File management program and file management device

Abstract

To easily perform collective management of a plurality of files using a timestamp.SOLUTION: A file management device implemented by a file management program identifies a wrapper file 14 to which a file 11 having the same file name as a file 21 is attached when one file 21 is designated by a user and a timestamp collective addition command is input, copies files 12 and 13 other than the file 11 attached to the wrapper file 14, attaches the file 21 and the copied files 12 and 13 to a wrapper file 22, obtains a timestamp token 23 for the wrapper file 22 to which the files 21, 12, and 13 are attached, and embeds the timestamp token 23 in the wrapper file 22 to which the files 21, 12, and 13 are attached.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a file management program and a file management device for managing files using time stamps. Note that the "file" refers to an electronic file. [Background technology]

[0002] Today, the method of managing files using timestamps is widely used. The method of managing files using timestamps is roughly as follows.

[0003] A file user obtains a time stamp token for a file that the user wishes to manage from a time stamp authority. Specifically, the user sends a hash value of the file to the time stamp authority. The time stamp authority encrypts the received hash value with time information indicating the current time using the time stamp authority's private key (applies a digital signature). The time stamp authority then generates a time stamp token by attaching a public key certificate containing a public key corresponding to the private key to the encrypted hash value and time information. The time stamp authority then sends the time stamp token to the user. The user receives the time stamp token and saves the file that the user wishes to manage and the time stamp token for the file received from the time stamp authority.

[0004] Thereafter, the user can use the timestamp token for the file to prove the existence and integrity of the file. That is, the timestamp token contains an encrypted hash value and time information. The user decrypts the encrypted hash value and time information with the public key contained in the timestamp token. Based on the time information obtained from the timestamp token in this way, the user can prove that the file existed at the date and time indicated by the time information. In addition, the user can generate a hash value for the file, compare the hash value with the hash value obtained from the timestamp token using the public key as described above, and prove that the two match, thereby proving that the file has not been tampered with after the date and time indicated by the time information obtained from the timestamp token.

[0005] By the way, when managing files using timestamps, it is important to clearly link a file with a timestamp token for that file. In order to clearly link a file with a timestamp token for that file, it is preferable to combine the file and the timestamp token for that file into one file.

[0006] The method of binding a file and a time stamp token includes a direct method and an attachment method.

[0007] The direct method is a method in which a file and a time stamp token are directly linked by embedding a time stamp token in the file. Currently, PDF files have a structure that allows a time stamp token to be embedded therein. When a file is a PDF file, the file and the time stamp token can be linked by the direct method. When a file and a time stamp token are linked by the direct method, a hash value of the file is sent to a time stamp authority, a time stamp token is generated by attaching a public key certificate to the encrypted hash value and time information of the file, and the received time stamp token is embedded in the file.

[0008] The attachment method is a method in which a file is attached to a wrapper file and a time stamp token is embedded in the wrapper file to which the file is attached. A wrapper file is a file that has a structure that allows other files to be attached to it and a structure that allows a time stamp token to be embedded inside it. A PDF file has these structures and can be used as a wrapper file. Some files, such as text files, CSV (Comma Separated Values) files, Word files, etc., do not have a structure that allows a time stamp token to be embedded inside them. For such files, the attachment method allows the file and the time stamp token to be combined via the wrapper file. When combining a file and a time stamp token using the attachment method, after attaching the file to a wrapper file, a hash value of the wrapper file to which the file is attached is sent to a time stamp authority, and a time stamp token generated by attaching a public key certificate to the encrypted hash value and time information of the wrapper file to which the file is attached is received from the time stamp authority, and the received time stamp token is embedded in the wrapper file to which the file is attached.

[0009] Japanese Patent Application Laid-Open No. 2017-182433 (Patent Document 1) describes a technique for embedding a timestamp token in a file. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2017-182433 A Summary of the Invention [Problem to be solved by the invention]

[0011] It would be convenient if multiple related files, such as a file of contracts, a file of invoices, and a file of receipts relating to a particular business, product, good, or service, could be managed collectively using timestamps.

[0012] One possible method for achieving this is to attach multiple files to one wrapper file and embed a time stamp token in the one wrapper file. Specifically, multiple files are attached to one wrapper file, a hash value of the one wrapper file to which the multiple files are attached is sent to a time stamp authority, and a time stamp token generated by the time stamp authority encrypting the hash value and time information and attaching a public key certificate to the encrypted hash value and time information is received from the time stamp authority, and the time stamp token is embedded in the one wrapper file to which the multiple files are attached. According to this method, multiple files and time stamp tokens can be collected together via a single wrapper file, and therefore multiple files can be easily managed collectively using time stamps.

[0013] However, the method of attaching multiple files to a single wrapper file and embedding a timestamp token in that single wrapper file has the following problems.

[0014] For example, suppose that a user uses the above method to create a wrapper file to which a first file and a second file that are related to each other are attached and a time stamp token is embedded, and stores the wrapper file in a storage device. Thereafter, it becomes necessary to partially change the contents of the first file, so a user who has the authority to change the contents of the first file creates a file in which the contents of the first file are partially changed. The content of the file is different from that of the first file, so it is a different file from the first file. This file is called a "third file." However, since the content of the third file is mostly the same as that of the first file, it is a file related to the second file, just like the first file. As a result of creating the third file, it becomes necessary to manage the third file using a time stamp, so the user obtains a new time stamp token for the third file from a time stamp authority, embeds the new time stamp token in the third file, and stores the third file in a storage device. In this case, a wrapper file with the first and second files attached and an embedded timestamp token, and a third file with a new embedded timestamp token, are stored in the storage device.

[0015] In this example, the first file and the second file, which are related to each other, are collected together through one file wrapper, making them easy to manage together. On the other hand, the third file and the second file, which are related to each other, are each distributed in separate files, making it difficult to manage them together. In this way, the method of attaching a plurality of files to one file wrapper and embedding a time stamp token in the one file wrapper has the following problem: when the first file and the second file, which are related to each other, are attached, a file wrapper file in which a time stamp token is embedded is created, and the file wrapper file is stored in a storage device, the first file and the second file can be easily managed together using the time stamp. However, when the contents of the first file are subsequently changed, a new time stamp token is embedded in the third file, which is a file in which the contents of the first file have been changed, and the third file is stored in a storage device, it becomes difficult to manage the third file and the second file, which are related to each other, together using the time stamp.

[0016] In this regard, one possible method is to attach a first file and a second file that are related to each other, store a wrapper file with an embedded timestamp token in a storage device, and then create a third file by partially modifying the contents of the first file, and when it becomes necessary to manage the third file using a timestamp, create a wrapper file with the third file and the second file attached and a new timestamp token embedded in it, and store the wrapper file in a storage device.

[0017] However, in order to create a wrapper file with the third file and the second file attached and with a new timestamp token embedded, the third file and the second file are required. At the time when the wrapper file with the first file and the second file attached and with a timestamp token embedded is created, the storage location of the second file is known, but at the time when the wrapper file with the third file and the second file attached and with a new timestamp token embedded is created, the storage location of the second file may be forgotten. In such a case, it becomes difficult to create a wrapper file with the third file and the second file attached and with a new timestamp token embedded.

[0018] The present invention has been made in consideration of problems such as those described above, and an object of the present invention is to provide a file management program and a file management device that can easily perform centralized management of multiple files using timestamps. [Means for solving the problem]

[0019] In order to solve the above-mentioned problems, a file management program of the present invention is a file management program for causing a computer having a storage device or connected to a storage device to function as a file management device that manages files using time stamps, and when a plurality of file wrapper files to which a plurality of files are attached and in which a time stamp token is embedded are stored in the storage device and a user specifies one file and a batch time stamp addition command is input to the file management device, the file management device identifies, from the plurality of file wrapper files stored in the storage device, a file to which a file with the same file name as the specified file is attached, and, from among the plurality of files present in the specified file in a form attached to the specified file, a file with the same file name as the specified file is identified, The file management program of the present invention includes a file attachment unit that copies all files except the specified file, reads an empty wrapper file stored in the storage device from the storage device, and attaches the specified file and the copied file to the read empty wrapper file, a time stamp token acquisition unit that acquires from a time stamp authority a time stamp token including a hash value and time information of the wrapper file to which the specified file and the copied file are attached, a time stamp token embedding unit that embeds the acquired time stamp token in the wrapper file to which the specified file and the copied file are attached, and a storage processing unit that stores the wrapper file to which the specified file and the copied file are attached and in which the acquired time stamp token is embedded as a new wrapper file in the storage device. According to the file management program of the present invention, a user can easily manage multiple files collectively by attaching multiple files to one wrapper file and embedding a time stamp token in the one wrapper file. Specifically, even after the content of one of multiple files related to each other is partially changed, the user can easily manage multiple files related to each other collectively by the above method in the same way as before the content of the one file was partially changed.

[0020] Furthermore, in the file management program of the present invention, the file management device may include a list generating section that generates, for each of the plurality of wrapper files stored in the storage device, a list that records, in association with one another, the file names of each file attached to the wrapper file, the file names of the wrapper files, and the storage locations of the wrapper files within the storage device, and the file attachment section may identify wrapper files to which a file with the same file name as the specified file is attached based on the file name of the specified file and the list. This makes it possible to quickly identify wrapper files to which a file with the same file name as the file specified by the user is attached.

