Abstract
In 1990 Rivest introduced the hash function MD4. Two years later RIPEMD, a European
proposal, was designed as a stronger mode of MD4. Recently we have found an attack against
two of three rounds of RIPEMD. As we shall show in the present note, the methods developed
to attack RIPEMD can be modified and supplemented such that it is possible to break the
full MD4, while previously only partial attacks were known. An implementation of our
attack allows to find collisions for MD4 in less than a minute on a PC.
