Information Security and Privacy

Volume 6812 of the series Lecture Notes in Computer Science pp 433-438

Improved Meet-in-the-Middle Cryptanalysis of KTANTAN (Poster)

  • Lei WeiAffiliated withNanyang Technological University
  • , Christian RechbergerAffiliated withESAT/COSIC and IBBT, Katholieke Universiteit Leuven
  • , Jian GuoAffiliated withInstitute for Infocomm Research, A*STAR
  • , Hongjun WuAffiliated withNanyang Technological University
  • , Huaxiong WangAffiliated withNanyang Technological University
  • , San LingAffiliated withNanyang Technological University

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This paper presents ongoing work towards extensions of meet-in-the-middle (MITM) attacks on block ciphers. Exploring developments in MITM attacks in hash analysis such as: (i) the splice-and-cut technique; (ii) the indirect-partial-matching technique. Our first contribution is that we show corrections to previous cryptanalysis and point out that the key schedule is more vulnerable to MITM attacks than previously reported. Secondly we further improve the time complexities of previous attacks with (i) and (ii), now the 80-bit secret key of the full rounds KTANTAN-{32,48,64} can be recovered at time complexity of 272.9, 273.8 and 274.4 respectively, each requiring 4 chosen-plaintexts.