JP5544905B2 - Image processing apparatus, data erasing method and program for image processing apparatus - Google Patents

Description

  The present invention relates to an image processing apparatus including a copying machine, a printing apparatus, and a multifunction machine, and a data erasing method and program for the image processing apparatus.

With the recent increase in security awareness, information security management has been required in offices and the like.
For example, security management of information handled by a personal computer (PC) is well known.
This security management is also required for image processing apparatuses including copiers, printing apparatuses (printers), and multifunction peripherals (MFPs).
In the conventional image processing apparatus, the scanned image data or the like has not been requested to be reused. Therefore, when the image data becomes unnecessary, the image data is deleted immediately and it is not necessary to handle the image data as a file.

However, recently, in response to user requests to manage and reuse image data as a file, such as storing and storing image data in an image processing apparatus or using it from the system, in addition to image data, There is provided an image processing apparatus incorporating a large-capacity storage device that stores system information and user information (for example, a hard disk device (HDD) that is a nonvolatile storage device that retains data even when the power is turned off). .
In such an image processing apparatus, if a file system is used, information for management as a file is automatically given, and an interface for management can also be used.
Further, if a standard file system is used in a UNIX (registered trademark) operating system (OS), image data can be handled as an easily manageable file.

In such an image processing device, in order to protect image data, system information, and user information (hereinafter referred to as “data etc.”) stored in a large-capacity storage device from security threats, the following Taking the way.
The first method encrypts data to be recorded in a large-capacity storage device.
In the second method, when the large-capacity storage device is discarded or the system is initialized, the entire contents of the large-capacity storage device are discarded.
The third method completely erases data and the like that are no longer necessary in the operation of the system from a large-capacity storage device.

As for the first method, encryption is often implemented by hardware.
For example, a high-speed encryption method that is easy to implement in hardware such as AES (Advanced Encryption Standard) is used. The AES is a standard encryption method selected by the United States Department of Commerce Standard Technology Bureau.
In addition, with regard to the second method described above, for example, there is a possibility that data can be restored by an analysis tool or the like simply by releasing (also referred to as “opening”) an area of data or the like in an erase process of data or the like by an operation such as formatting. A method of overwriting and erasing with another data (hereinafter referred to as “batch erasing method”) is used.

Furthermore, with respect to the third method described above, a method for reducing the remaining data that is problematic in terms of security by destroying data that is no longer necessary in normal system operation as quickly as possible (hereinafter referred to as “sequential erasing method”). Is used).
Conventionally, when erasing large-capacity image data, etc. stored in the HDD sequentially, if erasing in units of files, the area cannot be used until all of the image data is overwritten and erased. Thus, there has been an image processing apparatus (see, for example, Patent Document 1) that can efficiently use the storage area of the HDD by releasing the area finely.

This image processing apparatus has the following problems in terms of the file system mechanism because of the specifications for finely releasing the storage area of the HDD in units of blocks.
(1) The file system has a function to increase the speed by storing data in the cache buffer to a certain extent and recording it to the HDD at a time when a data write request is made. However, a large-capacity file stored in the HDD can be stored in units of blocks. In the specification of overwriting and releasing, when erasing a large-capacity image file sequentially, accumulation in the cache buffer and overwriting to the HDD are frequently repeated in units of blocks, which becomes overhead. As a result, the processing takes time and there is a problem that the system is loaded.

(2) In the UNIX-based OS, the fast file system (FFS) that is standardly implemented in the UNIX-based OS is used for sequential erasure, but from the viewpoint of security, the memory space is divided into user land and kernel land. When the overwrite erasure module erases data, the HDD driver can only process kernel land data, so it is necessary to copy the write data from the user land to the kernel land every time a write request is made. When erasing image files sequentially, the above-mentioned copy is frequently generated for each processing in units of blocks, which causes overhead, which takes time for processing, and causes a load on the system. .

