JP5420161B2 - Obfuscation device and program - Google Patents

Description

  The present invention relates to an image forming apparatus such as a digital copying machine, a printer, and a scanner, an obfuscation apparatus used in the image forming apparatus, and a program.

  Image processing apparatuses become multifunctional year by year, and in addition to basic functions such as a print function, a copy function, and a FAX function provided by the image processing apparatus, various additional settings that improve convenience such as duplex printing are possible. . In order to enable such additional setting, a large-capacity storage means is required, that is, a hard disk drive (HDD) having a low cost per storage capacity is used. Since the specifications of the HDD are generalized and products of various manufacturers can be adopted, it is not configured as an integral part of the image processing apparatus, but is configured so as to be removable, thereby providing flexibility in manufacturing and maintenance. It is improving.

  On the other hand, although various image data are stored in the HDD, these image data often include important data that must be prevented from leaking to the outside. Therefore, it is necessary to prevent the image data from being easily read even when the HDD is removed and taken out, considering that the possibility of theft is high because it is configured to be removable.

Therefore, for example, Japanese Patent Laid-Open No. 2006-259988 discloses an encryption / decryption module between a DMA controller and an HDD interface, and an encryption / decryption module that receives SEED from a CPU and generates an encryption key based on SEED. A security-related technology including an M-sequence random number generation module to be applied to the above is disclosed. According to the technology, since the technology stored in the HDD is encrypted, the data cannot be easily decrypted even if the HDD is stolen.
JP 2006-259988 A

  By applying encryption technology to data written to the HDD, it is expected that information leakage from the HDD will be prevented very firmly. However, the higher the encryption strength, the larger the amount of computation, so that it takes time to write / read data to / from the HDD, resulting in an increase in the burden on the device.

  Further, since recent image forming apparatuses have multiple functions, image data read by the scanner unit is usually temporarily stored in the HDD in order to provide the functions. That is, writing / reading to / from the HDD is frequently performed. On the other hand, it is not realistic to provide all data for strong encryption / decryption.

  In addition, in order to shorten the time, a high-performance CPU, encryption chip, and HDD must be used, resulting in a problem that costs increase.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus and the like that can obfuscate data in an HDD without a burden and with a simple configuration. To do.

The present invention employs the following means in order to achieve the above object. That is, the obfuscation apparatus according to the present invention uses an LBA (Logical Block Addressing) system in which a plurality of sectors constituting the storage area of the hard disk are used as blocks, and the blocks are specified using block numbers that can uniquely specify the blocks. It is assumed that data is written to and read from the hard disk. Then, the start block number of the block to be written, the first transmission / reception means for receiving the number of blocks to be written and the data corresponding to the number of blocks, the predetermined number of blocks, and the number corresponding to the number of blocks Block order conversion information storage means for storing first block order conversion information in which values consecutive from a predetermined value n0 are arranged in a predetermined order, the received start block number, and the reception from the block order conversion information storage means Based on the first block order conversion information corresponding to the number of blocks, second block order conversion information is generated by exchanging two values of the first block order conversion information paired with the start block number. conversion information generating means for, the data thus received, and divided in order from the prescribed order n0 in the number of blocks that have been received with the data Based on the newly generated second block order conversion information, reference is made to the predetermined n2 value n1 of the second block order conversion information, and the divided data is divided into the predetermined n1 corresponding to the value n1 the by be positioned in a predetermined second n2 value n1 of the second block permutation information, performs a permutation means for permutation of the divided data blocks units, and conversion data after permutation, the write A second transmission / reception unit configured to transmit the start block number of the block and the number of blocks to be written to the hard disk, and store the converted data in the hard disk from the start block number;

At the time of reading from the HDD, the first transmission / reception unit receives the start block number of the block to be read and the number of blocks to be read, and the second transmission / reception unit receives the start block number of the block to be read and , based on the number of blocks to read to obtain data from the hard disk, the order conversion means, the data acquired from the hard disk and divided in order from the prescribed order n0 in blocks to perform the reading, the block permutation The first block order conversion information corresponding to the number of blocks to be read from the information storage means is referred to, and the predetermined n2 value n1 of the first block order conversion information is referenced to correspond to the predetermined n2 The divided data divided into the predetermined number n2 is the predetermined number n2 value n1 of the first block order conversion information. By is positioned, and configured to inverse transform in the reverse order to that at the time of writing in accordance with the divided data the first block permutation information.

