotation and XOR based diffusion function is applied on 32-bit input with 8 branches and branch number 7 to optimize the security. The strength of RAZOR is proved against differential, linear, and impossible differential attacks. The number of active S-boxes in any 5-round differential characteristic of RAZOR is 21 in comparison to the 10, 6, 4, 7, and 6 for PRESENT, Rectangle, LBlock, GIFT, and SCENERY respectively. RAZOR provides better security than the existing lightweight designs. The average throughput of 1.47 mega bytes per second to encrypt the large files makes it a better choice for software oriented IoT applications

Heuristic algorithm for obtaining permutations with given cryptographic properties using a generalized construction

Исследована возможность построения с помощью обобщённой конструкции подстановок с заданными криптографическими характеристиками, обеспечивающими стойкость алгоритмов шифрования к линейному и разностному методам криптоанализа. Предложен эвристический алгоритм поиска параметров обобщённой конструкции, полученных посредством умножения на транспозиции. Исполь-зуются идеи генетического алгоритма, спектрально-линейного и спектрально-разностного методов. Изучены вопросы оптимизации вычисления криптографических характеристик на каждой итерации алгоритма. Экспериментальные исследования наиболее интересных с практической точки зрения 8-битовых подстановок показали, что можно построить 6-равномерные подстановки с нелинейностью 108

Differential cryptanalysis of new Qamal encryption algorithm

Currently, the Republic of Kazakhstan is developing a new standard for symmetric data encryption. One of the candidates for the role of the standard is the Qamal encryption algorithm developed by the Institute of Information and Computer Technologies (Almaty, Republic of Kazakhstan). The article describes the algorithm. Differential properties of the main operations that make up the Qamal cypher are considered in the questions of stability. We have shown that for a version with a 128-bit data block and the same secret key size for three rounds of encryption it is difficult to find the right pairs of texts with a probability of 2–120, which makes differential cryptanalysis not applicable to the Qamal cyphe

Differential cryptanalysis of new Qamal encryption algorithm

Currently, the Republic of Kazakhstan is developing a new standard for symmetric data encryption. One of the candidates for the role of the standard is the Qamal encryption algorithm developed by the Institute of Information and Computer Technologies (Almaty, Republic of Kazakhstan). The article describes the algorithm. Differential properties of the main operations that make up the Qamal cypher are considered in the questions of stability. We have shown that for a version with a 128-bit data block and the same secret key size for three rounds of encryption it is difficult to find the right pairs of texts with a probability of 2–120, which makes differential cryptanalysis not applicable to the Qamal cyphe