JP2004199229A - Method for disabling decryption of data stored in storage device and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively and quickly disable the decryption of privacy data or the like, not depending on the physical destruction of an HDD or the like, and to surely prevent the original data from being specified and decoded. <P>SOLUTION: This computer program for disabling the decryption of data stored in a storage device comprises a data area selecting process for selecting one or more data area for executing processing to disable the decryption of data, a reading process for reading one or more storage areas by the minimum access units being the target of decryption disabling processing from the selected data area, a dividing process for dividing one or more read storage areas into a plurality of logical blocks, an encryption process for encrypting the data included in the plurality of divided logical blocks and a storage area rewriting process for rewriting the encrypted storage area to the read position. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
[Industrial applications]
The present invention relates to a method and a computer program for making data recorded in a storage device such as a hard disk of a computer unreadable when discarding a computer or various recording media.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, when a company or the like discards an unnecessary computer (hereinafter, referred to as “PC”), a hard disk drive (hereinafter, referred to as an “HDD”) is provided with an HDD. Is physically destroyed so that it cannot be read. Further, since such physical destruction requires time and cost, it is impossible to decipher the data of the HDD or the like by a logical method using a computer program as described in Patent Documents 1 and 2 below. It has also been suggested to do so.
[0003]
[Patent Document 1]
JP-A-5-53891.
[0004]
[Patent Document 2]
JP-A-2001-92719.
[0005]
These patent documents disclose techniques for completely writing meaningless data such as a series of numbers or blanks in a file or storage area storing confidential data so that a third party cannot read the confidential data. Have been.
[0006]
[Problems to be solved by the invention]
However, the above-described logical data destruction method merely overwrites the original data with another data, so if the overwritten data can be identified by any method, the original data can be used to restore the original data. It is possible to recover the data. Therefore, this may result in decryption of the confidential data.
[0007]
For this reason, the fact is that a method of physically destroying an HDD or the like that can surely prevent data decoding even if it takes time and cost is still employed.
[0008]
The present invention has been made in view of such a problem, and makes it impossible to quickly and at low cost decode stored data without physical destruction of an HDD or the like, and to identify original data. It is an object of the present invention to provide a method and a computer program capable of reliably preventing decryption.
[0009]
[Means for Solving the Problems]
According to a first main aspect of the present invention, there is provided a method for rendering data stored in a data rewritable storage device unreadable, wherein the method comprises the steps of: A data area selecting step of selecting an area; a reading step of reading, from the selected data area, one or more storage areas of a minimum access unit to be deciphered; A dividing step of dividing the logical blocks into blocks, an encrypting step of respectively encrypting data included in the plurality of divided logical blocks, and a storage area writeback step of writing the encrypted storage area back to the read position. A method is provided.
[0010]
According to such a configuration, data recorded on the recording medium can be logically rendered unreadable. As a method for this, a process is adopted in which the data area is divided into minimum units, and each of the divided areas is encrypted by an arbitrary different algorithm. The selection of such an area and the selection of an encryption algorithm are performed extremely irregularly using random numbers or the like, so that each area and algorithm is specified later, and the data is decrypted into the original data and the original position is determined. The task of returning is virtually impossible. This makes it virtually impossible for not only third parties but also operators, managers and programmers who have executed the deciphering process to the PC to decipher the encrypted data, and Plagiarism and leakage can be effectively prevented.
[0011]
Further, this makes it possible to completely prevent the original data from being read even by a logical method that does not physically destroy the HDD or the like, so that the deciphering process of the confidential data can be quickly executed at low cost.
[0012]
According to a second main aspect of the present invention, there is provided a computer program for causing a computer system to perform a process of making data stored in a data rewritable storage device unreadable. A data area selecting function for selecting one or more data areas for performing a process for disabling decryption, and a storage area for reading, from the selected data area, at least one storage area of a minimum access unit to be decrypted A read function, a storage area division function of dividing one or more read storage areas into a plurality of logical blocks, a data encryption function of respectively encrypting data included in the plurality of divided logical blocks, A computer program provided with a write-back function of writing data of a logical block back to the position of the read storage area It is.
[0013]
According to such a configuration, it is possible to obtain a computer program capable of suitably executing the method according to the first main aspect using a computer system.
