JP5397062B2 - Tally file generation program and method, and data restoration program and method - Google Patents

Description

  The present technology relates to the field of data security maintenance technology.

  In recent years, information leakage due to theft or loss of, for example, a notebook PC (Personal Computer) or a USB (Universal Serial Bus) memory has been a problem.

  For example, electronic tally exists as a technique for preventing such information leakage. In the conventional electronic tally, for example, user data is encrypted using redundant data such as a random value, and the encrypted user data is divided into a plurality of tally files and stored in a distributed manner. As a result, even if a notebook PC or USB memory is stolen or lost, user data cannot be restored with only some tally files, so information leakage can be prevented. .

JP 2002-135247 A JP 2007-299088

  However, in the method described above, when restoring user data, redundant data used for encryption is required. Therefore, in addition to a plurality of tally files, redundant data is also stored in a notebook PC or USB memory. Must be stored and carried. For this reason, there is a problem that the data amount of the entire data necessary for preventing information leakage increases. For example, when encryption is performed using redundant data having the same size as the user data, it is necessary to store redundant data having the same size as the user data, and the entire data amount is doubled.

  Therefore, an object of the present technology is to provide a technology for preventing information leakage of user data while suppressing the entire data amount.

  A tally file generation method according to a first aspect includes a division step for dividing a file to be processed into n segments, and an exclusive OR operation for all the segments to calculate and store the file in the first storage device. A first tally file generation step for generating a first tally file and n-1 combinations among n combinations configured by selecting an arbitrary n-1 segments from n segments. A second tally file generation step for generating a second tally file for storage in the second storage device by calculating an exclusive OR of n−1 segments included in the combination for each Including.

  The data restoration method according to the second aspect is the first from the first storage device storing the first tally file including the exclusive OR of n segments obtained by dividing the file to be processed. A first acquisition step of acquiring a tally file of n, and n-1 combinations out of n combinations configured by selecting an arbitrary n-1 segments from n segments. A second acquisition step of acquiring n-1 second tally files from a second storage device storing a second tally file including an exclusive OR with n-1 segments included; a step of generating a new second tally file by calculating an exclusive OR of n-1 second tally files; a first tally file and a second tally file; By calculating the exclusive OR of the respective, and a step of restoring the n segments.

  Information leakage of user data can be prevented while suppressing the entire data amount.

FIG. 1 is a system configuration diagram according to the first embodiment of the present technology. FIG. 2 is a functional block diagram of the user terminal according to the first embodiment. FIG. 3 is a diagram showing a processing flow (first portion) of processing for generating a tally file. FIG. 4 is a diagram illustrating a screen example of the processing target file selection screen. FIG. 5 is a diagram illustrating an example of dividing a processing target file into three segments. FIG. 6 is a diagram illustrating an example in which a pseudo bit string is added to a segment. FIG. 7 is a diagram illustrating an example of additional bit specifying data. FIG. 8 is a diagram showing a processing flow (second part) of processing for generating a tally file. FIG. 9 is a diagram for explaining processing for generating a tally file P from three segments. FIG. 10 is a diagram illustrating a calculation example of an exclusive logical ring. FIGS. 11A and 11B are diagrams for explaining processing for generating a tally file U from two segments. FIG. 12 is a diagram illustrating a processing flow (third portion) of processing for generating a tally file. FIG. 13 is a diagram showing an example of a screen for informing the user of the storage location of the tally file. FIG. 14 is a diagram illustrating a screen example of a storage destination selection screen. FIG. 15 is a diagram illustrating a processing flow (first portion) of processing for restoring user data. FIG. 16 is a diagram illustrating a screen example of a storage folder selection screen. FIG. 17 is a diagram for explaining processing for generating a new tally file U from two tally files U. FIGS. 18A to 18C are diagrams for explaining a process of restoring a segment. FIG. 19 is a diagram illustrating a processing flow (second part) of processing for restoring user data. FIG. 20 is a diagram illustrating an example of a scene in which user data is carried to a customer. FIG. 21 is a diagram for explaining the outline of the second embodiment. FIG. 22 is a diagram illustrating a processing flow of processing according to the second embodiment. FIG. 23 is a diagram illustrating a processing flow of the tally file generation method according to the first aspect. FIG. 24 is a diagram illustrating a processing flow of the data restoration method according to the second aspect. FIG. 25 is a functional block diagram of a computer.

[Embodiment 1]
FIG. 1 shows a system configuration diagram according to the first embodiment of the present technology. In the first embodiment, when generating a tally file from user data or restoring user data, as shown in FIG. 1, the user terminal 1 that is a notebook PC is connected to an external storage that is a USB memory. It is assumed that the device 3 is attached. Although FIG. 1 shows an example in which the USB memory is the external storage device 3, a storage device other than the USB memory may be employed as long as it is a removable storage device.

  FIG. 2 shows a functional block diagram of the user terminal 1 shown in FIG. The user terminal 1 includes an input unit 101, a display unit 103, a user data storage unit 105, a processing target file acquisition unit 107, a tally file generation unit 109, a work memory 111, a storage destination determination unit 113, a storage Unit 115, tally file acquisition unit 117, and restoration processing unit 119.

