WO2005114429A1

WO2005114429A1 - Storage device auditing method and storage device

Info

Publication number: WO2005114429A1
Application number: PCT/JP2004/007406
Authority: WO
Inventors: Katsumi Honda
Original assignee: Hypergear Inc
Priority date: 2004-05-24
Filing date: 2004-05-24
Publication date: 2005-12-01

Abstract

Defects or falsification of a file to be audited are detected with certainty, and not only the live data of the file but also the attributes thereof are audited. Hash value producing means (11a) produces hash values (h#0-1, h#0-2, ···) from system area information (e.g., file name, date and time of production, producer) for all files to be audited (1, 2, ···), and further produces harsh values (h#1, h#2, ···) from the live data. Hash value table producing means (11b) produces a hash value table (ht) from the hash values (h#0-1, h#0-2, ···; h#1, h#2, ···). Time authentication requesting means (11c) produces and transmits a hash value (h#t) obtained by hashing the hash value table (ht) to a time authentication server (103), thereby requesting for a time authentication. The time authentication is executed at each predetermined timing.

Description

Specification

Method of auditing storage device, and storage device

The present invention provides a method of auditing a storage device that receives time authentication of a file stored in the storage device and detects missing or falsification of a file to be audited using a time-authenticated hash value, It relates to a storage device using the method. Background technology

In recent years, government offices, offices, and other offices have become increasingly paperless in recording documents, creating files such as electronic books and electronic medical records on workstations, editing them, and storing them on recording devices. ing.

However, conventional storage devices can easily read and write files, so that unauthorized operations such as file deletion and falsification can be performed easily. Therefore, in order to ensure the authenticity of the stored file, once the file is recorded, the storage medium is used once again, and the file is read and written using different heads. A hardware method, such as using a specially structured recording device, or a software method, in which a digital signature of the creator is attached to a file, is used.

However, such a hardware method is not cost-effective, and a soft method only proves that the creator who has the digital certificate has created the file. Since it does not become a proof, it is easy for the creator himself to falsify the electronic file.

Therefore, in recent years, time certification of files using a time certification organization has been adopted. That is, in this method, a trusted time certification authority receives the hash value of the file from the creator of the file, digitally signs the hash value and returns the digital signature, and compares the digital signature with the proof of existence of the electronic file at that time. (Time authentication).

However, even if such time authentication is performed, it merely proves the time authentication of each of the electronically signed files, and when multiple files are stored in the storage device, the Since it does not prove the entire contents of the aggregate, it is difficult to detect the unauthorized operation when a specific file is intentionally deleted by unauthorized operation.

Therefore, recently, a service as shown in US Pat. No. 5,136,464 has been used to create a hash value from each of a plurality of files, A hash tree is defined as a leaf with a hash value, and further hashing is performed hierarchically, so that a super hash value is created from the hash value of the final root. Therefore, if there is any falsification or intentional omission of the leaf specific file, the super-hash value will fluctuate when recalculation is performed. . Disclosure of the invention

However, according to Patent Document 1 described above, even if the falsification of the contents of a specific file can be detected, it is practically only the service provider that can verify that there is no omission in the time-authenticated file. Further, in proving that the contents of the particular file have not been tampered with or lost, the service provider will provide the weekly superhash value from which the hash value of the file was sent and the weekly hash value of the week. (A super-hash value published in a newspaper), but at present it is impossible for ordinary users to understand even the principle of the proof.

The present invention is proposed in consideration of the above circumstances, and creates hash values from each of the files stored in a storage device, and further creates a hash value list including those hash values. A method of auditing a storage device that can detect falsification or omission of a stored file by receiving an electronic signature from the hash value list at a time certification organization, and using that method It is intended to provide a storage device.

In order to solve the above problems, the present invention provides, as a first invention, a method of auditing a storage device according to claims 1 to 5, and further, as a second invention, claims 6 to 11 Accordingly, a storage device using the method is provided.

That is, a storage device auditing method according to a first aspect of the present invention includes a storage medium for storing a file in which a data area and a system area are formed, and a file is stored. In some cases, the actual data of the file is stored in the data storage area, while the file name and attribute information such as path information and creation date and time are stored in the system area in association with each other. In the compliant storage device, for each file to be audited, a hash value is created from a part of the system area and the actual data of the file, and the hash value created by the hash value creating means is created. A hash value list including each of the above is created, and the hash value further created from the hash value list created by the hash value list creation means is time-authenticated. Requesting time authentication by transmitting the time authentication token to the server via the network, and receiving the time authentication token from the time authentication server, a predetermined operation for storing the time authentication token in association with the hash value list is determined. Execute at every timing of When verifying files to be audited, hash values are created again by the hash value creation means in the same manner as in the hash value list for all the files to be verified, and the time authentication is performed. It is characterized in that the file is compared with the corresponding hash value in the hash value table stored in association with the token, and the file is audited for missing or tampered.

