The Biryukov-Demirci attack on reduced-round versions of IDEA and MESH ciphers

Abstract

This paper presents a dedicated known-plaintext attack on up to four rounds of the IDEA cipher, that trades-off a small number of known data blocks (114) for a larger time complexity (2114). This attack is also applied to up to 2.5-round MESH block ciphers, but are not more effective than previously known attacks. An advantage of this attack compared to previous known-plaintext attacks on IDEA/MESH is that no assumptions on the key value are required. Chosen-plaintext and chosen-plaintext-adaptively-chosen-ciphertext attacks can reach the full 8.5-round IDEA, and up to 5.5-round MESH ciphers, but always under weak-key assumptions. © Springer-Verlag Berlin Heidelberg 2004.