Klyucharev

pp. 142-152

pp. 132-142

pp. 200-213

pp. 92-105

pp. 188-199

pp.194-202

In the paper the author considers hardware implementation of the GRACE-H family general cellular automata based cryptographic hash functions. VHDL is used as a language and Altera FPGA as a platform for hardware implementation. Performance and effectiveness of the FPGA implementations of GRACE-H hash functions were compared with Keccak (SHA-3), SHA-256, BLAKE, Groestl, JH, Skein hash functions. According to the performed tests, performance of the hardware implementation of GRACE–H family hash functions significantly (up to 12 times) exceeded performance of the hardware implementation of previously known hash functions, and effectiveness of that hardware implementation was also better (up to 4 times).

In this article data on performance and effectiveness of the GRACE-S family of stream ciphers based on generalised cellular automata and expander graphs were discussed. Altera FPGA was used as a platform for hardware implementation. The performance of GRACE-S stream ciphers was compared with the performance of stream ciphers that had won the eSTREAM competition. According to the performed tests, the performance of the GRACE–S family of stream ciphers significantly (up to 60 times) exceeds the performance of the best-known stream ciphers.

In this paper we compute some characteristics of the spectrum of LiveJournal’s social graph and estimate the vertex and edge expansion ratios of this graph. We use the Power Iteration algorithm to compute first and second elements of the graph’s spectrum. The concept of application of the spectral graph theory methods to problems of social network analysis appeared to be very promising. Methods described in this paper could be applied to analysis of social networks, study of the social interactions between people and many other problems at the intersection of sociology, computer science and information security.

In this paper the authors investigates strength of block ciphers based on generalized cellular automata, against classical linear cryptanalysis. A linear cryptanalysis is one of the main standard techniques for cracking block ciphers. Sufficient condition for strength of this family of ciphers against linear cryptanalysis is the main result of this paper. This condition was used to demonstrate that with an arbitrary graph of a cellular automaton in case of correct selection of a local connecting function and other parameters in order to create ciphers with key length of 128 and 256 bits and block length of 128 bits which couldn’t be cracked by linear cryptanalysis when using 4 rounds and 7 steps of a cellular automaton per round.

In this paper the author introduces a family of cryptographic hash functions based on using generalized cellular automata. The structure of the proposed functions is a dendrogram which includes a one-way pseudorandom function built with the use of a generalized cellular automaton whose graph is a Ramanujan graph. The local link function of the cellular automata is a balanced function with large nonlinearity and some additional properties. The family of proposed hash functions may find practical application in a number of information security tasks, including authentication, integrity, digital signature, etc.

In this paper the author proposes a method of constructing block ciphers which is based on using generalized cellular automata. The Feistel network is used as the structure of the ciphers. Its combining function is a pseudo-random function based on generalized cellular automata; this automata’s graph is a Ramanujan graph. Statistical properties of the ciphers were studied by means of the NIST Statistical Test Suit. The empirical evidence showed that the ciphers have all necessary statistical properties and are indistinguishable from pseudorandom substitutions. There are a number of practical applications in the field of information security where ciphers constructed by means of developed method can be used.

The paper presents a method of constructing pseudorandom functions based on generalized cellular automata. In this case, Lubotzky-Phillips-Sarnak graphs - an explicit construction of Ramanujan graphs - are as used as such automata. An empirical study of statistical properties of pseudorandom functions obtained by applying a set of statistical NIST tests was conducted. The proposed method can be used to build S-units intended for use in block ciphers, hash functions and other cryptographic algorithms and protocols.

The author introduces a family of Boolean functions which can be used as local transition functions in generalized cellular automates for usage as part of stream cipher. The functions from this family are balanced. Функции из этого семейства являются равновесными, их нелинейность близка к максимальной. Each of these functions is a complete system and allows to prove the lower bound estimate of the length of the output sequence of the generalized cellular automaton. These properties are important for cryptographic applications of generalized cellular automatons.

This article deals with problems of creating generalized cellular automatons with specified lower bounds of the period. This property is very important for constructing pseudorandom sequence generators and stream ciphers based on generalized cellular automatons.

 Step backward problem for generalized cellular automaton was proved to be NP-hard in this article. This problem can be described as follows: to obtain the initial states of defined automaton when its states after the first step are given. The existence of polynomial solution algorithm for this problem was also proved for the case when local coupling function of generalized cellular automaton was binary. Obtained results have theoretical significance and can be applied to justify cryptosecurity of encryption algorithms based on generalized cellular automaton.

The problems of an explicit construction of generalized cellular automations for the generation of pseudorandom sequences are considered in this article. It is theoretically approved and empirically confirmed that the avalanche effect parameters of the generalized cellular automations based on Ramanujan graphs are nearly optimal. The pseudorandom sequence generator of the cryptographic quality based on these cellular automations is introduced in the article.