| 摘要 |
<p>Removable media such as optical discs (D) may carry valuable audio-visual data representing movies or the like, which are sold by content providers or studios. To prevent pirate copies, data (AVE) on these media are often encrypted for copy protection. This copy protection may use a disc specific electronic decryption key (K3), which is stored on the disc itself. Supplementary data (SD) such as games, subtitle or audio streams that are regarded as being closely related to disc contents, but are not stored on the disc itself, are encrypted so that decryption is only possible with a decryption key (K3) retrieved from the disc (D), or in particular the same decryption key that is used for the disc contents (AVE). The method is particularly effective for copy protection or cross usage exclusion of supplementary data (SDE) when the decryption key (K3) is prevented from being accessible to the user. <IMAGE></p> |