[0014]
According to a third main aspect of the present invention, there is provided a system for disabling data stored in a data rewritable storage device, wherein one or more processes for disabling data decryption are performed. Data area selecting means for selecting one of the data areas, storage area reading means for reading, from the selected data area, one or more storage areas of a minimum access unit to be deciphered, and one or more read storage areas A plurality of logical blocks, a data encryption unit for encrypting data included in each of the plurality of divided logical blocks, and an encrypted storage area at a position of the read data area. A storage area rewriting means for rewriting.
[0015]
According to such a configuration, it is possible to obtain a system that can suitably execute the method according to the first main aspect described above.
[0016]
The other features and remarkable effects of the present invention will be more clearly understood by referring to the following description of embodiments of the invention and the accompanying drawings.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following, a process of encrypting data recorded in the HDD and making it unreadable will be described by taking a HDD built in the PC as an example of the storage device.
[0018]
(Overall processing steps)
FIG. 1 is a flowchart showing the overall process of the data deciphering process according to an embodiment of the present invention, and a schematic diagram of the process in each process.
[0019]
First, an HDD built in a computer is selected as a target of data deciphering processing, and an arbitrary storage area is selected from the HDD (step S1). In the following description, the target area of the decryption disable processing is displayed as “OA”, and the selected storage area is displayed as “MA”. Next, one or more sectors (data) included in the selected MA are read (step S2). A division algorithm is applied to the four read sectors to divide them into logical blocks of an arbitrary size (step S3). Next, an encryption algorithm is applied to the divided logical blocks to encrypt data included in the blocks (step S4). The dividing step and the encrypting step are repeated until all the data included in the four sectors read in step S2 are encrypted. In this embodiment, four read sectors are divided into three logical blocks having different sizes and encrypted. When all the data has been encrypted, the sector is written back to the original position of the HDD read in step S2 (step S5). By repeatedly performing such decryption disable processing (steps S1 to S5) for all OA, decryption of data recorded on the HDD can be disabled. In this embodiment, a plurality of (four in the illustrated example) data that are physically continuous can be read out, so that data selection and readout processing can be performed quickly. In the following description, the above-described series of steps for encrypting data in the HDD to make it indecryptable is referred to as “data indecryption”, and the data is encrypted by applying a predetermined encryption algorithm. The specific process (step S4) will be referred to as “encryption”.
[0020]
(Explanation of terms)
Here, the meaning of the terms used in the description of the present embodiment will be briefly described. FIG. 2 schematically shows the relationship between the terms.
Minimum access unit: A minimum data area for hardware to access a storage medium (HDD, FD, memory card, etc.) for performing decryption disabling processing. The actual size of the minimum access unit differs depending on the type of the storage medium, the manufacturer of the hardware, and the like. If the storage medium is an HDD, the minimum access unit is a sector, and its size is 4 bytes in the present embodiment as described later. The number of minimum access units selected in the selection step (step S1 in FIG. 1) is the actual encryption number. The number of minimum access units read in one reading process (step S2 in FIG. 1) is the minimum number of encryption.
Minimum encryption unit: It means the minimum data amount required for performing the decryption decompression process. The actual size of the minimum encryption unit differs depending on the encryption logic and the like. Access count: means the data amount of OA divided by the minimum access unit (fraction is rounded up). When the OA data amount is large and the minimum access unit is small, this access count becomes a large numerical value, which is not preferable in terms of speeding up processing and the like. Therefore, in the present embodiment, up to a preset maximum count can be handled as one area.
Division area: means a data area included in each logical block when the MA is divided into a plurality of logical blocks in the division step (Step S3 in FIG. 1). The size of the divided area is set to be equal to or larger than the minimum encryption unit.
[0021]
(Schematic configuration of hardware and program)
FIG. 3 shows a schematic configuration of PC hardware and a program for executing the processing described in FIG.
Reference numeral 1 denotes a general-purpose PC. A RAM 2, a ROM 5, an HDD (storage device) 6 and an input / output interface (I / F) 7 are connected to a CPU 2 built in the PC 1 via a bus 3. I have. An output unit 8 such as a CRT display, an input unit 9 such as a keyboard and a mouse, a communication unit 10 such as a modem, and a drive 12 for a removable recording medium 11 such as an FD and a CD-ROM are connected to the input / output I / F 7, respectively. Have been. When the user operates the input unit 9 to input a command, the CPU 2 calls a predetermined program stored in the ROM 5 or the HDD 6 onto the RAM 4 and executes processing according to the program. .
