| 摘要 |
A method for controlling access to digital information is performed based on a plurality of decryption keys sent by the information provider. A first type of decryption key instructs (406, 410) a user's host system to reproduce the digital information in accordance with a first level of reproduction quality degradation. Additional keys may specify other degradation levels. The quali ty of the digital information may be degraded (314, 406, 410) based on a time condition or a use condition. Alternatively, only a portion of the informati on may be made viewable by a user. In order to obtain full and unrestricted access, the user must obtain a type (310) of decryption key from the provide r which removes all previous limitations on reproduction quality degradation. Preferably, the digital information is sent with a media player application program embedded with an initial decryption key. The program may include tamper-resistant features which provide a safeguard against hackers or other forms of unauthorized access. A business method uses a pricing structure whi ch makes the decryption keys available for different prices. |
