JP2006344177A - Data erasing system and data erasing program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a data erasing system which can perform data erasure processing in a short time and at a low cost by setting necessary and sufficient overwrite erasing (whitening) area. <P>SOLUTION: This system is a data erasing system which erases data stored in a storing means 15 of an electronic apparatus etc. The system has a locally overwrite erasing (locally whitening) means 16 which applies overwrite erasure to used storage area every time the storage area of the storing means 15 is locally used; a whole overwrite erasing (wholly whitening) means 17 which applies overwrite erasure to a prescribed area of the storage area, so that whole of storage area of the storing means 15 is erased; a block memory means 19 which stores blocks erased by the locally overwrite erasing (locally whitening) means 16; and an erased block management means 18 which sets an overwrite erasing (whitening) area to the whole overwrite erasing (wholly whitening) means 17, based on information stored in the block memory means 19. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a data erasing device that erases data stored in a storage unit such as an electronic device (for example, a computer or a mobile device), and a data erasing program that causes a data erasing device to execute data erasing of the storage unit.

  In recent years, various data storage means have been developed with the development of computers and mobile devices. Examples of computer storage means include a hard disk (hereinafter referred to as HDD), a magneto-optical disk (hereinafter referred to as MO), and an external storage device (hereinafter referred to as storage) such as a magnetic tape. Examples of the storage means of the mobile device include a memory card such as a PC card (registered trademark), a compact flash (registered trademark) card (hereinafter referred to as a CF card), and a smart media (registered trademark).

  In these storage means, data is divided into a file management area and an actual data area, and information such as the file name of the data, the storage location of the storage means, the directory name, and the creation date is stored in the file management area. The presence or absence of data in the storage means is determined based on the information in the file management area.

  For this reason, even if the data stored in the storage means is deleted by an operation of a computer or mobile device, the information in the file management area is only partially changed, and the actual data remains as it is. Further, even if these storage means are formatted, the actual data area remains as it is only by deleting the information in the file management area.

  By analyzing the data remaining in the actual data area, it is possible to infer information on the changed or deleted file management area. For this reason, data deleted or formatted by operation of a computer or mobile device cannot always be completely restored, but can be restored to the original data. In addition, for the sound reason of “rescuing an erroneously erased memory”, a lot of software for restoring data by such a method is commercially available. Therefore, anyone can easily restore the data stored in the storage means.

For this reason, when transferring or disposing of these storage means or a computer or mobile device equipped with the storage means, the confidential data stored in the storage means is restored and leaked or misused to develop a trouble. There is a problem.
Therefore, when transferring or discarding the storage means or the like, it is necessary to delete the data by a more reliable data erasing method so that the data deleted from the storage means cannot be restored. However, such processing requires a specialized engineer with a predetermined skill.

For this reason, an apparatus is provided in which a normal user, not a professional engineer, can automatically operate a personal computer (hereinafter referred to as a PC) to overwrite and erase (whitening) data in the HDD (for example, , See Patent Document 1).
The apparatus disclosed in Patent Document 1 includes, as means, an MS-DOS apparatus, an automatic startup file that is automatically read by the MS-DOS apparatus, and an overwrite erasure program that is started by the automatic startup file. The gist of the disk overwriting apparatus is that the overwriting program includes information obtaining means for obtaining information relating to the HDD of the PC and overwriting and erasing means for overwriting and erasing the inside of the HDD by the obtained information.
Therefore, according to this apparatus, information related to the HDD is acquired by the overwrite erasure program, and the inside of the HDD is overwritten by the acquired information, so that the overwrite erasure can be performed automatically and easily. It was.
JP 2001-344071 A

However, the above-described conventional technology has the following problems.
That is, according to the apparatus shown in Patent Document 1, since all data in the HDD is overwritten and erased, the time required for processing is long. In addition, it is considered sufficient to perform overwriting and erasing with meaningless data once. However, when overwriting once, data is recorded on the HDD due to vibration caused by rotation of the drive. Because there is a possibility that the residual magnetism generated by the angle deviation between the magnetic head and the magnetic surface can be read by a special device, the standard for data erasure such as the NAS recommended method is random number, fixed data and its complement. It is recommended to erase the data by overwriting three times. For this reason, in order to perform the overwrite erasure process with high quality, a process that exceeds at least those standards is required, so that the processing time becomes enormous and the cost increases.

  The present invention has been proposed in order to solve the problems of the conventional techniques as described above, and by setting a necessary and sufficient overwriting area, it can be performed in a short time and at a low cost. It is an object of the present invention to provide a data erasing apparatus and a data erasing program capable of erasing data.

