Method for improving accuracy of a time estimate used in digital rights management (DRM) license validation

• US 8,688,588 B2
• Filed: 06/08/2007
• Issued: 04/01/2014
• Est. Priority Date: 06/08/2007
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: Sandisk Technologies Incorporated (Western Digital Corporation)
• Inventors: Holtzman, Michael, Sela, Rotem, Barzilai, Ron, Jogand-Coulomb, Fabrice E.
• Primary Examiner(s): Nigh, James D
• Application Number:
  US11/811,354
• Publication Number:
  US 20100024000A1
• Time in Patent Office: 2,489 Days
• Field of Search: 705/59, 713/178
• US Class Current: 705/59
• CPC Class Codes: G06F 21/10 Protecting distributed programs or content, e.g. vending or licensing of copyrighted material protection in video systems or pay television H04N7/16 ; Digital rights management [DRM]
• CPC Class Codes: G06Q 2220/18 Licensing
• CPC Class Codes: G06Q 99/00 Subject matter not provided for in other groups of this subclass
• CPC Class Codes: H04L 2209/603 Digital right managament [DRM]
• CPC Class Codes: H04L 9/3268 using certificate validation, registration, distribution or revocation, e.g. certificate revocation list [CRL]
• CPC Class Codes: H04L 9/3297 involving time stamps, e.g. generation of time stamps

Abstract

A method for improving accuracy of a time estimate used in digital rights management (DRM) license validation is disclosed. In one embodiment, a memory device receives a request to validate a DRM license stored on the memory device, wherein the DRM license is associated with a time stamp update policy (TUP) that specifies when a new time stamp is needed. Before attempting to validate the DRM license, the memory device determines if a new time stamp is needed based on the TUP associated with the DRM license. If a new time stamp is needed, the memory device receives the new time stamp and then attempts to validate the DRM license using a time estimate based on the new time stamp. Other embodiments are disclosed, and each of the embodiments can be used alone or together in combination.

Claims

1. A method for validating a digital rights management (DRM) license, the method comprising:

performing the following in a processor of a memory device;

receiving a request to validate a digital rights management (DRM) license stored on the memory device;

in response to receiving the request to validate the DRM license but before attempting to validate the DRM license, determining if a new time stamp is needed based on a time stamp update policy (TUP) for the DRM license that specifies when a new time stamp is needed; and

based on a determination that a new time stamp is needed, receiving the new time stamp and then attempting to validate the DRM license using a time estimate based on the new time stamp.

2. The method of claim 1, wherein the TUP comprises one or more of the following parameters:

a number of power cycles of the memory device since a last time stamp received by the memory device, active time of the memory device since the last time stamp, and stretched active time of the memory device since the last time stamp.

3. The method of claim 1 further comprising:

with the memory device;

receiving a request to validate a second DRM license stored on the memory device;

before attempting to validate the second DRM license, determining if a new time stamp is needed based on a second TUP; and

based on a determination that a new time stamp is needed, receiving the new time stamp and then attempting to validate the second DRM license using a time estimate based on the new time stamp.

4. The method of claim 1, wherein the new time stamp is generated by a time server.

5. The method of claim 1, wherein the new time stamp is generated by a host device connected with the memory device.

6. The method of claim 1, wherein the memory device stores digital rights management (DRM) keys and licenses to unlock protected content stored on the memory device.

7. The method of claim 1 further comprising:

performing the following in the memory device prior to receiving the request to validate the DRM license;

receiving a request to authenticate an entity;

before attempting to authenticate the entity, determining if a new time stamp is needed based on a second TUP; and

based on a determination that a new time stamp is needed, receiving the new time stamp and then attempting to authenticate the entity using a time estimate based on the new time stamp.

8. The method of claim 1 further comprising:

based on a determination that a new time stamp is not needed, attempting to validate the DRM license using a time estimate based on a last time stamp received by the memory device, wherein the time estimate based on the last time stamp received is generated by;

measuring active time of the memory device with respect to the last time stamp received using a time counter in the memory device, wherein the time counter runs only when the memory device is active;

determining accuracy of active time previously measured by the memory device over a time period by comparing it with actual time over that time period, wherein inaccuracy is due at least in part to down time of the memory device;

adjusting the measured active time based on the determined accuracy; and

adding the adjusted measured active time to the last time stamp received.

9. A method for validating a digital rights management (DRM) license, the method comprising:

performing the following in a processor of a memory device;

receiving a request to validate one of a plurality of digital rights management (DRM) licenses stored on the memory device;

in response to receiving the request to validate the one of the plurality of DRM licenses but before attempting to validate the one of the plurality of DRM licenses, determining if a new time stamp is needed based on a time stamp update policy (TUP) for the DRM license that specifies when a new time stamp is needed; and

based on a determination that a new time stamp is needed, receiving the new time stamp and then attempting to validate the one of the plurality of DRM licenses using a time estimate based on the new time stamp.

10. The method of claim 9 further comprising:

with the memory device;

if the new time stamp is not needed, attempting to validate the one of the plurality of DRM licenses using a time estimate based on a last time stamp received by the memory device.

11. The method of claim 9, wherein the TUP comprises one or more of the following parameters:

a number of power cycles of the memory device since a last time stamp received by the memory device, active time of the memory device since the last time stamp, and stretched active time of the memory device since the last time stamp.

12. The method of claim 9, wherein the new time stamp is generated by a time server.

13. The method of claim 9, wherein the new time stamp is generated by a host device connected with the memory device.

14. The method of claim 9, wherein the memory device stores digital rights management (DRM) keys and licenses to unlock protected content stored on the memory device.