[0021] In the file management program of the present invention, the storage processor may identify a folder in which a file wrapper file having an attached file with the same file name as the specified file is stored based on the list, and store the new file wrapper file in the identified folder. In the file management program of the present invention, the storage processor may, when storing the new file wrapper file in the storage device, read a character string forming a file name of the file wrapper file having an attached file with the same file name as the specified file, and if the read character string does not contain a number indicating the number of revisions, set the read character string with a number indicating the number of revisions added thereto as the file name of the new file wrapper file, and if the read character string contains a number indicating the number of revisions, set the read character string with the number indicating the number of revisions included therein changed as the file name of the new file wrapper file.

[0022] In addition, in the file management program of the present invention, the file attachment unit attaches the specified file, the duplicated file, and the identified wrapper file to the empty wrapper file read out, the timestamp token acquisition unit acquires from a time stamp authority a timestamp token including a hash value and time information of the wrapper file to which the specified file, the duplicated file, and the identified wrapper file are attached, the timestamp token embedding unit embeds the acquired timestamp token in the wrapper file to which the specified file, the duplicated file, and the identified wrapper file are attached, and the storage processing unit stores the wrapper file to which the specified file, the duplicated file, and the identified wrapper file are attached and in which the acquired timestamp token is embedded as a new wrapper file in the storage device.

[0023] In addition, in order to solve the above-mentioned problems, a file management device of the present invention has a storage device or is connected to a storage device and manages files using time stamps, and when a plurality of file wrapper files to which a plurality of files are attached and in which a time stamp token is embedded are stored in the storage device and a user specifies one file and a batch time stamp addition command is input to the file management device, the file management device identifies, from the plurality of file wrapper files stored in the storage device, a file to which a file with the same file name as the specified file is attached, copies all files present in the identified file wrapper file in a form attached to the identified file wrapper file, except for the file with the same file name as the specified file, and performs a command to add a time stamp to the specified file. The file management device of the present invention comprises a file attachment unit which reads out an empty wrapper file stored in the device from the storage device and attaches the specified file and the duplicated file to the read empty wrapper file, a time stamp token acquisition unit which acquires from a time stamp authority a time stamp token including a hash value and time information of the wrapper file to which the specified file and the duplicated file are attached, a time stamp token embedding unit which embeds the acquired time stamp token in the wrapper file to which the specified file and the duplicated file are attached, and a storage processing unit which stores the wrapper file to which the specified file and the duplicated file are attached and in which the acquired time stamp token is embedded as a new wrapper file in the storage device. According to the file management device of the present invention, a user can easily manage multiple files collectively by attaching multiple files to one wrapper file and embedding a time stamp token in the one wrapper file. Specifically, even after the content of one of the multiple files related to each other is partially changed, the user can easily manage multiple files related to each other collectively by the above method in the same way as before the content of the one file was partially changed. Effect of the Invention

[0024] According to the present invention, it is possible to easily manage a plurality of files collectively using time stamps. [Brief description of the drawings]

[0025] [Figure 1] 1 is a block diagram showing a system including a file management device and a time stamp issuing device of a time stamp authority according to an embodiment of the present invention. [Diagram 2] FIG. 11 is an explanatory diagram showing a direct method of individual time stamp addition processing performed by the file management device according to the embodiment of the present invention. [Diagram 3] 11 is an explanatory diagram showing an individual time stamp addition process of the attachment method performed by the file management device according to the embodiment of the present invention; FIG. [Figure 4] FIG. 2 is an explanatory diagram showing a first batch time stamp addition process performed by the file management device according to the embodiment of the present invention. [Diagram 5] 11 is an explanatory diagram showing a second batch time stamp addition process performed by the file management device according to the embodiment of the present invention. FIG. [Figure 6] 5 is an explanatory diagram showing a method of inputting a command to the file management device in the file management device according to the embodiment of the present invention; FIG. [Figure 7] 1 is an explanatory diagram illustrating an example of a file attachment status list in the file management device according to an embodiment of the present invention. [Figure 8] 10 is an explanatory diagram showing a method for generating a file attachment status list in the file management device according to the embodiment of the present invention; [Figure 9] 11 is an explanatory diagram showing a second batch time stamp addition process performed by the file management device according to the embodiment of the present invention. FIG. [Figure 10] 3 is a flowchart showing an overall flow of processing performed by the file management device according to the embodiment of the present invention. [Figure 11] 10 is a flowchart showing a direct method of individually adding a time stamp, which is performed by the file management device according to the embodiment of the present invention. [Figure 12]10 is a flowchart showing an individual time stamp addition process of the attachment method performed by the file management device according to the embodiment of the present invention. [Figure 13] 5 is a flowchart showing a first batch time stamp addition process performed by the file management device according to the embodiment of the present invention. [Figure 14] 13 is a flowchart showing a second batch time stamp addition process performed by the file management device according to the embodiment of the present invention. [Figure 15] 1 is an explanatory diagram showing a file wrapper file generated by a first batch time stamp addition process and a file wrapper file generated by a second batch time stamp addition process in a file management device according to an embodiment of the present invention. FIG. [Figure 16] FIG. 2 is an explanatory diagram showing the state in which a file wrapper file is opened with a file reader. [Figure 17] FIG. 11 is an explanatory diagram showing a modified example of the second batch timestamp addition process in the file management device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, a file management device according to an embodiment of the present invention will be described, which is realized by a computer executing a file management program according to an embodiment of the present invention.

[0027] First, two expressions used in the description of the embodiment will be described. In the description of the embodiment, an expression such as "adding a timestamp to one file" will be used. This expression means obtaining a timestamp token for one file and combining the one file with the obtained timestamp token, and specifically means (a) obtaining a timestamp token including a hash value and time information of one file from a timestamp authority and embedding the timestamp token in the one file, or (b) attaching one file to a wrapper file, obtaining a timestamp token including a hash value and time information of the wrapper file to which the one file is attached from a timestamp authority, and embedding the timestamp token in the wrapper file to which the one file is attached. Note that "embedding a timestamp token in a file" means making the timestamp token a part of the file.

[0028] In addition, in the description of the embodiment, an expression such as "adding timestamps to multiple files at once" is used. This expression means obtaining timestamp tokens for multiple files and combining the multiple files with the obtained timestamp tokens, and specifically means attaching the multiple files to a wrapper file, obtaining a timestamp token including a hash value and time information of the wrapper file to which the multiple files are attached from a time-stamp authority, and embedding the timestamp token in the wrapper file to which the multiple files are attached.

[0029] (Systems including file management devices) FIG. 1 shows a system in which a file management device 51 according to an embodiment of the present invention and a time stamp issuing device 91 of a time stamp authority are connected to each other so as to be able to communicate with each other via a computer network 92 such as the Internet.

[0030] In Fig. 1, the file management device 51 has a function of managing files using time stamps. In this embodiment, the file management device 51 is, for example, a personal computer, but the file management device 51 is not limited to a personal computer and may be a server computer or a mobile terminal such as a tablet or a smartphone. Furthermore, the files are, for example, document files, image files, video files, audio files, etc., and the data contents contained in the files are not limited. Furthermore, the files are not limited to data files and may be program files.

[0031] The time stamp issuing device 91 is, for example, a server computer, and has a function of issuing a time stamp. The time stamp issuing device 91 is used by the time stamp issuing authority to issue a time stamp. The time stamp issuing device 91 performs the following process when issuing a time stamp. First, the time stamp issuing device 91 receives from the file management device 51 a hash value of one file, a hash value of a file wrapper file to which one file is attached, or a hash value of a file wrapper file to which multiple files are attached. Next, the time stamp issuing device 91 generates a time stamp token. The time stamp token is generated by attaching time information indicating the current time to the received hash value, encrypting the hash value and the time information with the private key of the time stamp authority (applying a digital signature), and attaching a public key certificate including a public key corresponding to the private key of the time stamp authority to the encrypted hash value and time information. The time stamp token is a set of data including the encrypted hash value, the time information, and the public key certificate. Next, the time stamp issuing device 91 transmits the generated time stamp token to the file management device 51 that is the source of the hash value.

[0032] (Main processing performed by the file management device) The file management device 51 performs a process of adding a timestamp to one file or a process of adding timestamps to multiple files at once, based on a command input by a user.

[0033] Specifically, the file management device 51 performs a direct-type individual time stamp addition process or an attachment-type individual time stamp addition process as a process for adding a time stamp to one file. The direct-type individual time stamp addition process is a process in which, as shown in Fig. 2, a time stamp token 2 including a hash value and time information of one file 1 is obtained from a time stamp authority, and the time stamp token 2 is embedded in the one file 1. The attachment-type individual time stamp addition process is a process in which, as shown in Fig. 3, a file 6 is attached to a wrapper file 7, a time stamp token 8 including a hash value and time information of the wrapper file 7 to which the one file 6 is attached is obtained from a time stamp authority, and the time stamp token 8 is embedded in the wrapper file 7 to which the one file 6 is attached.

[0034] When a user specifies a file stored in the storage unit of the file management device 51 and inputs an individual timestamp addition command to the file management device 51, the file management device 51 determines whether or not the file specified by the user has a structure in which a timestamp token can be embedded, and if the file specified by the user has a structure in which a timestamp token can be embedded, performs individual timestamp addition processing of the direct method, and if the file specified by the user does not have a structure in which a timestamp token can be embedded, performs individual timestamp addition processing of the attachment method. Note that an "individual timestamp addition command" is a command that commands the file management device 51 to perform processing to add a timestamp to one file.

