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Kosei SAKAMOTO Kazuhiko MINEMATSU Nao SHIBATA Maki SHIGERI Hiroyasu KUBO Yuki FUNABIKI Andrey BOGDANOV Sumio MORIOKA Takanori ISOBE
Tweakable block cipher (TBC) is an extension of conventional block cipher. We study how to build a TBC based on generalized Feistel structure (GFS), a classical block cipher construction. While known dedicated TBC proposals are based on substitution-permutation network (SPN), GFS has not been used for building TBC. In particular, we take 64-bit GFS block cipher TWINE and try to make it tweakable with a minimum change. To find a best one from a large number of candidates, we performed a comprehensive search with a help of mixed integer linear programming (MILP) solver. As a result, our proposal TWINE is quite efficient, has the same number of rounds as TWINE with extremely simple tweak schedule.
Hideki YOSHIKAWA Masahiro KAMINAGA Arimitsu SHIKODA Toshinori SUZUKI
We present a round addition differential fault analysis (DFA) for some lightweight 80-bit block ciphers. It is shown that only one correct ciphertext and two faulty ciphertexts are required to reconstruct secret keys in 80-bit Piccolo and TWINE, and the reconstructions are easier than 128-bit CLEFIA.