computer network moreover thanks to the encryption of frames in a separate manner it is possible to keep portions of the track unencrypted so as to allow partial playing thereof without having to replicate content in a redundant manner likewise the structure of the file remains unchanged thus making the content of the file encoded according to the teachings of the invention formally indistinguishable from a corresponding file encoded in a conventional manner numerous modifications are clearly possible and can be readily performed by the person skilled in the art without abandoning the scope of the protection of the present invention for example it is clear that the present invention can be applied also for the distribution of music video files independently of the internet a financial sponsor for example might use the method according to the present invention to generate executable software files that can be distributed through different channels for example on compact discs included in music or computer magazines or as bonuses in video games or computer programs in general moreover it is equally evident that the application of the digital signature in the portion 21 of the file 20 can be performed directly by the server 1 or by the distributor 3 if the user has been identified and that such digital signature can replace preceding signatures or be added to them in order to generate repayment.