Method of operating a conditional access system for broadcast applications
US7155611B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 18, 2000 |
| Grant date | Dec 26, 2006 |
| Priority date | — |
| Expiry date | Oct 17, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N21/4367
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In a method for operating a conditional access system for broadcast applications, the conditional access system comprising a number of subscribers and each subscriber having a terminal including a conditional access module and a secure device for storing entitlements, a source signal is encrypted using a first key (CW). The encrypted source signal is broadcasted for receipt by the terminals, wherein entitlement control messages (ECM's) are sent to the secure devices, the ECM's comprising the first keys (CW) encrypted using a service key (PT). Entitlement management messages (EMM's) are sent to the secure devices providing the service key (PT) required to decrypt encrypted first keys (CW). A cracked secure device which is used in an unauthorized manner is traced by sending different keys required to obtain the first keys to different terminals or groups of terminals and monitoring the key information provided by a pirate. To this end search EMM's are sent to at least a part of the terminals, the search EMM's providing at least the service key (PT) and a dummy key (PD1 or PD2). At least the search EMM's comprise identifiers identifying the keys (PT and PD1 or PD2), wherein first sear…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.