Apparatus and method for single encryption with multiple authorization of distributed content data
US7062048B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 18, 2003 |
| Grant date | Jun 13, 2006 |
| Priority date | — |
| Expiry date | Apr 7, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N21/4623
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A content data distribution system uses a single key and multiple program authorization to transmit a plurality of programs in multiplexed data packets such as those used in Digital Video Broadcasting. A receiver has a memory, a descrambler and a processor. Authorization indicators are transmitted among said data packets and stored in the memory. The authorization indicators identify a plurality of authorized data packets corresponding to at least one authorized program and further identifies a plurality of unauthorized data packets corresponding to at least one unauthorized program. Only authorized data packets are output from a receiver in decrypted form. Null sets are substituted for unauthorized data packets. Data packet tables may be rebuilt as necessary to replace tables lost in null set substitution. One key is used to encrypt all programs. Alternatively, a number of keys fewer than the number of authorized programs may be used for encryption. The keys may themselves be encrypted for transmission.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.