METHOD OF ESTABLISHING A CRYPTOGRAPHIC KEY, NETWORK HEAD AND RECEIVER FOR THIS METHOD, AND METHOD OF TRANSMITTING SIGNALS

• US 20090010434A1
• Filed: 02/21/2007
• Published: 01/08/2009
• Est. Priority Date: 02/22/2006
• Status: Active Grant

• Current Assignee: Viaccess
• Original Assignee: Viaccess
• Inventors: Carles, Philippe
• Granted Patent: US 8,885,825 B2
• Time in Patent Office: Days
• US Class Current: 380/255
• CPC Class Codes: H04L 63/061 for key exchange, e.g. in peer-to-peer networks cryptographic mechanisms or cryptographic arrangements for key agreement H04L9/0838
• CPC Class Codes: H04N 21/26613 for generating or managing keys in general key distribution for secret or secure communication involving central third party, e.g. key distribution center [KDC] or trusted third party [TTP] H04L9/083; network support of key management H04L63/06; key management for network security in communication control or processing H04W12/04
• CPC Class Codes: H04N 21/472 End-user interface for requesting content, additional data or services; End-user interface for interacting with content, e.g. for content reservation or setting reminders, for requesting event notification, for manipulating displayed content end-user interfaces for retrieving video data from a database G06F16/739; network services for supporting unicast streaming H04L65/612
• CPC Class Codes: H04N 21/64 Addressing network arrangements, protocols or services for addressing or naming H04L61/00; support for multicast or broadcast of one-way stream services H04L65/611
• CPC Class Codes: H04N 21/64322 IP
• CPC Class Codes: H04N 7/165 Centralised control of user terminal subsequent to an upstream request signal H04N7/17345; Registering at central by two-way working H04N7/17309

Abstract

This method of establishing a cryptographic session key comprises: a subscription phase (104) during which an identifier of a local loop to the end of which a receiver must be connected is acquired, and an authentication step comprising: a) an operation (142) of automatically obtaining an identifier of the local loop to the end of which the receiver is actually connected, and b) an operation (146) of verifying that the identifier obtained during the operation a) corresponds to the identifier acquired during the subscription phase so as to authenticate the receiver.

Claims

1. Method of establishing a cryptographic session key which is common to a network head which transmits scrambled multimedia signals and a receiver of those scrambled multimedia signals, that receiver being capable of unscrambling the signals received by means of a check word, the network head and the receiver being connected to each other by means of a telecommunications network, in which each local loop is identified in a unique manner among all the local loops by an identifier for a local loop, the receiver being able to be connected to the end of any one of the local loops of the network, the method comprising:

a step for authenticating the receiver and

a step for constructing the session key, the step being completely carried out only if the receiver has been correctly authenticated during the authentication step,

characterized in that the method comprises a prior subscription step during which an identifier for the local loop, to the end of which the receiver must be connected, is acquired from pieces of information which are provided by a user who wishes to subscribe,

and in that the authentication step comprises;

a) when the receiver is connected to the network head by means of the network, an operation for automatically obtaining the identifier for the local loop, to the end of which the receiver is really connected in order to establish that connection with respect to the network head, from pieces of information provided by at least one piece of equipment of the network which is connected to the end of the local loop opposite the end to which the receiver is connected, and

b) an operation for verifying that the identifier obtained during the operation a) corresponds to the identifier acquired during the subscription step in order to authenticate the receiver.

2. Method according to claim 1, characterized in that the operations a) and b) are reiterated each time the receiver is connected to the network head.

3. Method according to claim 1, characterized in that,

during the subscription step, the network head generates a unique activation code which is associated, in the network head, with the identifier acquired during the subscription step,

before the operation b), the receiver has the activation code,

when a connection is established with respect to the network head, the receiver transmits the activation code which it has to the network head by means of the network and,

during the operation b), the network head uses the activation code received in order to establish correspondence between the identifier acquired during the subscription step and the local loop identifier obtained during the operation a).

4. Method according to claim 3, characterized in that the activation code is generated by the network head and is transmitted to the client, and in that the receiver acquires this activation code by means of a human/machine interface.

5. Method according to claim 3, characterized in that, before the step b), the network head and the terminal generate, independently of each other, the activation codes in a unique manner on the basis of at least one identifier for the terminal known by both the terminal and the network head.

6. Method according to claim 1, characterized in that, before the step for constructing the key, the method comprises:

an activation step, during which either the receiver generates, by means of a random or pseudo-random generator, a pair of public/private keys K_STB-pub/K_STB-priv, then sends only the public key to the network head, or the network head generates, by means of a random or pseudo-random generator, a pair of public/private keys K_STB-pub/K_STB-priv, then sends that pair of keys to the receiver and, subsequently,

during the construction step, the network head transmits, to the receiver by means of the network, secret items which are encrypted by means of the public key K_STB-pub and the receiver decrypts those secret items by means of the private key K_STB-priv, those secret items which are exchanged between the network head and the receiver allowing the session key to be established.

