Local digital network, methods for installing new devices and data broadcast and reception methods in such a network

• US 20050278524A1
• Filed: 08/23/2002
• Published: 12/15/2005
• Est. Priority Date: 08/24/2001
• Status: Active Grant

• Current Assignee: Thomson Licensing SA (Vantiva SA)
• Original Assignee: Thomson Licensing SA (Vantiva SA)
• Inventors: Diehl, Eric, Durand, Alain, Andreaux, Jean-Pierre
• Granted Patent: US 9,210,137 B2
• Time in Patent Office: Days
• US Class Current: 713/150
• CPC Class Codes: H04L 2209/601 Broadcast encryption
• CPC Class Codes: H04L 63/0428 wherein the data content is protected, e.g. by encrypting or encapsulating the payload
• CPC Class Codes: H04L 63/0435 wherein the sending and receiving network entities apply symmetric encryption, i.e. same key used for encryption and decryption cryptographic mechanisms or cryptographic arrangements for symmetric key encryption H04L9/06
• CPC Class Codes: H04L 9/0822 using key encryption key
• CPC Class Codes: H04L 9/088 Usage controlling of secret information, e.g. techniques for restricting cryptographic keys to pre-authorized uses, different access levels, validity of crypto-period, different key- or password length, or different strong and weak cryptographic algorithms network architectures or network communication protocols for using time-dependent keys in a packet data network H04L63/068
• CPC Class Codes: H04L 9/3239 involving non-keyed hash functions, e.g. modification detection codes [MDCs], MD5, SHA or RIPEMD
• CPC Class Codes: H04N 21/4181 for conditional access
• CPC Class Codes: H04N 21/4345 Extraction or processing of SI, e.g. extracting service information from an MPEG stream
• CPC Class Codes: H04N 21/43615 Interfacing a Home Network, e.g. for connecting the client to a plurality of peripherals home Audio Video Interoperability [HAVI] data switching networks H04L12/2805
• CPC Class Codes: H04N 21/4367 Establishing a secure communication between the client and a peripheral device or smart card
• CPC Class Codes: H04N 21/4405 involving video stream decryption
• CPC Class Codes: H04N 21/4408 involving video stream encryption, e.g. re-encrypting a decrypted video stream for redistribution in a home network
• CPC Class Codes: H04N 21/4623 Processing of entitlement messages, e.g. ECM [Entitlement Control Message] or EMM [Entitlement Management Message] arrangements for conditional access to broadcast information or to broadcast-related services H04H60/14
• CPC Class Codes: H04N 7/1675 Providing digital key or authorisation information for generation or regeneration of the scrambling sequence pseudo-random number generators in general G06F7/58

Abstract

The invention relates to a local digital network comprising: at least one source device intended to broadcast data over the network; and at least one receiver device intended to receive said data. The source device uses a network active encryption key to encrypt data liable to be broadcast in the network and the receiver device contains: a network active decryption key for decrypting data encrypted using said active encryption key and at least one decryption key of the network for decrypting data encrypted with the aid of an encryption key used previously in the network. The invention also relates to the installing of new devices in such a network as well as the sending of data from a source device to a receiver device.

Claims

1. Local digital network comprising:

at least one source device intended to broadcast data over the network; and

at least one receiver device intended to receive said data, wherein the source device uses a network active encryption key to encrypt data liable to be broadcast in the network; and

in that the receiver device contains;

a network active decryption key for decrypting data encrypted using said active encryption key and

at least one decryption key of the network for decrypting data encrypted with the aid of an encryption key used previously in the network.

2. Local digital network according to claim 1, wherein the receiver device contains all the network'"'"'s decryption keys used previously since the creation of the network.

3. Local digital network according to claim 1, wherein the source device Contains the network active encryption key and in that it encrypts the data liable to be broadcast in the network with said active key of the network.

4. Local digital network according to claim 1, wherein the source device contains:

a first symmetric key as well as

said first symmetric key encrypted with the network active encryption;

in that it encrypts the data liable to be broadcast in the network with said first symmetric key and

in that it is adapted for transmitting, with said encrypted data, the first symmetric key encrypted with the network active encryption key.

5. Local digital network according to claim 1, wherein the source device and the receiver device use symmetric encryption processes and in that the encryption keys and the corresponding decryption keys used in the network are identical.

6. Method for installing a new receiver device in a local digital network according to claim 1 already comprising at least one receiver device, wherein a preexisting receiver device of the network, possessing the network active decryption key and at least one decryption key used previously in the network, and having the capacity to send them in a secure manner, sends said decryption keys to the new receiver device.

7. Method for installing a new source device in a local digital network according to claim 5 already comprising at least one receiver device, wherein a preexisting receiver device of the network, possessing the network active encryption/decryption key and at least one encryption/decryption key used previously in the network and having the capacity to send them in a secure manner, sends the network active encryption/decryption key to the new source device.

8. Method for transmitting data by a source device linked to a network according to claim 5, wherein it consists in:

encrypting the data with the aid of the network active encryption/decryption key; and

transmitting said encrypted data as well as a fingerprint of said active key, calculated with the aid of a one-way function applied to the active key of the network.

9. Method for receiving encrypted data in a receiver device linked to a network, said data having been broadcast according to the method of claim 8,

wherein, since the receiver device furthermore contains a fingerprint of each encryption/decryption key that it contains, calculated with the aid of a one-way function applied to said key,

the method consists in:

extracting a key fingerprint from the data received;

comparing the extracted fingerprint with the fingerprints of the encryption/decryption keys contained in the receiver device; and

in the case of equality between the extracted fingerprint and one of the fingerprints stored in the receiver device, decrypting the data with the key corresponding to said fingerprint.

10. Method for transmitting data by a source device linked to a network according to claim 1, wherein it consists in:

(a) applying a one-way function to a first part of the data;

(b) encrypting the result of the calculation performed in step (a) and a second part of the data to be protected with the aid of the network active encryption key; and

(c) transmitting said data encrypted in step (b) as well as the first part of the data over the network.

11. Method for receiving data in a receiver device linked to a network, said data having been broadcast according to the method of claim 10, characterized in that wherein it consists in:

(a) applying a one-way function to a first part of the nonencrypted data;

(b) decrypting a second part of the data with the aid of a network decryption key contained in the receiver device, and

(c) comparing the result of the decryption of a portion of the data decrypted in step (b) with the result of the calculation performed in step (a) so as,

in the case of equality, to recover the remaining portion of the data decrypted in step (b); and

in the case of difference, to return to step (b) to perform the decryption of the second part of the data with the aid of another network decryption key contained in the receiver device.

12. Method for transmitting data by a source device linked to a network according to claim 1, wherein it consists in:

encrypting the data with the aid of the network active encryption key; and

transmitting said encrypted data as well as an index corresponding to the active key of the network.

13. Method for receiving data in a receiver device linked to a network, said data having been broadcast according to the method of claim 12, wherein it consists in:

extracting from the data received an index corresponding to the network encryption key used to encrypt said data;

deducing a corresponding network decryption key from this index; and

decrypting the data with the aid of said decryption key.