In this paper, we formalize an attack scheme using the key-dependent property, called key-dependent attack. In this attack, the intermediate value, whose distribution is key-dependent, is considered. The attack determines whether a key is right by conducting statistical hypothesis test of the intermediate value. The time and data complexity of the key-dependent attack is also discussed.

We also apply key-dependent attack on reduced-round IDEA. This attack is based on the key-dependent distribution of certain items in Biryukov-Demirci Equation. The attack on 5.5-round variant of IDEA requires 221 chosen plaintexts and 2112.1 encryptions. The attack on 6-round variant requires 249 chosen plaintexts and 2112.1 encryptions. Compared with the previous attacks, the key-dependent attacks on 5.5-round and 6-round IDEA have the lowest time and data complexity, respectively.


Block Cipher Key-Dependent Attack IDEA 

Copyright information

© Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  • Xiaorui Sun
    • 1
  • Xuejia Lai
    • 1
  1. 1.Department of Computer ScienceShanghai Jiao Tong UniversityShanghaiChina

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