Observations on the truncated differential of SP block ciphers and their applications to mCrypton and CRYPTON V1.0

• Published in: IET information security Vol. 12; no. 5; pp. 419 - 424
• Main Authors: Yang, Dong, Qi, Wen-Feng, Chen, Hua-Jin
• Format: Journal Article
• Language: English
• Published: The Institution of Engineering and Technology 01.09.2018
• Subjects: cryptography; CRYPTON V1.0; Fast Software Encryption 1995; Feistel ciphers; FSE; generalised truncated difference; Li's technique; mCrypton; meet‐in‐the‐middle technique; Research Article; SP block ciphers; TDA; truncated differential attack; truncated differential distinguishers; Feistel ciphers; SP block ciphers; mCrypton; cryptography; meet-in-the-middle technique; Fast Software Encryption 1995; CRYPTON V1.0; TDA; Li's technique; generalised truncated difference; truncated differential distinguishers; truncated differential attack; FSE
• ISSN: 1751-8709; 1751-8717
• DOI: 10.1049/iet-ifs.2017.0196

Truncated differential attack (TDA) proposed by Knudsen in Fast Software Encryption 1995 (FSE'95) has been widely used in the analysis of block ciphers. In this study, the authors specifically study the security of SP block ciphers against TDA. In FSE'15, Li et al. introduced a meet-in-the-middle technique to construct truncated differential for Feistel ciphers. They first apply Li's technique to SP block ciphers and get some further results. Second, they introduce the concept of generalised truncated difference to control the diffusion of active S-boxes in the truncated differential. On the basis of these, two 5-round truncated differential distinguishers for mCrypton and CRYPTON V1.0 have been constructed. Using these two 5-round distinguishers, they present the first 8-round DA on mCrypton-64 and improve the former best TDA on CRYPTON V1.0 by one round.