Apparatus and method of reading a program into a processor

• US 6,141,756 A
• Filed: 04/27/1998
• Issued: 10/31/2000
• Est. Priority Date: 04/27/1998
• Status: Expired due to Term

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Bright, Michael W., Marquardt, Kelly Jo, Fuchs, Kenneth Carl
• Primary Examiner(s): Swann, Tod R.
• Assistant Examiner(s): Callahan, Paul E.
• Application Number:
  US09/067,110
• Time in Patent Office: 918 Days
• Field of Search: 380/4, 380/25, 380/287, 395/186, 713/200, 713/2, 713/189, 713/190, 713/191, 713/193, 705/57
• US Class Current: 726/22
• CPC Class Codes: G06F 21/572 Secure firmware programming, e.g. of basic input output system [BIOS]
• CPC Class Codes: G06F 21/575 Secure boot
• CPC Class Codes: G06F 21/6209 to a single file or object, e.g. in a secure envelope, encrypted and accessed using a key, or with access control rules appended to the object itself
• CPC Class Codes: G06F 2211/007 Encryption, En-/decode, En-/decipher, En-/decypher, Scramble, (De-)compress
• CPC Class Codes: G06F 2211/1097 Boot, Start, Initialise, Power
• CPC Class Codes: G06F 2221/2147 Locking files

Abstract

The following describes an apparatus for and method of providing a secure method of downloading a program into a processor (101) from a device (103) external to the processor (101). The program may be encrypted (207) prior to its entry into the external device (103). The program may also have authentication information added (203 and 207) to it. Authentication information may be provided on an unencrypted and/or an encrypted program. The processor (101) decrypts (307) and/or successfully authenticates (311) the program before allowing the program to be executed by the processor (101).

Claims

1. A method comprising the steps of:

entering a bootstrap mode of a processor;

during the bootstrap mode;

reading, into a memory within the processor, a bootstrap program from a device external to the processor;

decrypting the bootstrap program using a key embedded inside the processor, yielding a decrypted program;

performing authentication verification on the decrypted program;

executing, by the processor, the decrypted program only after the decrypted program is authenticated, and when the decrypted program fails to be authenticated, inhibiting execution of the decrypted program by the processor.

2. The method of claim 1, further comprising the steps of:

determining if the bootstrap program was properly encrypted;

when the bootstrap program was not properly encrypted, inhibiting execution of the program by the processor.

3. The method of claim 1, wherein the bootstrap program is stored as an encrypted bootstrap program in the device external to the processor.

4. The method of claim 1, wherein the step of inhibiting execution of the decrypted program by the processor comprises the step of stopping the processor from executing any code from the decrypted bootstrap program until a restart of the processor.

5. The method of claim 1, wherein the step of inhibiting execution of the decrypted program by the processor comprises the step of entering the processor into an infinite loop.

6. The method of claim 1, wherein the step of inhibiting execution of the decrypted program by the processor comprises the step of indicating the failure to authenticate with an error message.

7. The method of claim 1, wherein the step of inhibiting execution of the decrypted program by the processor comprises the step of starting the process again, beginning with the entering step.

8. The method of claim 3, wherein a key needed to decrypt the bootstrap program is not stored on the device external to the processor.

9. The method of claim 3, wherein the step of performing authentication verification comprises the step of performing a checksum on the decrypted program.

10. The method of claim 3, wherein the step of performing authentication verification comprises the step of performing a hash on the decrypted program.

11. The method of claim 3, wherein the step of performing authentication verification comprises the step of performing an encrypted checksum on the decrypted program.

12. The method of claim 3, wherein the step of performing authentication verification comprises the step of checking a digital signature of the decrypted program.

13. The method of claim 3, wherein the key embedded inside the processor is a public decryption key.

14. The method of claim 3, wherein the key embedded inside the processor is a private decryption key.

15. The method of claim 3, wherein the key embedded inside the processor is a symmetric decryption key.

16. The method of claim 3, wherein the key embedded inside the processor is processed into another key that is used to decrypt the program.

17. The method of claim 3, wherein the step of inhibiting execution of the decrypted program by the processor comprises the step of preventing the processor from exiting the bootstrap mode unless the decrypted program is authenticated.

18. A processor comprising:

a first memory, arranged and constructed to obtain a bootstrap program from a device external to the processor during a bootstrap mode;

a decryption processor, operably coupled to the first memory, arranged and constructed to decrypt the bootstrap program utilizing a key stored within the processor during the bootstrap mode;

a second memory arranged and constructed to store, during the bootstrap mode, the decrypted program for subsequent execution by the processor;

wherein the processor is arranged and constructed to performing authentication verification on the decrypted program and execute the decrypted program only after successful authentication of the decrypted program as an intended program.

19. The processor of claim 18, wherein the bootstrap program is stored as an encrypted bootstrap program in the device external to the processor.

20. The processor of claim 19, wherein a key needed to decrypt the bootstrap program is not stored on the device external to the processor.

21. The processor of claim 18, wherein the processor is arranged and constructed to inhibit execution of the decrypted program by stopping the processor from executing any code from the decrypted bootstrap program until the processor restarts.

22. The processor of claim 18, wherein the processor is arranged and constructed to exit the bootstrap mode only after successful authentication of the decrypted program.

23. A method comprising the steps of:

entering a bootstrap mode of a processor;

during the bootstrap mode;

reading, by a first memory within the processor, a bootstrap program stored as an encrypted bootstrap program in a device external to the processor;

decrypting the bootstrap program, yielding a decrypted program;

performing authentication verification on the decrypted program;

when the program is authenticated, executing, by the processor, the decrypted program;

when the decrypted program fails to be authenticated, inhibiting execution of the decrypted program by the processor.

24. The method of claim 23, wherein a key needed to decrypt the bootstrap program is not stored on the device external to the processor.

25. The method of claim 23, wherein the step of inhibiting execution of the decrypted program by the processor comprises the step of stopping the processor from executing any code from the decrypted bootstrap program until a restart of the processor.

26. The method of claim 23, wherein the step of inhibiting execution of the decrypted program by the processor comprises the step of preventing the processor from exiting the bootstrap mode unless the decrypted program is authenticated.