Paper 2020/1227

Integral Cryptanalysis of Reduced-Round Tweakable TWINE

Muhammad ElSheikh and Amr M. Youssef


textsf{Tweakable TWINE} is the first lightweight dedicated tweakable block cipher family built on Generalized Feistel Structure (GFS). \twine family is an extension of the conventional block cipher \textsf{TWINE} with minimal modification by adding a simple tweak based on the SKINNY's tweakey schedule. Similar to \textsf{TWINE}, \twine has two variants, namely \twine[80] and \twine[128]. The two variants have the same block size of 64 bits and a variable key length of 80 and 128 bits. In this paper, we study the implications for adding the tweak on the security of \twine against the integral cryptanalysis. In particular, we first utilize the bit-based division property to search for the longest integral distinguisher. As a result, we are able to perform a distinguishing attack against 19 rounds using $2^{6} \times 2^{63} = 2^{69}$ chosen tweak-plaintext combinations. We then convert this attack to key recovery attacks against 26 and 27 rounds (out of 36) of \twine[80] and \twine[128], respectively. By prepending one round before the distinguisher and using dynamically chosen plaintexts, we manage to extend the attack one more round without using the full codebook of the plaintext. Therefore, we are able to attack 27 and 28 rounds of \twine[80] and \twine[128], respectively.

Note: correct some typos and update Appendix B

Available format(s)
Secret-key cryptography
Publication info
Published elsewhere. Minor revision. The International Conference on Cryptology And Network Security - CANS2020
T-TwineGeneralized Feistel StructureIntegraldivision preoperty
Contact author(s)
m_elshei @ encs concordia ca
2020-12-09: revised
2020-10-06: received
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Creative Commons Attribution


      author = {Muhammad ElSheikh and Amr M.  Youssef},
      title = {Integral Cryptanalysis of Reduced-Round Tweakable {TWINE}},
      howpublished = {Cryptology ePrint Archive, Paper 2020/1227},
      year = {2020},
      note = {\url{}},
      url = {}
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