Abstract: A remote server is arranged to respond to a request from a user terminal for the download of a media file to cause a unique water-marked copy of a media file to be generated and sent to the user terminal. At the same time the remote server is arranged to access a seal server, which causes an electronically sealed record of the transaction to be generated and stored in a download database. Subsequently, if a suspect media file is identified the sealed record provides evidence of the original transaction which led to the water-marked copy of the media file being issued and hence the original source of the unauthorised copy of the file. Control of distributed media files can be enforced by imposing penalties in the event that unauthorised copies corresponding to the distributed water-marked media files are identified.

Abstract: A remote server is arranged to respond to a request from a user terminal for the download of a media file to cause a unique water-marked copy of a media file to be generated and sent to the user terminal. At the same time the remote server is arranged to access a seal server, which causes an electronically sealed record of the transaction to be generated and stored in a download database. Subsequently, if a suspect media file is identified the sealed record provides evidence of the original transaction which led to the water-marked copy of the media file being issued and hence the original source of the unauthorised copy of the file. Control of distributed media files can be enforced by imposing penalties in the event that unauthorised copies corresponding to the distributed water-marked media files are identified.