  The input unit 101 receives a tally instruction or restoration instruction from the user, and outputs a tally instruction to the processing target file acquisition unit 107, outputs a restoration instruction to the tally file acquisition unit 117, and displays various selection screens. The display unit 103 is instructed to do so. When receiving the tally instruction from the input unit 101, the processing target file acquisition unit 107 receives the user data (hereinafter also referred to as a processing target file) specified by the tally instruction from the user data storage unit 105 storing the user data. Acquire and output to the tally file generator 109. When receiving the processing target file from the processing target file acquisition unit 107, the tally file generation unit 109 performs processing for generating the tally file and outputs the generated tally file to the storage destination determination unit 113. Further, the tally file generation unit 109 instructs the display unit 103 to display a selection screen for selecting a storage destination of the generated tally file. The tally file generation unit 109 stores data being processed in the work memory 111 and reads data from the work memory 111. When the storage destination determination unit 113 receives the tally file from the tally file generation unit 109, the storage destination determination unit 113 automatically recognizes the attached external storage device 3 and stores the tally file in each of the external storage device 3 and the storage unit 115. To do.

  Further, when receiving the restoration instruction from the input unit 101, the tally file acquisition unit 117 automatically recognizes the attached external storage device 3, acquires the tally file from each of the external storage device 3 and the storage unit 115, and restores it. The data is output to the processing unit 119. When the restoration processing unit 119 receives the tally file from the tally file acquisition unit 117, the restoration processing unit 119 performs processing for restoring the processing target file and instructs the display unit 103 to display the processing result. The restoration processing unit 119 stores data being processed in the work memory 111 and reads data from the work memory 111.

  Next, processing for generating a tally file from a processing target file will be described with reference to FIGS. For example, when the input unit 101 receives a tally processing start instruction from the user, the processing unit file selection screen is displayed on the display unit 103. In response to an instruction from the input unit 101, the display unit 103 displays a processing target file selection screen as shown in FIG. In the example of FIG. 4, the processing target file selection screen displays “Please select a processing target file.” An input field 401 for inputting a folder (directory) and a file name of the processing target file, A reference button 402 for referring to user data (file) in the user data storage unit 105 and an OK button 403 are provided. For example, when the reference button 402 is clicked, a screen for selecting a file (not shown) is newly displayed, and the user selects a processing target file on the screen. In some cases, a folder and a file name are directly input in the input field 401. In addition, a plurality of processing target files may be designated by providing a plurality of input fields 401 or the like. Then, the user designates a processing target file and clicks an OK button 403.

  Then, the input unit 101 receives an input for specifying a processing target file from the user (FIG. 3: step S1), and outputs processing target file specifying data (for example, a folder and a file name) to the processing target file acquisition unit 107. When the processing target file acquisition unit 107 receives the processing target file designation data from the input unit 101, the processing target file acquisition unit 107 acquires the specified processing target file from the user data storage unit 105 (step S3), and sends it to the tally file generation unit 109. Output. When a plurality of processing target files are designated, all the processing target files are acquired and output to the tally file generation unit 109.

  When the tally file generation unit 109 receives the processing target file from the processing target file acquisition unit 107, the tally file generation unit 109 temporarily stores the processing target file in the work memory 111. Then, it is determined whether there are a plurality of files to be processed (step S5). When there are a plurality of processing target files (step S5: Yes route), the tally file generation unit 109 generates a single processing target file by concatenating the plurality of processing target files and stores it in the work memory 111 (step S1). S7). In addition, since the process itself which connects several files is not different from the past, detailed description is abbreviate | omitted. Thereafter, the process proceeds to step S9.

  On the other hand, when there is one processing target file (step S5: No route), step S7 is skipped, and the process proceeds to step S9.

  Then, the tally file generating unit 109 divides the processing target file stored in the work memory 111 into n segments (n is an odd number of 3 or more) and stores the segmented file in the work memory 111 (step S9). FIG. 5 shows an example in which the processing target file is divided into three segments (segments a, b, and c).

  Then, the tally file generation unit 109 determines whether the sizes of the segments stored in the work memory 111 are different (Step S11). When there is a segment having a different size from among the segments stored in the work memory 111 (step S11: Yes route), the tally file generation unit 109 selects the segment size stored in the work memory 111 from the segment sizes. The maximum size is specified (step S13). Then, the tally file generation unit 109 adds an arbitrary bit string (also referred to as a pseudo bit string) to each segment having a size smaller than the maximum size so that the size of the segment becomes equal to the maximum size, and additional bit specifying data Is generated (step S15). For example, FIG. 6 shows an example of a segment to which a pseudo bit string is added. In the example of FIG. 6, the size of the segment c is different from that of the segments a and b, and the pseudo bit string (the shaded portion in FIG. 6) is included in the segment c so that the size of the segment c is equal to the size of the segments a and b. It has been added.

  FIG. 7 shows an example of additional bit specifying data. In the example of FIG. 7, the additional bit specifying data includes a segment name and the start position of the pseudo bit string in the segment. Although the details will be described later, the additional bit specifying data is used to remove the pseudo bit string from the segment when the processing target file is restored.

  And after the process of step S15, it transfers to the process of step S17 (FIG. 8) via the terminal A. FIG.

  On the other hand, when all the sizes of the segments stored in the work memory 111 are the same (step S11: No route), step S13 and step S15 are skipped, and the process proceeds to step S17 (FIG. 8) via the terminal A.

  Moving to the description of FIG. 8, after the terminal A, the tally file generation unit 109 calculates exclusive OR (EOR: Exclusive OR, also referred to as XOR) by all the segments stored in the work memory 111. As a result, the tally file P is generated and temporarily stored in the work memory 111 (FIG. 8: Step S17). For example, when it is divided into three segments (in the case of n = 3), as shown in FIG. 9, the exclusive OR of the segments a, b and c is calculated, and the tally file P (= a ^ b ^ c) is generated. “^” Represents an exclusive OR operator (the same applies hereinafter).

