Content Protection scheme for a digital recording device
US6959090B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 20, 2000 |
| Grant date | Oct 25, 2005 |
| Priority date | — |
| Expiry date | Jun 3, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2005/91364
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A recording device for digital data streams, such as digital TV broadcasts or digitized music, stores copies of program content encrypted by a key unique to the recording device. Distribution of program content is thus discouraged, since intelligible playback of program content would not be obtained on another recording device, which would have a different key. To reduce manufacturing complexity which would result from requiring all bits of a key to inhere in hardware, a first portion of the key inheres in hardware and a second portion is selected from among several candidates residing in a memory device, the key being determined by combining the first and second portions according to predetermined rules. The second portion is reselected at predetermined intervals from among the candidates. Only payload portions of packets are encrypted while header portions are left in the clear in order to facilitate ancillary functions of recorder such as fast forward, fast rewind, and program search.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.