Yu. I. Shokin

A new test for randomness and its application to some cryptographic problems

Abstract We consider the problem of testing the hypothesis H 0 that the letters from some alphabet A ={ a 1 , a 2 ,…, a k } obey the uniform distribution, when k is large. The problem is of interest for random number testing and some cryptographic applications where k =2 10 ∼2 30 and greater. In such a case it is difficult to use the well-known chi-square test since the sample size for it must be greater than k . We suggest an adaptive chi-square test which can be successfully applied for testing some kinds of H 1 even if the sample size is much smaller than k . This statement is proved theoretically and confirmed experimentally.

Mining information science and Big Data concept for integrated safety monitoring in subsoil management

The discussed challenge and its prospects in mining geoinformation science are connected with Big Data concept—flows of large sets of various data on mining. The authors describe Big Data technology and its general implementation on mini-clusters using Hadoop and MapReduce with case studies presented.

Numerical simulation of the action of distant tsunamis on the Russian Far East coast

Results of a numerical simulation of the action of distant tsunamis on the coast of the Russian Far East are presented. It is shown that waves generated by focuses of the strongest M9 earthquakes in the region of South Chilean coast, as well as in the region of Papua New Guinea and Solomon Islands, are most dangerous for this coast. Other tsunamigenic zones of the Pacific Ocean, by virtue of their geographical position, orientation of focuses, and absence of pronounced channels (submarine ridges) along paths of tsunami propagation are not dangerous for it even at a limit magnitude of submarine subduction earthquakes. The simulation results are compared with historical data about manifestations of distant tsunamis on the Russian Far East coast.

Mathematical modeling of functioning of the p53-Mdm2 protein system.

Mathematical simulation of the time course of p53 and Mdm2 protein concentrations during their interactions was carried out. The system states corresponding to threatened uncontrolled apoptotic cell death accelerating aging processes and to situation with hypersuppression of p53-dependent apoptosis fraught with high risk of cancer were modeled. New data indicate the possibility of description (within the framework of mathematical model used in the study) of the p53 and Mdm2 proteins feedback mechanism, which could guarantee adequate reaction to serious DNA damage.

A New Type of Attacks on Block Ciphers

A new attack (called “gradient statistical”) on block ciphers is suggested and experimentally investigated. We demonstrate the possibility of applying it to ciphers for which no attacks are known except for the exhaustive key search.

Focusing of an oscillating shock wave emitted by a toroidal bubble cloud

An analysis of pressure-field dynamics is performed for an axially symmetric problem of interaction between a shock wave and a “free” bubble system (toroidal cluster) giving rise to a steady oscillating shock wave. The results of a numerical study of near-axis wave structure are presented for a focusing shock wave emitted by a bubble cluster. It is shown that the wave reflected from the axis has irregular structure. The Mach disk developing on the axis has a core of finite thickness with a nonuniform radial pressure distribution. The evolution of the Mach-disk core is analyzed, and the maximum pressure in the core is computed as a function of the gas volume fraction in the cluster. The effect of geometric parameters of the toroidal bubble cloud on the cumulative effect is examined.

Adaptive χ 2 Test for Discriminating between Close Hypotheses with a Large Number of Classes and Its Application to Some Cryptography Problems

The main problem considered consists in testing the hypothesis H0 that letters of an alphabet A = a1, a2, . . ., ak are generated with equal probabilities 1/k against the alternative complex hypothesis H1, the negation of H0. In many applications, in particular, those connected with cryptography, k is large, but possible deviations from the uniform distribution are small. Therefore, application of Pearsons χ2 test, which is one of the most wide-spread and efficient tests, requires samples of a very large size, certainly exceeding k. We propose a so-called adaptive χ2 test, whose power can be considerably higher than that of the traditional method in the case described. This conclusion is based on the theoretical analysis of the proposed criterion for some classes of alternatives as well as on experimental results related to discriminating between enciphered Russian texts and random sequences.

Generation of shock waves by spherical bubble clusters in a liquid

The problem on active media [1, 2] capable of absorbing and amplifying an external disturbance and then reemitting it in the form of an acoustic pulse is one of the problems of the so-called acoustic laser (acoustic analogue of laser systems). As was shown in [3] by numerical analysis of one-dimensional cases, bubble systems, both passive and containing explosive gaseous mixtures, can be treated as active media. In such media, an excitation caused by interactions with shock waves can lead to significantly amplifying the wave field and generating an intense shock pulse.

New Potentialities of Computational Experiment in Tsunami Problem

Computational experiment in tsunami problems is specified first of all by the multifactor physical process including the generation of the initial perturbation (Tsunami source) resulting from an underwater earthquake, volcano eruption or another similar large-scale hazard, propagation of the wave in deep ocean and its transformation in the coastal zone, interaction with floating and fixed objects and its running up on the shore.

Physical and mathematical modeling in the field of high-velocity hydrodynamics in the experimental base of the krasnoyarsk hydroelectric plant

Improvement of advanced technologies in the field of high-velocity hydrodynamics is strategically significant in terms of national security and stable and long-term growth of the economy due to regional development in Siberia and the Arctic, as well as support of Russia’s scientific and technological authority in the global arena. The practice of creating and operating large gravitational hydrodynamic tunnels with small Euler numbers is generalized to study cavitation processes under natural conditions and the motion of bodies in fluids at high velocities. Some results of model and field studies conducted in laboratories of the dam of the Krasnoyarsk hydroelectric plant are described. The authors suggest directions for follow-up studies and justify the need to set up a high-velocity hydrodynamics research center part of the High-Pressure Hydraulic Laboratory at the Krasnoyarsk hydroelectric plant, which is a completely unique facility.