7. Method according to claim 6, for receivers which are provided with at least one unique identifier, characterized in that the random or pseudo-random generator is further initialized on the basis of a unique identifier for the receiver.

8. Method according to claim 6, characterized in that, during the activation step, at least one cryptographic certificate of the public key K_STB-pub is created then used, and in that the creation of the cryptographic certificate of the key K_STB-pub is subject to the condition that the operation b) be successful.

9. Method according to claim 1, characterized in that the piece of equipment of the network providing those pieces of information is a localization server which, on the basis of an IP (Internet Protocol) address allocated to the receiver in order to connect to the network head, is capable of locating the identifier for the local loop, to the end of which the receiver is really connected in order to establish the connection.

10. Receiver which is capable of establishing a session key with a network head by carrying out a method in accordance with claim 4, characterized in that the receiver comprises a human/machine interface, and in that the receiver is capable of acquiring the activation code, by means of that human/machine interface, and transmitting that activation code acquired to the network head by means of the network.

11. Receiver which is capable of establishing a session key with a network head by carrying out a method in accordance with claim 5, characterized in that this receiver is capable of generating, independently of the network head, an activation code in a unique manner on the basis of an identifier for the receiver known by both the receiver and the network head.

12. Receiver according to claim 10,

this receiver being capable of establishing a session key with a network head by carrying out the method wherein before the step for constructing the key, the method further comprises:

an activation step, during which either the receiver generates, by means of a random or pseudo-random generator, a pair of pubic/private keys K_STB-pub/K_STB-priv, then sends only the public key to the network head or the network head generates, by means of a random or pseudo-random generator, a pair of public/private keys K_STB-pub/K_STB-priv, then sends that pair of keys to the receiver and, subsequently,

during the construction step, the network head transmits, to the receiver by means of the network, secret items which are encrypted by means of the public key K_STB-pub and the receiver decrypts those secret items by means of the private key K_STB-priv, those secret items which are exchanged between the network head and the receiver allowing the session key to be established,

characterized in that the key generator comprises a random or pseudo-random generator which is capable of generating the pair of public/private keys, and in that the receiver is capable of sending only the public key to the network head.

13. Receiver according to claim 12,

which is capable of establishing a session key with a network head by carrying out the method for receivers which are provided with at least one unique identifier, and characterized in that the random or pseudo-random generator is further initialized on the basis of a unique identifier for the receiver,

wherein the receiver comprises a unique identifier and the generator can be initialized on the basis of that unique identifier for the receiver.

14. Network head which is capable of transmitting scrambled multimedia signals and establishing a session key with a receiver of those scrambled multimedia signals by carrying out a method in accordance with claim 1,

characterized in that, when the receiver is connected to the network head by means of the network, the network head is capable of automatically obtaining the identifier for the local loop, to the end of which the receiver is really connected in order to establish that connection, from pieces of information which are provided by at least one piece of equipment of the network connected to the end of the local loop opposite the end to which the receiver is connected, and the network head is capable of verifying that the identifier obtained corresponds to the identifier acquired during the subscription step in order to authenticate the receiver.

15. Network head according to claim 14,

which is capable of establishing a session key by carrying out the method which is further characterized in that the operations a) and b) are reiterated each time the receiver is connected to the network head,

wherein the network head is capable of obtaining the identifier for a local loop and verifying that the identifier obtained corresponds to the identifier acquired during the subscription step each time the receiver is connected to the network head.

16. Network head according to claim 14,

which is capable of establishing a session key with the receiver by carrying out the method, further characterized in that,

during the subscription step, the network head generates a unique activation code which is associated, in the network head, with the identifier acquired during the subscription step,

before the operation b), the receiver has the activation code,

when a connection is established with respect to the network head, the receiver transmits the activation code which it has to the network head by means of the network and,

during the operation b), the network head uses the activation code received in order to establish correspondence between the identifier acquired during the subscription step and the local loop identifier obtained during the operation a),

wherein the network head is capable of using the activation code received in order to establish correspondence between the identifier acquired during the subscription step and the identifier for a local loop obtained.

17. Method of transmitting scrambled multimedia signals between a network head and a receiver of those scrambled multimedia signals, the receiver being capable of unscrambling the signals received by means of a check word, the network head and the receiver being connected to each other by means of a telecommunications network, wherein each local loop is identified in a unique manner among all the local loops by an identifier for a local loop, the receiver being able to be connected to the end of any one of the local loops of the network, characterized in that this method comprises:

a procedure for establishing a session key in accordance with the method according to claim 1 and

a step for encrypting the check word or a message containing the check word, by means of the session key established, before it is transmitted from the network head to the receiver by means of the network.