An Efficient AES-128 CMOS Architecture with Round Reuse and Composite Field S-Box to Secure IoT Devices

Abstract

The rapid growth of the Internet of Things (IoT) has intensified the demand for lightweight cryptographic solutions that deliver high security without compromising energy and area constraints. This paper presents a highly efficient AES -128 hardware architecture specifically optimised for resource-constrained IoT devices. The proposed design employs reusing a 128 -bit AES framework resource, enabling an extensive reduction in functional units across all transformation stages. Additionally, the elimination of intermediate registers and the reuse of a single round computation block for all encryption rounds significantly reduce area while balancing the trade -offs between throughput, frequency and power. A key innovation in this work is the implementation of a compact S-box using composite Galois Field GF28 arithmetic to enhance the substitution efficiency while maintaining cryptographic strength. The physical layout implemented on 32 nm technology reveals that the proposed architecture achieves a core area of only 0.015  mm , an operating 2 frequency of 200 MHz, with 0.014 Gbps throughput, and a low power consumption of 1.4 mW , offering a well-balanced trade-off among performance, security, and hardware efficiency. A comparative analysis with state-of-the-art designs demonstrates the superiority of this approach for achieving low-cost, energy-aware cryptographic protection. The proposed solution is highly suitable for secure resource constrained IoT deployments.