Рассмотрено применение атаки различения на ряд легковесных блочных шифров, основанных на ARX-операциях (сложение по модулю, циклический сдвиг и исключающее ИЛИ). Представлены экспериментальные результаты и теоретические оценки устойчивости легковесных шифров Speck, Simon, Simeck, HIGHT, LEA к атаке различения. Вывод, что семейство шифров Simeck не выдерживает эту атаку, сделан на основе прогнозов, полученных путем экстраполяции экспериментальных данных. The distinguishing attack on modern lightweight ARX-based block ciphers was applied. Distinguishing attack is any form of cryptanalysis on data encrypted by a cipher that allows an attacker distinguishing the encrypted data from random data.Purpose. Modern symmetric-key ciphers must be designed to be immune to such an attack. The purpose of the work was to estimate the resistance of lightweight ciphers Speck, Simon, Simeck, HIGHT, and LEA to a distinguishing attack.Methodology. We note that these ciphers are iterated block ciphers. It is means that they transform blocks of plain text into blocks of cipher text by using the cyclically repeated invertible function known as the round function where each iteration is to be referred as a round. We have experimentally found a maximum number of rounds where encrypted data looked like random bit-sequence by using statistical test “Book Stack”. Then we extrapolated the theoretical length required for a successful distinguishing attack on cipher with full-number rounds by a polynomial of a low degree. Note that cryptography attack is considered as successful if the length of the encrypted sequence is less than the length 2K (K — key size).Originality/value. Our experiments and estimations show, that Simeck with 48bit block size and 96-bit key size is not immune to distinguishing attack. We recommended increasing the number of rounds by 15–20% in order to improve the reliability of the Simeck 48/96.

Предложен основанный на теоретико-информационном подходе метод оценки эффективности сетей передачи данных. Метод позволяет получить априорную оценку эффективности проектируемой сети на основе информации о ее параметрах, так как для получения оценки не требуется наличия действующей сети и данных, получаемых в процессе ее эксплуатации. Дано описание метода, а также приведены примеры его использования для оценки эффективности сетей доставки контента и сетей на базе peer-to-peer-технологии. Purpose. Development and investigation of the method for analytical estimation for the efficiency of data transmission networks basing on the details of the supposed network parameters. This method allow us to evaluate a priori comprehensive estimation of efficiency of the network being designed without the necessity of collecting and analyzing real world network operational data. Methodology. A set of files to be downloaded by the network node is considered as a subsequence of letters generated by stationary and ergodic process. Basing on the fundamentals of Information theory the entropy efficiency was defined to characterize a capacity of data transmission network. Informally, the value actually indicates the growth rate of the amount of files that can be transmitted via the network depending on a certain unit of time. To model the distribution of the probability of access to files, Zipf’s law was used. Findings. A general description of a method for efficiency estimation of data transmission networks was presented in the paper. Detailed guidelines to apply the method to the estimation of multimedia content delivery networks and file sharing P2P networks, i. e. systems of two wide spread classes, were shown. The method was also investigated on the software models of the systems to show the possibility of using the method as a tool for optimal selection of network parameters. Originality/value. The suggested information-theoretic method is aimed to analytically estimate the efficiency of the data transmission networks. It can be used as a strong tool to construct both new multimedia data transmission systems and optimization of the existing services.

Предложен теоретико-информационный подход к оценке производительности суперкомпьютеров. Этот подход основан на характеристике “вычислительная способность”, которую можно определить теоретически, опираясь исключительно на описание архитектуры исследуемой системы. Предложен метод определения вычислительной способности суперкомпьютеров с учетом влияния межпроцессорного взаимодействия. Метод применяется в работе для оценки производительности пяти суперкомпьютеров среди первых 50 позиций в списке TOP500 (ноябрь 2016). Полученные результаты сравниваются с аналогичными значениями бенчмарка LINPACK и характеристиками Theoretical peak, используемыми для формирования рейтинга TOP500. По результатам сравнения делаются выводы относительно применимости указанного подхода для оценки производительности суперкомпьютеров на этапе разработки. In this paper we present the informational-theoretical approach to the evaluation of performance for supercomputers. This approach is based on the computer capacity characteristic which can be estimated theoretically (without any experiments over the working model of the investigated computer) relying on the description of the architecture of the system under study. We describe the method for estimation of the supercomputers Computer capacity which takes into account the influence of the interprocess communication. The described method is used in this paper to estimate the performance of the five supercomputers among the first fifty positions in TOP500 list (according to November 2016 data). The obtained results are compared with the values of LINPACK benchmark and Theoretical peak characteristic which are used to form the TOP500 rating. Based on the comparison we draw conclusions about the applicability of the presented approach to the evaluation of supercomputers performance at the design stage.

Making use of cryptographic algorithms RC5 and RC6 is considered as the generators of pseudo-random numbers. The algorithms RC5 and RC6 are briefly described. Practical recommendations for the application are given.