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Education and Innovation in Embedded Systems Design

USI Università della Svizzera italiana, USI Faculty of Informatics, Advanced Learning and Research Institute USI Università della Svizzera italiana USI Faculty of Informatics USI Advanced Learning and Research Institute
TitleExploring Energy Efficiency of Lightweight Block Ciphers
Publication TypeConference Paper
Year of Publication2015
AuthorsBanik, S., A. Bogdanov, and F. Regazzoni
Conference NameSelected Areas in Cryptography: 22nd International Conference (SAC)2015
Date Published08/2015
Conference LocationSackville, NB, Canada
ISBN Number978-3-319-31300-9
KeywordsAES, lightweight block cipher, Low Power Energy Circuits

In the last few years, the field of lightweight cryptography has seen an influx in the number of block ciphers and hash functions being proposed. One of the metrics that define a good lightweight design is the energy consumed per unit operation of the algorithm. For block ciphers, this operation is the encryption of one plaintext. By studying the energy consumption model of a CMOS gate, we arrive at the conclusion that the energy consumed per cycle during the encryption operation of an r-round unrolled architecture of any block cipher is a quadratic function in r. We then apply our model to 9 well known lightweight block ciphers, and thereby try to predict the optimal value of r at which an r-round unrolled architecture for a cipher is likely to be most energy efficient. We also try to relate our results to some physical design parameters like the signal delay across a round and algorithmic parameters like the number of rounds taken to achieve full diffusion of a difference in the plaintext/key.