However, recent image processing apparatuses process image data with higher image quality and higher resolution, and therefore the amount of image data tends to be enormous.
Also, when a file system is used, it can be managed as a file, but on the other hand, since various information is added, the processing amount at the time of deletion increases.
Therefore, when performing overwriting and erasing in units of blocks as in the conventional image processing apparatus described above, the block size is about 4 KB to 64 KB (this block size varies depending on the system), so image data In the case of data of such a large size, it is necessary to repeat a number of erasing cycles for overwriting and erasing in units of blocks.
Therefore, there is a problem that a high-speed sequential erasing method cannot be realized due to the overhead of (1) and (2) described above.

Further, in order to make it impossible to physically read data on a large-capacity storage device, the same block has to be overwritten a plurality of times, resulting in a problem that the overhead is further increased.
Furthermore, the sequential erasing method is often performed in parallel with job execution. When these are integrated, when using a file system, the processing load at the time of sequential erasing is larger than that of a conventional image processing apparatus, and productivity is increased. There was also a problem that the impact on
The present invention has been made in view of the above points, and an object of the present invention is to reduce the overhead when a file is overwritten and erased in units of blocks by using a file system so that it can be sequentially erased at a high speed. .

In order to achieve the above object, the present invention provides a writing unit that encrypts data and writes the data to a storage unit, a registration unit that registers data to be erased stored in the storage unit as a file, and the writing unit. An overwrite erasure unit for overwriting and erasing predetermined data in an area in which data corresponding to the registered file of the storage unit is recorded, and releasing the overwritten area of the storage unit after the overwriting. There is provided an image processing apparatus comprising: a releasing unit configured to cause the writing unit to encrypt the predetermined data with an encryption key used for the encryption and to perform overwriting .
Further, the overwrite erasure means checks whether there is an offset less than the block size in the file based on the file size of the registered file and the block size of the block in the file. The writing means causes the overwriting to be performed in order from the back block of the file to the first block, and if there is the offset, the writing means causes the overwriting to the offset and then the file. It is preferable to use means for overwriting and erasing in order from the rear block to the first block.

Further, it is preferable that the overwriting erasure unit includes a unit that causes the writing unit to perform the overwriting erasure a predetermined number of times.
Furthermore, it is preferable that the overwrite erasure unit includes a unit that causes the writing unit to release the encryption and overwrites the predetermined data without encrypting the data.
Also, a writing step of encrypting data and writing it to the storage means, a registration step of registering data to be erased stored in the storage means as a file, and the registered file of the storage means by the writing step An overwriting process for overwriting and erasing predetermined data in an area in which data corresponding to the data is recorded, and a releasing process for releasing the overwritten area in the storage means after the overwriting. There is also provided a data erasing method for an image processing apparatus, wherein the erasing step includes a step of overwriting and erasing the predetermined data with an encryption key used for the encryption in the writing step .
Furthermore, a program is also provided for causing a computer to realize the functions of the writing means, the registration means, the overwrite erasing means, and the releasing means constituting the image processing apparatus as described above.

According to the image processing apparatus and the data erasing method of the image processing apparatus according to the present invention, it is possible to sequentially erase at a high speed while reducing the overhead when the file is overwritten and erased in units of blocks using the file system.
In addition, the program according to the present invention can realize a function for allowing a computer to sequentially erase at a high speed by reducing overhead when a file is overwritten and erased in units of blocks using a file system. .

FIG. 3 is a block diagram showing a functional configuration related to overwrite erasure processing in a CPU shown in FIG. 2. 1 is a block diagram illustrating a configuration of a multifunction machine according to an embodiment of the present invention. It is a figure explaining the procedure of the overwrite deletion process which the overwrite deletion daemon shown in FIG. 1 performs. It is a flowchart figure which shows the overwrite deletion process for 1 file shown in FIG.

It is explanatory drawing which shows an example of the overwrite deletion process with respect to the offset in a file. FIG. 3 is a flowchart showing control processing of the virtual file system shown in FIG. 2. FIG. 3 is a flowchart showing a control process during an overwrite erasure process by the HDD driver shown in FIG. 2.