  FIG. 10 shows an example of the operation of exclusive OR. FIG. 10 shows an exclusive OR operation result “0101 0101 1010 1010” based on the bit string “1111 1111 1010 1010” stored in the register GR (General Register) 0 and the bit string “1010 1010 0000 0000” stored in the register GR1. "Is set in the register GR0. For example, in order to calculate an exclusive OR for three bit strings, first, an operation is performed on two bit strings, and an operation is performed using the result of the calculation and another bit string.

Then, the tally file generation unit 109 sets the counter i to 1 (step S19). Then, the tally file generation unit 109 calculates the exclusive OR of (n−1) segments excluding the i-th segment among the n segments stored in the work memory 111, thereby calculating the tally file U. _i is generated and temporarily stored in the work memory 111 (step S21). For example, if the segment is divided into three segments (in the case of n = 3) in step S9 (FIG. 3), when the processing of this step is performed when i = 1, the tally as shown in FIG. file _{U 1} is generated. Specifically, the tally file U ₁ (= b ^ c) is calculated by calculating the exclusive OR of the two segments (ie, segments b and c) excluding the first segment (ie, segment a). Is generated.

Then, the tally file generation unit 109 determines whether the counter i is smaller than n−1 (step S23). When the counter i is smaller than n−1 (step S23: Yes route), the tally file generating unit 109 increments the counter i by 1 (step S25). And it returns to the process of step S21 and repeats the process demonstrated above. For example, if the segment is divided into three segments in the step S9 (FIG. 3) (when n = 3) and the process of the step S21 is performed when i = 2, the tally as shown in FIG. file _{U 2} is generated. Specifically, the second segment (i.e., segment b) 2 segments excluding (i.e., segments a and c) by calculating the exclusive OR by the tally file U ₂ are generated.

On the other hand, when it is determined that the counter i is n−1 or more (step S23: No route), the process proceeds to the process of step S27 (FIG. 12) via the terminal B. In the process flow of FIG. 8, since the process of step S21 is repeated n−1 times, n−1 tally files U _i are generated. That is, there are n combinations for selecting an arbitrary n-1 segments from the n segments. Here, a tally file U is generated for n-1 combinations. Incidentally, when restoring the n segments is, n pieces of tally file U but is required, if any tally file U _{1 ~} tally file U _n-1 to so that describes later, tally file U _{Since n} can be generated, the tally file U _n is not generated here.

Shifting to the description of FIG. 12, after the terminal B, the tally file generation unit 109 extracts the generated tally file P and n−1 tally files U _i from the work memory 111, and stores them in the storage destination determination unit 113. Output. When additional bit specifying data is stored in the work memory 111, additional bit specifying data is also output.

Then, the storage destination determination unit 113 receives the tally file P and the (n−1) tally files U _i from the tally file generation unit 109. Then, the storage destination determination unit 113 performs automatic hardware recognition and detects the external storage device 3 (step S27). Note that automatic recognition may be performed when the external storage device 3 is attached. If the external storage device 3 has been detected, this step is skipped.

Then, the storage destination determination unit 113 stores the tally file P received from the tally file generation unit 109 in the external storage device 3 (step S29). Further, the storage destination determination unit 113 stores the (n−1) tally files U _i received from the tally file generation unit 109 in the storage unit 115 (step S31). Even if the tally file P is stored in the storage unit 115 and the n-1 tally files U _i are stored in the external storage device 3, no particular problem occurs. However, since the external storage device 3 generally has a smaller storage capacity than the storage unit 115 which is an internal storage device of the user terminal 1, the tally file P is stored in the external storage device 3 than the n-1 tally files U _i. It is preferable to store it in.

  Then, the storage destination determining unit 113 determines whether additional bit specifying data has been received from the tally file generating unit 109 (step S33). When the additional bit specifying data is received (step S33: Yes route), the storage destination determining unit 113 stores the additional bit specifying data in the external storage device 3 or the storage unit 115 (step S35). Thereafter, the process ends.

  On the other hand, if additional bit specifying data has not been received (step S33: No route), step S35 is skipped and the process is terminated.

By performing the processing as described above, it is possible to generate a tally file P and n-1 tally files U _{i in} which user data cannot be restored only by individual data. In this embodiment, a total of n tally files of one tally file P and n−1 tally files U _i are generated. Each tally file is the same as one segment. Size (ie, 1 / n size of user data). When a pseudo bit string is added, the amount of data increases somewhat, but the amount of data is very small, so the total amount of data is almost the same as the original user data. Therefore, information leakage of user data can be prevented while suppressing the entire data amount.

In the above description, the tally file is automatically stored in each of the external storage device 3 and the storage unit 115. However, it is also possible to adopt a configuration in which the tally file is manually stored by the user. is there. In this case, instead of step S29 and step S31, a screen for notifying the user of the storage location as shown in FIG. 13 may be displayed. In the example of FIG. 13, “Store file P in XXX.”, “Store file U ₁ in YYY.”, And so on are displayed. A button for starting another screen for performing file operations may be provided.

Further, for example, a storage location selection screen as shown in FIG. 14 may be displayed and designated by the user. In the example of FIG. 14, the storage location selection screen displays “Please select a storage location for the tally file.” The storage location input field 1401 and the reference button 1402 for the tally file P, and the tally file an input column 1403 and the reference button 1404 of the storage destination of U _1, and ..., and the OK button 1405 is provided. In this case, the storage destination determination unit 113 may store the tally file P and the tally file U _i according to the user's specification in step S29 and step S31.