Further, when using the second block order conversion information, the order conversion means, based on the newly generated second block order conversion information, the predetermined n2 value of the second block order conversion information. Referring to n1, the divided data divided into staple eyes n2 where corresponding to the office staple th n2 that is positioned n1-th value of the prescribed order n2 of the second block permutation information, data obtained from the hard disk It is set as the structure which performs inverse transformation of.

  Also provided are a program showing a procedure performed by each means of the obfuscation apparatus and an image forming apparatus provided with the obfuscation apparatus.

  The data order conversion means converts the order of the data obtained from the host controller in units of blocks based on the block order conversion information and writes the data in the HDD. As a result, the data written in the HDD is converted in order, that is, the data is in a damaged state, so that the content does not make sense by simply reading it, that is, it is obfuscated.

  Further, since the obfuscation process is simply switched in units of blocks, it can be configured with a simple circuit without cost, and there is almost no delay due to the obfuscation process.

  Furthermore, since the conventional procedure for writing / reading to / from the HDD is not changed by providing it between the host controller and the disk controller, it is not necessary to change the peripheral controller, CPU and other programs. Also, since the order of writing to the HDD does not change, random access does not occur during reading.

  Also, the conversion information generating means generates new block order conversion information B based on the start block number and the block order conversion information A, and performs order conversion based on this. Thereby, different block order conversion information can be generated every time based on the start block number, and the obfuscation strength can be increased. Further, since the start block number is a value that is always given in the LBA method, it can be realized without the need to add new processing (random number generation processing) or the like to peripheral controllers or CPUs.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention. In addition, the following embodiment is an example which actualized this invention, Comprising: It is not the thing of the character which limits the technical scope of this invention.

  The image forming apparatus according to the present invention will be described below.

  FIG. 1 is a schematic diagram of the image forming apparatus 100. However, details of each part not directly related to the present invention are omitted.

  The image forming apparatus 100 according to the present invention corresponds to, for example, a printer, a single scanner, or a multifunction machine including a printer, a copy, a scanner, and a fax machine.

  As an example, the operation of the image forming apparatus when copying a document using a multifunction machine will be briefly described.

  For example, when a user prints a document using the multifunction device, the document is placed on the document table 103 or the table 105 shown in FIG. 1, and a print instruction is given to the operation panel provided near the document table. Do. When the instruction is given, printing is performed by operating the following units (drive units).

  As shown in FIG. 1, an image forming apparatus 100 according to the present embodiment includes a main body 101 and a platen cover 102 attached above the main body 101. A document table 103 is provided on the upper surface of the main body 101, and the document table 103 is opened and closed by a platen cover 102. The platen cover 102 is provided with an automatic document feeder 104, a placing table 105, and a sheet discharging table 109.

  The automatic document feeder 104 includes a document conveyance path 108 formed inside the platen cover 102, a pickup roller 106 and a conveyance roller 107 provided inside the platen cover 102, and the like. The document conveyance path 108 is a document conveyance path that leads from the placement table 105 to the sheet discharge table 109 via a reading position P where reading is performed by the reading unit 110 provided in the main body 101.

  The automatic document feeder 104 pulls out each document placed on the placing table 105 to the inside of the transport path 108 by the pickup roller 106 and passes the document pulled out by the transport roller 107 and the like through the reading position P. The paper is discharged onto the paper base 109. When the document passes the reading position P, the document is read by the reading unit 110.

  The reading unit 110 is provided below the document table 103, and its details are shown in FIG. The reading unit 110 includes a first light source 111 that illuminates the document table 103 in the main scanning direction, a slit 116 that selectively passes light from the document table, and a mirror 112 that guides light from the document table. The movable carriage 117, the second movable carriage 118 including mirrors 113A and 113B that reflect the reflected light from the first movable carriage 117 again, and the lens group 119 that optically corrects the light guided by the mirror, An image sensor 115 that receives the light corrected by the lens group 119, and an image data generation unit 114 that converts the light received by the image sensor into an electrical signal and performs correction / correction as necessary. .