[0035] Furthermore, file management device 51 performs a batch time stamp addition process for adding time stamps to multiple files at once. The batch time stamp addition process is a process for attaching multiple files to a wrapper file, obtaining a time stamp token including a hash value and time information of the wrapper file to which the multiple files are attached from a time stamp authority, and embedding the time stamp token in the wrapper file to which the multiple files are attached.

[0036] There are two types of time stamp batch addition processes: a first time stamp batch addition process and a second time stamp batch addition process. The first time stamp batch addition process and the second time stamp batch addition process are the same except for the process of attaching multiple files to a wrapper file.

[0037] As shown in Fig. 4, when, for example, three files 11, 12, and 13 are stored in the storage unit 53 of the file management device 51, the file management device 51 performs a first batch time stamp addition process when the three files 11, 12, and 13 are designated by a user and a batch time stamp addition command is input to the file management device 51. In this case, in the first batch time stamp addition process, the file management device 51 attaches the three files 11, 12, and 13 stored in the storage unit 53 of the file management device 51 to the file wrapper file 14. Then, the file management device 51 obtains a time stamp token 15 including a hash value and time information of the file wrapper file 14 to which the three files 11, 12, and 13 are attached from a time stamp authentication authority, and embeds the time stamp token 15 in the file wrapper file 14 to which the three files 11, 12, and 13 are attached. Note that the "batch time stamp addition command" is a command that commands the file management device 51 to perform a process of adding time stamps to a plurality of files at once.

[0038] On the other hand, the file management device 51 performs the second batch time stamp addition process in the following case. That is, it is assumed that a plurality of file wrapper files, each having a plurality of files attached and a time stamp token embedded therein, are stored in the storage unit 53 of the file management device 51, and among them, for example, a file wrapper file 14, each having three files 11, 12, and 13 attached and a time stamp token 15 embedded therein, is included, as shown in Fig. 5. It is further assumed that a file 21 is stored in the storage unit 53, and the file name of the file 21 is the same as the file name of one of the three files 11, 12, and 13 attached to the file wrapper file 14, for example, the file name of the file 11. In this state, when the user specifies the file 21 and inputs a batch time stamp addition command to the file management device 51, the file management device 51 performs the second batch time stamp addition process.

[0039] In this case, in the second batch time stamp addition process, file management device 51 first identifies file wrapper file 14 to which file 11 having the same file name as file 21 is attached from among the multiple file wrapper files stored in storage unit 53. Next, file management device 51 copies all of files 12 and 13, except for file 11 having the same file name as file 21, among the multiple files 11, 12, and 13 present in file wrapper file 14 in a form attached to file wrapper file 14. Next, file management device 51 attaches file 21 specified by the user and the copied files 12 and 13 to a new file wrapper file 22 separate from file wrapper file 14. Thereafter, file management device 51 obtains from a time stamp authority a time stamp token 23 including a hash value and time information of file wrapper file 22 to which files 21, 12, and 13 are attached, and embeds the time stamp token 23 in file wrapper file 22 to which files 21, 12, and 13 are attached.

[0040] (Configuration of file management device) As shown in FIG. 1, the file management device 51 includes an arithmetic processing unit 52, a storage unit 53, a communication unit 54, an operation unit 55, and a display unit 56. The arithmetic processing unit 52 is, for example, a CPU (Central Processing Unit) and has a function of controlling the file management device 51. The storage unit 53 is, for example, a HDD (Hard Disk Drive) or an SSD (Solid State Drive) and has a function of storing and saving information such as programs and data. The storage unit 53 may be built into the file management device 51, or may be placed outside the file management device 51 and connected to the file management device 51. The storage unit 53 is a specific example of a "storage device". The communication unit 54 has a function of controlling communication between the file management device 51 and the time stamp issuing device 91. The operation unit 55 is, for example, a keyboard, a mouse, or a touch panel, and is a means for a user to operate the file management device 51. A user can use the operation unit 55 to specify a file stored in the storage unit 53 and input commands to the file management device 51. The display unit 56 is, for example, a display, and is a means for displaying various information to the user.

[0041] Furthermore, the storage unit 53 stores a file management program for causing the personal computer to function as the file management device 51. The calculation processing unit 52 reads and executes the file management program stored in the storage unit 53, thereby functioning as a process selection unit 61, a file attachment unit 62, a time stamp token acquisition unit 63, a time stamp token embedding unit 64, a storage processing unit 65, and a list generation unit 66.

[0042] The process selection unit 61 selects one of the following processes based on instructions input by a user to the file management device 51: direct method individual timestamp addition process, attachment method individual timestamp addition process, first batch timestamp addition process, and second batch timestamp addition process.

[0043] Specifically, when a file stored in the storage unit 53 of the file management device 51 is designated by the user and a time stamp individual addition command is input to the file management device 51, the process selection unit 61 judges whether the file designated by the user has a structure in which a time stamp token can be embedded therein, and selects the direct method of individual time stamp addition processing if the file designated by the user has a structure in which a time stamp token can be embedded therein, and selects the attachment method of individual time stamp addition processing if the file designated by the user does not have a structure in which a time stamp token can be embedded therein. For example, as shown in FIG. 6(A), the user operates the operation unit 55 of the file management device 51 to first open the folder 31 in the storage unit 53 and designate one file stored in the folder 31. Next, the user opens the context menu 32 and selects "individual time stamp addition" in the context menu 32. By the user selecting "individual time stamp addition" in the context menu 32, a time stamp individual addition command is input to the file management device 51. In this manner, the user can designate a file and input a time stamp individual addition command.

[0044] Furthermore, the process selection unit 61 selects the first batch time stamp addition process when a plurality of files stored in the storage unit 53 of the file management device 51 are specified by the user and a batch time stamp addition command is input to the file management device 51. For example, as shown in FIG. 6B, the user opens the folder 31, specifies a plurality of files stored in the folder 31, and then opens the context menu 32 and selects "Batch time stamp addition" in the context menu 32. When the user selects "Batch time stamp addition" in the context menu 32, a batch time stamp addition command is input to the file management device 51. In this manner, the user can specify files and input a batch time stamp addition command.

[0045] Furthermore, the process selection unit 61 selects the second batch time stamp addition process when the user designates one file stored in the storage unit 53 of the file management device 51 and inputs a batch time stamp addition command to the file management device 51. For example, as shown in FIG. 6C, when the user designates one file stored in the folder 31 and selects "add time stamp all at once" in the context menu 32, the process selection unit 61 selects the second batch time stamp addition process. That is, when the user inputs a batch time stamp addition command by selecting "add time stamp all at once" in the context menu 32, the process selection unit 61 selects the first batch time stamp addition process if the user has designated multiple files, and selects the second batch time stamp addition process if the user has designated one file.

[0046] In the individual time stamp addition process of the attachment method, the file attachment unit 62 reads out an empty wrapper file stored in the memory unit 53 from the memory unit 53, and attaches one file specified by the user to the read empty wrapper file. An "empty wrapper file" is a file that has a structure that allows a file to be attached to it and that allows a time stamp token to be embedded therein, and is a file to which no file is attached and to which no time stamp token is embedded. In this embodiment, an "empty wrapper file" is a PDF file to which no file is attached and to which no time stamp token is embedded.

[0047] In addition, in the first batch timestamp addition process, the file attachment unit 62 reads out from the memory unit 53 an empty wrapper file stored in the memory unit 53, and attaches multiple files specified by the user to the read empty wrapper file.

[0048] Furthermore, in the second batch timestamp addition process, as shown in Fig. 5, for example, file attachment unit 62 identifies wrapper file 14 to which file 11 having the same file name as one file 21 specified by the user is attached, and copies all files 12 and 13, except for file 11 having the same file name as file 21, among the multiple files 11, 12, and 13 attached to wrapper file 14. Next, file attachment unit 62 reads out an empty wrapper file stored in storage unit 53 from storage unit 53, and attaches file 21 specified by the user and the copied files 12 and 13 to the read empty wrapper file. The process of file attachment unit 62 in the second batch timestamp addition process will be described in detail later.

[0049] In the direct-type individual timestamp addition process, the timestamp token acquisition unit 63 calculates a hash value of one file specified by a user, transmits the calculated hash value to the timestamp authority, and receives and acquires a timestamp token including the hash value and time information from the timestamp authority. Also, in each of the attachment-type individual timestamp addition process, first timestamp batch addition process, and second timestamp batch addition process, the timestamp token acquisition unit 63 calculates a hash value of a wrapper file to which one or more files are attached by the file attachment unit 62, transmits the calculated hash value to the timestamp authority, and receives and acquires a timestamp token including the hash value and time information from the timestamp authority.

[0050] In the direct method individual timestamp addition process, the timestamp token embedding unit 64 embeds the timestamp token acquired by the timestamp token acquisition unit 63 into one file specified by the user. Also, in each of the attachment method individual timestamp addition process, first timestamp batch addition process, and second timestamp batch addition process, the timestamp token embedding unit 64 embeds the timestamp token acquired by the timestamp token acquisition unit 63 into a wrapper file to which one or multiple files are attached by the file attachment unit 62.