[0022]
The computer program 13 that causes the PC 1 to execute the deciphering process is introduced into the PC 1 to be processed through the recording medium 11 such as an FD or a CD-ROM, and cooperates with the hardware or the operation system (OS) of the PC 1. By demonstrating the following functions, the deciphering disable processing is executed. The deciphering process can be performed on another storage device (storage medium) by a computer program stored in the ROM 5 or the HDD 6. In this case, the PC 1 constitutes a decryption disable processing device.
[0023]
The deciphering processing program 13 includes a selection processing unit 15 for selecting the HDD (OA) 6 or the storage area (MA) of the PC 1 to be deciphered, and one or more sectors (data) included in the MA. A read processing unit 16, a division processing unit 17 that applies a division algorithm to the read sectors to divide the logical blocks into logical blocks of an arbitrary size, and an encryption program is applied to the divided logical blocks to apply them to each block. It causes the PC 1 to execute an encryption processing unit 18 for encrypting the included data and a write-back processing unit 19 for writing the data (sector) back to the original position of the HDD 6 from which the data was read.
[0024]
Here, the division processing unit 17 and the encryption processing unit 18 generate a random number for division or encryption using the time (system time) by a clock function built in the PC 1 and based on these random numbers. Each time the processing is executed, a different algorithm is generated. This system time corresponds to the “key information” in claims 7 and 8. The algorithm types include MD5 (Message Digest 5), SHA (Secure Hash Algorithm), DES (Data Encryption Standard), Triple DES, DESX (DES eXtension), IDEA (International Data Encryption Algorithm), RC2, Conventionally known various components such as RC4, RC5, FEAL, skipjack, RSA, etc. can be employed as they are or appropriately applied.
[0025]
The decryption disable processing program 13 can be introduced into an external HDD connected to the PC 1 to be processed or an external storage device that can start the OS. After the introduction of this program, the PC 1 can be restarted to execute the decryption disable processing. When introducing this program, the operation authority can be restricted by using operator authentication using an external security system such as a password or an IC card.
[0026]
(Description of each process)
Next, specific processing in each step shown in FIG. 1 will be described with reference to FIGS. These processes are executed by sequentially calling the function units 15 to 19 of the program 13 on the RAM 4 by the CPU 2 via the drive 12.
[0027]
(Selection process)
First, the processing of the selection step (step S1 in FIG. 1) executed by the selection processing unit 15 will be described with reference to FIGS. In this step, first, an access count is calculated by dividing the size of the decryption disable processing target data (OA) by the minimum access unit (rounded up) (step S101). For example, as shown in FIG. 5, when the size of the OA is 100 bytes and the minimum access unit is 4 bytes, the access count is 100/4 = 25.
[0028]
Next, a random number A is generated based on the system time (time information) of the PC 1 (step S102). This random number A is the actual encryption number, and is set in a range from the “minimum encryption unit” to the “access count”. For example, when the minimum encryption unit is set to 15, the access count is 25, and therefore the random number A, that is, the generation range of the actual encryption number is 15 ≦ A ≦ 25.
[0029]
For the generated random number A, a cumulative value is calculated each time the selection process is performed (step S103). When the total value of the random number A is equal to or smaller than the access count (YES in step S104), the generated random number A is determined as it is as the n-th actual encryption number (step S105). On the other hand, if the cumulative value of the random number A exceeds the access count (NO in step S104), the n-th (last) random number A (actual encryption number) is adjusted so that the cumulative value becomes equal to the access count. For example, when the access count is 25, if the actual encryption number in the first selection step is 17, and the actual encryption number in the second selection step is 12, the total number becomes 29, which exceeds the access count. Therefore, the value (8) obtained by subtracting the total value (17) of the random number A from the access count (25) to the previous time is determined as the second actual encrypted number (step S106). As a result of adjusting the actual number of encryptions in this manner, the size of the final data in the selection step may be smaller than the minimum access unit (4 bytes).
[0030]
(Reading process)
Next, a reading step (step S2 in FIG. 1) executed by the reading processing unit 16 will be described with reference to FIGS. First, when the reading process is performed first (YES in step S201), the head position of the selected storage area (MA) is specified as the reading start position (step S202). In the second and subsequent reading processes (NO in step 201), as shown in FIG. 7, the position next to the previous (n-1) reading end position is specified as the reading start position (step 203). . The specified read start position is recorded in the RAM 4 or the like in association with the number of processes n (step S204). Next, the processing target area MA obtained by multiplying the actual encryption number (random number A: 15 to 25) determined in the selection step by the minimum access unit is read from the specified read start position (step S205). ). In this embodiment, the time required for reading is shortened by reading a plurality of physically continuous sectors.
