Securely Recovering a Computing Device

• US 20080168275A1
• Filed: 01/07/2007
• Published: 07/10/2008
• Est. Priority Date: 01/07/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Sen, Shantonu, Smith, Michael, de Cesare, Joshua, De Atley, Dallas Blake, Wright, John Andrew, Reda, Matthew
• Granted Patent: US 8,239,688 B2
• Time in Patent Office: Days
• US Class Current: 713/189
• 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 sinned by a signature into a device, the code image being received from a host over a communication link;

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.

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 host over the communication link in response to a failure of verifying codes initially stored in the device in an attempt to establish the operating environment of the device, and wherein the host receives the code image from a server over a network.

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 host.

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

7. A 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 host over a communication link;

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.

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 host over the communication link in response to a failure of verifying codes initially stored in the device in an attempt to establish the operating environment of the device, and wherein the host receives the code image from a server over a network.

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 host.

12. The machine-readable medium of claim 7, wherein the device is a portable 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 host over a communication link;

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 and upon successfully verifying the code image, to execute the code image in the main memory to establish an operating environment of the digital processing system.

14. An apparatus, comprising:

means for loading a code image digitally signed by a signature into a device the code image being received from a host over a communication link;

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

means for executing the code image if the code image is certified to establish an operating environment of the device.

15. A computer implemented method, comprising:

in response to a failure of loading an executable image of a device, the device communicating with a host via a communication link to signal that the device is in a recovery mode to receive from the host a new executable image corresponding to the failed executable image;

verifying the new executable image using a digital certificate embedded within the secure ROM of the portable device;

upon successfully verifying the new executable image, executing the new executable image; and

optionally storing the verified new executable image in the mass storage of the portable device, replacing the failed executable image.

16. The method of claim 15, further comprising:

the host authenticating the portable device over the communication link based in pan on the unique ID of the portable device;

upon successfully authenticating the portable device, the host retrieving the new executable image from a server over a network; and

delivering the retrieved new executable image to the portable device over the communication link.

17. A computer implemented method, comprising:

in response to successfully authenticating a portable device over a communication link based in part on a unique identifier (ID) embedded within a secure ROM (read-only memory) of the portable device, determining whether the portable device is in a recovery mode as a result of a failure to initialize an operating environment of the portable device;

retrieving an executable image from a server over a network, the executable image being digitally signed by a signature if it is determined that the portable device is in the recovery mode; and

delivering the retrieved executable image to the portable device over the communication link, wherein the portable device verifies the signature of the executable image using a digital certificate embedded wit the secure ROM, and wherein the verified executable image is loaded in a main memory of the portable device to establish the operating environment for the portable device.

18. The method of claim 17, wherein the executable image comprises data representing at least a kernel of an operating system (OS) for the portable device, wherein the executable image, which when executed by the portable device, establishes a virtual bootable drive from which the at least the kernel of the OS is loaded in the main memory of the portable device.

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

in response to successfully authenticating a portable device over a communication line based in part on a unique identifier (ID) embedded within a secure ROM (read-only memory) of the portable device, determining whether the portable device is in a recovery mode as a result of a failure to initialize an operating environment of the portable device;

retrieving an executable image from a server over a network, the executable image being digitally signed by a signature if it is determined that the portable device is in the recovery mode; and

delivering the retrieved executable image to the portable device over the communication link, wherein the portable device verifies the signature of the executable image using a digital certificate embedded with the secure ROM, and wherein the verified executable image is loaded in a main memory of the portable device to establish the operating environment for the portable device.

20. The machine-readable medium of claim 19, wherein the executable image comprises data representing at least a kernel of an operating system (OS) for the portable device, wherein the executable image, which when executed by the portable device, establishes a virtual bootable drive from which the at least the kernel of the OS is loaded in the main memory of the portable device.