[0051] In the direct-type individual timestamp addition process, the storage processing unit 65 stores in the storage unit 53 a file in which a timestamp token is embedded by the timestamp token embedding unit 64. In each of the attachment-type individual timestamp addition process, the first timestamp batch addition process, and the second timestamp batch addition process, the storage processing unit 65 stores in the storage unit 53 a wrapper file to which one or more files are attached by the file attachment unit 62 and in which a timestamp token is embedded by the timestamp token embedding unit 64.

[0052] Furthermore, in the direct method of individual time stamp addition processing, the storage processing unit 65 requests the user to specify a folder in which to store the file and to input a file name for the file before storing the file in which the time stamp token is embedded in the storage unit 53. Then, the storage processing unit 65 sets the file name input by the user in response to the request as the file name for the file, and stores the file in the folder specified by the user.

[0053] In the individual time stamp addition process of the attachment method, before storing a new file wrapper file to which one file is attached and in which a time stamp token is embedded in the storage unit 53, the storage unit 65 determines whether or not a previous file wrapper file in which the number of attached files is one and the file name of the previous file is the same as the file name of the file attached to the new file wrapper file is stored in the storage unit 53. If such a previous file wrapper file is stored in the storage unit 53, the storage unit 65 reads the character string forming the file name of the previous file wrapper file, performs a process of adding or changing a number indicating the number of revisions to the read character string, and sets the processed character string as the file name of the new file wrapper file. The storage unit 65 then stores the new file wrapper file in the folder in which the previous file wrapper file is stored. The process of adding or changing a number indicating the number of revisions is, for example, a process of changing the number "01" indicating the number of revisions in the file name "X product related documents 01.pdf" to "02" to change "X product related documents 01.pdf" to "X product related documents 02.pdf". On the other hand, if there is only one file attached and no previous wrapper file whose file name is the same as the file name of the file attached to the new wrapper file is stored in memory unit 53, memory processing unit 65 requests the user to specify a folder in which to store the new wrapper file and to input a file name for the new wrapper file, sets the file name input by the user in response to the request as the file name of the new wrapper file, and stores the new wrapper file in the folder specified by the user.

[0054] Furthermore, in the first batch time stamp addition process, before storing a new wrapper file to which multiple files are attached and in which a time stamp token is embedded in storage unit 53, storage processor 65 determines whether or not a previous wrapper file to which the same number of files as the files attached to the new wrapper file are attached and whose file names are the same as those of the files attached to the new wrapper file is stored in storage unit 53. If such a previous wrapper file is stored in storage unit 53, storage processor 65 reads the character string forming the file name of the previous wrapper file, performs a process of adding or changing a number indicating the number of revisions to the read character string, and sets the processed character string as the file name of the new wrapper file. Storage processor 65 then stores the new wrapper file in the folder in which the previous wrapper file is stored. On the other hand, if the same number of files are attached as the files attached to the new wrapper file, and no previous wrapper files are stored in memory 53 whose file names are the same as those of the files attached to the new wrapper file, then memory processing unit 65 requests the user to specify a folder in which to store the new wrapper file and to input a file name for the new wrapper file, sets the file name input by the user in response to the request as the file name of the new wrapper file, and stores the new wrapper file in the folder specified by the user.

[0055] 5, before storing in storage unit 53 a new file wrapper file 22 to which file 21 specified by the user and duplicated files 12 and 13 are attached and in which time stamp token 23 is embedded, storage processing unit 65 reads a character string forming the file name of file wrapper file 14 to which file 11, which has the same file name as file 21 specified by the user, is attached, performs a process of adding or changing a number indicating the number of revisions to the read character string, and sets the processed character string as the file name of new file wrapper file 22. Next, storage processing unit 65 stores new file wrapper file 22 in the folder in which file wrapper file 14 is stored. The process of adding or changing a number indicating the number of revisions and the process of storing a new file wrapper file in a folder in which previous file wrapper files are stored will be described in detail later.

[0056] The list generating unit 66 generates the file attachment status list 34. FIG. 7 shows an example of the file attachment status list 34. The file attachment status list 34 is a list that records the attachment status of each file attached to each wrapper file by each of the time stamp individual addition process, the first time stamp batch addition process, and the second time stamp batch addition process of the attachment method for each file. The file attachment status list 34 records information that allows one to know which wrapper file each file is attached to, or what kind of file is attached to each wrapper file, or where each wrapper file is stored in the storage unit 53. Specifically, the file attachment status list 34 records, for each wrapper file stored in the storage unit 53, the file name of the file attached to the wrapper file, the file name of the wrapper file, and the storage location (folder name, etc.) of the wrapper file in the storage unit 53 in a form that is associated with each other. The file attachment status list 34 is also stored in the storage unit 53.

[0057] The file attachment status list 34 is formed by listing the file attachment status information. That is, in the time stamp individual addition process of the attachment method, the list generating unit 66 generates file attachment status information by recording the file name of the file attached to the wrapper file by the file attachment unit 62, the file name of the wrapper file set by the storage processing unit 65, and the storage location of the wrapper file stored by the storage processing unit 65 in association with each other. Then, the list generating unit 66 adds the generated file attachment status information to the file attachment status list 34. In addition, in each of the first time stamp batch addition process and the second time stamp batch addition process, the list generating unit 66 generates file attachment status information by recording the file name of each of the multiple files attached to the wrapper file by the file attachment unit 62, the file name of the wrapper file set by the storage processing unit 65, and the storage location of the wrapper file stored by the storage processing unit 65 in association with each other for each file attached to the wrapper file. Since the list generating unit 66 generates file attachment status information for each file attached to the wrapper file, when, for example, three files are attached to the wrapper file, three pieces of file attachment status information are generated. Then, the list generating unit 66 adds each piece of generated file attachment status information to the file attachment status list 34 .

[0058] Furthermore, when the list generating unit 66 adds the newly generated file attachment status information to the file attachment status list 34, if file attachment status information including the same "file name of the file attached to the wrapper file" as the "file name of the file attached to the wrapper file" included in the newly generated file attachment status information already exists in the file attachment status list 34, the list generating unit 66 deletes the file attachment status information already existing in the file attachment status list 34 and then adds the newly generated file attachment status information to the file attachment status list. Furthermore, when the list generating unit 66 adds the newly generated file attachment status information to the file attachment status list 34, if file attachment status information including the same "file name of the wrapper file" as the "file name of the wrapper file" included in the newly generated file attachment status information already exists in the file attachment status list 34, the list generating unit 66 deletes the file attachment status information already existing in the file attachment status list 34 and then adds the newly generated file attachment status information to the file attachment status list. As a result, only the latest file attachment status information for each file is listed in the file attachment status list 34.

[0059] An example of the generation of the file attachment status list 34 by the list generation unit 66 will be given. For example, in the first batch time stamp addition process, it is assumed that three files are attached to a wrapper file by the file attachment unit 62, and the file names of the three files are "Z product specification.docx", "Z product design drawing.dxf", and "Z product report.pdf", respectively. It is also assumed that the file name of the wrapper file set by the storage processing unit 65 is "Z product related document 01.pdf". It is also assumed that the storage location of the wrapper file stored by the storage processing unit 65 is "C:\documents\Z product". In this case, the list generation unit 66 first generates the three file attachment status information 38, 39, and 40 in FIG. 8(A).

[0060] Next, the list generating unit 66 checks whether or not file attachment status information including the same "file name of the file attached to the wrapper file" as the "file name of the file attached to the wrapper file" included in the newly generated file attachment status information 38 is already present in the file attachment status list 34 at the time when the new file attachment status information 38, 39, 40 is generated. Next, the list generating unit 66 checks whether or not file attachment status information including the same "file name of the wrapper file" as the "file name of the wrapper file" included in the newly generated file attachment status information 38 is already present in the file attachment status list 34 at the time when the new file attachment status information 38, 39, 40 is generated. Assume that the file attachment status list 34 shown in FIG. 8(B) is stored in the storage unit 53 at the time when the new file attachment status information 38, 39, 40 is generated. The file attachment status information 35 present in this file attachment status list 34 includes "Z product specification.docx" as the "file name of the file attached to the wrapper file". This is the same as "Z product specifications.docx" included as the "file name of the file attached to the wrapper file" in newly generated file attachment status information 38. In this case, list creation unit 66 deletes file attachment status information 35 existing in file attachment status list 34. Thereafter, list creation unit 66 adds the newly generated file attachment status information 38 to file attachment status list 34.

[0061] The list creation unit 66 performs the same process on the two newly created file attachment status information 39, 40. As a result, the file attachment status information 36 existing in the file attachment status list 34 is deleted, and then the newly created file attachment status information 39 is added to the file attachment status list 34, and then the file attachment status information 37 existing in the file attachment status list 34 is deleted, and then the newly created file attachment status information 40 is added to the file attachment status list 34. Finally, the file attachment status list 34 becomes the state shown in FIG. 7.

[0062] (File attachment process in the second batch timestamp addition process) In the second batch timestamp addition process, the file attachment unit 62 performs a process of identifying a wrapper file 14 to which a file 11 having the same file name as one file 21 specified by the user is attached, for example as shown in Fig. 5, duplicating all of the files 12, 13, except for the file 11 having the same file name as the file 21, out of the multiple files 11, 12, 13 attached to the wrapper file 14, and attaching the file 21 and the duplicated files 12, 13 to an empty wrapper file. Here, a detailed description will be given of how the file attachment unit 62 performs this process based on the file attachment status list 34.

