Method for improving accuracy of a time estimate used to authenticate an entity to a memory device

• US 20080307237A1
• Filed: 06/08/2007
• Published: 12/11/2008
• Est. Priority Date: 06/08/2007
• Status: Abandoned Application

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Inventors: Holtzman, Michael, Barzilai, Ron, Sela, Rotem, Jogand-Coulomb, Fabrice E.
• Application Number:
  US11/811,289
• Publication Number:
  US 20080307237A1
• Time in Patent Office: Days
• US Class Current: 713/193
• CPC Class Codes: G06F 21/725 operating on a secure reference time value
• CPC Class Codes: G06F 21/79 in semiconductor storage media, e.g. directly-addressable memories
• 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 to authenticate an entity to a memory device is disclosed. In one embodiment, a memory device receives a request to authenticate an entity. Before attempting to authenticate the entity, the memory device determines if a new time stamp is needed. If a new time stamp is needed, the memory device receives the new time stamp and then attempts to authenticate the entity using a time estimate based on the new time stamp. In another embodiment, the memory device comprises a plurality of different time stamp update policies (TUPs) that specify when a new time stamp is needed, and the determination of whether a new time stamp is needed is based on a TUP associated with the entity. Other embodiments are disclosed, and each of the embodiments can be used alone or together in combination.

Claims

1. A method for authenticating an entity to a memory device, the method comprising:

with a memory device;

receiving a request to authenticate an entity;

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

if 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.

2. The method of claim 1 further comprising:

with the memory device;

if a new time stamp is not needed, attempting to authenticate the entity using a time estimate based on a last time stamp received by the memory device.

3. The method of claim 1, wherein the determining of whether a new time stamp is needed is based on one or more of the following:

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.

4. The method of claim 1, wherein the attempt to authenticate the entity is made using an asymmetric authentication procedure.

5. The method of claim 1, wherein attempting to authenticate the entity comprises determining if a certificate is valid.

6. The method of claim 1, wherein attempting to authenticate the entity comprises determining if a certificate revocation list (CRL) is valid

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

8. The method of claim 7, the time server is independent from the entity.

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

10. 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.

11. The method of claim 1, wherein determining if a new time stamp is needed comprises determining whether a time stamp update policy (TUP) of an access control record (ACR) associated with the entity requires a new time stamp.

12. The method of claim 1, wherein the new time stamp is sent via a free channel.

13. A method for authenticating an entity to a memory device, the method comprising:

with a memory device comprising a plurality of different time stamp update policies (TUPs) that specify when a new time stamp is needed;

receiving a request to authenticate an entity;

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

if a new time stamp is needed, receiving the new time stamp and then attempting to authenticate the entity using the new time stamp.

14. The method of claim 13 further comprising:

with the memory device;

if a new time stamp is not needed, attempting to authenticate the entity using a last time stamp received by the memory device.

15. The method of claim 13, wherein the TUP associated with the entity 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.

16. The method of claim 13, wherein the attempt to authenticate the entity is made using an asymmetric authentication procedure.

17. The method of claim 13, wherein attempting to authenticate the entity comprises determining if a certificate is valid.

18. The method of claim 13, wherein attempting to authenticate the entity comprises determining if a certificate revocation list (CRL) is valid

19. The method of claim 13, wherein the new time stamp is generated by a time server.

20. The method of claim 19, wherein the time server is independent from the entity.

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

22. The method of claim 13, wherein the memory device stores digital rights management (DRM) keys and licenses to unlock protected content stored on the memory device.

23. The method of claim 13, wherein the plurality of different TUPs are part of a respective plurality of access control records (ACRs).

24. The method of claim 13, wherein the new time stamp is sent via a free channel.