Next, processing for restoring user data will be described with reference to FIGS. 15 to 19. For example, when the input unit 101 receives a restoration processing start instruction from the user or detects that the external storage device 3 is attached, the storage unit selection screen is displayed on the display unit 103. In response to an instruction from the input unit 101, the display unit 103 displays a screen as illustrated in FIG. In the example of FIG. 16, the storage folder selection screen displays “Please select the folder where the tally file is stored.” The folder 1 input field 1601 and the reference button 1602, and the folder 2 An input field 1603 and a reference button 1604,..., And an OK button 1605 are provided. For example, when the reference buttons 1602 and 1604 are clicked, a screen (not shown) for selecting a folder is newly displayed, and the user can select a folder in which the tally file P and the tally file U _i are stored. Select. Here, it is assumed that the folder in the external storage device 3 is selected as the storage destination of the tally file P, and the folder in the storage unit 115 is selected as the storage destination of the tally file U _i . Then, the user specifies a folder in which the tally file is stored and clicks an OK button 1605.

Then, the input unit 101 receives a designation input of a folder storing the tally file from the user (FIG. 15: step S41), and outputs the folder designation data to the tally file acquisition unit 117. When the tally file acquisition unit 117 receives the folder designation data from the input unit 101, the tally file acquisition unit 117 acquires the tally file P from the designated folder (for example, the folder in the external storage device 3) (step S43), and the restoration processing unit It outputs to 119. Also, the tally file acquisition unit 117 acquires n−1 tally files U _i from a designated folder (for example, a folder in the storage unit 115) (step S45), and outputs the acquired tally file to the restoration processing unit 119.

When the restoration processing unit 119 receives the tally file P and the (n−1) tally files U _i from the tally file acquisition unit 117, the restoration processing unit 119 temporarily stores them in the work memory 111. Then, the restoration processing unit 119 generates a new tally file U _n from the n−1 tally files U _i and stores it in the work memory 111 (step S47). Specifically, by calculating the exclusive OR by the tally file U _i n-1 pieces of from the tally file U ₁ to tally file U _n-1, to produce a tally file U _n. This process will be described with reference to FIG.

FIG. 17 shows an example in which the tally file U ₃ is generated from the tally file U ₁ (= b ^ c) and the tally file U ₂ (= a ^ c) when n = 3. In FIG. 17, the exclusive OR of the tally file U ₁ and the tally file U ₂ is U ₁ ^ U ₂ = (b ^ c) ^ (a ^ c) = a ^ b ^ c ^ c. Here, “c ^ c” is an exclusive OR of the same segments, and the operation result is 0 (that is, all bits are 0), so a ^ b ^ c ^ c = a ^ b = the U _3. That is, the tally file U ₃ is generated by calculating the exclusive OR of the tally file U ₁ and the tally file U ₂ . Thus, since the n-1 tally file U i _(i is 1 to n-1) can generate a tally file U _n from the processing flow of FIG. 8 described above, the tally file U _n There is no problem even if it is not generated.

Then, the restoration processing unit 119 sets the counter i to 1 (step S49). Then, the restoration processing unit 119 restores the i-th segment using the tally file P and U _i stored in the work memory 111, and stores them in the work memory 111 (step S51). Specifically, the i-th segment is restored by calculating the exclusive OR of the tally file P and the tally file U _i . This process will be described with reference to FIG.

FIG. 18 (a) shows an example of restoring a segment a from the tally file P and the tally file U _1. In FIG. 18A, the exclusive OR between the tally file P and the tally file U ₁ is P ^ U ₁ = (a ^ b ^ c) ^ (b ^ c) = a ^ b ^ b ^ c ^ c. It becomes. Here, “b ^ b” and “c ^ c” are exclusive ORs of the same segments, and the operation result is 0 (that is, all bits are 0). c ^ c = a. That is, by calculating the exclusive OR by the tally file P and the tally file U _1, segments a is restored.

  Then, the restoration processing unit 119 determines whether the counter i is smaller than n (step S53). When the counter i is smaller than n (step S53: Yes route), the restoration processing unit 119 increments the counter i by 1 (step S55). And it returns to the process of step S51 and repeats the process demonstrated above.

For example, when the counter i = 2, when carrying out the process of step S51, as shown in FIG. 18 (b), to restore the segment b from the tally file P and the tally file U _2. In FIG. 18B, the exclusive OR between the tally file P and the tally file U ₂ is P ^ U ₂ = (a ^ b ^ c) ^ (a ^ c) = a ^ a ^ b ^ c ^ c. It becomes. Here, “a ^ a” and “c ^ c” are exclusive ORs of the same segments, and the calculation result is 0 (that is, all bits are 0). c ^ c = b. That is, by calculating the exclusive OR by the tally file P and the tally file U _2, segment b is restored.

Further, for example, when the counter i = 3, when performing the processing of step S51, as shown in FIG. 18 (c), to restore the segment c from the tally file P and tally file U _3. In FIG. 18C, the exclusive OR between the tally file P and the tally file U ₃ is P ^ U ₃ = (a ^ b ^ c) ^ (a ^ b) = a ^ a ^ b ^ b ^ c It becomes. Here, “a ^ a” and “b ^ b” are exclusive ORs of the same segments, and the operation result is 0 (that is, all bits are 0). b ^ c = c. That is, by calculating the exclusive OR by the tally file P and tally file U _3, segment c is restored.