[0063] Fig. 9 shows the second batch time stamp addition process having the same contents as the second batch time stamp addition process shown in Fig. 5. Fig. 9 shows examples of file names of files 11, 12, 13, and 21 and wrapper files 14 and 22.

[0064] 9, it is assumed that the user specifies file 21 with the file name "Z product specification.docx" and inputs a time stamp batch addition command to file management device 51. In this case, process selection unit 61 selects the second time stamp batch addition process, and the second time stamp batch addition process is started. In the second time stamp batch addition process, file attachment unit 62 first identifies a wrapper file to which a file with the same file name as file 21 specified by the user is attached, based on the file name of file 21 and file attachment status list 34.

[0065] The file attachment status list 34 is shown in Fig. 7 and Fig. 8(B), and as can be seen from the above description, the file attachment status list 34 shown in Fig. 8(B) is the file attachment status list 34 before the file attachment status information 35, 36, 37 is replaced by the file attachment status information 38, 39, 40 by the list generating unit 66, and the file attachment status list 34 shown in Fig. 7 is the file attachment status list 34 after the file attachment status information 35, 36, 37 is replaced by the file attachment status information 38, 39, 40 by the list generating unit 66. It is assumed that the file attachment status list 34 shown in Fig. 8(B) is stored in the storage unit 53 at the time when the user specifies the file 21 and inputs the time stamp batch addition command. As can be seen from Fig. 8(B), the file attachment status list 34 records the file names of the files attached to each wrapper list stored in the storage unit 53 and the file names of each wrapper list stored in the storage unit 53 in a mutually associated manner. The file attachment unit 62 refers to the file attachment status list 34 shown in Figure 8 (B), identifies file 11 having the same file name as the file name of file 21, "Z product specifications.docx", and identifies the wrapper file 14 having the file name "Z product related documents.pdf" that corresponds to the file name of file 11, "Z product specifications.docx".

[0066] Next, file attachment unit 62 identifies all of the multiple files attached to file wrapper file 14, except for file 11, which has the same file name as file 21, based on file attachment status list 34. Specifically, file attachment unit 62 refers to file attachment status list 34 shown in Fig. 8(B) and identifies file 12 having the file name "Z product design drawing.dxf" that is associated with the file name "Z product related documents.pdf" of file wrapper file 14, and file 13 having the file name "Z product report.pdf" that is associated with the file name "Z product related documents.pdf" of file wrapper file 14.

[0067] Next, file attachment unit 62 duplicates two files 12 and 13 that exist in wrapper file 14 in a form attached to wrapper file 14. Next, file attachment unit 62 reads an empty wrapper file from storage unit 53, and attaches file 21 and the duplicated files 12 and 13 to the read empty wrapper file. Thereafter, time stamp token acquisition unit 63 performs a process of acquiring a time stamp token 23 including a hash value and time information of wrapper file 22 to which files 21, 12, and 13 are attached from a time stamp authority, time stamp token embedding unit 64 performs a process of embedding the time stamp token 23 in wrapper file 22, storage processing unit 65 performs a process of setting "Z product related document 01.pdf" as the file name of wrapper file 22 to which files 21, 12, and 13 are attached and in which time stamp token 23 is embedded, and storage processing unit 65 stores wrapper file 22 in the folder in which wrapper file 14 is stored.

[0068] (Set the file name and location of the wrapper file) In the individual time stamp processing of the attachment method, as described above, if a previous file is stored in storage unit 53 with one attached file and the file name of that file being the same as the file name of the file attached to the new file, storage processing unit 65 reads the character string forming the file name of the previous file, performs a process of adding or changing a number indicating the number of revisions to the read character string, and sets the processed character string as the file name of the new file. Storage processing unit 65 then stores the new file in the folder in which the previous file is stored. This process will be described in detail.

[0069] In the individual time stamp processing of the attachment method, after a new wrapper file to which one file is attached and in which a time stamp token is embedded is generated by the file attachment unit 62, the time stamp token acquisition unit 63, and the time stamp token embedding unit 64, the storage processing unit 65 first determines whether or not a previous wrapper file to which a file with the same file name as the file attached to the new wrapper file is attached is stored in the storage unit 53. If such a previous wrapper file is stored in the storage unit 53, the storage processing unit 65 then identifies the file name of the previous wrapper file. The storage processing unit 65 performs these processes using the file attachment status list 34. As shown in FIG. 7, the file names of the files attached to each wrapper list stored in the storage unit 53 and the file names of each wrapper list stored in the storage unit 53 are recorded in association with each other in the file attachment status list 34. Therefore, the memory processing unit 65 can determine, based on the file attachment status list 34, whether or not a previous wrapper file to which a file with the same file name as the file attached to the new wrapper file is attached is stored in the memory unit 53, and can also identify the file name of the previous wrapper file based on the file attachment status list 34.

[0070] Next, the storage processing unit 65 reads the character string forming the file name of the past file wrapper file to which a file with the same file name as the file attached to the new file wrapper file is attached, processes the read character string by adding or changing a number indicating the number of revisions, and sets the processed character string as the file name of the new file wrapper file. Specifically, if the read character string (the character string forming the file name of the past file wrapper file) does not contain a number indicating the number of revisions, the storage processing unit 65 adds the number indicating the number of revisions to the read character string and sets it as the file name of the new file wrapper file. For example, if the read character string is "W product related documents.pdf", the storage processing unit 65 adds the number "01" indicating the number of revisions to the string and sets it as the file name of the new file wrapper file as "W product related documents 01.pdf". Furthermore, if the read character string (the character string forming the file name of the past wrapper file) contains a number indicating the number of revisions, the storage processor 65 changes the number indicating the number of revisions contained in the read character string (for example, replaces the number indicating the number of revisions with a number obtained by adding 1 to it), and sets the character string after the number indicating the number of revisions is changed as the file name of the new wrapper file. For example, if the read character string is "X product related documents 01.pdf", the storage processor 65 changes the "01" in this string to "02", and sets "X product related documents 02.pdf" as the file name of the new wrapper file.

[0071] Next, storage processing unit 65 identifies the folder in which the past file wrapper file is stored based on file attachment status list 34. File attachment status list 34 records the file names and storage locations of each file wrapper list stored in storage unit 53 in association with each other. Therefore, storage processing unit 65 can identify the folder in which the past file wrapper file is stored based on file attachment status list 34. Thereafter, storage processing unit 65 stores a new file in the folder in which the past file wrapper file is stored.

[0072] In each of the first timestamp batch addition process and the second timestamp batch addition process, when a new wrapper file is stored in memory unit 53, memory processing unit 65 performs a process of adding or changing a number indicating the number of revisions, and a process of storing the new wrapper file in the folder in which the previous wrapper file is stored. However, the details of these processes are similar to the process of adding or changing a number indicating the number of revisions in the individual timestamp addition process of the attachment method, and the process of storing the new wrapper file in the folder in which the previous wrapper file is stored.

[0073] (Overall flow of processing performed by the file management device) Fig. 10 shows an overall flow of processing performed by the arithmetic processing unit 52 of the file management device 51. In Fig. 10, the arithmetic processing unit 52 monitors input of commands from the user (step S1). During this time, when the user designates one file and inputs an individual timestamp addition command (step S1: YES), the process selection unit 61 judges whether the command input by the user is a batch timestamp addition command or an individual timestamp addition command (step S2). Since the command input by the user this time is an individual timestamp addition command, the process selection unit 61 judges that the command input by the user is an individual timestamp addition command (step S2: NO).

[0074] In this case, the processing selection unit 61 then checks the file format of the file specified by the user and determines whether the file specified by the user is a file having a structure that allows a timestamp token to be embedded within it (step S3).

[0075] Currently, PDF files have a structure that allows a time stamp token to be embedded therein. On the other hand, many files other than PDF files, such as text files, CSV files, Word files, Excel files, etc., do not have a structure that allows a time stamp token to be embedded therein. In this embodiment, when the file format of the file specified by the user is PDF, the process selection unit 61 determines that the file specified by the user is a file that has a structure that allows a time stamp token to be embedded therein, and when the file format of the file specified by the user is not PDF, the process selection unit 61 determines that the file specified by the user is not a file that has a structure that allows a time stamp token to be embedded therein. In addition, the process selection unit 61 recognizes the file format of the file based on the file extension.

[0076] Note that even PDF files may have an internal structure that differs from the regular internal structure of PDF, and therefore may not have a structure that allows a time stamp token to be embedded therein. Taking this into consideration, in step S3, if the file format of the file specified by the user is PDF and the internal structure of the file is the regular internal structure of PDF, it may be determined that the file specified by the user is a file that has a structure that allows a time stamp token to be embedded therein, and if not, it may be determined that the file specified by the user is not a file that has a structure that allows a time stamp token to be embedded therein.

[0077] If the file specified by the user has a structure that allows a time stamp token to be embedded therein (step S3: YES), the process selection unit 61 selects the direct method of individual time stamp addition process, and the calculation processing unit 52 starts the direct method of individual time stamp addition process (step S4).

