Six shades lighter: a bit-serial implementation of the AES family

Recently, cryptographic literature has seen new block cipher designs such as , or that aim to be more lightweight than the current standard, i.e., . Even though family of block ciphers were designed two decades ago, they still remain as the de facto encryption standard, with being the most widely deployed variant. In this work, we revisit the combined one-in-all implementation of the family, namely both encryption and decryption of each as a single ASIC circuit. A preliminary version appeared in Africacrypt 2019 by Balli and Banik, where the authors design a byte-serial circuit with such functionality. We improve on their work by reducing the size of the compact circuit to 2268 GE through 1-bit-serial implementation, which achieves 38% reduction in area. We also report stand-alone bit-serial versions of the circuit, targeting only a subset of modes and versions, e.g., and . Our results imply that, in terms of area, and can easily compete with the larger members of recently designed family, e.g., , . Thus, our implementations can be used interchangeably inside authenticated encryption candidates such as , or in place of .