Random attacks

To perform a random attack one does not need to understand anything on how the marking algorithm works. The idea is simply to apply some kind of transformation to the song, and hope the mark cannot be detected anymore. This attack can be applied very easily but is rarely successful.

If one can get fast answers from an oracle (which was not the case in the contest), then maybe eventually, one will obtain a song where the mark cannot be detected anymore. It is in fact possible to work with a kind of dichotomy: one can very strongly degrade a song to obtain an unmarked version and try to find a song in the middle which would have the properties of not carrying the mark and yielding an acceptable quality.

Clearly, one might need a huge amount of trials before succeeding, and the quality of the final result is not guaranteed.