Key distribution in a conditional access system
US7296159B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 22, 2003 |
| Grant date | Nov 13, 2007 |
| Priority date | — |
| Expiry date | Jul 26, 2025 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N21/6405
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Methods and apparatus for key distribution in a conditional access system, assuming that the set of all user nodes which the system can accommodate is a complete set, and a subset is composed of all user nodes or part of user nodes. One method comprises: decomposing said subset into at least one secondary subset; assigning a different user key to each secondary subset, each said user key being transmitted to all users in a corresponding secondary subset; encrypting an entitlement key by using each said user key so as to generate a cipher text corresponding to each said secondary subset; and combining said cipher text to generate a media key control block and transmitting said media key control block to all users in said subset. Since a classification method of a binary tree and a multiple tree is used, the invention can save a lot of network resources.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.