专利名称：Method and apparatus for use of a
watermark and a unique time dependentreference for the purpose of copyprotection
发明人：Michael Epstein申请号：US09276437申请日：19990325公开号：US06865675B1公开日：20050308
专利附图：
摘要：A copyright protection system for protecting content wherein a time
dependent ticket is calculated at a source device by combining a checkpoint with a ticket.The checkpoint is transmitted from a display device to the source device prior to thesource device transmitting watermarked content to the display device. The checkpoint isalso stored at the display device. Thereafter, the source device transmits, to the displaydevice, watermarked content, the ticket, and the time dependent ticket. At the displaydevice, the stored checkpoint is compared to a current count of a local clock that wasutilized for producing the checkpoint. If the stored checkpoint is within a window of timeof the local clock, then the stored checkpoint is combined with the ticket in the same waythat the checkpoint is combined with the ticket at the source device. A result of thecombination is compared to the time dependent ticket and if the result equals the timedependent ticket, then the watermark and ticket may be compared in the usual way todetermine the copy protection status of the copy protected content.
申请人：Michael Epstein
地址：Spring Valley NY US
国籍：US
代理人：Edward W. Goodman
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