[0031]
(Division process and encryption process)
Next, with reference to FIGS. 8 and 9, a description will be given of the processing of the division step performed by the division processing unit 17 and the encryption step (steps S3 and S4 of FIG. 1) performed by the encryption processing unit 18.
First, in the division process (steps S301 to S307), a random number B for division is generated based on the system time of the PC 1 (step S301). The random number B is set in the range of the processing target area (MA) read in the reading step with the minimum encryption number (unit) or more. In the case of the first division process (“c _n : N = 1 ”(YES in step S302), the size of the generated random number B is set as a divided area as it is (step S303). In the second and subsequent division processes, (“c _n : N ≠ 1 ”NO in step S302), the total value of the random number B is calculated (step S304), and then the difference (R) between this total value and the size of the processing target area (MA) is calculated (step S304). S305). If the calculated difference (R) is larger than the minimum encryption unit, that is, if the cumulative value is equal to or smaller than MA (NO in step S306), the size of the generated random number B is reduced as in the first division. c _n The size is set as the size of the first divided area (step S303). On the other hand, if the calculated difference (R) is less than the minimum encryption unit, that is, if the cumulative value exceeds the size of the MA (YES in step S306), the size up to the final data of the MA is c. _n The size is set as the size of the first divided area (step S307). The above c _n Means the number of times in the processing routine of the division / encryption process, and is distinguished from the number of times n of the deciphering disabling process shown in FIGS.
[0032]
A specific setting method of the divided area will be described below.
When the MA size is 100 bytes and the minimum encryption unit is 8 bytes
When the first random number B is generated at 40, 40 is directly set as the first divided area size (steps S302 and S303).
When the second random number B is generated at 42, the sum of the random number B is 82 and the difference from the MA size is 18, so 42 is set as it is as the second divided area size (steps S302, S304 to S304). S306, S303).
When the third random number B is generated at 11, the total of the random number B is 93, and the difference from the MA size is 7. In this case, since the third difference 7 is less than the minimum encryption unit (8 bytes), the third divided area is set to 18 bytes which is the total difference up to the second time (steps S302, S304 to S307). ). If the third random number B is 50, the total of the random numbers B is 132, and the difference is -32 (less than 8 bytes). Therefore, in this case as well, the third divided area is set to 18 bytes, which is the difference of the total up to the second divided area.
[0033]
According to the divided area size set as described above, the MA is divided into three blocks having different sizes as shown in FIG. In this embodiment, by generating a random number B larger than the size of a sector at least once or more, a boundary between a plurality of sectors read by at least one or more logical blocks ((1) and (2) in FIG. 9) is read. I straddle it. As a result, the risk of data being decrypted is extremely low as compared with the case where encryption is performed on a sector-by-sector basis, and data leakage can be more effectively prevented.
[0034]
Next, in the encryption step, a random number C for encryption is generated based on the system time of the PC 1, and encryption processing is performed on the divided area set in the division step (step S401). In this case, the range is not set for the random number C like the random numbers A and B described above.
The above-described division / encryption process is repeatedly executed until the process is completed for all the areas of the MA selected in the selection process (NO in step S402). At this time, the number of processing c _n Are added one by one (step S403). In this embodiment, as shown in FIG. 9, the MA is divided into three areas (1) to (3) having different sizes, and each area is encrypted by an algorithm based on a different random number C.
As described above, since the random number B and the random number C are generated each time the process is performed, not only a third party but also an operator or the like operating the PC 1 cannot learn the division and encryption patterns. Even if the encryption pattern (random number C or the like) of one divided area can be analyzed and decrypted, the other divided areas are encrypted with different encryption keys. Must be compounded. It is practically impossible to perform such a work for all the divided areas, and the size (data capacity, unit) of the divided areas is also irregular. It is also difficult to specify a region to be applied. Therefore, by repeating the above-described division step and encryption step, the MA can be irreversibly encrypted, and the decryption of data can be made impossible.
[0035]
(Write-back process)
Next, a write-back step (step S5 in FIG. 1) executed by the write-back processing unit 19 will be described with reference to FIG.
In this step, the data of the plurality of divided areas ((1) to (3) in FIG. 9) encrypted in the encryption step are connected to restore the selected storage area (MA) read in the read step. Is performed (step S501). Next, the read start position of the restored MA is called from the RAM 4 based on the number of processes n, and the MA is written back to that position (steps S502 and S503).