  When reading a document on the automatic document feeder 104, the light source 111 moves to a position where the reading position P can be irradiated and emits light. Light from the light source 111 is reflected by a document that passes through the document table 103 and passes through the reading position P, and is guided to the image sensor 115 by the slit 116, mirrors 112, 113A, and 113B, and the lens group 119. The image sensor 115 converts the received light into an electrical signal and transmits it to the image data generation unit 114. The light received by the image sensor 115 is input to the image data generator 114 as analog electrical signals of R (red), G (green), and B (blue), where analog-to-digital conversion is performed. Digitized. Further, the image data generation unit 114 uses the sequentially converted digital signal as unit data, and corrects and corrects the unit data as necessary to generate image data including a plurality of unit data. Store in the storage unit 114B.

  The reading unit 110 can read not only the document conveyed by the automatic document feeder 104 but also the document placed on the document table 103. When reading a document placed on the document table 103, the first carriage 112 moves in the sub-scanning direction while emitting light from the light source 111, so that the optical path length from the light source 111 to the image sensor 115 is constant. The second moving carriage 118 moves in the direction of the image sensor 115 at a half speed of the first moving carriage 117.

  The image sensor 115 electrically outputs light from the document placed on the document table 103 based on the light guided to the mirrors 112, 113 </ b> A, 113 </ b> B, as in the case of the document conveyed to the automatic document feeder 104. The signal is converted into a signal, and based on this, the image data generation unit 114 generates image data and stores it in the first storage unit 114B. In addition, each part which comprises the said reading part 110 operate | moves as a reading means 401 mentioned later by performing a series of processes.

  A printing unit 120 that prints image data is provided below the reading unit 110 of the main body 101. The image data that can be printed by the printing unit 120 is generated by the image data generation unit 114 as described above, or from other terminals such as a personal computer connected to the image forming apparatus 100 and a network such as a LAN. For example, and stored in the first storage unit 114B.

  As a printing method performed by the printing unit 120, an electrophotographic method is used. That is, the photosensitive drum 121 is uniformly charged by the charger 122, and then the photosensitive drum 121 is irradiated by the laser 123 to form a latent image on the photosensitive drum 121, and toner is attached to the latent image by the developing device 124. In this method, a visual image is formed and the visible image is transferred onto a sheet by a transfer roller.

  Note that in the image forming apparatus corresponding to the full-color image, the developing device (rotary developing device) 124 is rotated in the circumferential direction around a rotation axis configured in a direction perpendicular to the paper surface of FIG. A developing unit in which color toner is stored is disposed at a position facing the photosensitive drum 121. In this state, the latent image on the photosensitive drum 121 is developed with toner stored in the developing device 124 and transferred to the intermediate transfer belt 125A. The developing device 124 includes four developing units 124 (Y), (C), (M), and yellow (Y), cyan (C), magenta (M), and black (K). (K). By repeating the transfer to the intermediate transfer belt 125A for each color, a full color image is formed on the intermediate transfer belt 125A.

  The print medium on which the visible image is printed, that is, the paper, is placed on a paper feed tray such as the manual feed tray 131 and the paper feed cassettes 132, 133, and 134.

  When the printing unit 120 performs printing, one sheet of paper is pulled out from any one of the paper feed trays by using the pickup roller 135, and the pulled-out paper is transported by the transport roller 137 (if the manual tray 131 is used) Roller 136) or registration roller 138 feeds between intermediate transfer belt 125A and transfer roller 125B.

  When the visible image on the intermediate transfer belt 125 is transferred onto the sheet fed between the intermediate transfer belt 125 and the transfer roller 125, the printing unit 120 uses the conveying belt 126 to fix the visible image. Send paper to 127. The fixing device 127 includes a heating roller 128 with a built-in heater and a pressure roller 129 pressed against the heating roller 128 with a predetermined pressure. When the sheet passes between the heating roller 128 and the pressure roller 129, the visible image is fixed to the sheet by heat and the pressing force to the sheet. The printing unit 120 discharges the sheet that has passed through the fixing device 127 to the discharge tray 130.

  The basic copy service processing in the image forming apparatus 100 has been described above.

In the image forming apparatus 100, as shown in the schematic configuration diagram of FIG. 3, a CPU (Central Processing Unit) 301, a RAM (Random Access Memory) 302, a ROM (Read Only Memory) 303, an obfuscation apparatus 310, an HDD (Hard Disk Drive) 304 and a driver 305 corresponding to each drive unit in the printing process are connected via an internal bus 306. The CPU 301 uses, for example, the RAM 302 as a work area, executes a program stored in the ROM 303, the HDD 304, and the like, and exchanges data and commands with the driver 305 based on the execution result, thereby performing the above-described FIG. 2 controls the operation of each driving unit 307 shown in FIG. The obfuscation apparatus 310 may be incorporated in a host controller (DMA (Direct Memory Access) controller).
<First embodiment>
Next, details of the conversion process of the obfuscation apparatus 310 according to the first embodiment of the present invention will be described with reference to FIGS.