[0078] FIG. 11 shows the flow of the direct method of individual time stamp addition processing. In FIG. 11, when the direct method of individual time stamp addition processing is started, first, the time stamp token acquisition unit 63 calculates a hash value of one file designated by the user, transmits the calculated hash value to the time stamp authority, and acquires a time stamp token including the hash value and time information from the time stamp authority (step S21). Next, the time stamp token embedding unit 64 embeds the time stamp token acquired by the time stamp token acquisition unit 63 into one file designated by the user (step S22). Next, the storage processing unit 65 stores the file in which the time stamp token is embedded by the time stamp token embedding unit 64 in the storage unit 53 (step S23). When storing the file in the storage unit 53, the storage processing unit 65 requests the user to specify a folder in which the file is to be stored and to input a file name of the file, as described above. Then, the storage processing unit 65 sets the file name input by the user in response to the request as the file name of the file, and stores the file in the folder designated by the user. After that, the processing returns to step S1 in FIG. 10.

[0079] On the other hand, in step S3, the process selection unit 61 checks the file format of the file specified by the user, and determines whether the file specified by the user is a file having a structure that allows a time stamp token to be embedded therein. If the file specified by the user is not a file having a structure that allows a time stamp token to be embedded therein (step S3: NO), the process selection unit 61 selects the attachment-type individual time stamp addition process. In this case, the calculation processing unit 52 starts the attachment-type individual time stamp addition process (step S5).

[0080] In addition, when a file having a file format that is highly likely to contain a computer virus or spyware is attached to a PDF file, there is a risk that the file attached to the PDF file cannot be opened later. Therefore, it is preferable to avoid attaching a file having a file format that is highly likely to contain a computer virus or spyware to a wrapper file by using the individual time stamp attachment process of the attachment method. Therefore, a file format list that records file formats (e.g., file extensions) that are not highly likely to contain a computer virus or spyware may be created in advance and stored in the storage unit 53, and in step S3, if the file specified by the user does not have a structure that allows a time stamp token to be embedded therein and has a file format recorded in the file format list, the individual time stamp attachment process of the attachment method may be selected.

[0081] FIG. 12 shows the flow of the individual time stamp addition process of the attachment method. In FIG. 12, when the individual time stamp addition process of the attachment method is started, first, the file attachment unit 62 reads out an empty wrapper file stored in the storage unit 53 from the storage unit 53, and attaches one file designated by the user to the read empty wrapper file (step S31). Next, the time stamp token acquisition unit 63 calculates a hash value of the wrapper file to which one file is attached by the file attachment unit 62, transmits the calculated hash value to the time stamp authority, and acquires a time stamp token including the hash value and time information from the time stamp authority (step S32). Next, the time stamp token embedding unit 64 embeds the time stamp token acquired by the time stamp token acquisition unit 63 into the wrapper file to which one file is attached by the file attachment unit 62 (step S33). Next, the storage processing unit 65 stores the wrapper file to which one file is attached by the file attachment unit 62 and in which the time stamp token is embedded by the time stamp token embedding unit 64 as a new wrapper file in the storage unit 53 (step S34). Furthermore, when storing the new wrapper file in memory unit 53, as described above, storage processing unit 65 determines whether or not a previous wrapper file which has one attached file and whose file name is the same as the file name of the one file attached to the new wrapper file is stored in memory unit 53, and if such a previous wrapper file is stored in memory unit 53, it reads the character string which forms the file name of the previous wrapper file, processes the read character string by adding or changing a number indicating the number of revisions, and sets the processed character string as the file name of the new wrapper file. Next, storage processing unit 65 stores the new wrapper file in the folder in which the previous wrapper file is stored.On the other hand, if there is only one file attached and no previous wrapper file with the file name of that file that is the same as the file name of the file attached to the new wrapper file is stored in memory unit 53, memory processing unit 65 requests the user to specify a folder in which to store the new wrapper file and to input a file name for the new wrapper file, sets the file name input by the user in response to the request as the file name of the new wrapper file, and stores the new wrapper file in the folder specified by the user.

[0082] After the individual timestamp addition process for the attachment method is completed, list creation unit 66 creates or updates file attachment status list 34 (step S6), as shown in Fig. 10. That is, as described above, list creation unit 66 creates file attachment status information by recording the file name of the file attached to the wrapper file by file attachment unit 62, the file name of the wrapper file set by storage processing unit 65, and the storage location of the wrapper file stored by storage processing unit 65 in association with each other, and adds the file attachment status information to file attachment status list 34. Then, processing returns to step S1.

[0083] Also, while the file management device 51 is monitoring the input of a command from the user, when the user inputs a command to add a time stamp all at once by specifying multiple files, the process selection unit 61 judges whether the command input by the user is a command to add a time stamp all at once or a command to add a time stamp individually. Since the command input by the user this time is a command to add a time stamp all at once, the process selection unit 61 judges that the command input by the user is a command to add a time stamp all at once (step S2: YES). In this case, the process selection unit 61 then judges whether the user has specified one file or multiple files (step S7). Then, since the user has specified multiple files this time, the process selection unit 61 judges that the user has specified multiple files (step S7: NO). In this case, the process selection unit 61 selects the first process to add a time stamp all at once. Then, the calculation processing unit 52 starts the first process to add a time stamp all at once (step S8).

[0084] FIG. 13 shows the flow of the first time stamp batch addition process. In FIG. 13, when the first time stamp batch addition process is started, first, the file attachment unit 62 reads out an empty wrapper file stored in the storage unit 53 from the storage unit 53, and attaches multiple files specified by the user to the read empty wrapper file (step S41). Next, the time stamp token acquisition unit 63 calculates a hash value of the wrapper file to which the multiple files are attached by the file attachment unit 62, transmits the calculated hash value to the time stamp authority, and acquires a time stamp token including the hash value and time information from the time stamp authority (step S42). Next, the time stamp token embedding unit 64 embeds the time stamp token acquired by the time stamp token acquisition unit 63 into the wrapper file to which the multiple files are attached by the file attachment unit 62 (step S43). Next, the storage processing unit 65 stores the wrapper file to which the multiple files are attached by the file attachment unit 62 and in which the time stamp token is embedded by the time stamp token embedding unit 64 as a new wrapper file in the storage unit 53 (step S44). Furthermore, when storing the new wrapper file in memory unit 53, as described above, storage processing unit 65 determines whether or not a previous wrapper file is stored in memory unit 53 which has the same number of files attached as the files attached to the new wrapper file and which has the same file names as the files attached to the new wrapper file, and if such a previous wrapper file is stored in memory unit 53, it reads the character string which forms the file name of the previous wrapper file, processes the read character string by adding or changing a number indicating the number of revisions, and sets the processed character string as the file name of the new wrapper file. Storage processing unit 65 then stores the new wrapper file in the folder in which the previous wrapper file is stored.On the other hand, if the same number of files are attached as the files attached to the new wrapper file, and no previous wrapper files are stored in memory 53 whose file names are the same as those of the files attached to the new wrapper file, then memory processing unit 65 requests the user to specify a folder in which to store the new wrapper file and to input a file name for the new wrapper file, sets the file name input by the user in response to the request as the file name of the new wrapper file, and stores the new wrapper file in the folder specified by the user.

[0085] After the first batch time stamp addition process is completed, the list creation unit 66 creates or updates the file attachment status list 34 (step S9), as shown in Fig. 10. Then, the process returns to step S1.

[0086] Furthermore, when the user inputs a timestamp batch addition command specifying one file while the file management device 51 is monitoring input of commands from the user, the process selection unit 61 determines that the command input by the user is a timestamp batch addition command (step S2: YES), and then determines that one file has been specified by the user (step S7: YES). In this case, the process selection unit 61 selects the second timestamp batch addition process. Then, the calculation processing unit 52 starts the second timestamp batch addition process (step S10).

[0087] FIG. 14 shows the flow of the second time stamp batch addition process. In FIG. 14, when the second time stamp batch addition process is started, first, the file attachment unit 62 identifies a past file wrapper file to which a file having the same file name as the one file specified by the user is attached from among a plurality of past file wrapper files stored in the storage unit 53 (step S51). Next, the file attachment unit 62 copies all files other than the file having the same file name as the one file specified by the user among the plurality of files attached to the identified past file wrapper file (step S52). Next, the file attachment unit 62 reads out an empty file wrapper file stored in the storage unit 53 from the storage unit 53, and attaches the one file specified by the user and the copied file to the read empty file (step S53). Next, the time stamp token acquisition unit 63 calculates a hash value of the wrapper file to which the one file specified by the user and the copied file are attached, transmits the calculated hash value to the time stamp authority, and acquires a time stamp token including the hash value and time information from the time stamp authority (step S54). Next, the time stamp token embedding unit 64 embeds the time stamp token acquired by the time stamp token acquisition unit 63 into a file to which the one file specified by the user and the duplicated files are attached (step S55). Next, the storage processing unit 65 stores the file to which the one file specified by the user and the duplicated files are attached and in which the time stamp token is embedded by the time stamp token embedding unit 64 as a new file in the storage unit 53 (step S56). When storing the new file in the storage unit 53, the storage processing unit 65 reads a character string forming the file name of a previous file to which a file having the same file name as the one file specified by the user is attached, performs a process of adding or changing a number indicating the number of revisions to the read character string, and sets the processed character string as the file name of the new file. Next, the storage processing unit 65 stores the new file in the folder in which the previous file is stored.