Such data deciphering processing is repeatedly executed until the processing is completed for all areas (OA) of the HDD 6 to be processed (NO in step S504). In this case, every time the write-back process is completed, the number of processes n is incremented (step S505), and the process returns to step S102 of the selection process.
[0036]
(Second embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. In this embodiment, in a selection step, a plurality of physically discontinuous sectors (minimum access units) are randomly selected using random numbers for data selection, and the data is read and encrypted. As a result, the encryption strength is improved, and data decryption can be more effectively prevented. In the following description, the same configurations or steps (steps) as those in the above-described first embodiment are denoted by the same reference numerals, and detailed description is omitted.
[0037]
(Schematic configuration of deciphering processing program)
First, FIG. 11 shows a schematic configuration of a computer program for causing a PC to execute the deciphering process according to this embodiment. The deciphering processing program 130 selects one or more sectors that are not physically continuous from a storage area to be deciphered by applying a predetermined selection algorithm, and specifies a data read start position. A read processing unit 31 for sequentially reading and connecting sectors from the specified read start position to generate a selected storage area (MA); a division processing unit 17 and an encryption processing unit 18; A write-back processing unit 32 is provided for writing the encrypted data to the read start position in units of a minimum access.
In addition, similarly to the first embodiment, the deciphering disable processing program 130 is introduced into a PC to be processed through a recording medium such as an FD, and cooperates with PC hardware or an operation system (OS). By demonstrating each of the above functions, the decryption disable processing is executed. In this embodiment, a read start position table 33 is generated in a RAM or the like of a PC, and a flag of “unselected / read / encrypted” is set for each sector, which is the minimum access unit, to manage the processing status. It is configured to Among the deciphering processes executed by the deciphering process program 130, the characteristic selecting step, reading step, and rewriting step in this embodiment will be described in order.
[0038]
(Selection process)
First, a specific process of the selection process performed by the selection processing unit 30 will be described with reference to FIGS. In the selection step according to this embodiment, the access count is calculated by dividing the size of the decryption target area (OA) by the minimum access unit (step S110), and then the preset maximum count is called (step S111). . The maximum count is called here because it is necessary to limit the size of the read start position table 33. If the called maximum count is smaller than the calculated access count (YES in step S112), after dividing the access count in units of the maximum count, a random number A ′ is generated based on the system time of the PC (step S113, S114). On the other hand, if the maximum count is equal to or greater than the access count (NO in step S112), a random number A 'is generated within a range of 1 to the access count (step S115).
[0039]
For the random number A 'generated in this manner, the first to n-th cumulative values are calculated in the same manner as in the first embodiment, and it is determined whether the cumulative value is larger than the access count (steps S116 and S117). . If the access count is equal to or greater than the total value (YES in step S116), the generated random number A 'is determined as the n-th actual encryption number (step S118). On the other hand, if the access count is less than the cumulative value (NO in step S117), a value obtained by subtracting "the cumulative value of A 'up to the (n-1) -th" from the access count is determined as the n-th actual encrypted number. (Step S119).
[0040]
Next, the access count and the maximum count are compared again, and if the access count exceeds the maximum count (YES in step S120), a random number D for data reading is generated in the range of 1 to the maximum count (step S120). S121). If the access count is equal to or less than the maximum count (NO in step S120), a random number D is generated in the range of 1 to access count (step S122). Next, by using the generated random number D, the D-th data from the head of the data group whose processing status of the read start position table 33 is “not (= unselected)” is r. _n The readout start position is specified (step S123). Where r _n Indicates the number of processes in this routine. For example, as shown in FIG. 13A, in the case of the first selection process, all the processing statuses of the access counts (1 to 15) are “not yet”. The tenth sector (minimum access unit) from the top is specified as the first read start position. For the sector specified as the read start position, a flag of “read (= read completed)” is set, and the processing status of the read start position table 33 is updated (step S124). Such specification of the read start position is repeated until reading of the actual encryption number (random number A ') determined in step S118 is completed (step S125). When the random number D is generated as a continuous value, physically continuous data (sector) may be selected as in the first embodiment.