Hereinafter, embodiments for carrying out the present invention will be specifically described with reference to the drawings.
〔Example〕
FIG. 2 is a block diagram showing the configuration of a multifunction machine according to an embodiment of the present invention.
The multi-function device 1 corresponds to an image processing apparatus, and includes a controller 2, an engine 3, an operation display unit 4, and a USB interface (I / F) 5, and is connected to a network 6, and illustration of the network 6 is omitted. Data can be exchanged with various devices including a computer (PC) and other image processing devices.
The controller 2 includes a CPU 10, a first ASIC 11, a memory (MEM) 12, a ROM 13, an NVRAM 14, an HDD 15, an SD card 16, and a second ASIC 17, and controls the entire multifunction device 1.

The engine 3 is connected to the first ASIC 11 of the controller 2 and is an image reading device (scanner) that reads image data from a document (not shown). A printing apparatus (printer) for printing on the recording medium.
The operation display unit 4 includes an input device that allows a user to input various types of operation information, and a display device that displays various types of information to the user.
The USB I / F 5 is connected to the second ASIC 17 of the controller 2 and connects various USB devices including an optical disk device and a digital camera, and manages data exchange with the USB device.
The network 6 is connected to the second ASIC 17 of the controller 2 and is various communication networks including a local area network and the Internet.

In the controller 2, the CPU 10, the memory 12, the ROM 13, the NVRAM 14, the HDD 15, the SD card 16, and the second ASIC 17 are connected to the first ASIC 11.
The CPU 10 performs overall control of the multi-function device 1 and causes the OS to execute the program according to the present invention to execute the data erasing method according to the present invention, thereby realizing the functional units of the respective means according to the present invention. Let
The first ASIC 11 is an IC for image processing, and includes an HDD image processor (IP) 20 that controls data exchange with the HDD 15 via a communication line such as ATA, and the HDD IP 20 includes the HDD 15. Various data including image data, document data, various programs to be operated on the multifunction machine 1 including the program according to the present invention, font data, forms, system information, and user information (hereinafter referred to as “data etc.”) An encryption processing unit 21 which is hardware for encryption is provided.

The encryption processing unit 21 performs encryption processing such as AES using an encryption key, for example. The switching of whether or not to execute the function of encrypting and storing data and the like by the encryption processing unit 21 and the setting of an encryption key such as AES used for encryption are software programs that are operated on the first ASIC 11 It is realized by executing.
The memory 12 is a storage device used as a memory for drawing image data.
The ROM 13, the NVRAM 14 and the SD card 16 are storage devices for storing various programs to be operated on the multi function device 1 including the program according to the present invention. For example, the NVRAM 14 is used as a work area when the CPU 10 performs processing. It is also a storage device used as a sequential overwrite erasure file registration unit.

The HDD 15 is a large-capacity storage for storing image data, document data, various programs to be operated on the multi-function peripheral 1 including the program according to the present invention, font data, forms, system information, various data including user information, and the like. Device.
The second ASIC 17 is an IC that performs power control as well as control of data exchange with the operation display unit 4, USB I / F 5, and network 6.
In FIG. 1, portions unnecessary for the description of this embodiment are omitted as appropriate.
In the multi function device 1, the CPU 10 performs the following overwrite erasure process in order to protect data recorded in the HDD 16 from security threats.

FIG. 1 is a block diagram showing a functional configuration related to overwrite erasure processing in the CPU 10 shown in FIG.
When a file erasure request from the process 30 that accesses a file is generated, the CPU 10 causes the standard overwriting erasure supporting standard library (libc) 31 to issue the above file erasure request regardless of the OS type by the library function 32 related to the sequential overwriting erasure. For example, a sequential overwrite deletion file registration unit 33 is provided on the NVRAM 14, and the file for which the file deletion request has been made is registered in the sequential overwrite deletion file registration unit 33.
Next, when the overwrite erasure daemon 34 detects the registration of a file in the sequential overwrite erasure file registration unit 33, it sends an overwrite erasure instruction to the file system 35 and overwrites the file registered in the sequential overwrite erasure file registration unit 33. Execute the process with low priority.

