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EXECUTIVE SUMMARYThis chapter is devoted to developing formalization methods for identification and security objects of critical information infrastructure (CII) in civil aviation. The analysis of modern approaches to the CII identification was carried out that gave a possibility to determine weaknesses and to formalize a scientific researches task. As a result, the unified data model was developed for formalizing the process of a list of CII objects forming in certain field and at the state level. Moreover, the specialized technique was developed. Besides, the identification method was proposed, and it gives a possibility to determine elements of CII field, mutual influences, and influence on functional operations of critical aviation information system. Furthermore, special software was developed and implemented that can be useful for CII elements identification and also for determining its influences on functional operations. Also, the basic aspects of cybersecurity ensuring for identified critical aviation information system were described in this chapter.

In up-to-date information and communication systems (ICS) cryptography is used for ensuring data confidentiality. The symmetric block ciphers (BC) are implemented in different ICS including critical applications. Today theory of analysis and security verification of BC with fixed substitution nodes against linear and differential cryptanalysis (LDC) is developed. There are also BC with substitution nodes defined by round keys. Random substitution nodes improve security of ciphers and complicate its cryptanalysis. But through it all, quantitative assessment is an actual and not simple task as well as the derivation of formulas for practical security verification for BC with random substitution nodes against LDC. In this paper analytical upper bounds of parameters characterized practical security of BC with random substitution nodes against LDC were given. These assessments generalize known analogs on BC with random substitution nodes and give a possibility to verify security improving against LDC. By using the example of BC Kalyna-128, it was shown that the use of random substitution nodes allows improving upper bounds of linear and differential parameters average probabilities in 246 and 290 times respectively. The study is novel as it is one of the few in the cryptology field to calculate analytical upper bounds of BC practical security against LDC methods as well as to show and prove that using random substitutions allows improving upper bounds of linear and differential parameters. The security analysis using quantitative parameters gives possibility to evaluate various BCs or other cryptographic algorithms and their ability to provide necessary and sufficient security level in ICS. A future research study can be directed on improving analytical upper bounds for analyzed LDC in context to practical security against LDC, as well as practical cryptographic security assessment for other BC with random substitutions against LDC and other cryptanalysis methods including quantum cryptanalysis (Shor, Grover, Deutsch-Jozsa algorithms).

This paper presents the results of differential cryptanalysis of the lightweight block cipher Cypress-256. The method for searching multi-round differential characteristic of the block cipher Cypress-256 is proposed. The searching assumes 1) building a big set of one-round differential characteristics and search for possible combinations of one-round characteristics into multi-round ones; 2) extending one-round differential characteristics with the probability up to certain threshold into multi-round characteristics. The following experiments show that the most probable one-round differential characteristics have input differences with 4-6 active bits which are distributed between different words. Besides that, high-probable one-round differential characteristics, which output differences have a small Hamming weight, cannot be extended to build high-probable multi-round differential characteristics. Due to application of the method assuming extension of one-round differential characteristics into multi-round ones, the differential characteristic up to 6 rounds was built, so 10-round block cipher Cypress-256 is resistant to differential cryptanalysis according to the requirements of practical criterion.

This chapter is devoted to developing formalization methods for identification and security objects of critical information infrastructure (CII) in civil aviation. The analysis of modern approaches to the CII identification was carried out that gave a possibility to determine weaknesses and to formalize a scientific researches task. As a result, the unified data model was developed for formalizing the process of a list of CII objects forming in certain field and at the state level. Moreover, the specialized technique was developed. Besides, the identification method was proposed, and it gives a possibility to determine elements of CII field, mutual influences, and influence on functional operations of critical aviation information system. Furthermore, special software was developed and implemented that can be useful for CII elements identification and also for determining its influences on functional operations. Also, the basic aspects of cybersecurity ensuring for identified critical aviation information system were described in this chapter.