[0041]
If the processing for the actual encryption number has not been completed (NO in step S125), the processing number r _n Is incremented by 1 and n is subtracted from the upper limit (access count or maximum count) for generating the random number D, and the process is repeated (steps S126 and S127). This is because the readable access count (maximum count) of the random number D decreases each time one reading process is completed, and therefore, the range in which the random number D is generated needs to be limited. For example, FIG. 13B shows a state where three readings have been completed. In this case, the range in which the random number D is generated is limited to 1 to 12.
[0042]
(Reading process)
Next, a reading process performed by the reading processing unit 31 will be described with reference to FIG. In this step, first, the sector at the read start position (D-th) specified in the selection step is read and stored in minimum access units (step S210). The read data (sectors) are sequentially linked to create continuous data as shown in FIG. 15 (step S211). In this connection processing, connection is performed in the reading order regardless of the reading start position. The created continuous data becomes the selected storage area (MA). Such data reading and linking processes are repeated until the number of actual encryptions (random number A ', 3 in the illustrated example) is completed (step S212). When the data reading is completed, the division processing unit 17 and the encryption processing unit 18 divide the continuous data (MA) and encrypt each logical block, as in the first embodiment.
[0043]
(Write-back process)
Next, a write-back process performed by the write-back processing unit 32 will be described with reference to FIGS. In this step, first, a data position in which a "selected" flag is set in the read start position table 33 is obtained, and a read start position is calculated based on the data position (step S510). Next, the encrypted continuous data is divided into minimum access units (sectors) (step S511), and written back to the calculated read start position as shown in FIG. 17 (step S512). At this time, since the sector located at the head of the continuous data is sequentially rewritten to the read start position, the read position of each sector may not coincide with the rewrite position. Next, the processing status of the read back position table 33 is updated to "encrypted" for the rewritten data (step S513). The data to which the encrypted flag has been added is excluded from the selection target data in the selection step, similarly to the read data (see step S123 in FIG. 12).
[0044]
Such a write-back process is repeated for all the continuous data (step S514). If there is an unprocessed area in the decryption disable processing area (OA) (NO in step S515), 1 is added to the number of processings n, and the process returns to step S111 in the selection step (FIG. 12) (step S111). S516). When the above processing (steps S110 to S514) is completed for all the areas and the processing status of the read start position table 33 becomes "encrypted", the decryption disable processing ends (YES in step S515). .
[0045]
(Modification)
Note that the present invention is not limited to the above embodiment, and can be variously modified without changing the gist of the invention.
[0046]
For example, in the above embodiment, the HDD of the PC is exemplified as the storage device. However, the above-described processing method can be executed for various HDDs such as a card type, a cartridge type, and an external type and a removable disk. In addition to the stand-alone storage device, the system according to the present invention is introduced to the server for the administrator on a network such as a LAN in which a plurality of user terminals are connected to one server for the administrator. The process of disabling decryption of HDD data of a plurality of user terminals may be performed by remote control. In this case, in the selection step (step S1 in FIG. 1), first, a terminal to perform the deciphering disable processing is selected from a plurality of user terminals connected to the network. Next, an arbitrary storage area is selected from the hard disk of the terminal. As a result, the deciphering process can be performed intensively with a small number of personnel, and the time and cost required for the process can be reduced.
[0047]
In addition, in addition to the above-mentioned system time, at least one of the identification information of the PC 1 to be processed, the attribute information of the user who uses the PC 1, and the attribute information of the operator who operates the PC 1, other than the system time described above, Key information including the above can be obtained and generated. Specifically, the identification information of the operator (employee ID, date of birth, password, etc.) input on the initial screen of the deciphering process, and the identification information of the IC card inserted into the card reader connected to the PC 1 It is also possible to generate an algorithm based on, for example, the serial number of the PC 1, the asset registration number, the identification information of the user using the PC 1, and the like. Also, a plurality of these may be combined. Further, it is preferable that the division algorithm and the encryption algorithm are generated based on different key information. This makes the algorithm more complex and more difficult to decipher.
[0048]
【The invention's effect】
As described above, according to the present invention, data stored in a storage area such as an HDD can be quickly and reliably unreadable at low cost.
[Brief description of the drawings]
FIG. 1 is a flowchart and a schematic diagram showing an overall processing step of an embodiment of the present invention.
FIG. 2 is a diagram schematically showing the interrelation of terms for describing the embodiment.
FIG. 3 is a block diagram showing a schematic configuration of a deciphering processing system according to an embodiment of the present invention.
FIG. 4 is a flowchart showing specific processing of a selection step.
FIG. 5 is a schematic diagram of the same.
