1,720,997 research outputs found
Particle Swarm Optimization based on S-Boxes Generation
No full textThe generation of nonlinear substitutions (S-boxes) is an important task in the design of modern symmetric cryptoalgorithms. Various cryptographic properties of S-boxes (nonlinearity, balance, delta-uniformity, correlation and algebraic immunity, etc.) characterize their resistance to linear, differential, algebraic and other cryptanalysis methods. This article explores a computational particle swarm optimization (PSO) method as applied to the problem of generating nonlinear substitutions. Having a set of possible solutions (particles) and moving these particles in the search space, the PSO tries to improve the possible solution in terms of some quality indicator. We use nonlinearity, balance, delta uniformity, algebraic immunity and linear redundancy as the main indicators, and randomly generated S-boxes are used as a set of particles. This article shows several PSO modifications for generating nonlinear substitutions. At first, we reproduce the previously known PSO modification for generating S-boxes and show its low efficiency. At second, we propose our own PSO implementation and show that this method can actually generate substitutions with high cryptographic properties. The experimental results allow us to establish the influence of the size of the population of particles and the number of iterations of the outer loop on the efficiency of the heuristic generation of nonlinear substitutions. In addition, we explore the similarity of the generated substitution tables with the AES cipher S-box
Extrapolation to calculate the probability of a double spending attack
No full textOne of the important aspects of the efficiency of modern distributed networks built using blockchain technologies is the study of the security of consensus protocols. In particular, the most common cryptocurrencies and blockchain systems with probabilistic consensus protocols are subjects to so-called double-spending attack. The basis of such an attack is the use of the attacker's computing capabilities to form alternative blockchains. If the generated sequence is longer than the public chain of blocks, the attacker can present it as the proof of work and thus disrupt the correct functioning of the network. In this article we explore the probability of a successful double-spending attack, derive formulas for evaluating the corresponding events, consisting of the formation by the attacker of an alternative sequence of blocks. These formulas are extremely cumbersome and difficult to calculate. The paper proposes simplified analytical expressions to quickly assess the probability of a successful double-spending attack. For this we use the extrapolation of intermediate calculations using the Lagrange interpolation formulas, as well as binomial approximation. The simulation results show that the use of simplified expressions allows us to provide acceptable accuracy of calculations
Lightweight stream ciphers for green IT engineering
No full textAt the moment the most widely used are symmetric cryptographic transformations, in particular, stream ciphers. The development of an efficient synchronous stream cipher is reduced to the construction of a pseudo-random sequence generator with defined cryptographic properties. It should be noted that in devices with limited computing power, low volume and low power consumption the implementation of reliable cryptographic methods is extremely complicated. Limited physical parameters, low power consumption, low computing power and other characteristic attributes of “green” IT engineering forces the use of new approaches for designing cryptographic protection tools. The main cryptographic transformations are considered and experimental studies of performance and statistical security are conducted. We propose new methods and hardware and software tools for lightweight stream encryption that meet the current requirements of “green” IT engineering. It is proposed synthesis method for the construction of nonlinear-feedback shift register, which allows creating nonlinear registers with design features that correspond to the certain predefined criteria
Application of Bluetooth, Wi-Fi and GPS Technologies in the Means of Contact Tracking
No full textThe spread of infectious diseases, including COVID-19, is a complex epidemiological situation that is exacerbated by strong transcontinental migration processes that pose a potential threat to human health worldwide. This requires the implementation of a set of tasks aimed at full control over the risks and threats to human life. Modern information technology can be useful in solving a number of scientific and technical problems related to the use of cyberspace for global population monitoring, ie when monitoring and tracking contacts can predict possible adverse scenarios and prevent the spread of emergencies and crises, especially in the COVID-19 pandemic. A high overall level of e-society can keep epidemics and pandemics at the national and international levels under control. Global solutions to build monitoring systems to prevent the spread of infectious diseases already exist and are evolving rapidly. This section analyzes, explores and substantiates the possibility of using various information technologies (eg, Bluetooth, Wi-Fi, GPS, etc.) in contact tracking tools as the main subsystem of global population monitoring. In particular, the principles of construction and the possibility of using these technologies to track contacts are studied. Their advantages and disadvantages, potential attacks on monitoring programs, etc. are analyzed
Cryptographic Transformations in a Decentralized Blockchain Environment
No full textDistributed decentralized systems built using Blockchain technology are becoming increasingly popular and widespread. This is due to their reliability and security. But their transparency and openness, the lack of centralized administrative levers that can interfere and impose their decision, are the most important and attractive. Blockchain is able to provide completely anonymous, decentralized and free (uncontrolled) storage of any digital assets: from electronic money, such as cryptocurrencies, to secure property inventories and election registers. Therefore, further intensive implementation of this technology in various applications should be expected, as Blockchain implements a reliable and secure way to store distributed data in the decentralized environment. This is achieved through the use of various cryptographic transformations. This section analyzes the promising methods and mechanisms of cryptographic transformation that can be used in a decentralized Blockchain environment to provide various security services, including confidentiality, integrity, accessibility, indisputability, both users and elements/nodes of a decentralized system, etc. The section considers and investigates algorithms and protocols of homomorphic encryption, ring signatures, protocols with zero disclosure, principles of construction of anonymous secure networks, etc