[0088] After the second batch time stamp addition process is completed, the list creation unit 66 creates or updates the file attachment status list 34 (step S11), as shown in Fig. 10. Then, the process returns to step S1.

[0089] In step S51 of the second batch timestamp addition process shown in FIG. 14, if there is no past wrapper file among the multiple past wrapper files stored in memory unit 53 to which a file with the same file name as the file specified by the user is attached, and therefore file attachment unit 62 is unable to identify such a past wrapper file, then, for example, an error message is displayed on display unit 56, the second batch timestamp addition process is aborted, and the process returns to step S1 in FIG. 10.

[0090] (Example of using the first and second timestamp batch addition process) An example of a method of using the first time stamp batch addition process and the second time stamp batch addition process will be described with reference to Fig. 15. Fig. 15(A) shows the file wrapper file 14 in Fig. 9, and Fig. 15(B) shows the file wrapper file 22 in Fig. 9.

[0091] For example, a user creates a file 11 of a product Z specification, a file 12 of a product Z design drawing, and a file 13 of a product Z report, and stores these in the memory unit 53. These three files 11, 12, and 13 are all related to the product Z, and therefore these three files 11, 12, and 13 are related to each other.

[0092] Thereafter, when the user specifies the three files 11, 12, and 13 and inputs a time stamp batch addition command to the file management device 51 in order to start managing the three files 11, 12, and 13 using time stamps, the file management device 51 performs a first time stamp batch addition process. As a result, the file wrapper file 14 shown in FIG. 15(A) is created. Also, when the file wrapper file to which the files 11, 12, and 13 are attached is stored in the storage unit 53 for the first time, that is, when the file wrapper file to which the files 11, 12, and 13 are attached has not yet been stored in the storage unit 53, the file management device 51 requests input of the file name of the file wrapper file 14. When the user inputs "Z product related documents" in response to this request, the file management device 51 sets the file name of the file wrapper file 14 to "Z product related documents.pdf", and the file wrapper file 14 is stored in the storage unit 53.

[0093] Thereafter, for example, a user who has the authority to change the contents of the Z product specification makes a partial change to the contents of file 11 of the Z product specification, and stores the file with the partially changed contents of file 11 in storage unit 53 without changing the file name. When the contents of a file are changed, the file before the content change and the file after the content change are different files, even if the file name of the file is not changed. The file with the partially changed contents of file 11 but the unchanged file name is called "file 21." Although file 21 has some different contents from file 11, like file 11, it is a document describing the specifications of the Z product, and therefore is a file related to files 12 and 13.

[0094] Thereafter, when the user designates file 21 and inputs a timestamp batch addition command to file management device 51 in order to manage file 21 together with files 12 and 13 using timestamps, a second timestamp batch addition process is performed by file management device 51. As a result, file wrapper file 22 shown in FIG. 15(B) is created. File management device 51 also automatically sets the file name of file wrapper file 22 to "Z product related processing.pdf" with the revision number "01" added, to "Z product related documents 01.pdf", and then file wrapper file 22 is stored in memory unit 53 in the same folder as file wrapper file 14.

[0095] In this way, when a user starts managing a plurality of files related to each other using time stamps, the user specifies the plurality of files and inputs a time stamp batch addition command to the file management device 51, causing the file management device 51 to execute a first time stamp batch addition process. As a result, a file wrapper file to which the plurality of files related to each other are attached and in which time stamp tokens for those files are embedded is stored in the storage unit 53. Thereafter, when the user partially changes the content of one of the plurality of files related to each other without changing the file name, and when the user wishes to continue managing the file with the changed content together with other files related to that file using time stamps, the user specifies the file with the changed content and inputs a time stamp batch addition command to the file management device 51, causing the file management device 51 to execute a second time stamp batch addition process. As a result, a file wrapper file to which the file with the changed content and other files related to that file are attached and in which time stamp tokens for those files are embedded is stored in the storage unit 53.

[0096] (View the file attached to the file wrapper) Fig. 16 shows the state in which the file wrapper file 22 shown in Fig. 15(B) is opened by a PDF file reader application. As shown in Fig. 16, the first page of the file wrapper file 22 contains a character string 41 indicating that the file wrapper file 22 is a file wrapper file, a file name 42 of the file wrapper file 22, and information 43 on the files 21, 12, and 13 attached to the file wrapper file 22, and also has a time stamp imprint 44. The reader application displays a list 45 of the file names of the files 21, 12, and 13 attached to the file wrapper file 22. The user can click any file name in the list 45 with the mouse to open the file having that file name.

[0097] As described above, the file management device 51 according to the embodiment of the present invention performs the second batch time stamp addition process when one file is designated by the user and a batch time stamp addition command is input to the file management device 51. That is, the file management device 51 identifies a wrapper file to which a file with the same file name as the file designated by the user is attached from among multiple wrapper files stored in the storage unit 53, copies all files other than the file with the same file name as the file designated by the user among multiple files present in the identified wrapper file in a form attached to the specified wrapper file, attaches the file designated by the user and the copied file to an empty wrapper file, obtains a time stamp token including a hash value and time information of the wrapper file to which the file designated by the user and the copied file are attached from a time stamp authority, embeds the obtained time stamp token in the wrapper file to which the file designated by the user and the copied file are attached, and stores the wrapper file in the storage unit 53 as a new wrapper file. According to this configuration, the method of attaching multiple files to one wrapper file and embedding a time stamp token in the one wrapper file makes it easy to manage multiple files in a batch.

[0098] Specifically, a user can use file management device 51 to create a wrapper file with one file and other files related to the one file attached, and with timestamp tokens embedded for these files, and if the user then makes a partial change to the contents of the one file without changing the file name, the user can simply specify the file with the partially changed contents and input a timestamp addition command to file management device 51, and can easily use file management device 51 to create a wrapper file with the partially changed file and the other files related to the one file attached, and with new timestamp tokens embedded for these files.

[0099] That is, a user can use file management device 51 to create a file in which one file, other related files, and the time stamp tokens for those files are bundled together via a wrapper file, thereby making it easy to collectively manage one file and other related files using time stamps. In addition, when a user partially changes the content of one file without changing the file name, the user can easily use file management device 51 to create a file in which the partially changed content, the other related files, and the time stamp tokens for those files are bundled together via a wrapper file, thereby making it easy to collectively manage the file after the content change and the other related files using time stamps.

[0100] In particular, before the content of the one file is partially changed, the user can use the file management device 51 to create a file in which the file before the content change and other files related to it are combined via a wrapper file, and after the content of the one file is partially changed, the user can use the file management device 51 to create a file in which the file after the content change and other files related to it are combined via a wrapper file. As a result, the identity of the combination of the file and other files related to it is maintained before and after the content of the file is partially changed. Therefore, according to the file management device 51, even if the user changes the content of a file, the file after the content change and other files related to it can be easily managed collectively using timestamps in the same way as the file before the content change and other files related to it. In other words, it is possible to prevent a situation in which it becomes difficult to collectively manage the file and other files related to it after the content of the file is partially changed.

[0101] 5, when file attachment unit 62 identifies file wrapper file 14 to which file 11 having the same file name as file 21 specified by the user is attached, and attaches all files 12 and 13 other than file 11 among the three files 11, 12, and 13 attached to identified file wrapper file 14 to an empty file, file attachment unit 62 copies files 12 and 13 that exist in file wrapper file 14 in a form that was attached to file wrapper file 14, and attaches the copied files 12 and 13 to the empty file wrapper file. As a result, as long as file wrapper file 14 to which files 11, 12, and 13 are attached is stored in storage unit 53, file wrapper file 22 to which files 21, 12, and 13 are attached can be generated even if files 12 and 13 are not stored as independent files in storage unit 53. In addition, even if the user forgets the storage location of the file 12 or 13 after creating the file wrapper file 14 with the files 11, 12, and 13 attached by using the file management device 51, the user can create the file wrapper file 22 with the files 21, 12, and 13 attached by using the file management device 51.

[0102] 5, the user can use file management device 51 to create file wrapper file 22 to which files 21, 12, and 13 are attached and in which time stamp token 23 is embedded, simply by specifying file 21 and inputting a command to add time stamps all at once. Thus, according to this embodiment, the user can create, with a simple operation, a file whose contents have been changed, other related files, and the time stamp tokens for those files, all organized together in a wrapper file.

[0103] 15, a post-revision file wrapper file 22, to which multiple files including file 21 after content change are attached and in which a time stamp token is embedded, is stored in the same folder as a pre-revision file wrapper file 14, to which multiple files including file 11 before content change are attached and in which a time stamp token is embedded. This allows the user to easily manage all versions of the wrapper files collectively and also to easily check the files before content change.

[0104] 15, the file name of a file wrapper file 22 that has been revised once, i.e., the second version of file wrapper file 22, has the revision number "01" automatically added to the file name of the first version of file wrapper file 14. Furthermore, thereafter, each time the file wrapper file is revised, the revision number in the file name of the revised file wrapper file is changed (incremented). This allows users to easily manage the versions of file wrapper files.

