[en] In April 2018, Beierle et al. launched the 3rd SKINNY cryptanalysis competition, a contest that aimed at motivating the analysis of their recent tweakable block cipher SKINNY . In contrary to the previous editions, the focus was made on practical attacks: contestants were asked to recover a 128-bit secret key from a given set of 2^20 plaintext blocks. The suggested SKINNY instances are 4- to 20-round reduced variants of SKINNY-64-128 and SKINNY-128-128. In this paper, we explain how to solve the challenges for 10-round SKINNY-128-128 and for 12-round SKINNY-64-128 in time equivalent to roughly 2^52 simple operations. Both techniques benefit from the highly biased sets of messages that are provided and that actually correspond to the encryption of various books in ECB mode.
Ankele, R., et al.: Related-key impossible-differential attack on reduced-round Skinny. In: Gollmann, D., Miyaji, A., Kikuchi, H. (eds.) ACNS 2017. LNCS, vol. 10355, pp. 208–228. Springer, Cham (2017). https://doi.org/10.1007/978-3-319-61204-1_11
Beaulieu, R., Shors, D., Smith, J., Treatman-Clark, S., Weeks, B., Wingers, L.: SIMON and SPECK: block ciphers for the internet of things. Cryptology ePrint Archive, Report 2015/585 (2015). http://eprint.iacr.org/2015/585
Beierle, C., et al.: The SKINNY family of block ciphers and its low-latency variant MANTIS. In: Robshaw and Katz [10], pp. 123–153
Derbez, P., Fouque, P.A.: Automatic search of meet-in-the-middle and impossible differential attacks. In: Robshaw and Katz [10], pp. 157–184
Jean, J.: TikZ for Cryptographers (2016). https://www.iacr.org/authors/tikz/
Jean, J., Nikolić, I., Peyrin, T.: Tweaks and keys for block ciphers: the TWEAKEY framework. In: Sarkar, P., Iwata, T. (eds.) ASIACRYPT 2014. LNCS, vol. 8874, pp. 274–288. Springer, Heidelberg (2014). https://doi.org/10.1007/978-3-662-45608-8_15
Knudsen, L.R.: Truncated and higher order differentials. In: Preneel, B. (ed.) FSE 1994. LNCS, vol. 1008, pp. 196–211. Springer, Heidelberg (1995). https://doi.org/10.1007/3-540-60590-8_16
Lai, X.: Higher Order Derivatives and Differential Cryptanalysis. In: Blahut, R.E., Costello, D.J., Maurer, U., Mittelholzer, T. (eds.) Communications and Cryptography. The Springer International Series in Engineering and Computer Science (Com-munications and Information Theory), vol. 276, pp. 227–233. Springer, Boston (1994). https://doi.org/10.1007/978-1-4615-2694-0_23
Liu, G., Ghosh, M., Song, L.: Security analysis of SKINNY under related-tweakey settings (long paper). IACR Trans. Symm. Cryptol. 2017(3), 37–72 (2017)
Robshaw, M., Katz, J. (eds.): CRYPTO 2016. LNCS, vol. 9815. Springer, Heidelberg (2016). https://doi.org/10.1007/978-3-662-53008-5