The file system 35 performs overwrite erasure processing on the HDD 15 via the HDD driver 38 under the control of the overwrite erasure daemon 34, and then releases the erased file from the file system (actual erasure).
The file system 35 includes a virtual file system 36 and a buffer cache 37.
The virtual file system 36 is a virtual file system, and provides a unified interface to the processes so that an actual file system, for example, a plurality of file systems such as FFS, ext2, and XFS can be handled in the same manner.
Thereby, the process side can use different file systems in the same manner.
The buffer cache 37 is a cache area shared by each file system.

In the normal erasure process, the data to be overwritten on the file to be erased is temporarily cached in the buffer cache 37 and sent to the HDD driver 38 at regular time intervals. If the capacity of the data to be erased is large, the data is overwritten to the buffer cache 37. The number of write operations increases and cannot be erased efficiently.
Therefore, in the case of this overwrite erasure process, the overwrite erasure is immediately executed via the HDD driver 38.
Also, the user I / F (setting / control process) 39 starts normal execution of overwriting when a file erasing request is issued to the standard library 31 and the overwriting daemon 34 for overwriting erasure, An instruction is issued to stop the execution of the erasure process so as not to execute the overwrite erasure process.

That is, the HDD driver 38 functions as a writing unit that encrypts data and writes it in the storage unit. The HDD 15 corresponds to the storage means.
Further, the sequential overwrite erasure file registration unit 33 functions as a registration unit that registers data to be erased stored in the storage unit as a file.
Further, the overwriting erasure daemon 34 and the virtual file system 36 of the file system 35 overwrite the predetermined data in the area where the data corresponding to the registered file of the storage means is recorded in the writing means. It functions as an overwriting erasure means for erasing.
Further, the file system 35 functions as a release means for releasing the overwritten area of the storage device after the overwriting.

  Furthermore, the overwrite erasure daemon 34 and the virtual file system 36 of the file system 35, based on the file size of the registered file and the block size of the block in the file, make the file a block of the block size. The offset is less than the block size, and if there is no offset, the writing means sequentially performs the overwrite erasure from the back block of the file to the top block, and if there is the offset, It also serves as a means for causing the writing means to perform the overwriting erasure to the offset and then performing the overwriting erasure in order from the back block to the top block of the file.

The overwrite erasure daemon 34 and the virtual file system 36 of the file system 35 also serve as a means for causing the writing means to encrypt the predetermined data with an encryption key used for the encryption and overwrite the data.
Further, the overwrite erasure daemon 34 and the virtual file system 36 of the file system 35 also function as means for causing the writing means to perform the overwrite erasure a predetermined number of times.
The overwrite erasure daemon 34 and the virtual file system 36 of the file system 35 also serve as a means for causing the writing means to release the encryption and overwriting the predetermined data without encrypting it.

Next, the overwrite erasure process performed by the overwrite erasure daemon 34 will be described.
FIG. 3 is a diagram for explaining the procedure of the overwrite erasure process performed by the overwrite erasure daemon 34 shown in FIG.
In step (indicated by “S” in the figure), the overwrite erasure daemon 34 determines whether or not a file (having a file erase request) is registered in the sequential overwrite deletion directory of the sequential overwrite deletion file registration unit 33. If it has been registered, the process proceeds to step 2, and if it has not been registered, the process is terminated.

