PROTECTION OF THE CONTENT FROM ILLEGAL REPRODUCTION BY MEANS OF CHECKING THE EXISTENCE OF THE COMPLETE DATA SET

摘要

A number of data elements are selected for inclusion in the data set in order to prevent the transfer of the complete set over a communication link with limited bandwidth, such as the Internet. Each part of the data set is related to the integrity of the data set so that parts of the data sets that are distributed independently can be distinguished. In the case of audio recording, for example, the data set includes an entire album; individual songs in the album form parts of this data set. By associating each song with an album, the corresponding playback device can be configured to refuse to play items in the absence of a complete set of data. Thus, illegal use of a song would require illegal use of a full album. Uncompressed digital recording of the full volume takes hundreds of megabytes of data, and the impossibility or impracticality of downloading hundreds of megabytes of data is expected to provide a sufficient obstacle to the theft of uncompressed content. In a preferred embodiment, a "watermark" is created for each section of the data being sent, which contains an "integrity parameter" associated with the data set. The integrity parameter is a hash value that is based on a random number stored in the watermarks of each section. During playback, the integrity parameter is read and the watermarks of a random collection of sections within the data set are compared with this integrity parameter to ensure with statistical certainty that the integrity of the data set is present.