According to the storage device audit method described in claim 2, at each predetermined timing, for each of the files to be audited, a no and a hash value are created from a part of the system area, Furthermore, it is characterized in that a hash value is created from the actual data of the file. _ ― ―

The storage device audit method according to claim 3 is characterized in that, at a predetermined timing, for each of the files to be audited, a part of the system area and the actual data of the file are compared. The method is characterized in that a hash value is created after combining in accordance with a predetermined rule.

The storage device audit method according to claim 4, wherein information indicating that the file has been erased can be written in the attribute information of each file stored in the system area, and the file to be audited is When erasing, the information indicating the erasure is added to the attribute information, and the actual data stored in the data storage area is left.

In the storage device audit method according to claim 5, when the hash value list is created, a history-type hash value list further including a hash value created from a previously created hash value list. Is created.

The storage device according to claim 6 as a second invention has a storage medium for storing a file in which a data area and a system area are formed, and when a file is stored, the actual data of the file is stored. Is stored in the above-mentioned temporary storage area, while the file name and attribute information such as path information and creation date and time are stored in the above-mentioned system area in association with each other. For each of the files to be audited, a hash value creating means for creating a hash value from a part of the system area and the actual data of the file, and a hash value creating means for the hash value creating means. A hash value list creating means for creating a hash value list including the hash value list, and a hash value list created by the hash value list creating means. The time authentication server requests the time authentication by transmitting the generated hash value to the time authentication server via the network. When the time authentication token is received from the time authentication server, the time authentication token and the hash value list are compared. It is provided with time authentication request means that is stored in association with it.

8. The storage device according to claim 7, wherein the hash value creation unit is configured to execute the audit. For each of the target files, a hash value is created from a part of the system area, and a hash value is created from the actual data of the file.

In the storage device according to the present invention, the hash value creating means determines a part of the system area and an actual data of the file for each of the files to be audited. It is configured to create a hash value after combining according to the rules of.

In the storage device according to the ninth aspect, in the storage medium, the Ji property information of each file stored in the system area can be written with information indicating that the file has been erased, and the audit is stored. When the target file is deleted, the information indicating that the file has been deleted is added to the attribute information, and the actual data stored in the data area is left. In the storage device according to the tenth aspect, the hash value list creation means includes a history type hash value further including a hash value created from a hash value list created last time. It is configured to create a hash value list.

In the storage device according to claim 11, when verifying the file to be audited, all of the files to be verified are processed by the hash value generating means in the same manner as the hash value list. After creating the hash values again, an auditing means for auditing the missing or falsified files by comparing them with the corresponding hash values in the hash value list stored in association with the time authentication token is further provided. Have.

According to Claims 1 to 5, at every predetermined timing, a time certification by an external certification organization is performed for a hash value list including the hash value of each file stored in the storage device and to be audited. When verifying a file, you need to recreate the respective hash values of the files to be audited and then compare them with the corresponding hash values in the time-validated hash table. In addition, missing or falsified files to be audited can be reliably detected.

In particular, according to claim 2, at each predetermined timing, for each of the files to be audited, a separate hash value is created from a part of the system area and the actual data of the file. Audits can be performed for file attributes in addition to actual data.

In particular, according to claim 3, at each predetermined timing, for each of the files to be audited, a part of the system area and the actual data of the file are combined according to a predetermined rule, and then a hash is performed. Since the value is created, it is possible to audit not only the actual data of the file but also the attributes of the file. In particular, according to claim 4, when erasing a file to be audited, information indicating that the file has been erased is added to the attribute information to leave the actual data stored in the data area. Playback and restore files deleted by unauthorized operation.

In particular, according to claim 5, the history type hash value list further including the hash value created from the previously created hash value list is created, so that the processing speed is improved in the write-once type storage device.

According to Claims 6 to 11, at each predetermined timing, a hash value list containing each of the files of the file stored in the storage device and subject to the audit is included in an external certification authority. The configuration is to receive the time certification by, so that the missing or falsified file to be audited can be detected without fail.

In particular, according to claim 7, for each predetermined timing, a separate hash value is created for each of the files to be audited from a part of the system area and the actual data of the file. Auditing can be performed on file attributes as well as actual file data.

In particular, according to claim 8, at each predetermined timing, for each of the files to be audited, a part of the system area and the actual data of the file are combined in accordance with a predetermined rule, Because the value is created, auditing can be performed for file attributes as well as actual file data.

In particular, according to claim 9, when erasing a file to be audited, information indicating that the file has been erased is added to the attribute information to leave the actual data stored in the data area. With this configuration, files deleted by unauthorized operations can be played back and restored.

In particular, according to Claim 10, since the history type hash value list further including the hash value created from the previously created hash value list is created, the processing speed is improved in the write-once type storage device. I do.

