Protecting Stored Data From Traffic Analysis

• US 20090048976A1
• Filed: 08/14/2007
• Published: 02/19/2009
• Est. Priority Date: 08/14/2007
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Hars, Laszlo
• Granted Patent: US 9,324,361 B2
• Time in Patent Office: Days
• US Class Current: 705/50
• CPC Class Codes: G06F 12/1408 by using cryptography for digital transmission H04L9/00
• CPC Class Codes: G06F 21/14 against software analysis or reverse engineering, e.g. by obfuscation
• CPC Class Codes: G11B 20/00086 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

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.

Claims

1. A method comprising:

reading a portion of stored data from a storage medium;

decrypting the portion of stored data;

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.

2. The method of claim 1, wherein:

the portion of stored data comprises an integer number of sectors of data.

3. The method of claim 1, wherein:

the portion of stored data is read from a track of data.

4. The method of claim 1, wherein the step of encrypting the changed data uses wide block encryption.

5. The method of claim 1, wherein:

the storage medium comprises a disc.

6. An apparatus comprising:

a storage medium; and

a processor for reading a portion of stored data from the storage medium, for decrypting the portion of stored data, if changes are requested, for making the changes to the portion of stored data to produce changed data, for encrypting the changed data, and for writing the encrypted changed data to the storage medium.

7. The apparatus of claim 6, wherein:

the portion of stored data comprises an integer number of sectors of data.

8. The apparatus of claim 6, wherein:

the portion of stored data comprises a track of data.

9. The apparatus of claim 6, wherein the processor uses wide block encryption.

10. The apparatus of claim 6, wherein:

the storage medium comprises a disc.

11. A method comprising:

storing encrypted blocks of data on a storage medium;

re-encrypting selected ones of the blocks of data; and

storing the re-encrypted blocks of data at different locations on the storage medium.

12. The method of claim 11, wherein the selected blocks are randomly chosen.

13. The method of claim 11, wherein:

the selected blocks of the data are re-encrypted using a second encryption scheme that differs from a first encryption scheme that was used to originally encrypt the blocks of data.

14. The method of claim 11, wherein the step of storing the re-encrypted blocks of data at different locations on the storage medium introduces gaps between the blocks on the storage medium.

15. The method of claim 11, wherein the step of storing the re-encrypted blocks of data at different locations on the storage medium occurs when a device containing the storage medium is idle.

16. An apparatus comprising:

a storage medium; and

a processor for storing encrypted blocks of data on the storage medium, for re-encrypting selected ones of the blocks of data, and for storing the re-encrypted blocks of data at different locations on the storage medium.

17. The apparatus of claim 16, wherein the selected blocks are randomly chosen.

18. The apparatus of claim 16, wherein:

the selected blocks of the data are re-encrypted using a second encryption scheme that differs from a first encryption scheme that was used to originally encrypt the blocks of data.

19. The apparatus of claim 16, wherein the blocks on the storage medium are separated by gaps.

20. A method comprising:

encrypting blocks of data to produce encrypted blocks of data;

storing the encrypted blocks of data on a storage medium;

storing auxiliary data related to times at which the encrypted blocks of data were stored on the storage medium;

reading the encrypted blocks of data from the storage medium;

re-encrypting the encrypted blocks of data;

storing the re-encrypted blocks of data on the storage medium; and

storing auxiliary data related to times at which the re-encrypted blocks of data were rewritten on the storage medium.

21. An apparatus comprising:

a storage medium; and

a processor for encrypting blocks of data to produce encrypted blocks of data, storing the encrypted blocks of data on the storage medium, storing auxiliary data related to times at which the encrypted blocks of data were stored on the storage medium, reading the encrypted blocks of data from the storage medium, re-encrypting the encrypted blocks of data, storing the re-encrypted blocks of data on the storage medium, and storing auxiliary data related to times at which the re-encrypted blocks of data were rewritten on the storage medium.