Design of Dynamic F-Function for Lightweight Block Ciphers

Lightweight block ciphers are crucial for securing data in resource-constrained IoT devices and sensors, where low energy consumption, minimal latency, and high efficiency are essential. However, existing ciphers often fail to balance these requirements. This article proposes a dynamic F-function that reduces iterative rounds while ensuring optimal security, flexibility, and scalability. The function integrates a fixed substitution layer with a dynamic permutation layer, employing Hamming weight-based transformations, circular shifts, and XOR operations for enhanced diffusion. It is integrated into SLIM and Lightweight Block Cipher for IoT (LBC-IoT) ciphers and evaluated. Results confirm improved security and efficiency, making it a promising solution for IoT applications.