FlexENM: A Flexible Encrypting-Near-Memory with Refresh-Less eDRAM-Based Multi-Mode AES

On-chip cryptography engines face significant challenges in efficiently processing large volumes of data while maintaining security and versatility. Most existing solutions support only a single AES mode, limiting their applicability across diverse use cases. This paper introduces FlexENM, a low-power and areaefficient near-eDRAM encryption engine. The FlexENM implements refresh-less operation by leveraging inherent characteristics of the AES algorithm, reordering AES stages, and employing a simultaneous read and write scheme using dual-port eDRAM. Furthermore, FlexENM supports three AES modes, parallelizing their operations and sharing hardware resources across different modes to improve compute efficiency. Compared to other AES engines, FlexENM achieves 16% lower power consumption and 83% higher throughput per unit area, on average, demonstrating improved power- and area-efficiency for on-chip data protection.