Apparatus, a system, a method and a computer program for erasing data stored on a storage device

• US 9,286,231 B2
• Filed: 07/05/2013
• Issued: 03/15/2016
• Est. Priority Date: 07/05/2012
• Status: Active Grant

• Current Assignee: Blancco Technology Group Ip Oy
• Original Assignee: Blancco Oy Ltd. (Blancco Technology Group Plc)
• Inventors: Vaisanen, Kim, Lalli, Lauri, Brew, Jonathan
• Primary Examiner(s): KIM, HONG CHONG
• Application Number:
  US14/412,788
• Publication Number:
  US 20150169462A1
• Time in Patent Office: 984 Days
• Field of Search: 711/159, 711/154, 711/165, 711/170
• US Class Current: 1/1
• CPC Class Codes: G06F 11/0727 in a storage system, e.g. in a DASD or network based storage system drivers for digital recording or reproducing units G06F3/06; circuits for error detection or correction within digital recording or reproducing units G11B20/18; for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS], H04L67/1097
• CPC Class Codes: G06F 11/2635 using a storage for the test inputs, e.g. test ROM, script files
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/0891 using clearing, invalidating or resetting means
• CPC Class Codes: G06F 21/78 to assure secure storage of data address-based protection against unauthorised use of memory G06F12/14; record carriers for use with machines and with at least a part designed to carry digital markings G06K19/00
• CPC Class Codes: G06F 21/79 in semiconductor storage media, e.g. directly-addressable memories
• CPC Class Codes: G06F 2212/7201 Logical to physical mapping or translation of blocks or pages
• CPC Class Codes: G06F 2212/7205 Cleaning, compaction, garbage collection, erase control
• CPC Class Codes: G06F 2221/2143 Clearing memory, e.g. to prevent the data from being stolen
• CPC Class Codes: H04L 9/0662 with particular pseudorandom sequence generator

Abstract

An approach for erasing data being stored in a data storage apparatus is provided. The approach may be provided e.g. as an apparatus, as a method, as a system or as a computer program. The approach comprises obtaining a sequence of uncompressible data fulfilling predetermined criteria, which predetermined criteria comprises a statistical measure indicative of compressibility or uncompressibility of the sequence of uncompressible data meeting a predetermined criterion, wherein the sequence of uncompressible data is divided into one or more blocks of uncompressible data, the sum of the sizes of the one or more blocks of uncompressible data being larger than or equal to the storage capacity of the data storage apparatus, and providing, to the data storage apparatus, the one or more blocks of uncompressible data for storage therein to overwrite the data being currently stored in the data storage apparatus.

Claims

1. A data erasure apparatus for erasing data being stored in a data storage apparatus, the data erasure apparatus comprising:

a data provision portion configured to obtain a sequence of uncompressible data fulfilling predetermined criteria, said predetermined criteria comprised of a P-value derived on basis of the sequence of uncompressible data using a predetermined statistical test indicative of compressibility of the data exceeding a predetermined threshold,

wherein a null-hypothesis is that the sequence of uncompressible data is non-random, and

wherein the sequence of uncompressible data is divided into one or more blocks of uncompressible data, the sum of sizes of the one or more blocks of uncompressible data being larger than or equal to an addressable storage capacity of the data storage apparatus; and

a data writing portion configured to

provide, to the data storage apparatus, the one or more blocks of uncompressible data for storage therein to overwrite the data being currently stored in the data storage apparatus,

issue to the data storage apparatus, following a provision of said one or more blocks of uncompressible data, a firmware level sanitization command that is arranged to cause initialization of all user addressable memory locations of the data storage apparatus, and

compare, after issuance of the firmware level sanitization command, one or more selected portions of data stored in the data storage apparatus with respective portions of the one or more blocks of uncompressible data most recently provided for storage in the data storage apparatus to verify that the respective portions of the one or more blocks of uncompressible data most recently provided for storage in the storage apparatus are not anymore stored therein, thereby providing an indication of successful application of the firmware level sanitization command.

2. The apparatus according to claim 1, wherein the predetermined threshold is 0.01.

3. The apparatus according to claim 1, wherein the predetermined statistical test comprises the Overlapping Template Matching Test, the Discrete Fourier Transform (Spectral) Test or the Maurer'"'"'s Universal Statistical Test.

4. The apparatus according to claim 1, wherein obtaining the sequence of uncompressible comprises employing a random number generator configured to generate the sequence of pseudo random data fulfilling the predetermined criteria.

5. The apparatus according to claim 4, wherein employing a random number generator comprises repeated calls to one of a KISS random number generator, a xorshift random number generator or a Mersenne twister random number generator.

6. The apparatus according to claim 1, wherein obtaining the sequence of uncompressible data comprises employing a data compressor for compressing source data to generate the sequence of compressed data in accordance with a predetermined rule.

