Sector map-based rapid data encryption policy compliance

• US 9,477,614 B2
• Filed: 10/03/2014
• Issued: 10/25/2016
• Est. Priority Date: 08/30/2011
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Basmov, Innokentiy, Nystrm, Magnus Bo Gustaf, Semenko, Alex M., MacIver, Douglas M., Li, Donghui
• Primary Examiner(s): SHOLEMAN, ABU S
• Application Number:
  US14/506,167
• Publication Number:
  US 20150033039A1
• Time in Patent Office: 753 Days
• Field of Search: 713/1, 713/2, 713/189, 713/193, 711/112
• US Class Current: 1/1
• CPC Class Codes: G06F 12/14 Protection against unauthorised use of memory or access to memory
• CPC Class Codes: G06F 12/1408 by using cryptography for digital transmission H04L9/00
• CPC Class Codes: G06F 16/2237 Vectors, bitmaps or matrices
• CPC Class Codes: G06F 21/602 Providing cryptographic facilities or services
• CPC Class Codes: G06F 21/6218 to a system of files or objects, e.g. local or distributed file system or database
• CPC Class Codes: G06F 3/0623 in relation to content
• CPC Class Codes: G06F 3/0644 Management of space entities, e.g. partitions, extents, pools
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0673 Single storage device

Abstract

To comply with a policy for a computing device indicating that data written by the computing device to the storage volume after activation of the policy be encrypted, a sector map is accessed. The sector map identifies one or more sectors of a storage volume and also identifies, for each of the one or more sectors of the storage volume, a signature of the content of the sector. In response to a request to read the content of a sector, the content of the sector is returned without decrypting the content if the sector is one of the one or more sectors and the signature of the content of the sector matches the signature of the sector identified in the sector map. Otherwise, the content of the sector is decrypted and the decrypted content is returned.

Claims

1. A method comprising:

receiving, by a computing device, a request to activate a policy for the computing device, the policy indicating that data written by the computing device to a storage volume after activation of the policy be encrypted;

activating, in response to the request, the policy for the computing device, including;

encrypting data written to the storage volume after returning an indication of compliance with the policy,

using a sector map to identify one or more sectors of the storage volume that are not encrypted, the sector map identifying one or more sectors of the storage volume written to prior to the sector map being locked to prohibit changes to the sector map and the sector map including signatures of sectors that were written to the storage volume prior to the sector map being locked, data written to the storage volume after the sector map is locked being encrypted but at least some data written to the storage volume before the sector map is locked not being encrypted, and

using the sector map to determine whether to decrypt content of a sector of the storage volume in response to a request to read the content of the sector; and

returning, in response to the request to activate the policy, the indication of compliance with the policy despite one or more sectors of the storage volume being unencrypted.

2. A method as recited in claim 1, the returning comprising returning the response without waiting for the storage volume to be encrypted.

3. A method as recited in claim 1, the activating further comprising returning, in response to the request to read the content, the content without decrypting the content in response to the sector being one of the one or more sectors written to prior to the sector map being locked and the signature of the content of the sector matching the signature of the sector identified in the sector map, and otherwise decrypting the content of the sector and returning the decrypted content.

4. A method as recited in claim 1, the activating further comprising:

checking a bit corresponding to the sector, the bit being one of multiple bits in a bitmap corresponding to the storage volume, each of the multiple bits indicating whether a corresponding sector of the storage volume has been written to after the sector map was locked to prohibit changes to the sector map;

decrypting the content of the sector and returning the decrypted content in response to the bit corresponding to the sector indicating the sector has been written to after the sector map was locked; and

in response to the bit corresponding to the sector indicating the sector has not been written to after the sector map was locked, returning the content without decrypting the content in response to the sector being one of the one or more sectors written to prior to the sector map being locked and the signature of the content of the sector matching the signature of the sector identified in the sector map, and otherwise decrypting the content of the sector and returning the decrypted content.

5. A method as recited in claim 1, the sector map being locked in response to the request to activate the policy for the computing device.

6. A method as recited in claim 5, further comprising, prior to the sector map being locked:

maintaining a first version of the sector map on the storage volume;

maintaining a second version of the sector map in volatile memory;

grouping the sector identifiers and sector signatures into multiple groups, each group including sector signatures for one or more sectors;

updating, in response to data being written to a sector identified in a group, a flag value of the group to indicate that the group is dirty; and

copying the groups that are indicated as dirty from the second version of the sector map to the first version of the sector map in response to a threshold number of the multiple groups being indicated as dirty.

7. A method as recited in claim 1, further comprising maintaining the sector map on the storage volume, and mapping the sector map from the storage volume into a sector map in volatile memory when the computing device starts operation.

8. A method as recited in claim 1, further comprising:

encrypting unencrypted data from sectors of the storage volume;

determining when no unencrypted data remains on the storage volume; and

deleting the sector map and ceasing using the sector map in response to no unencrypted data remaining on the storage volume.

9. A method as recited in claim 8, further comprising removing, from the sector map, an identifier and corresponding signature of a sector in response to unencrypted data from the sector being encrypted.

10. A method as recited in claim 1, the signature of the content of the sector comprising a value generated as a function of the content of the sector.

