Some methods of hash functions analysis with application to the GOST P 34.11-94 algorithm

A class of hash functions with a special finalization round (containing the GOST R 34.11-94 hash function) is considered. For functions from this class we propose a new multicollision attack and show that by means of Wagner's method it is possible to construct a description of a large number of different collisions. For GOST R 34.11-94 hash function we propose a modification of the known collision attack using smaller amount of memory. We obtain lower estimate for the amount of memory permitting the modified attack to be faster than generic ones.