Secure booting of an electronic apparatus with SMP architecture

• US 7,624,261 B2
• Filed: 05/11/2006
• Issued: 11/24/2009
• Est. Priority Date: 11/13/2003
• Status: Active Grant

• Current Assignee: Stmicroelectronics France (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SA (STMicroelectronics NV)
• Inventors: Volp, Marcus
• Primary Examiner(s): SURYAWANSHI, SURESH
• Application Number:
  US11/432,727
• Publication Number:
  US 20070113088A1
• Time in Patent Office: 1,293 Days
• Field of Search: 713/2
• US Class Current: 713/2
• CPC Class Codes: G06F 15/177 Initialisation or configuration control processor initialisation G06F9/4405
• CPC Class Codes: G06F 21/575 Secure boot
• CPC Class Codes: G06F 9/4405 Initialisation of multiprocessor systems

Abstract

A method of secure booting of an SMP architecture apparatus provides for the formation of a secure domain comprising a first processor and a part of a shared memory, before the booting of the operating system of the first processor. The operating system of a second processor is booted only after the reciprocal authentication with the first processor and, in case of authentication, the extension of the secure domain to the second processor.

Claims

1. A method of secure booting of an electronic apparatus that includes plural processors and an external shared memory that are linked by at least one communication bus, each processor having hardware elements and a stack of software elements that can execute on said hardware elements, the method comprising:

a) securely booting of a first of said processors, up to but not including a software element corresponding to an operating system;

b) protecting, by said first processor, a part of the shared memory, in such a way as to form a secure domain that includes said first processor and of said protected part of the shared memory;

c) booting the operating system of said first processor, including storing data of said operating system in said protected part of the shared memory;

d) securely booting a second of said processors, up to but not including a software element corresponding to an operating system;

then

e) authenticating the second processor with the first processor and vice versa, and, in case of successful authentications,

f) extending the secure domain to the second processor, wherein said first processor provides to said second processor, a write-access entitlement to said protected part of the shared memory;

then

g) booting the operating system of said second processor, including storing data of said operating system of the second processor in said protected part of the shared memory.

2. The method according to claim 1, wherein the authenticating of the first processor and of the second processor is controlled by a software element of the first processor corresponding to an authentication manager.

3. The method according to claim 2, wherein the software element corresponding to the authentication manager implements a public key and private key authentication algorithm.

4. The method according to claim 1, wherein the first processor is selected from among the processors of the apparatus, by a software element corresponding to a boot code which is loaded into an internal RAM of the processors from an external ROM.

5. The method according to claim 4, wherein the authenticating of the first processor and of the second processor is controlled by a software element of the first processor corresponding to an authentication manager and wherein the processors other than the first processor interrupt their boot sequence before the booting of their operating system, until the reception from the first processor of a boot signal which is emitted by the first processor only after the installation of the software element corresponding to the authentication manager, then resume their boot sequence.

6. The method according to claim 1, wherein the protecting of the part of the shared memory is performed by a software element of the first processor, by assigning a write-access entitlement to the protected part of the shared memory and an entitlement of modification of the access entitlements to the shared memory exclusively to the first processor.

7. The method according to claim 1, wherein step a) and step d) are performed substantially in parallel.

8. The method according to claim 1, wherein step d) begins only after step c).

9. The method according to claim 1, wherein, the data stored by step c) include processor tables used by the operating system of the first processor and the data stored by step g) include processor tables used by the operating system of the second processor.

26. The method of claim 1, wherein step b) further includes initializing a first encryption unit of the first processor, the first encrtyption unit for encrypting data exchanged between the first processor and the protected part of the shared memory, the method further comprising:

after authenticating the second processor with the first processor and vice versa, and, in case of successful authentications,

issuing by the first proccessor to the second processor an encryption key used by the first encryption unit; and

initializing a second encyption unit of the second processor for encrypting data exchanged between the second processor and the protected part of the shared memory with the issued encyrption key.

27. The method of claim 1, wherein the securely booting of the first of said processors and the securely booting the second of said processors is implemented using at least one of an incremental secure boot method and a secure boot tracking method.

