Protecting stored data from traffic analysis

Patent metadata

Field	Value
Publication number	US-9324361-B2
Application number	US-83842507-A
Country	US
Kind code	B2
Filing date	Aug 14, 2007
Priority date	Aug 14, 2007
Publication date	Apr 26, 2016
Grant date	Apr 26, 2016

Abstract

A method including: reading a portion of stored data from a storage medium, decrypting the portion of stored data, then if changes are requested, making the changes to the portion of stored data to produce changed data, encrypting the changed data, and writing the encrypted changed data to the storage medium. An apparatus that performs the method is also included.

First claim

What is claimed is:

1. A method of processing data internal to a computing device comprising:
determining, at a data storage controller, a specific portion of data to modify based on a request from a host computer to store data associated with a specific logical block address;
in response to determining the specific portion is to be modified, retrieving, via the data storage controller, encrypted selected data from a disc data storage medium, the encrypted selected data including the specific portion and another portion of data that is not associated with the request, where the specific portion and the another portion are both located in a same track of the disc data storage medium;
decrypting, via the data storage controller, the encrypted selected data to reveal the specific portion and the another portion;
modifying, via the data storage controller, the specific portion to produce a changed portion, while not modifying the another portion;
encrypting, via the data storage controller, the changed portion and the another portion to produce encrypted changed selected data; and
storing the encrypted changed selected data to the disc data storage medium.

2. The method of claim 1 , wherein the encrypted selected data comprises an integer number of sectors of data from the same track.

3. The method of claim 1 , wherein the encrypted selected data includes a whole track of data from the same track of the disc data storage medium.

4. The method of claim 1 , wherein encrypting the changed portion and the another portion includes performing wide block encryption.

5. The method of claim 1 wherein the specific portion includes the data associated with the specific logical block address and the another portion does not include the data associated with the specific logical block address.

6. The method of claim 5 further comprising randomly selecting the another portion from a multitude of available data portions of the same track.

7. The method of claim 6 , further comprising: writing the encrypted changed selected data to the storage medium includes selecting a different physical location to store the encrypted changed selected data that is not a same physical location that the encrypted selected data was stored.

8. The method of claim 7 further comprising encrypting the changed portion and the another portion using a different encryption key than the encrypted selected data was encrypted with.

9. The method of claim 8 wherein the encryption is performed by a data storage device such that the encryption is transparent to the host computer.

10. The method of claim 8 wherein the encryption is performed by the host computer.

11. A device comprising:
a computer processor configured to:
process a request from a host to store data associated with a specific logical block address;
retrieve selected data, including first data associated with the specific logical block address and second data not associated with the specific logical block address, from a storage medium in response to an indication to change the first data but not the second data, the first data and the second data both including host data having different corresponding logical block addresses,
decrypt the selected data via a cryptographic module,
make changes to the first data to produce changed data,
encrypt, via the cryptographic module, the changed data and the second data to produce encrypted changed selected data, and
store the encrypted changed selected data to the storage medium.

12. The device of claim 11 further comprising the storage medium communicatively coupled to the computer processor to allow retrieving of data from the storage medium and storing of data to the storage medium.

13. The device of claim 11 wherein the changes correspond to the request to store data associated with the specific logical block address and the first data includes the data associated with the specific logical block address and the second data does not include the data associated with the specific logical block address.

14. The device of claim 11 wherein the computer processor is further adapted to select a different physical location of a data storage medium to store the encrypted changed selected data, where the different physical location is not a same physical location that the selected data was previously stored at.

15. The device of claim 11 wherein the computer processor is further adapted to produce the encrypted changed selected data using a different encryption key than the selected data was encrypted with.

16. A method of decryption and encryption performed internal to a computing device comprising:
process a request to change specific data associated with a specific logical block address of a data storage device;
based on the request to change the specific data, retrieving a first data portion mapped to the specific logical block address, and retrieving a second data portion not mapped to the specific logical block address and having a different logical block address than the first data portion;
decrypting data including the first data portion and the second data portion;
changing the first data portion to produce a changed first data portion;
not changing the second data portion;
encrypting together the changed first data portion and the second data portion that is unchanged to produce encrypted changed data; and
storing the encrypted changed data to the data storage device.

Assignees

• Hars Laszlo
• Seagate Technology Llc

Inventors

• Hars Laszlo

Classifications

• G11B20/00086 Primary

  Circuits for prevention of unauthorised reproduction or copying, e.g. piracy (indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00) · CPC title

• G06F12/1408

  by using cryptography (for digital transmission H04L9/00) · CPC title

• G06F21/14

  against software analysis or reverse engineering, e.g. by obfuscation · CPC title