System and method for trustworthy metering and deactivation

• US 20060206718A1
• Filed: 03/08/2005
• Published: 09/14/2006
• Est. Priority Date: 03/08/2005
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Westerinen, William J., Frank, Alexander
• Granted Patent: US 7,406,446 B2
• Time in Patent Office: Days
• US Class Current: 713/182
• CPC Class Codes: G06F 21/84 output devices, e.g. displays or monitors
• CPC Class Codes: G06F 2221/2105 Dual mode as a secondary aspect
• CPC Class Codes: G06F 2221/2135 Metering
• CPC Class Codes: G06F 2221/2137 Time limited access, e.g. to a computer or data
• CPC Class Codes: G06Q 30/04 Billing or invoicing
• CPC Class Codes: G06Q 30/06 Buying, selling or leasing transactions

Abstract

A computer is adapted for use in different operating modes by configuring an output controller, such as a graphics processing unit, to screen output signals prior to presenting them to the output device. A secure environment in the output controller verifies a digital signature or a hash of the output signal to determine whether the output signal is compatible with the current mode of operation. Thus only authorized output signals are presented when the computer is operating in a limited function mode, such as when metered usage time is expired. The apparatus and method also disclose similar output signal screening for determining whether the computer should be returned from a standby, or no-metering, mode to an active, or metered mode.

Claims

1. A method for operating a computer comprising:

setting the computer in a first operating mode;

determining when an output signal is consistent with the first operating mode; and

presenting the output signal to a corresponding output device when the output signal is consistent with the first operating mode.

2. The method of claim 1, further comprising:

blocking the output signal from presentation to the corresponding output device when the output signal is not consistent with the first operating mode.

3. The method of claim 1, further comprising:

presenting the output signal to the corresponding output device when the output signal is not consistent with the first operating mode and signaling the computer to change to a second operating mode.

4. The method of claim 1, further comprising:

degrading the output signal to the corresponding output device when the output signal is not consistent with the first operating mode.

5. The method of claim 1, wherein the determining when an output signal is consistent with the first operating mode further comprises verifying a digital signature of the output signal.

6. The method of claim 1, wherein the determining when an output signal is consistent with the first operating mode further comprises verifying a hash of the output signal.

7. The method of claim 1, wherein the determining when an output signal is consistent with the first operating mode further comprises cryptographically verifying a portion of the output signal.

8. A computer adapted for operation in a plurality of operating modes comprising:

a first output device; and

a first output controller coupled to the first output device comprising;

a first isolated computing environment; and

a memory storing a bit pattern corresponding to output data intended for presentation to the first output device, wherein the first isolated computing environment analyzes the bit pattern to determine if the output data are consistent with a current operating mode of the computer.

9. The computer of claim 8, further comprising a second isolated computing environment in communication with the first isolated computing environment for conveying the current operating mode to the first isolated computing environment.

10. The computer of claim 9, wherein first isolated computing environment instructs the second isolated computing environment to change the current operating mode of the computer when the output data are not consistent with the current operating mode of the computer.

11. The computer of claim 8, further wherein the first output controller is at least one of a display controller, a sound controller, and a haptics controller.

12. The computer of claim 8, wherein the first isolated computing environment further comprises a cryptographic capability and analyzes the bit patterns using at least one of a digital signature and a hash code.

13. The computer of claim 8, wherein the bit pattern corresponds to a portion of the output data intended for presentation to the first output device.

14. The computer of claim 8, wherein the first output controller one of alters or blocks the output data to the first output device when the output data are not consistent with the current operating mode of the computer.

15. An output controller for use in a computer comprising:

an input coupled to the computer;

an output coupled to a device;

a processor coupled between the input and the output for receiving data from the computer and presenting a form of the data to the device; and

a communication interface for communicating with a component of the computer;

wherein the processor receives information corresponding to an operating mode of the computer and analyzes the data to determine if the data is consistent with the operating mode of the computer.

16. The output controller of claim 15, wherein the device is one of a display device, a sound device, and a haptics device.

17. The output controller of claim 15, wherein the processor one of blocks or degenerates presentation of the data to the device when the data are not consistent with the operating mode of the computer.

18. The output controller of claim 15, wherein the processor presents the data to the device when the data is consistent with the operating mode of the computer.

19. The output controller of claim 15, further comprising an isolated computing environment for analyzing if the data is consistent with the operating mode of the computer responsive to the processor.

20. The output controller of claim 19, wherein the isolated computing environment further comprises a cryptographic facility and the isolated computing environment analyzes if the data is consistent with the operating mode of the computer by verifying at least one of a digital signature and a hash code.