Data transmission method between a broadcasting center and a multimedia unit

• US 20060056632A1
• Filed: 08/31/2005
• Published: 03/16/2006
• Est. Priority Date: 09/10/2004
• Status: Active Grant

• Current Assignee: Nagravision SA (Kudelski SA)
• Original Assignee: NagraCard SA (Kudelski SA)
• Inventors: Fischer, Nicolas, Kudelski, Andre, Nicolas, Christophe
• Granted Patent: US 7,433,473 B2
• Time in Patent Office: Days
• US Class Current: 380/259
• CPC Class Codes: H04N 21/25816 involving client authentication restricting access to computer systems by authenticating users using a predetermined code G06F21/33; cryptographic authentication protocols H04L9/32; networks authentication protocols H04L63/08; authentication in wireless network security H04W12/06
• CPC Class Codes: H04N 21/26606 for generating or managing entitlement messages, e.g. Entitlement Control Message [ECM] or Entitlement Management Message [EMM] arrangements for conditional access to broadcast information or to broadcast-related services H04H60/14

Abstract

The aim of this invention is to propose a flexible solution to the risk represented by access to a temporary memory of a specialized decryption/decompression circuit for a Pay-TV decoder. This aim is achieved by a data transmission method between a diffusion centre and a multimedia unit, the latter comprising at least one unique key and a security module having a transport key, this method comprising the following stages: generation of a session key by a management centre, transmission of the session key to the diffusion centre, encryption of the session key by the unique key of the multimedia unit, transmission of a message encrypted by the transport key comprising the encrypted session key to the multimedia unit, transmission of the message to the security module by the multimedia unit, decryption of the message by the transport key of the security module and transmission of the encrypted session key to the multimedia unit, decryption of the session key encrypted by the unique key of the multimedia unit, creation of a connection secured by the encryption and decryption, by the session key, of data exchanged between the diffusion centre and the multimedia unit.

Claims

1. Data transmission method between a diffusion centre and a multimedia unit, the latter comprising at least one unique key and a security module (MS) having a transport key, this method comprising the following steps:

generation of a session key by a management centre,

transmission of the session key to the diffusion centre,

encryption of the session key by the unique key of the multimedia unit,

transmission of a management message encrypted by the transport key comprising the encrypted session key to the multimedia unit,

transmission of the management message to the security module by means of the multimedia unit,

decryption of the management message by the transport key of the security module and transmission of the encrypted session key to the multimedia unit,

decryption of the session key encrypted by the unique key of the multimedia unit,

creation of a secure connection by the encryption and decryption, by the session key, of data exchanged between the diffusion centre and the multimedia unit.

2. Data transmission method according to claim 1, wherein the transport key is a key common to several security modules.

3. Data transmission method according to claim 1, wherein the transport key is a key specific to the security module.

4. Data transmission method according to claim 1, wherein the diffusion centre and the management centre form one single entity.

5. Data transmission method according to claim 1, wherein the diffusion centre and the management centre form two distinct entities with communication means between each other.

6. Data transmission method according to claim 1, wherein the multimedia unit includes communication channels to which is applied an encryption/decryption layer using the session key.