  In order to achieve the above object, a data erasing apparatus according to the present invention is a data erasing apparatus for erasing data stored in a storage means, as described in claim 1, wherein a storage area of the storage means is a local area. A local overwriting erasure unit for overwriting and erasing the used storage area, and a whole overwriting and erasing a predetermined area of the storage area so that the entire storage area of the storage unit is erased. Overwrite erasure means, block storage means for storing information related to the area overwritten by the local overwrite erasure means, and an erased block for setting an overwrite erasure area for the overall overwrite erasure means based on the information related to the area And a management means.

  According to the data erasing apparatus having such a configuration, when the entire storage area of the storage unit is overwritten by the whole overwrite erasing unit, the area erased by the local overwriting unit needs to be overwritten. Absent. For this reason, it is possible to shorten the overwrite erasure time by the entire overwrite erasure means, and it is possible to perform efficient processing at a low cost.

In the data erasing apparatus of the present invention, as described in claim 2, the block storage means stores an unused area after initialization of the storage area as storage information, and the erased block management means When setting the overwrite erasure area for the overall overwrite erasure means, the unused area is excluded from the area overwritten by the overall overwrite erasure means.
According to the data erasing apparatus having such a configuration, when the entire storage area of the storage unit is overwritten by the whole overwrite erasing unit, the storage area is initialized in addition to the area erased by the local overwrite erasing unit. It is not necessary to overwrite the unused area later. For this reason, it is possible to further shorten the overwrite erasing time by the entire overwrite erasing means, and to perform efficient processing at low cost.

According to a third aspect of the present invention, in the data erasing apparatus according to the third aspect, the block storage means stores the standard used for overwriting by the local overwriting erasure as storage information, and the erased block The management means, when setting the overwriting erasure area for the whole overwriting erasure means, the area overwritten and erased by the local overwriting erasure unit in the same standard as that used for overwriting by the whole overwriting erasure means, In this configuration, the area is overwritten and erased by the overwriting means.
According to the data erasing apparatus having such a configuration, when the entire storage area of the storage unit is overwritten by the whole overwrite erasing unit, the local overwriting unit uses the same standard as the overwriting erasure by the whole overwriting unit. The erased area need not be overwritten by the whole overwrite erasing means. For this reason, by removing the area from the overwrite erasure area for the entire overwrite erasure means, the overwrite erasure time by the overall overwrite erasure means can be further shortened, and efficient processing can be performed at low cost.

  According to a fourth aspect of the present invention, there is provided a data erasing program for causing a data erasing apparatus to execute a procedure for erasing data stored in a storage means, as described in claim 4. When a local memory is used locally, a local overwriting procedure for overwriting the used storage area and overwriting a predetermined area of the storage area so that the entire storage area of the storage means is erased An entire overwrite erasing procedure to be erased, a block storage procedure for storing information related to the area overwritten by the local overwrite erasing process, and an erasure for setting an overwrite erasing area for the entire overwrite erasing means based on the information related to the area The data erasing apparatus is configured to execute a completed block management procedure.

  According to such a data erasing program, when the entire storage area of the storage means is overwritten by the whole overwriting process, it is not necessary to make the area erased by the local overwriting process the target of overwriting. For this reason, it is possible to shorten the overwrite erasure time by the entire overwrite erasure process, and it is possible to perform an efficient process at a low cost.

As described above, according to the data erasing apparatus and the data erasing program of the present invention, it is possible to shorten the overwrite erasing time by the entire overwrite erasing means.
Therefore, the data stored in the storage unit can be efficiently erased in a short time and at a low cost when the electronic device or the like is transferred or discarded or the storage unit is initialized.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram illustrating a configuration of an image forming apparatus including a data erasing apparatus according to a preferred embodiment of the present invention.
As shown in FIG. 1, the image forming apparatus 10 includes a front panel 11, an input / output interface (hereinafter referred to as an input / output I / F) 12, a main storage device 13, a CPU 14, and storage means (storage medium (HDD)). 15 and a device bus 22.

The front panel 11 is composed of a liquid crystal panel or the like, and is a device that performs operation input and the like of the image forming apparatus 10.
The input / output I / F 12 is connected to a network such as a LAN (not shown) so that the image forming apparatus 10 can be shared and used by a plurality of PCs as clients on the network.
The main storage device 13 is constituted by a RAM or the like, and performs print processing of print data input from the input / output I / F 12.
The CPU (control unit) 14 executes predetermined processes in each component of the image forming apparatus 10 or executes predetermined processes by itself in order to execute various functions of the image forming apparatus 10.