7. The apparatus according to claim 6, wherein the source data is obtained by employing a random number generator.

8. The apparatus according to claim 6, wherein the data compressor comprises a Deflate data compressor or a BZip2 data compressor.

9. The apparatus according to claim 1, wherein

the data provision portion is further configured to obtain one or more further sets of one or more blocks of uncompressible data, the sum of the sizes of the one or more blocks of uncompressible data in each further set being larger than or equal to the addressable storage capacity of the data storage apparatus, and

the data writing portion is further configured to provide to the data storage apparatus the one or more further sets of one or more blocks of uncompressible data, one set at a time, for storage therein to overwrite the data currently being stored in the data storage apparatus.

10. A system for erasing data, comprising:

a data storage apparatus containing data to be erased; and

a data erasure apparatus according to claim 1, the data storage apparatus being configured to

apply compression to the one or more blocks of uncompressible data to provide corresponding one or more blocks of compressed data, wherein, for each of the one or more compressed blocks of data, the size of a block of compressed data is no smaller than the size of the corresponding block of uncompressible data, and

store the one or more blocks of compressed data in a physical memory.

11. The system according to claim 10, wherein the data storage apparatus comprises a Solid State Drive.

12. A method for erasing data being stored in a data storage apparatus, the method comprising:

obtaining a sequence of uncompressible data fulfilling predetermined criteria, said predetermined criteria comprised of a P-value derived on basis of the sequence of uncompressible data using a predetermined statistical test indicative of compressibility of the data exceeding a predetermined threshold, wherein a null-hypothesis is that the sequence of uncompressible data is non-random, and wherein the sequence of uncompressible data is divided into one or more blocks of uncompressible data, a sum of the sizes of the one or more blocks of uncompressible data being larger than or equal to an addressable storage capacity of the data storage apparatus, providing, to the data storage apparatus, the one or more blocks of uncompressible data for storage therein to overwrite the data being currently stored in the data storage apparatus;

issuing to the data storage apparatus, following a provision of said one or more blocks of uncompressible data, a firmware level sanitization command that is arranged to cause initialization of all user addressable memory locations of the data storage apparatus; and

comparing, after issuance of the firmware level sanitization command, one or more selected portions of data stored in the data storage apparatus with respective portions of the one or more blocks of uncompressible data most recently provided for storage in the data storage apparatus to verify that the respective portions of the one or more blocks of uncompressible data most recently provided for storage in the data storage apparatus are not anymore stored therein, thereby providing an indication of successful application of the firmware level sanitization command.

13. The method according to claim 12, wherein the predetermined threshold is 0.01.

14. The method according claim 12, wherein the predetermined statistical test comprises the Overlapping Template Matching Test, the Discrete Fourier Transform (Spectral) Test or the Maurer'"'"'s Universal Statistical Test.

15. The method according to claim 12, wherein obtaining the sequence of uncompressible data comprises employing a random number generator configured to generate the sequence of pseudo random data fulfilling the predetermined criteria.

16. The method according to claim 15, wherein employing a random number generator comprises repeated calls to one of a KISS random number generator, a xorshift random number generator or a Mersenne twister random number generator.

17. The method according to claim 12, wherein obtaining the sequence of uncompressible data comprises employing a data compressor for compressing source data to generate the sequence of compressed data in accordance with a predetermined rule.

18. The method according to claim 17, wherein the source data is obtained by employing a random number generator.

19. The method according to claim 17, wherein the data compressor comprises a Deflate data compressor or a BZip2 data compressor.

20. The method according to claim 12, further comprising:

obtaining one or more further sets of one or more blocks of uncompressible data, the sum of the sizes of the one or more blocks of uncompressible data in each further set being larger than or equal to the addressable storage capacity of the data storage apparatus; and

providing provide to the data storage apparatus the one or more further sets of one or more blocks of uncompressible data, one set at a time, for storage therein to overwrite the data currently being stored in the data storage apparatus.

21. The method according to claim 12, further comprising:

applying, in the data storage apparatus, compression to the one or more blocks of uncompressible data to provide corresponding one or more blocks of compressed data, wherein, for each of the one or more compressed blocks of data, the size of a block of compressed data is no smaller than the size of the corresponding block of uncompressible data; and

storing the one or more blocks of compressed data in a physical memory of the data storage apparatus.

22. The method according to claim 21, wherein the data storage apparatus comprises a Solid State Drive.

23. A computer program recorded on a non-transitory data recording medium readable by an apparatus that comprises one or more processors, the computer program including one or more sequences of one or more instructions which, when executed by the one or more processors, cause the apparatus to perform at least the method according to claim 12.

24. A computer program product, comprising at least one computer readable non-transitory medium having program code stored thereon, the program code being such that, when executed by an apparatus, causes the apparatus to perform at least the method according to claim 12.