[0105] In file management device 51, list generator 66 generates file attachment status list 34 for each of a plurality of wrapper files stored in memory 53, in which the file name of each file attached to the wrapper file, the file name of the wrapper file, and the storage location of the wrapper file in memory 53 are recorded in association with each other. Then, in the second batch time stamp addition process, file attachment unit 62, when identifying a wrapper file to which a file with the same file name as one file specified by the user is attached from among the plurality of wrapper files stored in memory 53, identifies the wrapper file based on file attachment status list 34. This makes it possible to quickly identify a wrapper file to which a file with the same file name as one file specified by the user is attached. In other words, compared to the process of searching for and identifying a wrapper file based on the file name of the wrapper file, the process of searching for and identifying a wrapper file based on the file name of a file attached to the wrapper file is not easy. It is certainly possible to search for and identify a wrapper file based on the file name of a file attached to a wrapper file by reading out the wrapper files stored in memory unit 53 one by one and checking the file names of the files attached to each wrapper file, but this process may take a long time if there are a large number of wrapper files stored in memory unit 53. In contrast, in this embodiment, the process of searching for and identifying a wrapper file based on the file name of a file attached to a wrapper file is performed based on file attachment status list 34, so that the time required for this process can be shortened even if there are a large number of wrapper files stored in memory unit 53.

[0106] Furthermore, when storing a new file wrapper file in memory unit 53, storage processing unit 65 reads the character string forming the file name of the past file wrapper file corresponding to the new file wrapper file, and in the process of setting the file name of the new file wrapper file after processing to add or change a number indicating the number of revisions to the character string, identifies the file name of the past file wrapper file based on file attachment status list 34. This makes it possible to quickly identify the file name of the past file wrapper file.

[0107] Furthermore, in the process of storing a new file wrapper file in a folder in which a previous file wrapper file corresponding to the new file has been stored, storage processing unit 65 identifies the folder in which the previous file has been stored based on file attachment status list 34. This makes it possible to quickly identify the folder in which the previous file wrapper file has been stored.

[0108] In the second batch time stamp addition process of the above embodiment, the file attachment unit 62 identifies the file wrapper file 14 to which the file 11 having the same file name as the file 21 specified by the user is attached, as shown in Fig. 5, copies all files 12 and 13 other than the file 11 attached to the file wrapper file 14, and attaches the file 21 specified by the user and the copied files 12 and 13 to a new file wrapper file 22. However, instead of this process, as shown in Fig. 17, the file wrapper file 14 to which the file 11 having the same file name as the file 21 specified by the user is attached may be identified, all files 12 and 13 other than the file 11 attached to the file wrapper file 14 may be copied, and the file 21 specified by the user, the copied files 12 and 13, and the file wrapper file 14 may be attached to a new file wrapper file 47. In this case, time stamp token acquisition unit 63 acquires time stamp token 48 including the hash value and time information of wrapper file 47 to which files 21, 12, 13 and wrapper file 14 are attached, time stamp token embedding unit 64 embeds the acquired time stamp token 48 in wrapper file 47 to which files 21, 12, 13 and wrapper file 14 are attached, and storage processing unit 65 stores wrapper file 47 to which files 21, 12, 13 and wrapper file 14 are attached and in which time stamp token 48 is embedded, in storage unit 53. This allows the user to easily manage the version of the wrapper file or check the contents of the file before the contents were changed, etc.

[0109] In the above embodiment, when the user inputs a time stamp batch addition command to the file management device 51, the file management device 51 determines whether to perform the first time stamp batch addition process or the second time stamp batch addition process depending on whether the user has specified multiple files or one file. However, the present invention is not limited to this. For example, a first time stamp batch addition command commanding the start of the first time stamp batch addition process and a second time stamp batch addition command commanding the start of the second time stamp batch addition process may be provided, and whether to perform the first time stamp batch addition process or the second time stamp batch addition process may be determined depending on whether the first time stamp batch addition command or the second time stamp batch addition command has been input. In this case, for example, command names such as "Add timestamps individually," "Add new timestamps all at once," and "Add timestamps all at once when revision occurs" are displayed in the context menu 32 in Figure 6, and when the user selects "Add new timestamps all at once," a first timestamp addition command is input to the file management device, and when the user selects "Add timestamps all at once when revision occurs," a second timestamp addition command is input to the file management device.

[0110] Furthermore, the wrapper file is not limited to a PDF file, but may be any other file format that can attach files to itself and can embed a timestamp token therein.

[0111] In addition, in the above embodiment, an example was given of using the second timestamp batch addition process when the contents of a file are partially changed without changing the file name. However, even if the contents of a file are completely changed without changing the file name, the second timestamp batch addition process can be used in the same way as when the contents of a file are partially changed without changing the file name.

[0112] Furthermore, the present invention can be modified as appropriate within the scope that does not contradict the gist or idea of ​​the invention that can be read from the claims and the entire specification, and file management programs and file management devices involving such modifications are also included in the technical idea of ​​the present invention. [Industrial Applicability]

[0113] The file management program of the present invention can be used in application software for managing files, or in a document reader or operating system having a function for managing files, etc. Furthermore, the file management device of the present invention can be used in various devices having a function for managing files. [Explanation of symbols]

[0114] 11, 12, 13, 21 files 14, 22, 47 File envelope 15, 23, 48 Time Stamp Token 34 File Attachment Status List 51 File management device 52 Processing unit 53 Storage section 61 Processing selection section 62 File Attachment 63 Time stamp token acquisition unit 64 Time stamp token embedding section 65 Memory Processing Unit 66 List Generation Unit

Claims

1. A file management program for causing a computer having a storage device or connected to the storage device to function as a file management device that manages files using time stamps, comprising: The file management device includes: a file attachment section which, when a user designates one file and inputs a batch timestamp addition command to the file management device while a plurality of wrapper files to which a plurality of files are attached and in which a timestamp token is embedded are stored in the storage device, identifies a wrapper file to which a file with the same file name as the designated file is attached from among the plurality of wrapper files stored in the storage device, copies all files other than the designated file and the file with the same file name as the designated file from among the plurality of files present in the identified wrapper file in a form attached to the identified wrapper file, reads from the storage device an empty wrapper file stored in the storage device, and attaches the designated file and the copied file to the read empty wrapper file; a time stamp token acquisition unit that acquires from a time stamp authority a time stamp token including a hash value and time information of a wrapper file to which the specified file and the copied file are attached; a time stamp token embedding unit that embeds the acquired time stamp token into a wrapper file to which the specified file and the copied file are attached; A file management program characterized by having a storage processing unit that stores a wrapper file to which the specified file and the duplicated file are attached and in which the acquired timestamp token is embedded as a new wrapper file in the storage device.

2. the file management device includes a list generating unit that generates, for each of the plurality of file wrapper files stored in the storage device, a list that records, in association with one another, the file name of each file attached to the file wrapper file, the file name of the file wrapper file, and the storage location of the file wrapper file within the storage device; The file management program according to claim 1, characterized in that the file attachment section identifies a wrapper file to which a file having the same file name as the specified file is attached based on the file name of the specified file and the list.

3. The file management program according to claim 2, characterized in that the storage processing unit identifies a folder based on the list in which a file wrapper file having an attached file with the same file name as the specified file is stored, and stores the new file wrapper file in the identified folder.

4. The file management program described in claim 2, characterized in that, when storing the new wrapper file in the storage device, the memory processing unit reads a character string that forms the file name of a wrapper file to which a file with the same file name as the specified file is attached, and if the read character string does not contain a number indicating the number of revisions, sets the read character string with a number indicating the number of revisions added as the file name of the new wrapper file, and if the read character string contains a number indicating the number of revisions, sets the read character string with the number indicating the number of revisions contained in the string changed as the file name of the new wrapper file.

5. the file attachment unit attaches the specified file, the duplicated file, and the identified wrapper file to the read empty wrapper file; the time stamp token acquisition unit acquires from a time stamp authority a time stamp token including hash values ​​and time information of a file wrapper file to which the specified file, the duplicated file, and the identified file wrapper file are attached; the time stamp token embedding unit embeds the acquired time stamp token into a wrapper file to which the specified file, the duplicated file, and the identified wrapper file are attached; The file management program of claim 1, characterized in that the storage processing unit stores the specified file, the duplicated file, and the identified wrapper file attached, and the wrapper file in which the acquired timestamp token is embedded, as a new wrapper file in the storage device.

6. A file management device having a storage device or connected to the storage device, and managing files using time stamps, a file attachment section which, when a user designates one file and inputs a batch timestamp addition command to the file management device while a plurality of wrapper files to which a plurality of files are attached and in which a timestamp token is embedded are stored in the storage device, identifies a wrapper file to which a file with the same file name as the designated file is attached from among the plurality of wrapper files stored in the storage device, copies all files other than the designated file and the file with the same file name as the designated file from among the plurality of files present in the identified wrapper file in a form attached to the identified wrapper file, reads from the storage device an empty wrapper file stored in the storage device, and attaches the designated file and the copied file to the read empty wrapper file; a time stamp token acquisition unit that acquires from a time stamp authority a time stamp token including a hash value and time information of a wrapper file to which the specified file and the copied file are attached; a time stamp token embedding unit that embeds the acquired time stamp token into a wrapper file to which the specified file and the copied file are attached; A file management device characterized by having a storage processing unit that stores a wrapper file to which the specified file and the duplicated file are attached and in which the acquired timestamp token is embedded as a new wrapper file in the storage device.

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