Device theft protection associating a device identifier and a user identifier

1. A method implemented in a computing device, the method comprising:

determining that theft protection is to be enabled on the computing device;

sending, to an identity service over a network, user credentials of a user of the computing device;

receiving, from the identity service, a ticket indicating that the user credentials have been verified by the identity service;

sending, to a key service over the network, the ticket;

receiving, from the key service, a data value having been generated by the key service by applying a cryptographic hash function to a combination of a recovery key for the computing device and a device identifier that identifies the computing device;

saving the data value as an authenticated variable on the computing device by writing the data value to an authenticated variable storage system of the computing device;

receiving user input that is the recovery key of the computing device;

writing the recovery key to the authenticated variable storage system as an unauthenticated variable;

generating an additional data value based on the user input as well as the device identifier that identifies the computing device;

determining whether the data value and the additional data value are the same value; and

changing the computing device to an unprotected state in response to the data value and the additional data value being the same value.

2. The method as recited in claim 1 , the recovery key having been generated by the key service.

3. The method as recited in claim 1 , further comprising preventing rollback of an operating system of the computing device to a previous version of the operating system that does not support the theft protection.

4. The method as recited in claim 3 , the preventing including:

checking whether an operating system version identifier list included in the authenticated variable storage system of the computing device includes an identifier of an operating system being booted on the computing device; and

preventing the operating system from booting on the computing device if the operating system version identifier list includes the identifier of the operating system being booted on the computing device.

5. The method as recited in claim 1 , further comprising:

determining that ownership of the computing device is to be verified;

obtaining, in response to access to the key service over the network being available, an indication from the key service whether the user is the owner of the computing device, the indication being based on user credentials input to the computing device;

allowing the user to access the computing device in response to the user being determined to be the owner of the computing device; and

denying the user access to the computing device in response to the user being determined to not be the owner of the computing device.

6. The method as recited in claim 1 , the authenticated variable storage system implementing the unified extensible firmware interface specification.

7. The method as recited in claim 1 , the combination of the recovery key and the device identifier comprising a concatenation of the recovery key and the device identifier.

8. A computing device comprising:

one or more hardware processors; and

computer-readable storage medium having stored thereon multiple instructions that, responsive to execution by the one or more processors, cause the one or more processors to perform acts including:

determining that theft protection is to be enabled on the computing device;

sending, to an identity service over a network, user credentials of a user of the computing device;

receiving, from the identity service, a data structure indicating that the user credentials have been verified by the identity service;

sending, to a key service over the network, the data structure;

receiving, from the key service, a first data value having been generated by the key service by applying a cryptographic hash function to a combination of a recovery key for the computing device and a device identifier that identifies the computing device;

saving the first data value as an authenticated variable on the computing device by writing the first data value to an authenticated variable storage system of the computing device;

receiving user input that is the recovery key of the computing device;

writing the recovery key to the authenticated variable storage system as an unauthenticated variable;

generating a second data value based on the user input as well as the device identifier that identifies the computing device;

determining whether the first data value and the second data value are the same value; and

changing the computing device to an unprotected state in response to the first data value and the second data value being the same value.

9. The computing device as recited in claim 8 , the recovery key having been generated by the key service.

10. The computing device as recited in claim 8 , the acts further comprising preventing rollback of an operating system of the computing device to a previous version of the operating system that does not support the theft protection.

11. The computing device as recited in claim 10 , the preventing including:

checking whether an operating system version identifier list included in the authenticated variable storage system of the computing device includes an identifier of an operating system being booted on the computing device; and

preventing the operating system from booting on the computing device if the operating system version identifier list includes the identifier of the operating system being booted on the computing device.

12. The computing device as recited in claim 8 , the acts further comprising:

determining that ownership of the computing device is to be verified;

obtaining, in response to access to the key service over the network being available, an indication from the key service whether the user is the owner of the computing device, the indication being based on user credentials input to the computing device;

allowing the user to access the computing device in response to the user being determined to be the owner of the computing device; and

denying the user access to the computing device in response to the user being determined to not be the owner of the computing device.

13. The computing device as recited in claim 8 , the authenticated variable storage system implementing the unified extensible firmware interface specification.

14. A device comprising:

one or more hardware processors;

an authenticated variable storage system; and

computer-readable storage medium having stored thereon multiple instructions that, responsive to execution by the one or more processors, cause the one or more processors to:

determine that theft protection is to be enabled on the device;

send, to an identity service over a network, user credentials of a user of the device;

receive, from the identity service, a ticket indicating that the user credentials have been verified by the identity service;

send, to a key service over the network, the ticket;

receive, from the key service, a data value having been generated by the key service by applying a cryptographic hash function to a combination of a recovery key for the device and a device identifier that identifies the device;

save the data value as an authenticated variable on the device by writing the data value to the authenticated variable storage system;

receive user input that is the recovery key of the device;

write the recovery key to the authenticated variable storage system as an unauthenticated variable;

generate an additional data value based on the user input as well as the device identifier that identifies the device;

determine whether the data value and the additional data value are the same value; and

change the device to an unprotected state in response to the data value and the additional data value being the same value.

15. The device as recited in claim 14 , the recovery key having been generated by the key service.

16. The device as recited in claim 14 , the instructions further causing the one or more processors to prevent rollback of an operating system of the device to a previous version of the operating system that does not support the theft protection.

17. The device as recited in claim 16 , wherein to prevent rollback includes to:

check whether an operating system version identifier list of the device includes an identifier of an operating system being booted on the device; and

prevent the operating system from booting on the device if the operating system version identifier list includes the identifier of the operating system being booted on the device.

18. The device as recited in claim 17 , the operating system version identifier list being included in the authenticated variable storage system.

19. The device as recited in claim 14 , the instructions further causing the one or more processors to:

determine that ownership of the computing device is to be verified;

obtain, in response to access to the key service over the network being available, an indication from the key service whether the user is the owner of the computing device, the indication being based on user credentials input to the computing device;

allow the user to access the computing device in response to the user being determined to be the owner of the computing device; and

deny the user access to the computing device in response to the user being determined to not be the owner of the computing device.

20. The device as recited in claim 14 , the authenticated variable storage system implementing the unified extensible firmware interface specification.