  As illustrated in FIG. 4, the obfuscation apparatus 310 is connected to a host controller 314 included in the image forming apparatus 100 and a disk controller 406 included in the HDD 304. The host controller 314 can be a DMA controller, for example.

  When the image forming apparatus 100 writes data to the HDD 304 in such a connected state, the CPU 301 transmits the start block number, the number of blocks, and the block to the first transmission / reception unit 401 of the obfuscation apparatus 310 via the host controller 310. Data is given. Here, the block means a block in the LBA (Logical Block Addressing) system, and indicates one sector when the storage area constituting the disk 407 of the HDD 304 is divided into a plurality of sectors. An address that can uniquely designate each block is a block number. The data is obtained by the host controller and the roller 314 acquiring the data stored in the memory (RAM 302) of FIG. 6A.

  That is, when writing data, the first transmission / reception means 401 obtains the start block number of the block to be written, the number of blocks to be written, that is, the number of blocks, and the data corresponding to the number of blocks. Receive (FIG. 5: S501).

  Here, it is assumed that “0” is given as the start block number and “8” is given as the number of blocks.

  When the first transmission / reception means 401 receives the start block number, the number of blocks, and the data, the data order conversion means 402 refers to the block order conversion information from the block order conversion information storage means 403 (FIG. 5: S502).

  Here, it is assumed that the block order conversion information stores a value of “0x54023176” as the block order conversion information A.

  Next, the data order conversion unit 401 divides the received data into a size corresponding to each block (sector) (FIG. 5: S503). The processed data is divided into 0 sector data “0x000000...” To 7 sector data “0x777777...” As shown in the memory of FIG. For the sake of understanding, the data contents are indicated by sector numbers.

  However, when the host controller 314 transmits several blocks (eight) of data in units of blocks, the division process is not necessarily required.

  Subsequently, the divided data is rearranged in order according to the block order conversion information, with one block as the divided size as a unit (FIG. 5: S504).

  Specifically, the data order conversion unit 402 refers to the 0th value “5” of the block order conversion information A “0x54023176”, and positions the fifth sector data at the top (0th) of the data in the SRAM 405. . Further, referring to the first value “4”, the data of the fourth sector is positioned at the first of the data in the SRAM 405. By performing such processing on the data of the 0 sector to the 7 sector, the order conversion is performed in the order of 5, 4, 0, 2, 3, 1, 7, 6 as shown in the center of FIG. 6A.

  When the order conversion process is completed, the data after the order conversion stored in the SRAM 405, the start block number “0”, and the number of blocks “8” are transmitted to the disk controller 406 of the HDD 304 via the second transmission / reception means 404. (FIG. 5: S505).

  The disk controller 406 that has received the data stores the data after the order conversion in eight blocks (block numbers 0 to 7) starting with block number 0. As a result, as shown in the HDD of FIG. 6, block 0 stores data of 5 sectors, block 1 stores data of 4 sectors,..., Block 7 stores data of 6 sectors.

  Next, processing when data is read from the HDD will be described.

  When reading the stored data, the first transmission / reception means 401 receives the start block number and the number of blocks from the host controller 314. At this time, the data whose order is actually changed is read out, but the host controller only needs to transmit the same command as that when the order is not changed. That is, the host controller 314 transmits the start block number “0” and the block number “8”.

  When the start block number “0” and the number of blocks “8” are received, the fact is notified to the disk controller 406 and the data stored in the blocks 0 to 7 is read. The data contents are in the order of sectors 5, 4, 0, 2, 3, 1, 7, and 6, which are data after the order conversion, as shown at the left end of FIG. 6B.

  Subsequently, the data order conversion unit 402 that has received the data after the order conversion similarly reads the block order conversion information A from the block order conversion information storage unit 403 and performs a process reverse to the order conversion (inverse conversion process). . Specifically, the data order conversion unit 402 refers to the 0th value “5” of the block order conversion information A “0x54023176”, and positions the data of the block 0 at the fifth of the data in the SRAM 405. Further, referring to the first value “4”, the data of the block 1 is positioned at the fourth of the data in the SRAM 405. By performing such processing on the data of blocks 0 to 7, the order conversion is performed in the order of 0, 1, 2, 3, 4, 5, 6, and 7 as shown in the center of FIG. 6B. The converted data is transmitted to the host controller 314 via the first transmission / reception means 401.

