Cryptology ePrint Archive: Report 2020/052

Impossible Differential Cryptanalysis of Reduced-Round Tweakable TWINE

Mohamed Tolba and Muhammad ElSheikh and Amr M. Youssef

Abstract: Tweakable TWINE (T-TWINE) is a new lightweight tweakable block cipher family proposed by Sakamoto $et$ $al$. at IWSEC 2019. T-TWINE is the first Tweakable Block Cipher (TBC) that is built on Generalized Feistel Structure (GFS). It is based on the TWINE block cipher in addition to a simple tweak scheduling based on SKINNY’s tweakey schedule. Similar to TWINE, it has two versions, namely, T-TWINE-80 and T-TWINE-128, both have a block length of 64 bits and employ keys of length 80 and 128 bits, respectively. In this paper, we present impossible differential attacks against reduced-round versions of T-TWINE-80 and T-TWINE-128. First, we present an 18-round impossible differential distinguisher against T-TWINE. Then, using this distinguisher, we attack 25 and 27 rounds of T-TWINE-80 and T-TWINE-128, respectively.

Category / Keywords: secret-key cryptography / Cryptanalysis, Impossible differential attacks, Tweakable, Block ciphers, TWINE, T-TWINE

Date: received 16 Jan 2020

Contact author: m_elshei at encs concordia ca

Available format(s): PDF | BibTeX Citation

Version: 20200117:083033 (All versions of this report)

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