DIGITAL RIGHTS MANAGEMENT LICENSE IDENTIFICATION

• US 20100070416A1
• Filed: 09/18/2008
• Published: 03/18/2010
• Est. Priority Date: 09/18/2008
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: McKelvey, Alexander
• Granted Patent: US 10,453,003 B2
• Time in Patent Office: Days
• US Class Current: 705/50
• CPC Class Codes: G06Q 10/06 Resources, workflows, human or project management; Enterprise or organisation planning; Enterprise or organisation modelling
• CPC Class Codes: G06Q 50/18 Legal services

Abstract

A digital rights management license provides access to a content key that can be used to decrypt an encrypted digital content item. The digital rights management license also includes a policy that defines circumstances in which the content key is allowed to decrypt the encrypted digital content item. Further, the digital rights management license includes a license identifier. The license identifier is a digital fingerprint of at least a portion of the policy of the license.

Claims

1. A method of building a license for implementing digital rights management, the method comprising:

assigning a content key to the license, the content key configured to decrypt content data encrypted by a symmetric cryptographic content key;

assigning a policy to the license, the policy defining circumstances in which the content key is allowed to decrypt content data encrypted by the symmetric cryptographic content key;

finding a digital fingerprint of a portion of the policy; and

assigning the digital fingerprint to the license as an identifier for the license.

2. The method of claim 1, where finding a digital fingerprint includes applying a deterministic sequence of finite instructions to a portion of the policy.

3. The method of claim 2, where the deterministic sequence of finite instructions includes a hash function.

4. The method of claim 2, where the deterministic sequence of finite instructions outputs a digital fingerprint including a fixed-length string.

5. The method of claim 1, where the policy includes an indication of the content data to which the license applies.

6. The method of claim 1, where the policy includes an indication of when the license expires.

7. The method of claim 1, where the policy includes an indication of to whom the license is issued.

8. The method of claim 1, where the policy includes an indication of whether the license allows playback.

9. The method of claim 1, where the policy includes an indication of whether the license allows copying.

10. The method of claim 1, where the content key is itself encrypted with a public key so that only a device with a corresponding symmetric private key can decrypt the content key and thereby decrypt the content data.

11. The method of claim 1, where the content key is itself encrypted with a public key so that only a device belonging to a domain having access to a corresponding symmetric private key can decrypt the content key and thereby decrypt the content data.

12. The method of claim 1, further comprising assigning a content key identifier to the license, the content key identifier identifying which content key is assigned to the license.

13. A method of building a license for implementing digital rights management, the method comprising:

assigning a policy to the license, the policy defining circumstances in which a content key is allowed to decrypt content data encrypted by a symmetric cryptographic content key;

hashing a digital fingerprint of a portion of the policy; and

assigning the digital fingerprint to the license as an identifier for the license.

14. The method of claim 13, where the policy includes an indication of the content data to which the license applies.

15. The method of claim 13, where the policy includes an indication of when the license expires.

16. The method of claim 13, where the policy includes an indication of to whom the license is issued.

17. The method of claim 13, where the policy includes an indication of whether the license allows playback.

18. The method of claim 13, where the policy includes an indication of whether the license allows copying.

19. The method of claim 13, further comprising assigning a content key identifier to the license, the content key identifier identifying which content key is assigned to the license.

20. A digital rights management system, comprising:

a library of encrypted digital content items;

for each encrypted digital content item, one or more content keys configured to decrypt that encrypted digital content item; and

one or more licenses including a policy and a license identifier, the policy defining circumstances in which a particular one of the one or more content keys is allowed to decrypt an encrypted digital content item, and the license identifier identifying that license with a digital fingerprint of a portion of the policy.