Key Escrow Service

• US 20090327702A1
• Filed: 06/27/2008
• Published: 12/31/2009
• Est. Priority Date: 06/27/2008
• Status: Abandoned Application

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Schnell, Patrik
• Application Number:
  US12/163,681
• Publication Number:
  US 20090327702A1
• Time in Patent Office: Days
• US Class Current: 713/155
• CPC Class Codes: G06F 21/107 License processing; Key processing
• CPC Class Codes: H04L 2209/603 Digital right managament [DRM]
• CPC Class Codes: H04L 9/0894 Escrow, recovery or storing of secret information, e.g. secret key escrow or cryptographic key storage

Abstract

A key escrow service is described. In embodiment(s), the key escrow service maintains an escrow license that includes an escrow content key that is associated with protected media content which is distributed from a content distributor to a media device. A content key that is associated with the protected media content can be received from the content distributor, and the content key can then be encrypted with a public escrow key to generate the escrow content key. The escrow license can be generated to include the escrow content key, and the escrow content key can then be communicated back to the content distributor that provides a digital rights management (DRM) license to the media device. The DRM license can include both the escrow content key and the content key encrypted with a public key that corresponds to the media device.

Claims

1. A key escrow service, comprising:

a storage media configured to maintain an escrow license that includes an escrow content key that is associated with protected media content distributed from a content distributor to a media device;

a license server configured to;

receive a content key from the content distributor, the content key being associated with the protected media content;

encrypt the content key with a public escrow key to generate the escrow content key;

generate the escrow license that includes the escrow content key; and

communicate the escrow content key back to the content distributor that then provides a digital rights management (DRM) license to the media device, the DRM license including both the escrow content key and the content key encrypted with a public key that corresponds to the media device.

2. A key escrow service as recited in claim 1, wherein the license server is further configured to:

receive the DRM license from an additional media device that is requesting the content key to decrypt the protected media content that has been acquired from the media device;

correlate the escrow license with the DRM license;

generate a new license that includes the content key encrypted with the escrow content key and includes the content key encrypted with a public key that corresponds to the additional media device; and

communicate the new license back to the additional media device to decrypt the protected media content with the content key.

3. A key escrow service as recited in claim 2, wherein the license server is further configured to receive the DRM license from the additional media device as a redirected request from the content distributor.

4. A key escrow service as recited in claim 2, wherein the license server is further configured to authenticate the additional media device before responding to the request for the content key.

5. A key escrow service as recited in claim 4, wherein the license server is further configured to authenticate the additional media device based on DRM properties received as part of the DRM license from the additional media device.

6. A key escrow service, comprising:

a storage media configured to maintain an escrow certificate that includes one or more escrow domain keys that are associated with a media device registered in a domain;

an escrow service domain controller configured to;

receive one or more domain private keys from a domain controller of the media device;

encrypt the one or more domain private keys with a public escrow key to generate the one or more escrow domain keys;

generate the escrow certificate that includes the one or more escrow domain keys; and

communicate the one or more escrow domain keys back to the domain controller that provides a domain certificate to the media device, the domain certificate including the one or more escrow domain keys and a device public key that corresponds to the media device.

7. A key escrow service as recited in claim 6, wherein the escrow service domain controller is further configured to:

receive the domain certificate from an additional media device that is requesting the one or more domain private keys to access protected media content that is associated with the domain;

correlate the escrow certificate with the device certificate;

generate a new certificate that includes the one or more domain private keys encrypted with the escrow domain key and includes a device public key that corresponds to the additional media device; and

communicate the new certificate back to the additional media device.

8. A key escrow service as recited in claim 7, wherein the escrow service domain controller is further configured to receive the domain certificate from the additional media device as a redirected request from the domain controller of the additional media device.

9. A key escrow service as recited in claim 7, wherein the escrow service domain controller is further configured to authenticate the additional media device before responding to the request for the one or more domain private keys.

10. A key escrow service as recited in claim 9, wherein the escrow service domain controller is further configured to authenticate the additional media device based on DRM properties received as part of the device certificate from the additional media device.

11. A method, comprising:

receiving a content key from a content distributor, the content key being associated with protected media content that is distributed to a media device;

encrypting the content key with a public escrow key to generate an escrow content key;

generating an escrow license that includes the escrow content key, the escrow license being stored for future reference; and

communicating the escrow content key back to the content distributor that then provides a digital rights management (DRM) license to the media device, the DRM license including both the escrow content key and the content key encrypted with a public key that corresponds to the media device.

12. A method as recited in claim 11, further comprising:

receiving the DRM license from an additional media device that is requesting the content key to decrypt the protected media content that has been acquired from the media device;

correlating the escrow license with the DRM license;

generating a new license that includes the content key encrypted with the escrow content key and includes the content key encrypted with a public key that corresponds to the additional media device; and

communicating the new license back to the additional media device to decrypt the protected media content with the content key.

13. A method as recited in claim 12, further comprising receiving the DRM license from the additional media device as a redirected request from the content distributor.

14. A method as recited in claim 12, further comprising authenticating the additional media device before responding to the request for the content key.

15. A method as recited in claim 14, further comprising authenticating the additional media device based on DRM properties received as part of the DRM license from the additional media device.

16. A method as recited in claim 11, further comprising:

receiving one or more domain private keys from a domain controller of the media device that is registered in a domain;

encrypting the one or more domain private keys with the public escrow key to generate one or more escrow domain keys;

generating an escrow certificate that includes the one or more escrow domain keys, the escrow certificate being stored for future reference; and

communicating the one or more escrow domain keys back to the domain controller that provides a domain certificate to the media device, the domain certificate including the one or more escrow domain keys and a device public key that corresponds to the media device.

17. A method as recited in claim 16, further comprising:

receiving the domain certificate from an additional media device that is requesting the one or more domain private keys to access protected media content that is associated with the domain;

correlating the escrow certificate with the domain certificate;

generating a new certificate that includes the one or more domain private keys encrypted with the escrow domain key and includes a device public key that corresponds to the additional media device; and

communicating the new certificate back to the additional media device.

18. A method as recited in claim 17, further comprising receiving the domain certificate from the additional media device as a redirected request from the domain controller of the additional media device.

19. A method as recited in claim 17, further comprising authenticating the additional media device before responding to the request for the one or more domain private keys.

20. A method as recited in claim 19, further comprising authenticating the additional media device based on DRM properties received as part of the domain certificate from the additional media device.