  On the other hand, when it is determined that the counter i is greater than or equal to n (step S53: No route), the process proceeds to the process of step S57 (FIG. 19) via the terminal C. In the process flow of FIG. 15, since the process of step S51 is repeated n times, n segments are restored.

19, after the terminal C, the restoration processing unit 119 instructs the tally file acquisition unit 117 to check whether the additional bit specifying data is stored in the external storage device 3 or the storage unit 115. Then, the tally file acquisition unit 117 determines whether the additional bit specifying data is stored in the external storage device 3 or the storage unit 115 (FIG. 19: Step S57). For example, it is determined whether additional bit specifying data is stored in the folder in which the tally file P or the tally file U _i is stored. When the additional bit specifying data is stored in the external storage device 3 or the storage unit 115 (step S57: Yes route), the tally file acquisition unit 117 acquires the additional bit specifying data from the external storage device 3 or the storage unit 115. The data is output to the restoration processing unit 119 (step S59).

  Then, when receiving the additional bit specifying data from the tally file acquisition unit 117, the restoration processing unit 119 removes the pseudo bit string specified by the additional bit specifying data for each segment specified by the additional bit specifying data (step S61). ).

  On the other hand, if the additional bit specifying data is not stored in either the external storage device 3 or the storage unit 115 (step S57: No route), the tally file acquisition unit 117 restores the confirmation result (no additional bit specifying data). The processing unit 119 is notified. And step S59 and step S61 are skipped and it transfers to the process of step S63.

  Then, the restoration processing unit 119 restores the processing target file by concatenating n segments stored in the work memory 111 (step S63). Then, the restoration processing unit 119 determines whether the restored processing target file includes a plurality of processing target files (step S65). That is, it is determined whether the processing target file is generated by concatenating a plurality of processing target files. When the restored processing target file includes a plurality of processing target files (step S65: Yes route), the restoration processing unit 119 divides the restored processing target file into individual processing target files (step S67). . In addition, since the process itself for returning the linked file itself is not different from the conventional one, the detailed description is omitted. Thereafter, the process ends.

  On the other hand, if the restored processing target file does not include a plurality of processing target files (step S65: No route), step S67 is skipped, and the processing ends.

By performing the processing as described above, it is possible to restore n segments from the tally file P and the (n−1) tally files U _i, and further restore the processing target file from the n segments. Can do.

For example, FIG. 20 shows an example of a scene in which a user carries a certain file (user data) to a customer. First, a tally file P and tally files U ₁ and U ₂ are generated from user data to be carried, the tally file P is stored in a USB memory, and the tally files U ₁ and U ₂ are stored in an internal storage device of a notebook PC. . Then, the USB memory is removed from the notebook PC, and the user carries each to the customer.

Here, even if the USB memory is stolen or lost while moving to the customer, the user data cannot be restored only by the tally file P. Similarly, even if the notebook PC is stolen or lost, the user data cannot be restored only with the tally files U ₁ and U ₂ .

On the other hand, when arriving at the customer without losing the notebook PC and the USB memory, the tally file P and the tally files U ₁ and U ₂ are prepared, so the processing as described above is performed. Thus, the user data can be restored. Since the amount of data to be carried is basically almost the same as the amount of user data, it is possible to prevent information leakage of user data without increasing the total amount of data.

[Embodiment 2]
Next, a second embodiment will be described with reference to FIGS. In the first embodiment described above, the tally file P is stored in the external storage device 3, but in the second embodiment, the tally file P is connected via a network. Send (upload) to the server.

The outline of the present embodiment will be described with reference to FIG. In FIG. 21, it is assumed that the user terminal 1 and the server 5 are connected via a network 7 which is the Internet, for example. First, the user terminal 1 generates a tally file P and a tally file U _i from a file (user data) (FIG. 21: step (1)). The processing itself for generating the tally file P and the tally file U _i is the same as that in the first embodiment. Then, the generated tally file P is uploaded from the user terminal 1 to the server 5 (step (2)). The tally file U _i is stored in the storage unit 115 of the user terminal 1.

  Thereafter, the user moves to the customer with the user terminal 1 (step (3)). Since step (3) is a user operation, it is indicated by a dotted arrow in FIG.

Then, when the user arrives at the customer, the user terminal 1 is operated to connect to the network 7. Then, the user terminal 1 acquires (downloads) the tally file P from the server 5 (step (4)). Then, the user terminal 1 restores user data by using the downloaded tally file P and the tally file U _i stored in the storage unit 115 (step (5)).

For example, even if the tally file P is eavesdropped at the time of uploading or downloading, the user data cannot be restored only by the tally file P. Further, even if the notebook PC is stolen or lost, the user data cannot be restored only by the tally file U _i . That is, it is possible to prevent information leakage of user data without having the external storage device 3.

  The configuration of the user terminal 1 according to the present embodiment is the same as the functional block diagram shown in FIG. 2 except for the external storage device 3. The processing of the user terminal 1 is basically the same as the processing described in the first embodiment, but when generating a tally file, the processing shown in FIG. 22 is used instead of the processing of FIG. Perform the process. Hereinafter, the process of FIG. 22 will be described.

FIG. 22 shows a processing flow after transitioning from FIG. Since the processing up to the terminal B is the same as that in the first embodiment, detailed description thereof is omitted. When the process proceeds to FIG. 22 via the terminal B, the tally file generation unit 109 extracts the generated tally file P and n−1 tally files U _i from the work memory 111 and outputs them to the storage destination determination unit 113. To do. When additional bit specifying data is stored in the work memory 111, additional bit specifying data is also output.

