Method of managing user key for broadcast encryption

• US 20060129805A1
• Filed: 11/14/2005
• Published: 06/15/2006
• Est. Priority Date: 11/12/2004
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Jho, Nam-su, Yoo, Eun-sun, Kim, Dae-youb, Jin, Weon-il, Kim, Hwan-joon, Park, Sung-joon, Cheon, Jung-hee, Kim, Myung-hwan
• Granted Patent: US 7,929,705 B2
• Time in Patent Office: Days
• US Class Current: 713/158
• CPC Class Codes: H04L 2209/601 Broadcast encryption
• CPC Class Codes: H04L 2209/606 Traitor tracing
• CPC Class Codes: H04L 9/0822 using key encryption key
• CPC Class Codes: H04L 9/0827 involving distinctive intermediate devices or communication paths network architectures or network communication protocols using different networks H04L63/18
• CPC Class Codes: H04L 9/0836 using tree structure or hierarchical structure
• CPC Class Codes: H04L 9/0869 involving random numbers or seeds
• CPC Class Codes: H04L 9/0891 Revocation or update of secret information, e.g. encryption key update or rekeying
• CPC Class Codes: H04L 9/50 using hash chains, e.g. blockchains or hash trees
• CPC Class Codes: H04N 21/222 Secondary servers, e.g. proxy server, cable television Head-end provisioning of proxy services in data packet switching networks H04L67/56
• CPC Class Codes: H04N 21/2585 Generation of a revocation list, e.g. of client devices involved in piracy acts
• 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 7/162 Authorising the user terminal, e.g. by paying; Registering the use of a subscription channel, e.g. billing
• 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

A user key management method for a broadcast encryption includes assigning node path identifiers (IDs) to nodes arranged in sequence; assigning random seed value keys to the nodes according to the node path IDs; generating key values by repeatedly applying a hash function to the assigned random seed value keys; and assigning the generated key values to the nodes in sequence. Accordingly, it is possible to reduce the transmission overhead that is most important matter in the broadcast encryption to less than the number of the revoked users. Further, there is an advantage that the transmission overhead of the exemplary embodiments of the present invention is remarkably reduced compared with the Subset Difference method.

Claims

1. A method of managing a user key for a broadcast encryption, the method comprising:

assigning node path identifiers (IDs) to nodes which are arranged in sequence;

assigning random seed value keys to the nodes according to the node path IDs;

generating key values by repeatedly applying a hash function to the assigned random seed value keys; and

assigning the generated key values to the nodes in sequence.

2. The method of claim 1, wherein an encryption key for an interval formed with N-ary nodes which are arranged in sequence is generated by repeatedly applying the hash function N-1 times to a seed value key which is assigned to a first node in the interval.

3. The method of claim 2, wherein the interval is a set of consecutive non-revoked nodes.

4. The method of claim 2, wherein the interval includes more than one revoked node and an independent hash function is applied to the revoked node.

5. A method of managing a user key for a broadcast encryption, the method comprising:

assigning random seed value keys to nodes which are sequentially arranged;

generating first key values by repeatedly applying a first hash function to the assigned random seed value keys;

assigning the first key values to the nodes in sequence;

setting special nodes in a certain interval among the nodes which are sequentially arranged;

assigning special seed value keys to the special nodes;

generating second key values by repeatedly applying a second hash function to the assigned special seed value keys; and

assigning the second key values to the special nodes in sequence.

6. The method of claim 5, wherein, when a special node key K is assigned to a first special node of the special nodes, a second key value which is obtained by applying the second hash function to the special node key K is assigned to a second special node located away from the first special node in the certain interval.

7. The method of claim 5, wherein an encryption key for an interval formed with N-ary nodes which are arranged in sequence is generated by repeatedly applying the hash function N-1 times to a seed value key which is assigned to a first node in the certain interval.

8. The method of claim 7, wherein the certain interval is a set of consecutive non-revoked nodes.

9. The method of claim 7, wherein the interval includes more than one revoked node and an independent hash function is applied to the revoked node.

10. A method of managing a user key for a broadcast encryption, the method comprising:

assigning node path identifiers (IDs) to nodes configured as a circular group;

assigning random seed value keys to the nodes according to the node path IDs;

generating key values by repeatedly applying a hash function to the assigned random seed value keys; and

assigning the generated key values to the nodes in a cyclic way.

11. The method of claim 10, wherein an encryption key for a cyclic interval constructed with N-ary nodes in the circular group is generated by repeatedly applying the hash function N-1 times to a seed value key which is assigned to a first node in the interval.

12. The method of claim 11, wherein the cyclic interval is a set of consecutive non-revoked nodes.

13. The method of claim 10, wherein a layered structure of circular groups is formed by linking nodes configuring a new circular group below each node configuring the circular group.

14. The method of claim 13, wherein the layered structure has 16 layers.

15. The method of claim 13, wherein a number of nodes in the circular groups is identical.

16. The method of claim 10, wherein the cyclic interval formed with the N-ary nodes in the circular group includes more than one revoked node and an independent hash function is applied to the revoked node.

17. The method of claim 10, wherein N-ary nodes form the circular group and are assigned the node path IDs from 0 to N-1.

18. The method of claim 13, wherein a node having at least one revoked node is regarded as a revoked node in the layered structure.

19. A method of managing a user key for a broadcast encryption, the method comprising:

assigning random seed value keys to nodes configured as a circular group;

generating first key values by repeatedly applying a first hash function to the assigned random seed value keys;

assigning the first key values to the nodes in a cyclic way;

setting special nodes in a certain interval among the nodes;

assigning random special seed value keys to the special nodes;

generating second key values by repeatedly applying a second hash function to the assigned random seed value keys; and

assigning the second key values to the special nodes in a cyclic way.

20. The method of claim 19, wherein, if a special node key K is assigned to a first special node of the special nodes, a second key value which is obtained by applying the second hash function to the special node key K is assigned to a second special node located away from the first special node at the certain interval.

21. The method of claim 19, wherein an encryption key for an interval formed with N-ary nodes which are arranged in sequence is generated by repeatedly applying the hash function N-1 times to a seed value key which is assigned to a first node in the interval.

22. The method of claim 21, wherein the cyclic interval is a set of consecutive non-revoked nodes.

23. The method of claim 21, wherein the cyclic interval includes more than one revoked node and an independent hash function is applied to the revoked node.