Conditional access
US7403618B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 19, 2001 |
| Grant date | Jul 22, 2008 |
| Priority date | — |
| Expiry date | Apr 1, 2024 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N21/4782
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A transmitter provides receivers conditional access to data transmitted via a network. A content encryptor is used to encrypt the data under control of a same authorization key before it is transmitted to all receivers. The transmitter has a storage with a plurality of device keys. A further encryptor is used for producing a key block with a plurality of entries, where each entry is associated with a respective one of the device keys. At least some of the entries contain a representation of the authorization key encrypted with the associated device key. The transmitter transmits the same key block to all receivers.The receiver has a subset of the device keys. A first decryptor is used to retrieve the authorization key by decrypting at least one entry of the key block that is associated with one of the device keys of the receiver. A second decryptor is used for decrypting the data under control of the authorization key.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.