Compatible trust in a computing device

• US 20090063108A1
• Filed: 08/31/2007
• Published: 03/05/2009
• Est. Priority Date: 08/31/2007
• Status: Active Grant

• Current Assignee: Apple Computer Incorporated (Apple Inc.), Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Smith, Michael, de Cesare, Joshua, Bush, Jeffrey, De Atley, Dallas Blake, Hauck, Jerry
• Granted Patent: US 8,230,412 B2
• Time in Patent Office: Days
• US Class Current: 703/2
• CPC Class Codes: G06F 21/575 Secure boot
• CPC Class Codes: G06F 21/577 Assessing vulnerabilities and evaluating computer system security

Abstract

A method and apparatus for executing a first executable code image having a first version number into a memory of a device in an attempt to establish an operating environment of the device are described. The first executable code image retrieves a second version number from the second executable code image after successfully authenticating the second executable code image. If the first version number and the second version number do not satisfy a predetermined relationship, the second executable code image is prevented from being loaded by the first executable code image.

Claims

1. A computer implemented method for establishing an operating environment of a device, the method comprising:

executing a first executable code image into a memory of a device in an attempt to establish an operating environment of the device, the first executable code image being associated with a first version number;

the first executable code image, which when executed from the memory, authenticating a second executable code image, which when successful, to retrieve a second version number from the second executable code image; and

preventing the second executable code image from being loaded by the first executable code image if the first version number and the second version number do not satisfy a predetermined relationship.

2. The method of claim 1, wherein the second version number of the second executable code image is revealed from the second executable code image when the second executable code image is successfully authenticated by the first executable code image.

3. The method of claim 1, further comprising the first executable code image loading the second executable code image only if the first version number and the second version number satisfy the predetermined relationship.

4. The method of claim 3, further comprising:

executing the loaded second executable code image to receive the first version number from the first executable code image;

verifying a compatibility with the first code image based on the first version number and the second version number; and

interrupting the executing the second executable code image if the compatibility is not verified.

5. The method of claim 4, wherein the compatibility is verified according to the predetermined relationship.

6. The method of claim 1, wherein the second executable code image is prevented from being loaded when the first version number is higher than the second version number.

7. The method of claim 1, wherein the predetermined relationship includes matching the first version number and the second version number.

8. The method of claim 6 further comprising restoring at least the second executable code image from a host communicatively coupled to the device if the first version number and the second version number satisfy the predetermined relationship, the restored second executable code image having a third version number higher than at least one of the first version number and the second version number.

9. The method of claim 1, wherein the first executable code image is executed by a boot code stored in a secure ROM (read-only memory) of the device, wherein the boot code is configured to authenticate the first executable code image using a hardware key embedded within the device.

10. The method of claim 1, wherein the device is a portable device.

11. A machine-readable medium having instructions stored therein, which when executed by a machine, cause a machine to perform a method for establishing an operating environment of a device, the method comprising:

executing a first executable code image into a memory of a device in an attempt to establish an operating environment of the device, the first executable code image being associated with a first version number;

the first executable code image, which when executed from the memory, authenticating a second executable code image, which when successful, to retrieve a second version number from the second executable code image; and

preventing the second executable code image from being loaded by the first executable code image if the first version number and the second version number do not satisfy a predetermined relationship.

12. The machine-readable medium of claim 11, wherein the second version number of the second executable code image is revealed from the second executable code image when the second executable code image is successfully authenticated by the first executable code image.

13. The machine-readable medium of claim 11, wherein the method further comprises the first executable code image loading the second executable code image only if the first version number and the second version number satisfy the predetermined relationship.

14. The machine-readable medium of claim 13, further comprising:

executing the loaded second executable code image to receive the first version number from the first executable code image;

verifying a compatibility with the first code image based on the first version number and the second version number; and

interrupting the executing the second executable code image if the compatibility is not verified.

15. The machine-readable medium of claim 11, wherein the second executable code image is prevented from being loaded when the first version number is higher than the second version number.

16. The machine-readable medium of claim 11, wherein the second executable code image is prevented from being loaded if the second version number cannot be retrieved from the second executable code image.

17. The machine-readable medium of claim 15, wherein the method further comprises restoring at least the second executable code image from a host communicatively coupled to the device if the first version number and the second version number satisfy the predetermined relationship, the restored second executable code image having a third version number higher than at least one of the first version number and the second version number.

18. The machine-readable medium of claim 11, wherein the first executable code image is executed by a boot code stored in a secure ROM (read-only memory) of the device, wherein the boot code is configured to authenticate the first executable code image using a hardware key embedded within the device.

19. The machine-readable medium of claim 11, wherein the device is a portable device.

24. The method of claim 18, further comprising the second operating environment servicing the service request if the first version and the second version satisfy the predetermined relationship.

25. The method of claim 18, wherein the device is a portable device having computing functionality and communication functionality, wherein the first processor is a microprocessor and the second processor is a communication processor communicatively coupled to the first processor, and wherein when the service request is denied, the communication functionality of the device is disabled.

20. A computer-implemented method for establishing an operating environment of a device, the method comprising:

authenticating an executable image to be loaded into a memory of the device in an attempt to establish an operating environment of the device;

in response to successfully authenticating the executable code image, examining a version number associated with the executable code image to determine whether the version number satisfies a predetermined condition; and

preventing the executable code image from being executed if the version number does not satisfy the predetermined condition.

21. The method of claim 20, wherein the executable code image is executed only if the executable code image is successfully authenticated and the version number associated with the executable code image satisfies the predetermined condition.

22. A computer-implemented method, comprising:

receiving a plurality of executable code images to be loaded in sequence in order to establish an operating environment of a portable device; and

sequentially loading the plurality of executable code images, wherein a current executable code image is configured to authenticate a next executable code image in the sequence and upon successfully authenticating the next executable code image, to examine a version of the next executable code image, and to prevent the next executable code image from being loaded if the version of the next executable code image does not satisfy a predetermined relationship with respect to a version of the current executable code image.

23. A computer implemented method, comprising:

in response to a service request from a first operating environment executed by a first processor of a device, the service request requesting for a service provided by a second operating environment executed by a second processor, examining a first version of the first operating environment in view of a second version of the second operating environment; and

denying the service request if the first version and the second version do not satisfy a predetermined relationship.