The storage unit 15 is a storage medium or the like that stores data input from the input / output I / F 12, and is configured by an HDD in the present embodiment. However, a storage built in the image forming apparatus 10 or a memory card externally attached to the image forming apparatus 10 may be used.
The device bus 22 is a transmission path for each device to exchange data within the image forming apparatus 10.
The configuration of the data erasing apparatus provided in the image forming apparatus 10 is shown in FIG. 2 and will be described below.

Next, FIG. 2 is a block diagram showing a configuration of a data erasing apparatus which is a preferred embodiment of the present invention.
As shown in FIG. 2, the data erasing apparatus of the present invention includes a local overwrite erasing unit 16, an entire overwrite erasing unit 17, and an erased block management unit 18, and the processing of these units is performed by the image forming apparatus 10. A data erasure program stored in the storage unit (ROM, hard disk, etc.) is loaded into the RAM and executed by the CPU.

  The local overwriting erasure means 16 receives data input from the input / output I / F 12 and stored locally in the storage area of the storage means 15 in the drawing process, job management process, etc. Overwrite and erase at the timing of. As a local storage area (block) to be overwritten and erased by the local overwrite erasing means 16, a file (file) or a partition (Partition) can be cited. It may be work data generated by processing. In addition, the storage unit 15 stores data that is used for a relatively long period of time, such as downloaded font data and user account information.

  The entire overwrite erasure unit 17 overwrites and erases the overwrite erasure area set by the erased block management unit 18 so that the entire storage area of the storage unit 15 is erased.

  The erased block management means 18 is a block (address) written when data is written in the storage area of the storage means 15, a block (address) erased by the local overwrite erasure means 16, and a local overwrite erase. It has a management table (block storage means) 19 containing the standard (erasing method) used for overwriting and erasing by means 16 and the unused area (address) after initialization of the storage area. Based on the information stored in the block storage unit 19 (information relating to the area overwritten and erased by the local overwriting unit), an overwriting area for the entire overwriting unit 17 is set.

Specifically, as shown in FIG. 2, the management table 19 includes an address (flag B) of the written local area when data is written in the storage area of the storage means 15, the local overwrite erasing means 16. And the erase management table 20 for managing and storing the address erased by the flag (flag A) and the address of the unused area after initialization of the storage area (no flag: indicated by ○) and overwriting by the local overwrite erasing means 16 And a standard table 21 for managing and storing used standards (erasing method).
One or more standards are written in the standard table 21. Specifically, for example, “0 is written once”, “1 is written once”, “random number is written once” ”,“ NSA method ”,“ old NSA method ”,“ US Department of Defense method ”,“ NATO method ”,“ Gutmann method ”, and the like.

When a format request is issued from the control unit of the image forming apparatus 10 when the image forming apparatus 10 is transferred or discarded, or when the storage unit 15 is initialized, the erased block management unit 18 reads the management table 19. Referring to the address (flag A) erased by the local overwrite erasing means 16, the address whose erasure standard is the same as the erase standard by the overall overwrite erasure means 17, and the unused area after initialization of the storage area An area other than the area address (no flag: ◯ displayed) is set as an overwrite erase area for the entire overwrite erase means 17.
That is, in this embodiment, when the data is written in the storage area of the storage means 15, the address of the written local area (flag B) and the address erased by the local overwrite erasure means 16 (flag A) are stored. Among them, an address whose erasure standard is different from the erasure standard by the global overwrite erasure means 17 is set as an overwrite erasure area for the global overwrite erasure means 17, and the set overwrite erasure area is overwritten by the global overwrite erasure means 17. The As a result, the entire storage area of the storage unit 15 is erased.

  When the storage area of the storage means 15 is initialized, the management table 19 does not need to be overwritten and erased, so it is in a clear state, and each address column of the erase management table 20 is an unused area (no flag: o display) )). When data is written in the storage area of the storage means 15, the flag B is set for the first time, and the flag B is dropped and the flag A is set at the place where the local overwrite deletion means 16 is overwritten. The management table 19 may be expanded to have a flag for each erasure standard. However, in any case, the following two methods (1) and (2) are conceivable.

