Paper 2005/327

On the Security of Encryption Modes of MD4, MD5 and HAVAL

Jongsung Kim and Alex Biryukov and Bart Preneel and Sangjin Lee

Abstract

MD4 is a cryptographic hash function introduced in 1990 by Rivest. After MD4 was proposed, several hash functions such as MD5, HAVAL, RIPEMD, RIPEMD-160, SHA-1 and SHA-256 were designed based on the MD4 structure. In this paper, we cryptanalyze the compression functions of MD4, MD5 and 4-, 5-pass HAVAL in encryption modes. We exploit the recently proposed related-key rectangle and boomerang techniques to show non-randomness of MD4, MD5 and 4-, 5-pass HAVAL and to distinguish them from a randomly chosen cipher. The attacks are highly practical and have been confirmed by our experiments.