Securely recovering a computing device

• US 8,806,221 B2
• Filed: 08/03/2012
• Issued: 08/12/2014
• Est. Priority Date: 01/07/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: De Atley, Dallas, de Cesare, Joshua, Smith, Michael, Reda, Matthew, Sen, Shantonu, Wright, John Andrew
• Primary Examiner(s): Hoffman, Brandon
• Assistant Examiner(s): Anderson, Michael D
• Application Number:
  US13/566,969
• Publication Number:
  US 20130036298A1
• Time in Patent Office: 739 Days
• Field of Search: 713/1, 713/2, 713/201
• US Class Current: 713/187
• CPC Class Codes: G06F 11/1417 Boot up procedures
• CPC Class Codes: G06F 21/51 at application loading time, e.g. accepting, rejecting, starting or inhibiting executable software based on integrity or source reliability
• 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 21/64 Protecting data integrity, e.g. using checksums, certificates or signatures
• CPC Class Codes: H04L 63/06 for supporting key management in a packet data network cryptographic mechanisms or cryptographic arrangements for key management H04L9/08
• CPC Class Codes: H04L 63/08 for authentication of entities cryptographic mechanisms or cryptographic arrangements for entity authentication H04L9/32
• CPC Class Codes: H04L 9/14 using a plurality of keys or algorithms
• CPC Class Codes: H04L 9/302 involving the integer factorization problem, e.g. RSA or quadratic sieve [QS] schemes
• CPC Class Codes: H04L 9/3239 involving non-keyed hash functions, e.g. modification detection codes [MDCs], MD5, SHA or RIPEMD
• CPC Class Codes: H04L 9/3247 involving digital signatures
• CPC Class Codes: H04L 9/3249 using RSA or related signature schemes, e.g. Rabin scheme

Abstract

A method and an apparatus for establishing an operating environment by certifying a code image received from a host over a communication link are described. The code image may be digitally signed through a central authority server. Certification of the code image may be determined by a fingerprint embedded within a secure storage area such as a ROM (read only memory) of the portable device based on a public key certification process. A certified code image may be assigned a hash signature to be stored in a storage of the portable device. An operating environment of the portable device may be established after executing the certified code.

Claims

1. A computer implemented method, comprising:

loading a code image digitally signed by a signature into a device, the code image being received from a server over a communication network;

determining if the code image is certified by verifying the signature using a fingerprint embedded within ROM (read only memory) of the device; and

executing the code image if the code image is certified to establish an operating environment of the device;

entering a DFU (Device Firmware Upgrade) mode if the code image is not certified to establish the operating environment of the device, wherein the DFU mode performs system management tasks for the device.

2. The method of claim 1, wherein the executing comprises:

determining if the code image matches the signature based on a public key compatible with X.509 standard; and

determining if the fingerprint matches the public key, wherein the fingerprint is based on a hash value of the public key.

3. The method of claim 2, further comprising

deriving a hash value based on the code image;

and

encrypting the hash value into a header value based on a key stored in the ROM of the device.

4. The method of claim 1, wherein the code image is received from the server over the communication network in response to a failure of verifying codes initially stored in the device in an attempt to establish the operating environment of the device.

5. The method of claim 4, further comprising repairing the fail-to-verified codes initially stored in the device, such that subsequent operating environment can be established using the repaired codes without having to involve the server.

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

14. The method of claim 1, wherein the ROM (read only memory) of the device is a secure ROM associated with a UID (Unique Identifier) of the device.

7. A non-transitory machine-readable medium having instructions stored therein, which when executed by a machine, cause the machine to perform a method, the method comprising:

loading a code image digitally signed by a signature into a device, the code image being received from a server over a communication network;

determining if the code image is certified by verifying the signature using a fingerprint embedded within ROM (read only memory) of the device; and

executing the code image if the code image is certified to establish an operating environment of the device;

entering a DFU (Device Firmware Upgrade) mode if the code image is not certified to establish the operating environment of the device, wherein the DFU mode performs system management tasks for the device.

8. The machine-readable medium of claim 7, wherein the executing comprises:

determining if the code image matches the signature based on a public key compatible with X.509 standard; and

determining if the fingerprint matches the public key, wherein the fingerprint is based on a hash value of the public key.

9. The machine-readable medium of claim 8, wherein the method further comprises deriving a hash value based on the code image;

and

encrypting the hash value into a header value based on a key stored in the ROM of the device.

10. The machine-readable medium of claim 7, wherein the code image is received from the server over the communication network in response to a failure of verifying codes initially stored in the device in an attempt to establish the operating environment of the device.

11. The machine-readable medium of claim 10, wherein the method further comprises repairing the fail-to-verified codes initially stored in the device, such that subsequent operating environment can be established using the repaired codes without having to involve the server.

12. The machine-readable medium of claim 7, wherein the device is a portable device.

15. The machine-readable medium of claim 7, wherein the ROM (read only memory) of the device is a secure ROM associated with a UID (Unique Identifier) of the device.

13. A digital processing system, comprising:

a ROM (read only memory) to store a fingerprint embedded therein;

a mass storage to store a code image digitally signed by a signature and received from a server over a communication network;

a main memory; and

a processor coupled to the ROM, the mass storage, and the main memory to verify the code image using the fingerprint, to execute the code image in the main memory to establish an operating environment of the digital processing system if the code image is successfully verified, and to enter a DFU (Device Firmware Upgrade) mode if the code image is not successfully verified, wherein the DFU mode performs system management tasks for the device.

16. The digital processing system of claim 13, wherein the processor verifies the code image by:

determining if the code image matches the signature based on a public key compatible with X.509 standard; and

determining if the fingerprint matches the public key, wherein the fingerprint is based on a hash value of the public key.

17. The digital processing system of claim 16, wherein the processor derives a hash value based on the code image and encrypts the hash value into a header value based on a key stored in the ROM of the digital processing system.

18. The digital processing system of claim 13, wherein the code image is received from the server over the communication network in response to the processor failing to verify codes initially stored in the digital processing system in an attempt to establish the operating environment of the digital processing system.

19. The digital processing system of claim 18, wherein the processor repairs the fail-to-verified codes initially stored in the digital processing system, such that subsequent operating environment can be established using the repaired codes without having to involve the server.

20. The digital processing system of claim 13, wherein the digital processing system is a portable system.