(1) Method of loading a flag in the data management area (meta area) of an existing file device When the FAT 32 is taken as an example, the representable area is 1.37 TB. That is, in the case of a device smaller than this size, surplus bits exist in the FAT area. It is possible to express the erasure standard in the standard table 21 by this surplus bit. In the case of an 80 GB HDD on the market, at least 4 bits are left, so 16 erasure standards can be stored together with address information.
Note that when a 32 MB removable disk is used in FAT16, the surplus bits become 0, but surplus bits can be created by making the cluster size (access size) more rough.

(2) A method for providing a separate area Sector-by-sector control becomes possible and is not affected by the file device. For example, when a plurality of erasure standards are operated in a mixed manner, each standard is stored as a separate flag, so that it is possible to determine only an area that matches the standard at the time of erasure.

  The significance of storing a plurality of erasure standards in the standard table 21 is, for example, “the local erasure that is sequentially executed may be an erasure standard that is overwritten once or twice in consideration of productivity. If you want to use an erasing method that overwrites three times when discarding, "the area that was overwritten and erased only once was overwritten twice, and overwritten and erased only twice. The area can be overwritten once. Of course, an area that has been overwritten and erased three times or an unused area is excluded from overwriting by the entire overwriting erasure means 17.

FIG. 3 is a sequence diagram for explaining the operation of the data erasing apparatus which is a preferred embodiment of the present invention.
First, when a local overwriting process is requested from the control unit of the image forming apparatus 10 in step S1, the local overwriting unit 16 is locally stored in the storage area of the storage unit 15 in step S2. The data is overwritten and erased at the timing of the end of output or the end of the job. When the local overwriting is completed, the local overwriting erasure unit 16 sets the flag A to the erased block management unit 18 in step S3.

  Next, the erased block management means 18 erases the flag B of the address stored in the erase management table 20 when data is written in the storage area of the storage means 15 in step S4, sets the flag A, and The standard used for overwrite erasure by the automatic overwrite erasure means 16 is stored in the standard table 21. As a result, the overwriting by the local overwriting erasure unit 16 is completed, and a local overwriting process end signal is output from the erased block management unit 18 to the control unit of the image forming apparatus 10.

  Next, when the image forming apparatus 10 is transferred or discarded, or when the storage unit 15 is initialized, a request for formatting is issued from the control unit of the image forming apparatus 10 to the entire overwrite erasing unit 17 in step S5. In step S6, the entire overwrite erasure unit 17 requests the erased block management unit 18 to obtain an overwrite erasure setting area. Further, the global overwrite erasure unit 17 uses the address (flag B) of the written local area and the local overwrite erasure unit 16 when data is written from the local overwrite erase unit 16 to the storage area of the storage unit 15. Of the erased address (flag A), an address whose standard is different from the standard for erasing by the whole overwrite erasing unit 17 is read as a setting overwriting area.

  Next, in step S7, the entire overwrite erasure unit 17 overwrites the overwrite erasure area set by the erased block management unit 18, thereby erasing the entire storage area of the storage unit 15 and completing the formatting. To do.

As is clear from the above description, in this embodiment, when the entire storage area of the storage unit 15 is overwritten by the whole overwrite erasing unit 17, the unused area of the storage unit 15 and the local overwrite erasing unit 16 Blocks that have already been overwritten and erased with the same erasure standard do not need to be overwritten. For this reason, the overwriting erasure time by the whole overwriting erasure means 17 can be shortened.
As a result, when the image forming apparatus 10 is transferred or discarded, or when the storage unit 15 is initialized, the data stored in the storage unit 15 can be efficiently erased in a short time and at a low cost. .

  A data erasure program according to a preferred embodiment of the present invention is a program that causes each component to execute a data erasure processing procedure in the above-described data erasure apparatus.

Next, the data erasing program will be described.
The data erasing function of the computer (image forming apparatus or the like) in the above embodiment is realized by a data erasing program stored in a storage means (for example, ROM or HDD).

The data erasure program is read by a computer control means (CPU or the like), and sends instructions to each component of the computer to perform predetermined processing, for example, local overwrite erasure processing of the storage area by the local overwrite erasure means 16 Then, the overwritten erase area setting process for the entire overwrite erasure means 17 by the erased block management means 18 and the overwriting erasure process by the entire overwrite erasure means 17 for the set overwrite erasure area are performed.
Thus, the data erasing function is realized by the cooperation of the data erasing program as software and each component of a computer (image forming apparatus or the like) as hardware resources.

