Digital rights management operating system

• US 6,330,670 B1
• Filed: 01/08/1999
• Issued: 12/11/2001
• Est. Priority Date: 10/26/1998
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: England, Paul, Lampson, Butler W., DeTreville, John D.
• Primary Examiner(s): Heckler, Thomas M.
• Application Number:
  US09/227,561
• Time in Patent Office: 1,068 Days
• Field of Search: 713/1, 713/2, 713/155, 713/164-167, 713/200, 717/11
• US Class Current: 713/2
• 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: G06F 21/575 Secure boot
• CPC Class Codes: G06F 2221/2113 Multi-level security, e.g. mandatory access control
• CPC Class Codes: G06F 9/4406 Loading of operating system
• CPC Class Codes: G06F 9/468 Specific access rights for resources, e.g. using capability register

Abstract

A digital rights management operating system protects rights-managed data, such as downloaded content, from access by untrusted programs while the data is loaded into memory or on a page file as a result of the execution of a trusted application that accesses the memory. To protect the rights-managed data resident in memory, the digital rights management operating system refuses to load an untrusted program into memory while the trusted application is executing or removes the data from memory before loading the untrusted program. If the untrusted program executes at the operating system level, such as a debugger, the digital rights management operating system renounces a trusted identity created for it by the computer processor when the computer was booted. To protect the rights-managed data on the page file, the digital rights management operating system prohibits raw access to the page file, or erases the data from the page file before allowing such access. Alternatively, the digital rights management operating system can encrypt the rights-managed data prior to writing it to the page file. The digital rights management operating system also limits the functions the user can perform on the rights-managed data and the trusted application, and can provide a trusted clock used in place of the standard computer clock.

Claims

1. A computerized method for a digital rights management operating system comprising:

assuming a trusted identity;

executing a trusted application;

loading rights-managed data into memory for access by the trusted application; and

protecting the rights-managed data from access by an untrusted program while the trusted application is executing.

2. The computerized method of claim 1, wherein protecting the rights-managed data comprises:

refusing to load the untrusted program into memory.

3. The computerized method of claim 1, wherein protecting the rights-managed data comprises:

removing the rights-managed data from memory before loading the untrusted program.

4. The computerized method of claim 3, further comprising:

terminating the execution of the trusted program.

5. The computerized method of claim 3, further comprising:

renouncing the trusted identity before loading the untrusted program when the untrusted program executes at the operating system level.

6. The computerized method of claim 1, wherein protecting the rights-managed data comprises:

securing the rights-managed data written to a page file by the digital rights management operating system.

7. The computerized method of claim 6, wherein securing the rights-managed data written to a page file comprises:

prohibiting raw access to the page file while the trusted application is executing.

8. The computerized method of claim 6, wherein securing the rights-managed data written to a page file comprises:

erasing the page file before allowing raw access to the page file.

9. The computerized method of claim 8, further comprising:

terminating the execution of the trusted application.

10. The computerized method of claim 6, wherein securing the rights-managed data written to a page file comprises:

encrypting the rights-managed data prior to writing it to the page file.

11. The computerized method of claim 1, further comprising:

protecting the trusted application from modification by an untrusted process while the trusted application is executing.

12. The computerized method of claim 11, wherein protecting the trusted application comprises:

refusing to attach the untrusted process to the trusted application.

13. The computerized method of claim 11, wherein protecting the trusted application comprises:

preventing the untrusted process from accessing memory allocated to the trusted application.

14. The computerized method of claim 1, further comprising:

restricting a user to a subset of available functions for manipulating the rights-managed data.

15. The computerized method of claim 1, further comprising:

restricting a user to a subset of functions available for modifying the trusted application during execution.

16. The computerized method of claim 1 wherein the elements are performed in the order recited.

17. A computer system comprising:

a processing unit;

a system memory coupled to the processing unit through a system bus;

a computer-readable medium coupled to the processing unit through a system bus; and

a digital rights management operating system executed from the computer-readable medium by the processing unit, wherein the digital rights management operating system causes the processor to create a trusted identity for the digital rights management operating system.

18. The computer system of claim 17, further comprising:

a trusted application executed from the computer-readable medium by the processing unit, wherein the trusted application causes the processor to load rights-managed data into the system memory, and

wherein the digital rights management operating system further causes the processor to protect the rights-managed data while the trusted application is executing.

19. The computer system of claim 18, wherein the digital rights management operating system further causes the processor to write the rights-managed data into a page file on the computer-readable medium and causes the processor to secure the rights-managed data on the page file from access by an untrusted program.

20. The computer system of claim 19, wherein the digital rights management operating system further causes the processor to erase the rights-managed data from the page file before allowing access to the page file by the untrusted program.

21. The computer system of claim 18, wherein digital rights management operating system further causes the processor to revoke the trusted identity and terminate the trusted application prior to loading an untrusted program.

22. A computer-readable medium having computer-executable instructions for a digital rights management operating system stored thereon comprising:

obtaining, from a computer processor, a first value for a monotonic counter;

presenting, to a trusted time server, the first value for the monotonic counter;

receiving, from the trusted time server, a certificate binding the first value of the monotonic counter to a time on the trusted time server;

obtaining, from the processor, a second value for the monotonic counter before loading a trusted component;

calculating, using the certificate and the second value, a trusted current time;

comparing a time stamp on a trusted component with the trusted current time; and

determining whether to load the trusted component based on the comparison.

23. The computer-readable medium of claim 22, wherein obtaining and presenting the first value of the monotonic counter occurs on a pre-determined schedule.

24. The computer-readable medium of claim 22, wherein the time stamp comprises a date and time at which the trusted component becomes invalid and the trusted component is loaded when the trusted current time is less than the time stamp.