Edge-Driven Key Generation for Lightweight Image Encryption Using Hardware-Accelerated Sobel Filtering on PYNQ-Z2

The execution of image processing tasks on edge and IoT devices is always coupled with the need to develop encryption algorithms with a guarantee of security and low computation complexity. Most classical encryption algorithms employ a constant secret key and software-based implementation, making them unsuitable for resource-constrained devices and platforms. The study proposes the idea of implementing edgedriven key generation for hardware-assisted lightweight image encryption with Sobel edge detection on the PYNQ-Z2 System on a Chip. The Sobel filter algorithm is implemented in the FPGA hardware for the detection of structural edge characteristics in a real-time process, and the statistical analysis of the resulting edge map is implemented in software to develop dynamic imagerelated encryption keys, with the keys further employed in a lightweight symmetric encryption technique implemented with no reliance on any cryptography software library. The experimental outcome has efficiently shown the best performance on the PYNQ-Z2 platform, confirming the usability of the proposed technique in secure image processing of IoT edge devices.