Then, the storage destination determination unit 113 receives the tally file P and the (n−1) tally files U _i from the tally file generation unit 109. Then, the storage location determination unit 113 transmits the tally file P received from the tally file generation unit 109 to the server 5 (FIG. 22: step S71). In addition, the storage destination determination unit 113 stores the n−1 tally files U _i received from the tally file generation unit 109 in the storage unit 115 (step S73). Note that there is no particular problem even if the tally file P is stored in the storage unit 115 and n−1 tally files U _i are transmitted to the server 5. However, the communication load (communication amount) can be reduced by transmitting the tally file P to the server 5 from the n-1 tally files U _i .

  Then, the storage destination determining unit 113 determines whether additional bit specifying data has been received from the tally file generating unit 109 (step S75). When the additional bit specifying data is received (step S75: Yes route), the storage destination determining unit 113 stores the additional bit specifying data in the storage unit 115 (step S77). The additional bit specifying data may be transmitted to the server 5. Thereafter, the process ends.

  On the other hand, if additional bit specifying data has not been received (step S75: No route), step S77 is skipped and the process is terminated.

  The processing for restoring user data is the same as that in the first embodiment except that the tally file P is acquired (downloaded) from the server 5 in step S43 (FIG. 15).

  By performing the processing as described above, it is possible to prevent information leakage of user data even if the external storage device 3 is not present.

  Although one embodiment of the present technology has been described above, the present technology is not limited to this. For example, the functional block diagram of the user terminal 1 described above does not necessarily correspond to an actual program module configuration. Also in the processing flow, if the processing result does not change, the processing order can be changed. Further, it may be executed in parallel.

  Further, the additional bit specifying data shown in FIG. 7 is an example, and the configuration as described above is not necessarily required. Furthermore, the screen examples described above are merely examples, and other screen configurations that display similar contents can be employed.

  In the above description, the embodiment has been described by way of example in which user data is divided into three segments. However, the division number n is not limited to three. Even when n is an odd number of 5 or more, the processing as described above may be performed.

  The user terminal 1 described above is a computer device, and as shown in FIG. 25, a memory 2501, a CPU 2503, a hard disk drive (HDD) 2505, a display control unit 2507 connected to the display device 2509, and a removable device. A drive device 2513 for the disk 2511, an input device 2515, and a communication control unit 2517 for connecting to a network are connected by a bus 2519. An operating system (OS) and an application program for executing the processing in this embodiment are stored in the HDD 2505, and are read from the HDD 2505 to the memory 2501 when executed by the CPU 2503. If necessary, the CPU 2503 controls the display control unit 2507, the communication control unit 2517, and the drive device 2513 to perform necessary operations. Further, data in the middle of processing is stored in the memory 2501 and stored in the HDD 2505 if necessary. In an embodiment of the present technology, an application program for performing the above-described processing is stored in a computer-readable removable disk 2511 and distributed, and installed from the drive device 2513 to the HDD 2505. In some cases, the HDD 2505 may be installed via a network such as the Internet and the communication control unit 2517. Such a computer apparatus realizes various functions as described above by organically cooperating hardware such as the CPU 2503 and the memory 2501 described above with the OS and necessary application programs.

  The present embodiment can be summarized as follows.

  The tally file generation method according to the first aspect includes a dividing step (corresponding to S101 in FIG. 23) for dividing the processing target file into n segments, and calculating the exclusive OR of all the segments. A first tally file generation step (corresponding to S103 in FIG. 23) for generating a first tally file for storage in the storage device, and selecting any n-1 segments from the n segments For storing each of n-1 combinations among the n combinations to be stored in the second storage device by calculating an exclusive OR of n-1 segments included in the combination. A second tally file generation step (corresponding to S105 in FIG. 23) for generating a second tally file.

  In this way, it is possible to generate the first tally file and the second tally file in which the processing target file (user data) cannot be restored only by the individual tally file. Note that a total of n tally files, one first tally file and n-1 second tally files, are generated, but the size of each tally file is the same size as one segment. Therefore, the total data amount is the same as the processing target file (n segments). That is, information leakage of the processing target file can be prevented while suppressing the entire data amount.

  Further, in the first aspect, when the size of each segment is different before the first tally file generation step described above, the maximum size among the segment sizes is specified, and for each of the segments smaller than the maximum size, Additional bit specifying data for adding an arbitrary bit string to the segment so that the size of the segment is equal to the maximum size, and a segment to which the arbitrary bit string is added and the position of the arbitrary bit string in the segment May be stored in the first storage device or the second storage device. In this way, it is possible to cope with the case where the processing target file cannot be divided into segments of the same size.

  Furthermore, in the first aspect, when there are a plurality of processing target files before the dividing step described above, a step of generating one processing target file by concatenating the plurality of processing target files is further included. Also good. In this way, it is possible to cope with a case where a plurality of files to be processed exist.

  In the first aspect, the first storage device described above may be a removable external storage device, and the second storage device described above may be an internal storage device of a computer. The method further includes a step of automatically recognizing an external storage device attached to the computer and storing the first tally file in the external storage device and a step of storing the second tally file in the internal storage device. Good. For example, when the external storage device has a smaller storage capacity, it is more efficient to store one first tally file in the external storage device than to store n-1 second tally files. It is.

