A Power Reduction Technique Based on Linear Transformations for Block Ciphers

Abstract

In this paper, we present a novel method for power reduction based on linear transforms for realization of cryptographic block ciphers on hardware platforms. The proposed technique is applicable to both substitution-permutation and Feistel networks, which are widely-used design choices for block ciphers. In our method, an isomorphic transform and its inverse is applied within every round of the target cipher, while the inputs and outputs are also transformed in order to have the same behavior as the original cipher. Hence, our method does not lead to any change of the cryptographic properties of the original cipher. We showcase our method on certain lightweight block ciphers, including the ISO-standard PRESENT, in order to achieve even lower power consumption figures compared to the original designs. Using our proposed technique, we reach power reductions of up to 20%. In some cases, the method can also lead to area reduction in addition to power reduction, which is surprising because the selected lightweight ciphers were already optimized for low area.