BCIM: Constant-Time and High-Throughput B lock- C ipher- i n- M emory With Massively-Parallel Bit-Serial Execution
Andrew Dervay, Wenfeng Zhao · IEEE Transactions on Emerging Topics in Computing · 2025
In-memory computing (IMC) emerges as one of the most promising computing technologies for data-intensive applications to ameliorate the “memory wall” bottleneck in von Neumann computer systems. Meanwhile, IMC also shows promising prospects towards high-throughput and energy-efficient processing of cryptographic workloads. This paper presents Block-Cipher-In-Memory (BCIM), a constant-time, high-throughput, bit-serial in-memory cryptography scheme to support versatile Substitution-Permutation and Feistel network based block ciphers, such as standard ciphers like Advanced Encryption Standard (AES), and lightweight block ciphers like RECTANGLE and Simon. In addition, BCIM employs a processor-assisted key loading scheme and prudent memory management strategies to minimize the memory footprint needed for cryptographic algorithms to improve the peak operating frequency and energy efficiency. Built upon these, BCIM can also support alternative block cipher modes of operation like counter mode beyond electronic-codebook. Furthermore, the bit-serial operation of BCIM inherently ensures constant-time execution and exploits column-wise single instruction multiple data (SIMD) processing, thereby providing strong resistance to side-channel timing attacks, and achieves high-throughput encryption and decryption via massively-parallel compact round function implementation. Experimental results suggest that BCIM shows substantial performance and energy improvements over state-of-the-art bit-parallel IMC ciphers. Additionally, BCIM show competitive performance and orders of magnitude energy advantages over the bitsliced software implementations on MCU/CPU platforms.