Nanyang Technological University
The authors revisit narrow-pipe designs that are in practical use, and their security against pre-image attacks. Their results are the best known pre-image attacks on Tiger, MD4, and reduced SHA-2, with the result on Tiger being the first cryptanalytic shortcut attack on the full hash function. Their attacks runs in time 2(188.8) for finding pre-images, and 2(188.2) for second pre-images. Both have memory requirement of order 28, which is much less than in any other recent pre-image attacks on reduced Tiger.