15. The method of claim 9 further comprising:

with the memory device, prior to receiving the request to validate the one of the plurality of DRM licenses;

receiving a request to authenticate an entity;

before attempting to authenticate the entity, determining if a new time stamp is needed based on a second TUP; and

based on a determination that a new time stamp is needed, receiving the new time stamp and then attempting to authenticate the entity using a time estimate based on the new time stamp.

16. The method of claim 9 further comprising:

based on a determination that a new time stamp is not needed, attempting to validate the one of the plurality of DRM licenses using a time estimate based on a last time stamp received by the memory device, wherein the time estimate based on the last time stamp received is generated by;

measuring active time of the memory device with respect to the last time stamp received using a time counter in the memory device, wherein the time counter runs only when the memory device is active;

determining accuracy of active time previously measured by the memory device over a time period by comparing it with actual time over that time period, wherein inaccuracy is due at least in part to down time of the memory device;

adjusting the measured active time based on the determined accuracy; and

adding the adjusted measured active time to the last time stamp received.

17. A memory device comprising:

a memory array; and

a processor in communication with the memory array and operative to;

receive a request to validate a digital rights management (DRM) license stored on the memory device;

in response to receiving the request to validate the DRM license but before attempting to validate the DRM license, determine if a new time stamp is needed based on a time stamp update policy (TUP) for the DRM license that specifies when a new time stamp is needed; and

based on a determination that a new time stamp is needed, receive the new time stamp and then attempt to validate the DRM license using a time estimate based on the new time stamp.

18. The memory device of claim 17, wherein the processor is further operative to:

if the new time stamp is not needed, attempt to validate the DRM license using a time estimate based on a last time stamp received by the memory device.

19. The memory device of claim 17, wherein the TUP comprises one or more of the following parameters:

a number of power cycles of the memory device since a last time stamp received by the memory device, active time of the memory device since the last time stamp, and stretched active time of the memory device since the last time stamp.

20. The memory device of claim 17, wherein the processor is further operative to:

receive a request to validate a second DRM license stored on the memory device;

before attempting to validate the second DRM license, determine if a new time stamp is needed based on a second TUP; and

based on a determination that a new time stamp is needed, receive the new time stamp and then attempt to validate the second DRM license using a time estimate based on the new time stamp.

21. The memory device of claim 17, wherein the new time stamp is generated by a time server.

22. The memory device of claim 17, wherein the new time stamp is generated by a host device connected with the memory device.

23. The memory device of claim 17, wherein the memory device stores digital rights management (DRM) keys and licenses to unlock protected content stored on the memory device.

24. The memory device of claim 17, wherein the processor is further operative to, prior to receiving the request to validate the DRM license:

receive a request to authenticate an entity;

before attempting to authenticate the entity, determine if a new time stamp is needed based on a second TUP; and

based on a determination that a new time stamp is needed, receive the new time stamp and then attempt to authenticate the entity using a time estimate based on the new time stamp.

25. The memory device of claim 17, wherein the processor is further operative to:

based on a determination that a new time stamp is not needed, attempting to validate the DRM license using a time estimate based on a last time stamp received by the memory device, wherein the time estimate based on the last time stamp received is generated by;

measuring active time of the memory device with respect to the last time stamp received using a time counter in the memory device, wherein the time counter runs only when the memory device is active;

determining accuracy of active time previously measured by the memory device over a time period by comparing it with actual time over that time period, wherein inaccuracy is due at least in part to down time of the memory device;

adjusting the measured active time based on the determined accuracy; and

adding the adjusted measured active time to the last time stamp received.

26. A memory device comprising:

a memory array; and

a processor in communication with the memory array and operative to;

receive a request to validate one of a plurality of digital rights management (DRM) licenses stored on the memory device;

in response to receiving the request to validate the one of the plurality of DRM licenses but before attempting to validate the one of the plurality of DRM licenses, determine if a new time stamp is needed based on a time stamp update policy (TUP) for the one of the plurality of DRM licenses that specifies when a new time stamp is needed;

based on a determination that a new time stamp is needed, receive the new time stamp and then attempt to validate the one of the plurality of DRM licenses using a time estimate based on the new time stamp.

27. The memory device of claim 26, wherein the processor is further operative to:

if the new time stamp is not needed, attempt to validate the one of the plurality of DRM licenses using a time estimate based on a last time stamp received by the memory device.

28. The memory device of claim 26, wherein the TUP comprises one or more of the following parameters:

a number of power cycles of the memory device since a last time stamp received by the memory device, active time of the memory device since the last time stamp, and stretched active time of the memory device since the last time stamp.

29. The memory device of claim 26, wherein the new time stamp is generated by a time server.

30. The memory device of claim 26, wherein the new time stamp is generated by a host device connected with the memory device.

31. The memory device of claim 26, wherein the memory device stores digital rights management (DRM) keys and licenses to unlock protected content stored on the memory device.

32. The memory device of claim 26, wherein the processor is further operative to, prior to receiving the request to validate the one of the plurality of DRM licenses:

receive a request to authenticate an entity;

before attempting to authenticate the entity, determine if a new time stamp is needed based on a second TUP; and

based on a determination that a new time stamp is needed, receive the new time stamp and then attempt to authenticate the entity using a time estimate based on the new time stamp.

33. The memory device of claim 26, wherein the processor is further operative to:

based on a determination that a new time stamp is not needed, attempting to validate the one of the plurality of DRM licenses using a time estimate based on a last time stamp received by the memory device, wherein the time estimate based on the last time stamp received is generated by;

measuring active time of the memory device with respect to the last time stamp received using a time counter in the memory device, wherein the time counter runs only when the memory device is active;

determining accuracy of active time previously measured by the memory device over a time period by comparing it with actual time over that time period, wherein inaccuracy is due at least in part to down time of the memory device;

adjusting the measured active time based on the determined accuracy; and

adding the adjusted measured active time to the last time stamp received.