IDEA is a 64-bit block cipher with 128-bit keys which was introduced by Lai and Massey in 1991. The best previously published attack on IDEA could only handle 6 of its 8.5-rounds. In this paper, we combine a highly optimized meet-in-the-middle attack with a keyless version of the Biryukov–Demirci relation to obtain a greatly improved attack on 6-round IDEA which requires only two known plaintexts, and the first key recovery attacks on versions of IDEA with 6.5 to 8.5 rounds.
Bibliographical noteFunding Information:
O. Dunkelman was supported in part by the German–Israeli Foundation for Scientific Research and Development through grant No. 2282-2222.6/2011.
© 2013, International Association for Cryptologic Research.
- Biryukov–Demirci relation
- Zero-in-the-Middle attack
ASJC Scopus subject areas
- Computer Science Applications
- Applied Mathematics