In step 2, sequential overwrite deletion file information lists for the number of files registered in the sequential overwrite deletion directory are created.
This sequential overwrite erasure file information list includes “file name”, “file size”, and “block size” of the file that has been requested to be erased. After the sequential overwrite erasure file information list is created, the sequential overwrite erasure file information list is sequentially selected one by one, and the processes in steps 3 to 5 are repeated for the number of created sequential overwrite erasure file information lists.
In step 3, it is determined whether or not the file size included in the selected sequential overwrite erasure file information list is 0. If it is 0, the process proceeds to step 6;

In step 4, an overwriting process for one file is executed using the selected sequential overwriting file information list, and the process proceeds to step 5.
In step 5, the association between the file information list for sequential overwriting and erasing is canceled (unlinked), and the process proceeds to step 6.
In step 6, it is determined whether or not the processing in steps 3 to 5 for the number of lists in the sequential overwrite erasure file information list has been completed. The process of No. 5 is executed, and when all the processes are completed, the process is terminated.

Next, the overwriting process for one file will be described.
FIG. 4 is a flowchart showing the overwriting process for one file shown in FIG. FIG. 5 is an explanatory diagram showing an example of overwrite erasure processing for an offset in a file.
In this overwrite erasure process for one file, a file to be erased in the HDD 15 is sought, and data is erased and released from the back side of the file.
As shown in FIG. 4, the overwrite erasure daemon 34 uses the file size and block size included in the selected sequential overwrite erasure file information list in step (indicated by “S” in the figure) 11 to obtain Then, the offset and the number of processing blocks are calculated from Equation 2 and the process proceeds to Step 12.

[Expression 1] Remainder value of offset = (file size / block size) [Expression 2] number of processing blocks = file size / block size The offset is a data size less than the block size.
In this process, when the file size is divisible by the block size, the offset is 0, and it can be seen that there is no offset in the file to be erased. On the other hand, when the file size is not divisible by the block size, it can be seen that the file to be erased has an offset.
In step 12, it is determined whether or not the offset is 0. If it is 0 (no offset block), the process proceeds to step 16, and if it is not 0 (offset block exists), the process proceeds to step 13.

That is, when there is an offset block in the file to be erased, first, the offset block is erased in steps 13 to 15, and then the entire block is erased for the remaining blocks.
If there is no offset block in the file to be erased, the entire block is erased for all blocks.
In step 13, overwriting processing is executed for the offset block, and the process proceeds to step 14.
In step 14, the file size is set to file size-offset, the file size to be processed is reduced by the offset, and the process proceeds to step 15.

In step 15, the area for the offset of the HDD 15 is released from the file system 35, and the process proceeds to step 16.
For example, as shown in FIG. 5A, with respect to a file to be erased before overwrite erasure processing, a block in which data is recorded in all the block sizes of processing blocks and an offset that is less than the block size As shown in FIG. 5B, seek is performed from the sector behind the file to be erased, and the offset is determined based on the file size and the number of processed blocks. The head sector of the block is found, and data overwrite erasure processing is executed from the head side of the block for each sector including the size of the offset from the head sector of the offset block based on the offset. After that, as shown in FIG. 5C, the offset block is released from the file system 35.

Returning to FIG. 4, in step 16, 1 is subtracted from the number of processing blocks to obtain a new number of processing blocks, and the process proceeds to step 17.
Thus, the file to be overwritten and erased has a file size that is a multiple of the block size and has no offset.
In step 17, it is determined whether or not the number of processing blocks is 0 or less. If it is 0 or less, there is no block to be overwritten.
On the other hand, if the number of processing blocks is not less than or equal to 0 in the determination of step 17, since there are remaining blocks to be overwritten, the process proceeds to step 18.
In step 18, the block is overwritten, and the process proceeds to step 19.
In step 19, the file size is set to file size-block size, the file size to be processed is reduced by one block size, and the process proceeds to step 20.