10. An electronic apparatus, comprising:

a shared memory;

a communication bus; and

a plurality of processors coupled to the shared memory by the communication bus, the plurality of processors including first and second processors, wherein the first processor includes;

means for securely booting the first processor without booting a software element corresponding to an operating system;

means for protecting a part of the shared memory in such a way as to form a secure domain that includes the first processor and the protected part of the shared memory;

means for booting the operating system of the first processor, including storing data of the operating system in the protected part of the shared memory;

means for authenticating the second processor; and

means for extending the secure domain to the second processor if the second processor is successfully authenticated, wherein the first processor provides to the second processor a write-access entitlement to the protected part of the shared memory,

wherein the second processor includes;

means for securely booting the second processor without booting a software element corresponding to an operating system of the second processor;

means for authenticating the first processor, wherein the means for extending the secure domain to the second processor operates in response to successful authentication of the first and second processors; and

means for booting the operating system of the second processor, including storing data of said operating system of the second processor in the protected part of the shared memory.

11. The apparatus of claim 10, wherein the means for authenticating the second processor includes a software element of the first processor corresponding to an authentication manager.

12. The apparatus of claim 11, wherein the software element corresponding to the authentication manager is structured to implement a public key and private key authentication algorithm.

13. The apparatus of claim 10, further comprising a ROM that includes a software element corresponding to a boot code that is structured to select the first processor from among the plurality of the processors.

14. The apparatus of claim 10, wherein the second processor includes means for interrupting the booting of the second processor until the reception from the first processor of a boot signal that is emitted by the first processor only after an authentication manager of the first processor is installed.

28. The electronic appartus of claim 10, wherein the first and second processors respectively include a first and second encryption unit, the first and second encryption unit configured to encrypt and decrypt data respectively written to and read from the shared memory, wherein the first processor further includes means for issuing to the second processor an encryption key used by the first encryption unit, in response to successful authentication of the first and second processors, and wherein the second processor includes means for initializing the second encryption unit with the encryption key.

29. The electronic apparatus of claim 10, where the means for securely booting the first processor and the means for securely booting the second processor include means for securely booting using at least one of an incremental secure boot method and a secure boot tracking method.

15. A method of secure booting of an electronic apparatus that includes first and second processors, comprising:

booting a portion of the second processor that does not include an operating system of the second processor;

authenticating the second processor using the first processor;

authenticating the first processor using the second processor;

if both of the first and second processors are successfully authenticated, then;

providing from the first processor to the second processor access to a protected memory portion of a shared memory; and

booting the operating system of the second processor, including storing data used by the operating system in the protected memory portion.

16. The method of claim 15, further comprising:

protecting, by the first processor, the protected memory portion of the shared memory, in such a way as to form a secure domain that includes the first processor and the protected memory portion of the shared memory.

17. The method of claim 16, further comprising:

securely booting the first processor without booting a software element corresponding to an operating system of the first processor, before protecting the protected memory portion; and

booting the software element corresponding to the operating system of the first processor after protecting the protected memory portion, including storing data of the operating system in the protected memory portion of the shared memory.

18. The method of claim 16, wherein the protecting step is performed by assigning exclusively to the first processor a write-access entitlement to the protected memory portion and an entitlement of modification of the access entitlements to the shared memory.

19. The method of claim 15, wherein the authenticating of the first processor and of the second processor is controlled by a software element of the first processor corresponding to an authentication manager.

20. The method of claim 15, wherein the software element corresponding to the authentication manager implements a public key and private key authentication algorithm.

21. The method of claim 15, wherein the first processor is selected from among a plurality of processors of the apparatus, by a software element corresponding to a boot code which is loaded into an internal RAM of the processors from a ROM that is external to the processors.

22. The method of claim 15, wherein the authenticating of the first processor and of the second processor is controlled by a software element of the first processor corresponding to an authentication manager and wherein the second processor interrupts its boot sequence before booting its operating system, until receiving from the first processor a boot signal that is emitted by the first processor only after the installation of the software element corresponding to the authentication manager, then resumes the boot sequence.

23. The method of claim 15, further comprising securely booting a portion of the first processor substantially in parallel with the step of booting a portion of the second processor.

24. The method of claim 15, further comprising securely booting the first processor and storing data in the protected memory portion before beginning the step of booting the portion of the second processor.

25. The method of claim 15, wherein, the data stored in the protected memory portion include processor tables used by the operating system of the second processor.

30. The method of claim 15, further comprising:

if both of the first and second processors are successfully authenticated, then;

issuing by the first processor to the second processor an encryption key used by a first encrytion unit of the first processor, the first encryption unit for encrypting data exchanged between the first processor and the protected memory portion of a shared memory; and

initializing a second encryption unit of the second processor with the issued encryption key, the second encryption unit for encrypting data exchanged between the second processor and the protected memory portion of a shared memory.

31. The method of claim 15, where the booting a portion of the second processor that does not include an operating system of the second processor includes securely booting the portion of the second processor using at least one of an incremental secure boot method and a secure boot tracking method.