  As described above, the data order conversion means converts the order of the data obtained from the host controller in units of blocks based on the block order conversion information, and writes it to the HDD. As a result, the data written in the HDD is converted in order, that is, the data is in a damaged state, so that the content does not make sense by simply reading it, that is, it is obfuscated.

  Further, since the obfuscation process is simply switched in units of blocks, it can be configured with a simple circuit without cost, and there is almost no delay due to the obfuscation process.

  Furthermore, since the conventional procedure for writing / reading to / from the HDD is not changed by providing it between the host controller and the disk controller, it is not necessary to change the peripheral controller, CPU and other programs. Also, since the order of writing to the HDD does not change, random access does not occur during reading.

The same effect can be obtained if the obfuscation device 310 is provided as a driver program that mediates when an instruction is transmitted from the application software to the OS (operation system) or a host controller driver program that mediates between the OS and the host controller. Can be obtained. In this case, the application software may transmit the start block number, the number of blocks, and data to the driver program, and the driver program may execute the conversion process using the RAM 302 instead of the SRAM 405.
<Second Embodiment>
Next, details of the conversion process of the obfuscation apparatus 310 according to the second embodiment of the present invention will be described.

  In the present embodiment, the obfuscation apparatus 310 further includes conversion information generation means 408, and generates second block order conversion information based on the received start block number and the first block order conversion information. This is different from the first embodiment.

  First, when data is written, the first transmission / reception means 401 receives the start block number of the block to be written, the number of blocks to be written, and the data corresponding to the number of blocks. The number is transmitted to the conversion information generation means 408.

  Subsequently, the conversion information generation unit 408 refers to the block order conversion information from the block order conversion information storage unit 403, and as the block order conversion information A, for example, the same value as in the first embodiment, that is, “0x54023176”. obtain.

  Next, the conversion information generation means 408 newly generates block order conversion information B corresponding to the start block number based on the block order conversion information A and the start block number.

  The procedure for generating the block order conversion information B will be specifically described with reference to FIG.

  First, it is assumed that the start block number 701 is obtained as “0x0000003CAA2C” in hexadecimal notation. The conversion information generation means 408 extracts the lower 3 bytes 702 “0x3CAA2C” from the obtained start block number 701. The lower 3 bytes are represented as “001111001010101000101100” in binary notation 703. Further, the binary number notation 703 is decomposed every 6 bits 704 and further decomposed by 3 bits 705. When the values separated by 3 bits are expressed in decimal notation 706 in order from the top, they are 1, 7, 1, 2, 5, 0, 5, 4. If this value is paired by two from the top, “1, 7”, “1, 2”, “5, 0”, “5, 4” are obtained.

  Subsequently, the conversion information generation unit 408 calculates the first (4) and the seventh (6) of the block order conversion information A “0x54023176” based on the upper first pair (“1, 7”). Replace. Thereby, the block order conversion information “0x56023174” after the first conversion is obtained. Next, when replacement is performed based on the block order conversion information “0x56023174” after the first conversion and the upper second pair (“1, 2”), the block order conversion information “0x50623174” after the second conversion is obtained. can get. By repeating this up to the fourth (last) pair, block order conversion information B711 (“0x10625374”) is obtained.

  The obtained block order conversion information B is transferred to the data order conversion means 402, and the data order conversion means 402 performs the order conversion processing shown in the first embodiment based on the block order conversion information B. Do it.

  Also, when reading from the HDD 304, new block order conversion information B is generated based on the start block number obtained from the host controller 314 and the block order conversion information A. When the written data is referred to, the same start block number as that at the time of writing is always given, so that the same block order conversion information B can be generated (restored). After that, normal data can be obtained by performing the inverse conversion process shown in the first embodiment using the block order conversion information B.

  As described above, in the second embodiment, the conversion information generating unit generates new block order conversion information B based on the start block number and the block order conversion information A, and based on this, the order conversion is performed. To do. Thereby, different block order conversion information can be generated every time based on the start block number, and the obfuscation strength can be increased. Further, since the start block number is a value that is always given in the LBA method, it can be realized without the need to add new processing (random number generation processing) or the like to peripheral controllers or CPUs.