A new cost function for heuristic search of nonlinear substitutions
No full textThis work investigates the development of an improved cost function specifically designed for the rapid generation of highly nonlinear substitution or S-boxes, a key component in modern symmetric key ciphers. The S-boxes are generated via a tailored hill-climbing algorithm, a heuristic search method typically employed in solving complex computational problems. The novel cost function proposed in this paper is shown to expedite this generation process, reducing the iteration count by 25% relative to the best-known prior result, which required about 65,000 iterations. Furthermore, the approach enhances the likelihood of obtaining target S-boxes, with a threefold increase in successful outcomes compared to existing methods. Our method yields S-boxes that adhere to critical cryptographic measures, such as delta-uniformity, algebraic immunity, and others. This study emphasizes the specific application of the cost function to the generation of S-boxes, noting that its effectiveness may vary in other combinatorial optimization problems
Research of Computational Complexity of Cost Functions in S-boxes Generation Problems
No full textThe generation of non-linear substitutions (S-boxes) is an important task in the design of cryptographic algorithms with a secret key. The properties of S-boxes determine the cryptographic strength of symmetric ciphers against various attacks, for example, linear and differential cryptanalysis. In addition, substitutions must be random in order to be resistant to algebraic cryptanalysis methods. Many authors explore the problem of generating random S-boxes. The most effective technique is heuristic search, which is based on the use of various cost functions (special heuristics). Heuristic search consists of iteratively modifying a randomly generated substitution. At each iteration, the value of the cost function is calculated, the search continues until a substitution is found that minimizes the cost function. In this article we explore several options for cost functions and evaluate the complexity of their calculation. We estimate the number of iterations required by the heuristic search to generate S-boxes with given cryptographic indicators as well as the computational complexity of generation taking into account the complexity of calculating the cost function
Optimization of the PCF Cost Function for the Generation of Highly Nonlinear S-boxes
No full textCreation of reliable telecommunication communication channels providing confidential data, it is currently impossible to have reliable encryption algorithms. The most popular services that provide encryption algorithms include confidentiality, integrity, and authenticity services. Most modern symmetric encryption algorithms use nonlinear substitutions or abbreviated S-boxes. Their properties have a direct impact on the cryptographic strength of symmetric encryption. So, generating S-boxes with the right properties is certainly an important task for creating S-boxes. In this paper, we consider heuristic methods for generating nonlinear substitutions that use special cost functions (heuristics). During generation, the search algorithm changes the randomly generated substitution at each iteration and tries to reduce the value of the cost function. Search attempts are stopped either after finding the S-box with the desired properties, or after performing a certain number of iterations. Doubtless, the search efficiency depends on the chosen heuristic, namely, on the parameters of the cost function. In this paper, we consider the PCF cost function and optimize its parameters. We managed to optimize the parameters of this heuristic and achieve the least number of search iterations
Fundamentals of Functioning of Global Contact Monitoring Systems in the Context of COVID-19 Spread Prevention
No full textCoronavirus disease 2019 (COVID-19) has a clear potential for a prolonged global pandemic, high mortality and overload of health systems. Until vaccines become widely available, the only available approaches to infection prevention are case isolation, contact and quarantine tracking, physical distancing, decontamination, and hygiene measures. The paper considers the conceptual principles of combining the bases of transparency and confidentiality of personal life and the need to track personal contacts, substantiates the need for such a combination and provides a possible technical solution using blockchain technology. The practical development and deployment of the system based on such protocols will allow each citizen to track the personal history of probable contact with infected persons or other potential risks (including deciding on the need for self-isolation or additional examination). In this case, the decentralized system guarantees the privacy of such information both for each participant (due to the inability to determine the personal data of a potentially infected person) and for the system as a whole
Combining and filtering functions based on the nonlinear feedback shift registers
No full textStrong cryptography of stream ciphers is determined, among other things, by the ability of a generated pseudorandom sequence to resist analytical attacks. One of the main components of the pseudorandom stream cipher sequence generating algorithm are Boolean functions for combining and filtering. The paper considers the possibility of applying nonlinear-feedback shift registers that generate a maximum length sequence as a combining or filtering function. This work examines the main indicators of cryptographic strength of such functions, as: balance, the prohibitions presence, correlation immunity and nonlinearity. The study analyzes and demonstrates correlation experimental immunity and nonlinearity values for all nonlinear feedback shift registers, that generate a maximum length sequence, for register sizes up to 6 cells inclusively, and registers sizes up to 9 cells inclusively with algebraic degree of the polynomial under 2. The possibility of optimizing the process of selecting the Boolean functions according to the criteria of maximum correlation immunity and nonlinearity with various algebraic degree and minimization of the number of monomials in the polynomial are studied
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