  Furthermore, in the first aspect, the first storage device described above is a storage device managed by a server connected to the computer via a network, and the second storage device described above is a computer. May be an internal storage device. Then, the method may further include a step of transmitting the first tally file to the server and a step of storing the second tally file in the internal storage device. In this way, it is possible to cope with a case where no external storage device is provided. Note that the transmission load can be reduced by transmitting one first tally file to the server rather than transmitting n-1 second tally files to the server.

  The data restoration method according to the second aspect is the first from the first storage device storing the first tally file including the exclusive OR of n segments obtained by dividing the file to be processed. The first acquisition step (corresponding to S111 in FIG. 24) for acquiring the tally file and n−1 of n combinations configured by selecting any n−1 segments from the n segments N-1 second tally files from a second storage device storing a second tally file including an exclusive OR of n-1 segments included in the combination for each combination. A new second tally file is generated by calculating the exclusive OR of the second obtaining step (corresponding to S113 in FIG. 24) and n-1 second tally files. Step (corresponding to S115 in FIG. 24) and the step of restoring n segments by calculating the exclusive OR of each of the first tally file and the second tally file (S117 in FIG. 24). Equivalent).

  In this way, n segments can be restored using the first tally file and the second tally file, and the processing target file can be restored from the n segments. Become.

  In the second mode, additional bit specifying data for specifying a segment to which an arbitrary bit string is added and the position of the arbitrary bit string in the segment is stored in the first storage device or the second storage device. The additional bit specifying data from the first storage device or the second storage device, and for each segment specified by the additional bit specifying data and to which an arbitrary bit string is added, from the segment And a step of removing an arbitrary bit string specified by the additional bit specifying data. In this way, since the arbitrary bit string can be removed from the segment to which the arbitrary bit string is added, the segment can be correctly restored.

  Furthermore, in the second aspect, a step of restoring the processing target file by concatenating the restored n segments may be further included.

  In the second aspect, the first storage device described above may be a removable external storage device, and the second storage device described above may be an internal storage device of a computer. The first acquisition step described above may include a step of automatically recognizing an external storage device attached to the computer and acquiring a first tally file from the external storage device.

  Further, in the second aspect, the first storage device described above is a storage device managed by a server connected to the computer via a network, and the second storage device described above is a computer. May be an internal storage device. The first acquisition step described above may include a step of acquiring the first tally file from the server.

  In the first or second aspect, n may be an odd number of 3 or more.

  A program for causing a computer to execute the above processing can be created, and the program is stored in a storage medium or storage device such as a flexible disk, a CD-ROM, a magneto-optical disk, a semiconductor memory, or a hard disk. . The intermediate processing result is temporarily stored in a storage device such as a main memory.

  The following supplementary notes are further disclosed with respect to the embodiments including the above examples.

(Appendix 1)
A division step of dividing the file to be processed into n segments;
A first tally file generating step for generating a first tally file for storing in the first storage device by calculating an exclusive OR of all the segments;
Of the n combinations configured by selecting any n-1 segments from the n segments, n-1 combinations included in the combination are included in each of the n-1 combinations. A second tally file generating step for generating a second tally file for storing in a second storage device by calculating an exclusive OR of the segments;
A tally file generation program for making a computer execute.

(Appendix 2)
If the size of each segment is different before the first tally file generation step, the maximum size among the segment sizes is specified, and for each of the segments smaller than the maximum size, the size of the segment is the maximum size. Adding an arbitrary bit string to the segment to be equal in size;
Storing additional bit specifying data for specifying the segment to which the arbitrary bit string is added and the position of the arbitrary bit string in the segment in the first storage device or the second storage device;
The tally file generation program according to appendix 1, for causing a computer to execute the above.

(Appendix 3)
Supplementary note 1 or 2 for causing a computer to further execute a step of generating one processing target file by concatenating a plurality of processing target files when there are a plurality of processing target files before the dividing step. Tally file generation program.

(Appendix 4)
The first storage device is a removable external storage device;
The second storage device is an internal storage device of the computer;
Automatically recognizing the external storage device attached to the computer and storing the first tally file in the external storage device;
Storing the second tally file in the internal storage device;
The tally file generation program according to any one of supplementary notes 1 to 3, further causing the computer to execute the above.

(Appendix 5)
The first storage device is a storage device managed by a server connected to the computer via a network;
The second storage device is an internal storage device of the computer;
Sending the first tally file to the server;
Storing the second tally file in the internal storage device;
The tally file generation program according to any one of supplementary notes 1 to 3, further causing the computer to execute the above.

(Appendix 6)
6. The tally file generation program according to any one of appendices 1 to 5, wherein n is an odd number of 3 or more.

(Appendix 7)
A first acquisition step of acquiring the first tally file from a first storage device storing a first tally file including an exclusive OR of n segments obtained by dividing the file to be processed; When,
According to n-1 segments included in the combination for every n-1 combinations out of n combinations configured by selecting an arbitrary n-1 segments from the n segments. A second acquisition step of acquiring n-1 second tally files from a second storage device storing a second tally file including an exclusive OR;
generating a new second tally file by calculating an exclusive OR with n-1 said second tally files;
Restoring n segments by calculating an exclusive OR of each of the first tally file and the second tally file;
Data restoration program to make computer execute.

(Appendix 8)
When additional bit specifying data for specifying the segment to which an arbitrary bit string is added and the position of the arbitrary bit string in the segment are stored in the first storage device or the second storage device Obtaining the additional bit specifying data from the first storage device or the second storage device;
Removing the arbitrary bit string specified by the additional bit specifying data from the segment for each of the segments specified by the additional bit specifying data and to which the arbitrary bit string is added;
The data restoration program according to appendix 7, for causing the computer to further execute.

