The Biryukov-Demirci Attack on IDEA and MESH Ciphers

This report elaborates on an observation by Alex Biryukov on the computational graph of the IDEA cipher, and combines it with Demirci’s attack presented at SAC’2002. Further, this attack is also applied to reduced-round versions of the MESH block ciphers. Particular features of these attacks are: (i) they require only known-plaintext (such as in linear cryptanalysis); (ii) they trade-off the number of known plaintext/ciphertext blocks for computing time.