Midori A Block Cipher for Low Energy: A Review

Abstract

Lightweight cryptography has become a popular research discipline with a number of ciphers and hash functions proposed. The designer's focus has been predominantly to minimize the hardware area, while other goals such as low latency have been addressed rather recently only. However, the optimization goal of low energy for block cipher design has not been explicitly mentioned so far. Indeed, a cipher optimized with respect to energy has wide range of applications, especially in constrained environments running on a tight power/energy budget such as medical implants. The block cipher Midori is optimized with respect to the energy consumed per bit in encryption or decryption process. The design choices that lead to low energy consumption in an electrical circuit, and which try to optimize each component of the circuit as well as its entire architecture for energy. An added motivation is to make both encryption and decryption functionalities available by small tweak in the circuit that would not affect significant area or energy overheads. Two energy-efficient block ciphers Midori128 and Midori64 with block sizes equal to 128 and 64 bits respectively is presented. These ciphers have a circuit that provides both the functionalities of encryption and decryption can be designed with very low overhead in terms of area and energy respectively.

Keywords: AES, lightweight block cipher (LWC), low energy circuits