11. A method as recited in claim 1, the storage volume being included as part of the computing device.

12. A computing device comprising:

one or more hardware processors; and

one or more computer storage media devices having stored thereon multiple instructions that, when executed by the one or more processors to comply with a policy for the computing device, cause the one or more processors to;

access a sector map identifying one or more sectors of a storage volume written to prior to changes to the sector map being locked to prohibit changes to the sector map, the sector map further identifying, for each of the one or more sectors, a signature of the content of the sector, the policy indicating that data written by the computing device to the storage volume after activation of the policy be encrypted;

in response to a request to read the content of a sector of the storage volume;

read the content of the sector from the storage volume and return the content of the sector of the storage volume without decrypting the content in response to both the sector not having been written to after the sector map was locked to prohibit changes to the sector map and the signature of the content of the sector matching the signature of the sector identified in the sector map; and

read the content of the sector from the storage volume, decrypt the content of the sector of the storage volume, and return the decrypted content in response to the sector having been written to after the sector map was locked to prohibit changes to the sector map.

13. A computing device as recited in claim 12, the sector map being locked in response to a request to activate the policy for the computing device.

14. A computing device as recited in claim 13, the multiple instructions further causing the one or more processors to, prior to the sector map being locked:

maintain a first version of the sector map on the storage volume;

maintain a second version of the sector map in volatile memory;

group the sector identifiers and sector signatures into multiple groups, each group including sector signatures for one or more sectors;

update, in response to data being written to a sector identified in a group, a flag value of the group to indicate that the group is dirty; and

copy the groups that are indicated as dirty from the second version of the sector map to the first version of the sector map in response to a threshold number of the multiple groups being indicated as dirty.

15. A computing device as recited in claim 12, the multiple instructions further causing the one or more processors to:

encrypt unencrypted data from sectors of the storage volume;

determine when no unencrypted data remains on the storage volume; and

delete the sector map and ceasing using the sector map in response to no unencrypted data remaining on the storage volume.

16. A computing device as recited in claim 15, the multiple instructions further causing the one or more processors to remove, from the sector map, an identifier and corresponding signature of a sector in response to unencrypted data from the sector being encrypted.

17. A method, implemented in a computing device, to comply with a policy for the computing device, the method comprising:

accessing a sector map identifying one or more sectors of a storage volume written to prior to changes to the sector map being locked to prohibit changes to the sector map, the sector map further identifying, for each of the one or more sectors, a signature of the content of the sector, the policy indicating that data written by the computing device to the storage volume after activation of the policy be encrypted;

in response to a request to read the content of a sector of the storage volume;

reading the content of the sector from the storage volume and returning the content of the sector of the storage volume without decrypting the content in response to both the sector not having been written to after the sector map was locked to prohibit changes to the sector map and the signature of the content of the sector matching the signature of the sector identified in the sector map; and

reading the content of the sector from the storage volume, decrypting the content of the sector of the storage volume, and returning the decrypted content in response to the sector having been written to after the sector map was locked to prohibit changes to the sector map.

18. A method as recited in claim 17, further comprising locking the sector map in response to a request to activate the policy for the computing device.

19. A method as recited in claim 18, further comprising, prior to the sector map being locked:

maintaining a first version of the sector map on the storage volume;

maintaining a second version of the sector map in volatile memory;

grouping the sector identifiers and sector signatures into multiple groups, each group including sector signatures for one or more sectors;

updating, in response to data being written to a sector identified in a group, a flag value of the group to indicate that the group is dirty; and

copying the groups that are indicated as dirty from the second version of the sector map to the first version of the sector map in response to a threshold number of the multiple groups being indicated as dirty.

20. A method as recited in claim 17, further comprising:

encrypting unencrypted data from sectors of the storage volume;

determining when no unencrypted data remains on the storage volume; and

deleting the sector map and ceasing using the sector map in response to no unencrypted data remaining on the storage volume.

21. The method as recited in claim 17, further comprising encrypting data written by the computing device to at least one sector of the storage volume regardless of whether the sector of the storage volume is one of the one or more sectors.

22. A computing device comprising:

one or more hardware processors; and

one or more computer storage media devices having stored thereon multiple instructions that, when executed by the one or more processors to comply with a policy for the computing device, cause the one or more processors to;

receive a request to activate a policy for the computing device, the policy indicating that data written by the computing device to a storage volume after activation of the policy be encrypted;

activate, in response to the request, the policy for the computing device, including;

encrypting data written to the storage volume after returning an indication of compliance with the policy,

using a sector map to identify one or more sectors of the storage volume that are not encrypted, the sector map identifying one or more sectors of the storage volume written to prior to the sector map being locked to prohibit changes to the sector map and the sector map including signatures of sectors that were written to the storage volume prior to the sector map being locked, data written to the storage volume after the sector map is locked being encrypted but at least some data written to the storage volume before the sector map is locked not being encrypted, and

using the sector map to determine whether to decrypt content of a sector of the storage volume in response to a request to read the content of the sector; and

return, in response to the request to activate the policy, the indication of compliance with the policy despite one or more sectors of the storage volume being unencrypted.

23. The computing device as recited in claim 22, the sector map being locked in response to the request to activate the policy for the computing device.

24. The computing device as recited in claim 22, the multiple instructions further causing the one or more processors to:

encrypt unencrypted data from sectors of the storage volume;

determine when no unencrypted data remains on the storage volume; and

delete the sector map and cease using the sector map in response to no unencrypted data remaining on the storage volume.