Bart Van Rompay

Cryptanalysis of 3-Pass HAVAL

HAVAL is a cryptographic hash function proposed in 1992 by Zheng, Pieprzyk and Seberry. Its has a structure that is quite similar to other well-known hash functions such as MD4 and MD5. The specification of HAVAL includes a security parameter: the number of passes (that is, the number of times that a particular word of the message is used in the computation) can be chosen equal to 3, 4 or 5. In this paper we describe a practical attack that finds collisions for the 3-pass version of HAVAL. This means that it is possible to generate pairs of messages hashing to the same value. The computational complexity of the attack corresponds to about 229 computations of the compression function of 3-pass HAVAL; the required amount of memory is negligible.

New (Two-Track-)MAC Based on the Two Trails of RIPEMD

We present a new message authentication code. It is based on a two trail construction, which underlies the unkeyed hash function RIPEMD-160. It is in comparison with the MDx-MAC based on RIPEMD-160, much more efficient on short messages (that is on messages of 512 or 1024 bits) and percentage-wise a little bit more efficient on long messages. Moreover, it handles key-changes very efficiently. This positive fact remains if we compare our Two-Track-MAC with HMAC based on RIPEMD-160.

Differential Cryptanalysis of the ICE Encryption Algorithm

ICE is a 64-bit block cipher presented at the Fast Software Encryption Workshop in January 1997. It introduced the concept of a keyed permutation to improve the resistance against differential and linear cryptanalysis. In this paper we will show however that we can use low Hamming weighted differences to perform a practical, key dependent, differential attack on ICE. The main conclusion is that the keyed permutation is not as effective as it was conjectured to be.