(Appendix 9)
The data restoration program according to appendix 7 or 8, further causing the computer to execute the step of restoring the file to be processed by concatenating the restored n segments.

(Appendix 10)
The first storage device is a removable external storage device;
The second storage device is an internal storage device of the computer;
The first acquisition step includes:
The data restoration program according to any one of appendices 7 to 9, including a step of automatically recognizing the external storage device attached to the computer and acquiring the first tally file from the external storage device.

(Appendix 11)
The first storage device is a storage device managed by a server connected to the computer via a network;
The second storage device is an internal storage device of the computer;
The first acquisition step includes:
The data restoration program according to any one of appendices 7 to 9, including the step of obtaining the first tally file from the server.

(Appendix 12)
12. The data restoration program according to any one of appendices 7 to 11, wherein n is an odd number of 3 or more.

(Appendix 13)
A division step of dividing the file to be processed into n segments;
A first tally file generating step for generating a first tally file for storing in the first storage device by calculating an exclusive OR of all the segments;
Of the n combinations configured by selecting any n-1 segments from the n segments, n-1 combinations included in the combination are included in each of the n-1 combinations. A second tally file generating step for generating a second tally file for storing in a second storage device by calculating an exclusive OR of the segments;
A tally file generation method executed by a computer.

(Appendix 14)
A first acquisition step of acquiring the first tally file from a first storage device storing a first tally file including an exclusive OR of n segments obtained by dividing the file to be processed; When,
According to n-1 segments included in the combination for every n-1 combinations out of n combinations configured by selecting an arbitrary n-1 segments from the n segments. A second acquisition step of acquiring n-1 second tally files from a second storage device storing a second tally file including an exclusive OR;
generating a new second tally file by calculating an exclusive OR with n-1 said second tally files;
Restoring n segments by calculating an exclusive OR of each of the first tally file and the second tally file;
A data restoration method executed by a computer.

DESCRIPTION OF SYMBOLS 1 User terminal 3 External storage device 5 Server 7 Network 101 Input part 103 Display part 105 User data storage part 107 Processing object file acquisition part 109 Tally file generation part 111 Work memory 113 Storage destination determination part 115 Storage part 117 Tally file acquisition part 119 Restoration processing unit

Claims (6)

A division step of dividing the file to be processed into n segments (n is an odd number of 3 or more) ;
A first tally file generating step for generating a first tally file for storing in the first storage device by calculating an exclusive OR of all the segments;
A process of calculating an exclusive OR of n-1 segments excluding the i-th segment (i is a natural number) among the n segments is executed for each of i satisfying 1 ≦ i ≦ n−1. A second tally file generating step for generating a second tally file for storing in the second storage device,
A tally file generation program for making a computer execute. If the size of each segment is different before the first tally file generation step, the maximum size among the segment sizes is specified, and for each of the segments smaller than the maximum size, the size of the segment is the maximum size. Adding an arbitrary bit string to the segment to be equal in size;
Storing additional bit specifying data for specifying the segment to which the arbitrary bit string is added and the position of the arbitrary bit string in the segment in the first storage device or the second storage device;
The tally file generation program according to claim 1, further causing a computer to execute. The first tally from the first storage device storing the first tally file including the exclusive OR of n (n is an odd number of 3 or more) segments obtained by dividing the file to be processed A first acquisition step of acquiring a file;
A process of calculating an exclusive OR of n-1 segments excluding the i-th segment (i is a natural number) among the n segments is executed for each of i satisfying 1 ≦ i ≦ n−1. A second acquisition step of acquiring n-1 second tally files from a second storage device storing second tally files generated by
generating a new second tally file by calculating an exclusive OR with n-1 said second tally files;
Restoring n segments by calculating an exclusive OR of each of the first tally file and the second tally file;
Data restoration program to make computer execute. When additional bit specifying data for specifying the segment to which an arbitrary bit string is added and the position of the arbitrary bit string in the segment are stored in the first storage device or the second storage device Obtaining the additional bit specifying data from the first storage device or the second storage device;
Removing the arbitrary bit string specified by the additional bit specifying data from the segment for each of the segments specified by the additional bit specifying data and to which the arbitrary bit string is added;
The data restoration program according to claim 3 , further causing a computer to execute. A division step of dividing the file to be processed into n segments (n is an odd number of 3 or more) ;
A first tally file generating step for generating a first tally file for storing in the first storage device by calculating an exclusive OR of all the segments;
A process of calculating an exclusive OR of n-1 segments excluding the i-th segment (i is a natural number) among the n segments is executed for each of i satisfying 1 ≦ i ≦ n−1. A second tally file generating step for generating a second tally file for storing in the second storage device,
A tally file generation method executed by a computer. The first tally from the first storage device storing the first tally file including the exclusive OR of n (n is an odd number of 3 or more) segments obtained by dividing the file to be processed A first acquisition step of acquiring a file;
A process of calculating an exclusive OR of n-1 segments excluding the i-th segment (i is a natural number) among the n segments is executed for each of i satisfying 1 ≦ i ≦ n−1. A second acquisition step of acquiring n-1 second tally files from a second storage device storing second tally files generated by
generating a new second tally file by calculating an exclusive OR with n-1 said second tally files;
Restoring n segments by calculating an exclusive OR of each of the first tally file and the second tally file;
A data restoration method executed by a computer.

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