Improved Meet-in-the-Middle Attacks on Reduced-Round Tweakable Block Cipher Deoxys-BC. (2nd June 2021)

• Record Type: Journal Article
• Authors: Li, Manman; Chen, Shaozhen
• Is Part Of: Computer journal. Volume 65:Number 9(2022)
• Page Start: 2411
• Page End: 2420
• Publication Date: 2021-06-02
• Subjects: Deoxys-BC -- cryptanalysis -- tweakable block cipher -- meet-in-the-middle attack; Computers -- Periodicals; 005.1
• DOI: 10.1093/comjnl/bxab076
• Languages: English
• ISSNs: 0010-4620

Abstract

Abstract: Deoxys-BC is an internal tweakable block cipher of the authenticated encryption algorithm Deoxys, which is a third-round finalist in the CAESAR competition. In this paper, we study the property of Deoxys-BC, such as the subtweakey difference cancelation and the freedom of the tweak. Combining the differential enumeration technique with these properties, the authors achieve the key-recovery attacks on Deoxys-BC under the meet-in-the-middle attack. As a result, we get an attack on 9-round Deoxys-BC-128-128 by constructing a 6-round meet-in-the-middle distinguisher with $2^{113}$ plaintext–tweak combinations, $2^{97}$ Deoxys-BC blocks and $2^{121.6}$ 9-round Deoxys-BC-128-128 encryptions. We also present an attack on 11-round Deoxys-BC-256-128 for the first time by constructing a 7-round meet-in-the-middle distinguisher with $2^{113}$ plaintext-tweak combinations, $2^{226}$ Deoxys-BC blocks and $2^{251}$ 11-round Deoxys-BC-256-128 encryptions.