In step 20, the area of one block of the HDD 15 is released from the file system 35, and the process proceeds to step 21.
In step 21, 1 is subtracted from the number of processing blocks to obtain a new number of processing blocks, and the process returns to step 17.
In this way, the process of steps 18 to 20 is repeated for all remaining blocks to perform the overwriting process.
In this way, by overwriting and erasing sequentially from the block behind the file to be erased toward the beginning, and releasing from the file system 35, an area in which a file having a large file size including an image file is recorded Can be released little by little.
In other words, the multifunction device 1 can quickly create a free area in the HDD 15.
If the block is in units of physical sectors, the multi-function device 1 can perform overwriting and erasing in order in units of physical sectors from the back of the file and release it from the file system 35.

Next, the control process of the virtual file system 36 of the file system 35 in the overwriting process (steps 13 and 18) by the overwriting erasure daemon 34 will be described.
FIG. 6 is a flowchart showing a control process of the virtual file system 36 shown in FIG.
The virtual file system 36 determines in step (indicated by “S” in the figure) 31 whether the system call from the overwrite erasure daemon 34 is Io control (ioctl), and if it is icotl, proceeds to step 32. If it is not ioctl, the process proceeds to step 34.

If it is determined in step 32 that the command specified by ioctl is an overwrite instruction command, the HDD driver 38 is instructed to execute the overwrite process, and the process ends.
On the other hand, in step 34, other file processing corresponding to the designated command is performed, and this processing is terminated.
In the above processing, for example, in POSIX (Portable Operating System Interface (registered trademark)) generally compliant with a UNIX OS, write data must be specified as an argument of a write system call. In the example, since the write data is created on the HDD driver 38 side, an overwrite erase instruction command is sent as an ioctl system call to the file to be erased.

Next, the control process of the HDD driver 38 instructed to execute the overwrite erasure process by the virtual file system 36 (step 33) will be described.
FIG. 7 is a flowchart showing a control process in the overwrite erasure process by the HDD driver 38 shown in FIG.
First, when the overwrite deletion daemon 34 obtains the start sector of the file to be deleted from the virtual file system 36 based on the inode information, the overwrite deletion daemon 34 sends an overwrite deletion instruction of the file to be deleted to the virtual file system 36 based on the start sector. The file system 36 sends an instruction to overwrite the file to be erased based on the start sector to the HDD driver 38, and the HDD driver 38 sets the file to be erased on the basis of the start sector in hardware or in units of offset or sector. Overwrite is performed by DMA (Direct Memory Access) of the wearer.

When the HDD driver 38 receives the start sector of the file to be erased in step 41, it proceeds to step 42.
In step 42, it is determined whether or not the data to be overwritten on the file to be erased is encrypted and written. If encrypted and written, the process proceeds to step 43. If not encrypted, the process proceeds to step 48.
In this step, the overwriting method set in advance for the HDD driver 38 is confirmed. When encryption is used, the encryption key is used in the same manner as in the case of normal encryption and writing to the HDD 15. Based on this, predetermined data is encrypted to switch between a method of making the overwritten data a random value and a method of using the predetermined data for overwriting without using encryption.

In step 43, a plurality of encryption keys are stored in order to encrypt and write data to be overwritten on the file to be erased, and the process proceeds to step 44.
In step 44, one of the stored encryption keys is randomly set, predetermined data is encrypted based on the set encryption key, and the process proceeds to step 45.
In step 45, the data encrypted based on the encryption key is overwritten on the sector string, the data stored in the sector string is overwritten and erased, and the process proceeds to step 46.
In step 46, it is determined whether or not a predetermined number of overwrites have been completed.
In this determination, it is determined whether or not the number of times of overwriting with respect to the file to be erased set in advance for the HDD driver 38 has been completed. If not completed, the process returns to step 44. If completed, the process proceeds to step 47.

For example, if the file to be erased is set to be erased by being overwritten three times, the processing of steps 44 and 45 is repeated until the processing of steps 44 and 45 is completed three times. Overwrite the encrypted data with the encryption key set in.
In this way, random data can be written three times by writing arbitrary data to the entire sector string three times.
The number of overwriting can be set any number of times.
Therefore, by performing overwrite erasure using the encryption processing unit 21 that is encryption hardware, it is possible to increase the speed of overwrite erasure while reducing the load on the CPU 10.
In step 47, the stored encryption key is restored and the process is terminated.