FIG. 6 is a flowchart showing a specific process of a reading step.
FIG. 7 is a schematic diagram of the same.
FIG. 8 is a flowchart showing specific processing of a division step and an encryption step.
FIG. 9 is a schematic diagram of the same.
FIG. 10 is a flowchart showing specific processing of a write-back step.
FIG. 11 is a block diagram showing a schematic configuration of a decryption disable processing program according to a second embodiment of the present invention.
FIG. 12 is a flowchart showing a specific process of the selection step.
FIG. 13 is a schematic diagram of the same.
FIG. 14 is a flowchart showing a specific process of a reading step of the same.
FIG. 15 is a schematic diagram for explaining the connection processing.
FIG. 16 is a flowchart showing specific processing of the write-back step.
FIG. 17 is a schematic diagram for explaining a write-back process.
[Explanation of symbols]
1. Computer (PC)
6 ... Hard disk (HDD)
11 Recording medium
13: Decryption disable processing program
15 Selection processing unit
16 read processing unit
17 division processing unit
18 ... Encryption processing unit
19 Write-back processing unit
30 ... Selection processing unit
31 ... Read processing unit
32 Write-back processing unit
33: Read start position table
130: Decryption disable processing program

Claims (12)

A method for making data stored in a rewritable storage device unreadable,
A data area selecting step of selecting one or more data areas for performing a process of disabling data decoding;
A reading step of reading, from the selected data area, one or more storage areas of a minimum access unit to be subjected to the decryption disable processing;
A dividing step of dividing the read one or more storage areas into a plurality of logical blocks;
An encryption step of encrypting data included in each of the plurality of divided logical blocks,
Writing back the encrypted storage area to the read location. The method of claim 1, wherein
The reading step is for reading a storage area of two or more minimum access units in the storage device, and the dividing step is for reading a plurality of logical blocks across the read two or more storage areas of the minimum access unit. The method characterized in that it is divided into. 3. The method of claim 2, wherein
The method according to claim 1, wherein the reading step reads a storage area of two or more minimum access units that are physically continuous in the storage device. The method of claim 1, wherein
The method according to claim 1, wherein the encrypting step encrypts data included in the logical block by applying a plurality of encryption algorithms. The method of claim 4, wherein
The method according to claim 1, wherein the encrypting step encrypts data included in a logical block by applying a different encryption algorithm to each of the plurality of logical blocks. The method of claim 1, wherein
The method according to claim 1, wherein the encrypting step includes an encryption algorithm generating step of generating an algorithm for performing an encryption process on each logical block. The method of claim 1, wherein
A key information acquisition step of acquiring key information including at least one of identification information of the storage device, attribute information of a user using the storage device, attribute information of an operator operating the storage device, or time;
An algorithm generating step of generating a division algorithm for dividing a storage area into a plurality of logical blocks based on the obtained key information or an encryption algorithm for encrypting data included in the logical blocks. Method. The method of claim 7, wherein
The method according to claim 1, wherein the algorithm generating step generates the division algorithm and the encryption algorithm based on different key information. The method of claim 1, wherein
The method according to claim 1, wherein the data area selecting step is to select one or more data areas to be decrypted from a plurality of storage devices connected to a network. The method of claim 1, wherein
The method according to claim 1, wherein the data area selecting step is to select one or more data areas to be decrypted from a plurality of storage devices included in one computer. A computer program for causing a computer system to perform a process of making data stored in a data rewritable storage device unreadable,
A data area selection function for selecting one or more data areas for performing a process of disabling data decoding;
A storage area reading function for reading, from the selected data area, one or more storage areas of a minimum access unit to be subjected to decryption disable processing;
A storage area dividing function of dividing the read one or more storage areas into a plurality of logical blocks;
A data encryption function for encrypting data included in a plurality of divided logical blocks,
A computer program for causing a computer to execute a write-back function of writing back data of an encrypted logical block to the position of the read storage area. A system for making data stored in a rewritable storage device unreadable,
Data area selection means for selecting one or more data areas for performing a process of disabling data decoding;
Storage area reading means for reading, from the selected data area, one or more storage areas of a minimum access unit to be subjected to decryption disable processing;
Logical block dividing means for dividing the read one or more storage areas into a plurality of logical blocks;
Data encryption means for respectively encrypting data included in the plurality of divided logical blocks,
A storage area rewriting means for rewriting the encrypted storage area to the position of the read data area.

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