Annotation: Nowadays, the development of smart city concepts and cyber-physical systems is impossible without considering information security issues. In the conditions of limited computational resources, it is necessary to find a trade-off between the cryptographic strength of the encryption algorithm and its requirements. As part of the study, lightweight modifications of the AES symmetric block cipher are compared to identify the most balanced solution for ensuring the confidentiality of low-power devices communication. The comparison is made both in terms of theoretical indicators that determine cryptographic strength, and in terms of encryption and decryption time, depending on the size of the input data. The obtained results demonstrate that the Modified AES is the most balanced solution in relation to the specified requirements. It outperforms not only other modifications, but also the standard algorithm, improving the diffusion and confusion values by 5% and 30% respectively, and also reducing the average encryption/decryption time by one and a half times.

Keywords: AES, lightweight modifications, resource-constrained environment, cryptographic protection, smart city