More or less unauthorized copying of media content that is copyright protected has been an important issue for a long period of time. For example, audio records have been copied onto cassette tapes and television programs and films have been copied onto video tape. Unauthorized copies of such types of analog recording media have all been marred by at least a slight decrease of quality as compared to the original recordings.
However, the issue has become even more important as the media industry has entered “the digital era”. Music and films are now being distributed in digitally encoded form and copies of these are usually indistinguishable from the original, creating an even bigger market for “pirate” of media content.
To illustrate the situation one can consider the recordable compact disc, i.e. the CD-R. These are usually intended for recording audio content. However, any media content may be recorded on such discs. Moreover, while the following discussion will be exemplified by CD-R, there exist other digital recording media capable of recording media in the form of, e.g., films that are equally relevant for the discussion.
Ever since its market introduction, CD-R has been an overwhelming success story. One of the main factors contributing to its rapid acceptance is that consumers now have the possibility to make digital quality copies of the most popular audio format—the Compact Disc—that will play in any CD player. Whereas CE style CD recorders, i.e. dedicated digital audio copying devices, have to implement the Serial Copy Management System (SCMS), which limits duplication of copyright asserted discs to first generation copies, there are no built-in limitations for PC based CD recorders. The latter has become a huge problem from the perspective of the content owners, which are facing the horror scenario that immediately after release of, e.g., a new music album, large numbers of CD-R copies are traded or offered for sale on school yards and similar environments. Consequently, and especially in combination with the mp3 phenomenon on the Internet, content owners consider CD-R a major factor in the stagnating growth of CD sales.
Technical measures that prevent misuse of recorders, such as making large numbers of copies are therefore highly desirable. At the same time the convenience of the devices should not be compromised, e.g. if copying is allowed by the owner of the content, then one should be able to do so at high speed.
A prior art solution within the technical field of copy protection of digital data is presented in the International Patent Application published with the number WO 00/04688. There, a method and a system for protecting digitally watermarked media content includes generating digital tickets associated with the media content. The ticket holds information regarding a receiver and the copy protection status of the content as well as the digital watermark. The content of the ticket is processed by the receiver in order to determine whether or not the receiver is allowed to copy the content.