  In the above-described two embodiments, the number of blocks is described as “8”. However, the number of blocks is not limited to “8”. For example, the block order conversion information corresponding to each block number is stored one by one so that any number of blocks can be handled. As a result, plural types of block order conversion information are stored in the block order conversion information storage means, and the data order conversion means The conversion table generation unit may selectively acquire corresponding block order conversion information from a plurality of types of block order conversion information according to the number of received blocks.

  The obfuscation apparatus according to the present invention is useful as an obfuscation apparatus that realizes obfuscation of data in the HDD without a burden and with a simple configuration.

1 is a schematic diagram of an image forming apparatus according to the present invention. The enlarged view of a reading part. 1 is a schematic configuration diagram of an image forming apparatus according to the present invention. 1 is a schematic functional block diagram of an obfuscation apparatus according to the present invention. The flowchart which shows the process sequence which concerns on this invention. The figure which shows the transition by the order conversion process of data. The figure which shows the production | generation procedure of block order conversion information.

Explanation of symbols

310 obfuscation device 314 host controller 401 first transmission / reception means 402 data order conversion means 403 block order conversion information storage means 404 second transmission / reception means 405 SRAM
406 disk controller 407 disk 408 conversion information generating means

Claims (4)

A hard-to-read read / write to / from the hard disk using the LBA (Logical Block Addressing) method that specifies a block using a block number that can uniquely specify the block as a plurality of sectors constituting the storage area of the hard disk Device.
A first transmission / reception means for receiving a start block number of a block to be written, the number of blocks to be written, and data corresponding to the number of blocks;
A block order conversion information storage unit for storing first block order conversion information in which a predetermined number of blocks and a number corresponding to the number of blocks are arranged in a predetermined order from values that are consecutive from the predetermined value n0;
Based on the received start block number and the first block order conversion information corresponding to the number of blocks received from the block order conversion information storage means, the first block order paired with the start block number Conversion information generating means for generating second block order conversion information by exchanging two values of conversion information;
The received data is sequentially divided from the predetermined number n0 by the number of received data and the number of received blocks, and based on the newly generated second block order conversion information, the second block order conversion information is predetermined. By referring to the value n1 of the n2nd and dividing the divided data divided into the predetermined n1 corresponding to the value n1 at the predetermined n2 of the value n1 of the second block order conversion information, each divided data is and permutation means for permutation in block units,
Second transmission / reception means for transmitting the converted data after the order conversion, the start block number of the block to be written, and the number of blocks to be written to the hard disk, and storing the converted data in the hard disk from the start block number When,
An obfuscation device comprising: The order conversion means refers to a predetermined n2 value n1 of the second block order conversion information based on the newly generated second block order conversion information, and a predetermined number corresponding to the predetermined n2 The obfuscation apparatus according to claim 1, wherein the data obtained from the hard disk is inversely converted by positioning the divided data divided into n2 at a predetermined n2 value n1 of the second block order conversion information . An image forming apparatus comprising the obfuscation device according to claim 1 . A program for writing / reading data to / from a hard disk using an LBA (Logical Block Addressing) system in which a plurality of sectors constituting the storage area of the hard disk are used as a block and the block is specified using a block number that can be uniquely specified. Because
A reception step of receiving a start block number of a block to be written, the number of blocks to be written, and data corresponding to the number of blocks;
A division step of dividing the received data in order from a predetermined number n0 by the number of received blocks and the data;
The block received from the block order conversion information storage means for storing the first block order conversion information in which a predetermined number of blocks and a value corresponding to the number of blocks are consecutive from the predetermined value n0 are arranged in a predetermined order. A second block in which two values of the first block order conversion information paired with the start block number are exchanged based on the first block order conversion information corresponding to the number and the received start block number A conversion information generation step for generating order conversion information;
Based on the newly generated second block order conversion information, reference is made to the predetermined n2 value n1 of the second block order conversion information, and the divided data is divided into the predetermined n1 corresponding to the value n1 a data order conversion step of permutation at that is positioned in a predetermined second n2 value n1 of the second block permutation information, block units each divided data,
Transmitting the converted data after the order conversion, the start block number of the block to be written, and the number of blocks to be written to the hard disk, and storing the converted data from the start block number in the hard disk;
A program that causes a computer to execute.

Images