Midori: A Block Cipher for Low Energy
In the past few years, lightweight cryptography has become a popular research discipline with a number of ciphers and hash functions proposed. The designers’ 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 addressed so far. At the same time, it is a crucial measure of goodness for an algorithm. Indeed, a cipher optimized with respect to energy has wide applications, especially in constrained environments running on a tight power/energy budget such as medical implants.
This paper presents the block cipher Midori (The name of the cipher is the Japanese translation for the word Green.) that is optimized with respect to the energy consumed by the circuit per bt in encryption or decryption operation. We deliberate on the design choices that lead to low energy consumption in an electrical circuit, and 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 incur significant area or energy overheads. We propose two energy-efficient block ciphers Midori128 and Midori64 with block sizes equal to 128 and 64 bits respectively. These ciphers have the added property that a circuit that provides both the functionalities of encryption and decryption can be designed with very little overhead in terms of area and energy. We compare our results with other ciphers with similar characteristics: it was found that the energy consumptions of Midori64 and Midori128 are by far better when compared ciphers like PRINCE and NOEKEON.
KeywordsLightweight block cipher Low energy circuits
- 1.Albrecht, M.R., Driessen, B., Kavun, E.B., Leander, G., Paar, C., Yalçın, T.: Block ciphers – focus on the linear layer (feat. PRIDE). In: Garay, J.A., Gennaro, R. (eds.) CRYPTO 2014, Part I. LNCS, vol. 8616, pp. 57–76. Springer, Heidelberg (2014) Google Scholar
- 3.Banik, S., Bogdanov, A., Regazzoni, F.: Exploring energy efficiency of lightweight block ciphers. To appear in proceedings of SAC (2015)Google Scholar
- 4.Barreto, P., Rijmen, V.: The WHIRLPOOL Hash Function. http://www.larc.usp.br/pbarreto/WhirlpoolPage.html
- 5.Batina, L., Das, A., Ege, B., Kavun, E.B., Mentens, N., Paar, C., Verbauwhede, I., Yalçin, T.: Dietary recommendations for lightweight block ciphers: power, energy and area analysis of recently developed architectures. In: Hutter, M., Schmidt, J.-M. (eds.) RFIDsec 2013. LNCS, vol. 8262, pp. 101–110. Springer, Heidelberg (2013) CrossRefGoogle Scholar
- 6.Beaulieu, R., Shors, D., Smith, J., Treatman-Clark, S., Weeks, B., Wingers, L.: The SIMON and SPECK families of lightweight block ciphers. In: IACR eprint archive. https://eprint.iacr.org/2013/404.pdf
- 7.Bertoni, G., Macchetti, M., Negri, L., Fragneto, P.: Power-efficient ASIC synthesis of cryptographic S-boxes. In: 14th ACM Great Lakes Symposium on VLSI, pp. 277–281. ACM (2004)Google Scholar
- 12.Borghoff, J., Canteaut, A., Güneysu, T., Kavun, E.B., Knezevic, M., Knudsen, L.R., Leander, G., Nikov, V., Paar, C., Rechberger, C., Rombouts, P., Thomsen, S.S., Yalçın, T.: PRINCE – a low-latency block cipher for pervasive computing applications. In: Wang, X., Sako, K. (eds.) ASIACRYPT 2012. LNCS, vol. 7658, pp. 208–225. Springer, Heidelberg (2012) CrossRefGoogle Scholar
- 15.Daemen, J., Peeters, M., Assche, G.V., Rijmen, V.: Nessie Proposal: NOEKEON. http://gro.noekeon.org/Noekeon-spec.pdf
- 18.Gong, Z., Nikova, S., Law, Y.W.: KLEIN: a new family of lightweight block ciphers. In: Juels, A., Paar, C. (eds.) RFIDSec 2011. LNCS, vol. 7055, pp. 1–18. Springer, Heidelberg (2012) Google Scholar
- 20.Iwata, T., Minematsu, K., Guo, J., Morioka, S.: CLOC: authenticated encryption for short input. In: Cid, C., Rechberger, C. (eds.) FSE 2014. LNCS, vol. 8540, pp. 149–167. Springer, Heidelberg (2015) Google Scholar
- 22.Khoo, K., Peyrin, T., Poschmann, A.Y., Yap, H.: FOAM: searching for hardware-optimal SPN structures and components with a fair comparison. In: Batina, L., Robshaw, M. (eds.) CHES 2014. LNCS, vol. 8731, pp. 433–450. Springer, Heidelberg (2014) Google Scholar
- 23.Lallemand, V., Naya-Plasencia, M.: Cryptanalysis of KLEIN. In: Cid, C., Rechberger, C. (eds.) FSE 2014. LNCS, vol. 8540, pp. 451–470. Springer, Heidelberg (2015) Google Scholar