Cryptographic Complexity Analysis and Testing of the Symmetric Block Algorithm WBC2

Introduction. Modern developments in the field of block-oriented algorithms are aimed at improving performance, reducing computational costs, and integrating such algorithms into quantum-resistant national standards. To enhance the security of the WBC1 algorithm, this paper proposes its modification – the WBC2 algorithm – which is a modern symmetric block cipher that extends the WBC1 model to a more robust, nonlinear, and flexible structure. WBC2 is an interesting example of a cryptographic model with a visual representation (the Rubik’s Cube), which enables the creation of unique key-dependent operations. The paper presents a detailed description of the encryption process, an analysis of the algorithm’s complexity and execution speed, and the results of its testing. The purpose. The aim of this work is to describe a new symmetric block cryptographic algorithm, WBC2, to investigate its computational complexity and execution speed, and to conduct its testing. Results. An improved symmetric block cryptographic algorithm, WBC2, has been developed. The complexity analysis and execution speed of the algorithm have been investigated. The applicability of the new algorithm is demonstrated through illustrative examples. Conclusions. The WBC2 algorithm represents a cryptographically secure encryption method that provides a high level of security through the use of complex dynamic permutations, cyclic shifts, round transformations, extended S-boxes, and diffusion procedures. The increase in processing time in WBC2 is the cost of additional cryptographic complexity and an enhanced avalanche effect. One of the directions for improving the efficiency of the algorithm is the use of parallel computations, which significantly reduces execution time without compromising security. Further research is aimed at developing a parallel modification, PWBC2, and a quantum version, WBCQ, which employs parameterized quantum mixing (PQM) to increase key dynamism and the nonlinearity of transformations. Keywords: symmetric block cryptographic algorithm, complexity analysis of symmetric block ciphers, performance analysis of cryptographic algorithms, S-box, diffusion, round key, NIST Statistical Test Suite.