The data erasure program for realizing the data erasure function is stored in a computer ROM, hard disk, or the like, or may be stored in a computer-readable recording medium, such as an external storage device or a portable recording medium. it can.
The external storage device refers to a memory expansion device that incorporates a storage medium such as a CD-ROM and is externally connected, such as an image forming device. On the other hand, the portable recording medium is a recording medium that can be mounted on a recording medium driving device (drive device) and is portable, and refers to, for example, a flexible disk, a memory card, a magneto-optical disk, and the like.

Then, the program recorded on the recording medium is loaded into a RAM or the like of the computer and executed by the CPU (control means or control unit). By this execution, the above-described data erasure processing function of the present embodiment is realized.
Furthermore, when the data erasure program of the present invention is loaded by a computer, the data erasure program held by another computer can be downloaded to its own RAM or external storage device using a communication line. The downloaded data erasing program is also executed by the CPU, and the data erasing function of this embodiment is realized.

The data erasing apparatus of the present invention has been described with reference to the preferred embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention. Needless to say.
For example, in the above-described embodiment, the deletion management table 20 of the management table 19 includes the address (flag B) of the written local area when data is written in the storage area of the storage means 15, the local overwrite erasing means. The address erased by 16 (flag A) and the address of the unused area after initialization of the storage area (no flag: indicated by ◯) are managed and stored. However, instead of this, the erasure management table 20 was erased by the address (flag B) of the written local area and the local overwrite erasure means 16 when data was written in the storage area of the storage means 15. Only the address (flag A) is managed and stored, and the address (flag B) of the written local area when the data is written to the storage area of the storage means 15 and the address erased by the local overwrite erasure means 16 Of the (flag A), an address whose erasure standard is different from the erasure standard by the global overwrite erasure unit 17 may be set as an overwrite erasure area for the global overwrite erasure unit 17.
In the embodiment described above, the data erasing device is mounted on the image forming apparatus, but may be mounted on other electronic devices such as a PC.

  As described above, the data erasing apparatus and the data erasing program according to the present invention include a device having a non-volatile memory such as an HDD, an image forming apparatus, a PC, an HDD recorder, a portable terminal (for example, a cellular phone), and the like. It can utilize suitably for the electronic device.

1 is a block diagram illustrating a configuration of an image forming apparatus including a data erasing apparatus that is a preferred embodiment of the present invention. It is a block diagram which shows the structure of the data erasing apparatus which is preferable embodiment of this invention. It is a sequence diagram for demonstrating operation | movement of the data erasing apparatus which is preferable embodiment of this invention.

Explanation of symbols

10 Image forming apparatus 11 Front panel 12 Input / output I / F
13 Main memory 14 CPU
DESCRIPTION OF SYMBOLS 15 Storage means 16 Local overwrite deletion means 17 Whole overwrite deletion means 18 Erased block management means 19 Management table (block storage means)
20 Erasing management table 21 Standard table 22 Device bus

Claims (4)

A data erasing device for erasing data stored in a storage means,
When the storage area of the storage means is used locally, the local overwrite erasure means for overwriting and erasing the used storage area;
An overall overwrite erasure unit for overwriting and erasing a predetermined area of the storage area so that the entire storage area of the storage unit is erased;
Block storage means for storing information on the area overwritten by the local overwriting means;
A data erasing apparatus comprising: an erased block management unit that sets an overwrite erasure area for the entire overwrite erasure unit based on information on the area. The block storage means stores an unused area after initialization of the storage area as storage information,
2. The erased block management means, when setting an overwrite erase area for the overall overwrite erase means, removes the unused area from an area to be overwritten by the overall overwrite erase means. Data eraser. The block storage means stores the standard used for overwriting by the local overwriting means as storage information,
The erased block management means is an area overwritten by the local overwrite erasure means in accordance with the same standard as that used for overwriting by the overall overwrite erasure means when setting an overwrite erasure area for the overall overwrite erasure means. The data erasing apparatus according to claim 1 or 2, wherein the data erasing device is excluded from an area that is overwritten and erased by the whole overwriting and erasing unit. A data erasing program for causing a data erasing device to execute a procedure for erasing data stored in a storage means,
A local overwriting procedure for overwriting the used storage area when the storage area of the storage means is used locally;
An overall overwrite erasure procedure for overwriting and erasing a predetermined area of the storage area so that the entire storage area of the storage means is erased;
A block storage procedure for storing information on the area overwritten by the local overwriting process;
Based on information on the area, an erased block management procedure for setting an overwrite erase area for the entire overwrite erase means;
A data erasing program that causes the data erasing device to execute

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