On the other hand, when the predetermined data is written without being encrypted in step 48, if the predetermined data is, for example, “0”, “0 × FF”, and “0”, the encryption key is stored and the encryption process is performed. The encryption is canceled for the unit 21 (setting so that the encryption processing is not performed), and the process proceeds to step 49. The predetermined data may be other data of “0”, “0 × FF”, and “0”.
In step 49, 0 data is overwritten on the entire sector string, and the process proceeds to step 50.
In step 50, 0xFF data is overwritten on the entire sector column, and the process proceeds to step 51.
In step 51, 0 data is overwritten on the entire sector string, and the process proceeds to step 52.
In step 52, after the stored encryption key is restored, the setting is returned to the encryption processing unit 21 so that the encryption is performed again, and this process ends.

Thus, after the encryption is temporarily canceled at the time of writing to the HDD 15, the data “0”, “0 × FF”, and “0” are written to the entire sector column. Therefore, it can be guaranteed that 0 or FF is written.
According to the MFP 1 of this embodiment, as described above, it is possible to sequentially erase at a high speed while reducing the overhead when the file is overwritten and erased in units of blocks using the file system.

  The image processing apparatus, the data erasing method of the image processing apparatus, and the program according to the present invention can be applied to all image forming apparatuses including a copying machine, a printing apparatus, and a multifunction peripheral.

1: MFP 2: Controller 3: Engine 4: Operation display unit 5: USB I / F 6: Network 10: CPU 11: First ASIC 12: Memory 13: ROM 14: NVRAM 15: HDD 16: SD card 17: Second ASIC 20: HDDIP 21: Encryption processing unit 30: File access process 31: Standard library (libc) corresponding to sequential overwrite deletion 32: Library function related to sequential overwrite deletion 33: Sequential overwrite deletion file registration unit 34: Overwrite deletion daemon 35 : File system 36: Virtual file system 37: Buffer cache 38: HDD driver 39: User I / F (setting / control process)

JP 2009-152878 A

Claims (6)

Writing means for encrypting data and writing to the storage means;
Registration means for registering data to be erased stored in the storage means as a file;
An overwrite erasure unit for causing the writing unit to overwrite predetermined data on an area in which data corresponding to the registered file of the storage unit is recorded;
A release means for releasing the overwritten area of the storage means after the overwriting ,
The image processing apparatus according to claim 1, wherein the overwriting erasure unit includes a unit that causes the writing unit to encrypt the predetermined data with an encryption key used for the encryption and overwrite the data .   The overwrite erasing means checks whether there is an offset less than the block size in the file based on the file size of the registered file and the block size of the block in the file. The writing means is made to perform the overwriting in order from the block at the back side of the file to the head block, and if there is the offset, the writing means is made to perform the overwriting to the offset and then the back of the file The image processing apparatus according to claim 1, wherein the overwriting and erasing is performed in order from the block on the side to the head block. Said overwriting means, the image processing apparatus according to claim 1, wherein further comprising means for said overwriting to the write means is performed for a predetermined number of times.   The image processing apparatus according to claim 1, wherein the overwrite erasing unit includes a unit that causes the writing unit to cancel the encryption and overwrites the predetermined data without encrypting the data. A writing step of encrypting the data and writing it to the storage means ;
A registration step of registering the data to be erased stored in the storage means as a file ;
An overwrite erasure step of overwriting and erasing predetermined data in an area in which data corresponding to the registered file of the storage means is recorded by the writing step ;
A release step of releasing the overwritten area of the storage means after the overwriting ,
The data erasing method of an image processing apparatus, wherein the overwriting erasing step includes a step of overwriting and erasing the predetermined data with an encryption key used for the encryption in the writing step .   A program for causing a computer to realize functions as means of writing means, registration means, overwrite erasing means, and releasing means constituting the image processing apparatus according to claim 1.

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