Independent external security module for a digitally upgradeable television signal decoder
US5237610A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 29, 1991 |
| Grant date | Aug 17, 1993 |
| Priority date | — |
| Expiry date | Mar 29, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N21/426
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A decoder for descrambling encoded satellite transmissions comprises an internal security module and a resplaceable security module. The program signal is scrambled with a key and then the key itself is twice-encrypted and multiplexed with the scrambled program signal. The key is first encrypted with a first secret serial number (SSN.sub.1) which is assigned to a given replaceable security module. The key is then encrypted with a second secret serial number (SSN.sub.2) which is assigned to a given decoder. The decoder performs a first key decryption using the second secret serial number (SSN.sub.2) stored within the decoder. The partially decrypted key is then further decrypted by the replaceable security module using the first secret serial number (SSN.sub.1) stored within the replaceable security module. The decoder then descrambles the program using the twice-decrypted key. The replaceable security module can be replaced, allowing the security system to be upgraded or changed following a system breach. Either security module may become the active security module to finally decrypt the seed, selectable by a signal transmitted from the encoder. Also disclosed is a method for trans…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.