In particular, according to claim 11, when the auditing means verifies the files to be audited, each of the files to be audited has the same hash value as the hash value list by the hash value creating means. After re-creating the files, they are compared with the corresponding hash values in the time-certified hash value list, and the file is audited for missing or falsified data, so special equipment is required for audit processing. Not. Brief Description of Drawings

FIG. 1 is an example of a network system to which the storage device of the embodiment is connected. FIG. 2 is a data flow diagram of the storage device of FIG. Figure 3 shows an example of a hash value list

Fig. 4 is a flowchart explaining the procedure of time authentication.

Figure 5 is a flowchart illustrating the audit procedure.

Figure 6 shows another example of a hash value list.

Figure 7 shows an example of attribute information in a directory (system area) entry. Figure 8 shows an example of a history-type hash value list. BEST MODE FOR CARRYING OUT THE INVENTION

—Hereinafter, the storage device will be described in detail with reference to the drawings by applying the storage device auditing method proposed by the present specification.

(Embodiment 1)

FIGS. 1 and 2 are respectively a network system for explaining the configuration of a storage device having an audit function according to the embodiment of the present invention, and a flow chart for explaining the data flow. The storage device S of the embodiment shown in the figure stores various files created by the workstation 102 of the client connected to the network 101 in a secure state for preventing erasure and tampering, and erasing the files. It is a network-compatible storage device that audits data and tampering. The network 101 is also connected with a time authentication server ′ that performs time authentication in response to a time authentication request of the storage device S.

Here, the storage device S is in the form of a so-called NAS (Network Attached Storage), but in addition to this, it is connected as a workstation with a built-in storage device or in SCS I, etc. It is also possible to form a combination of a storage device and a workstation.

The form of the network 101 is not particularly limited, but is preferably a network connected to the Internet in order to facilitate connection with a remote time authentication server managed by another company.

As shown in FIG. 1, this storage device S is a storage medium for storing files that secures a storage area 12 for audited files in which a file system having a data area 12c and system areas 12a and 12b is formed. A control unit 11 for managing and controlling the storage area 12 for files to be audited by software processing of an MPU (not shown) or hardware-like control by a dedicated LSI, a network interface 13, and a hash value list htt. And a hash value list holding means 14 for holding.

In this case, the control unit 11 transmits the system information to each of the files to be audited 1, 2,... In the above-described system area (in this embodiment, the directory 12a and the allocation table 12b. Not limited to) That is, the attribute information necessary for auditing the erasure or falsification of the audited file, such as the creator, creation date and time, and path information, excluding the physical arrangement information of the file in the audited file storage area 12 is extracted. Hash value obtained by hashing] i # 0—1, h # 0—2,…, and the hash value that hashes the actual data of the audited file located in the data area 12c. hash value generating means 11a for generating h # 1, h # 2,…, and hash values h # 0—1, h # 0—2,… h # 1, A hash value list creator 1 lb that creates a hash value list ht listing h # 2,..., and a hash value hashed from the hash value list ht created by the hash value list creator 11 b t to the time authentication server 103 via the network 101 to require time authentication. Upon receipt of the time authentication token tt from the time authentication server 103, the hash value list holding means as a time-authenticated hash value list ht t that associates the time authentication token tt with the hash value list ht Hash value h # 0—1, h # 0—2,... における in the time authenticated hash value list htt held in the hash value list holding means 14 held in the time authentication requesting means 1 1 c held in 14 h # 1, h # 2,… When the audit target file is to be verified at a predetermined timing (such as a specific time every day), the hash value creation means 11a has the hash value h # 0—1, h Hash values h, # 0—1, h 're-created for all audited files 1, 2, ... according to the same procedure as for the creation of # 0—2, ···, h # 1, h # 2,… # 0 - 2, ...ヽ^{h 5 # 1, h '#} 2, ... and in contrast to the one-to-one, the audited files missing or falsification of Is adapted to perform the function of the verification unit 11 d for performing 査. In this example, the auditing means 1 Id is mounted on the control unit 11 of the storage device S. However, as another configuration, the auditing means 11 d may be mounted on any of the workstations 102.

Here, an example in which the two audit target files 1 and 2 are stored is shown, but this is only a reference example, and the actual audit target file is very large.

The file system of the storage area 12 for audited files will be further described with reference to FIG. In the storage area 12 for the file to be audited, a file system is pre-formed on the storage medium for storing the file, similarly to the storage medium of the storage device such as the conventional hard disk, and the directory 12a which is the system area, the allocation table 12b and a data area 12c. The storage medium may be a magnetic disk, a writable optical disk, or a semiconductor storage device composed of a writable ROM or the like, but from the viewpoint of the writing / reading speed and the storage capacity, the magnetic disk Is desirable.

Audited file storage area 12 in which such a file system is formed In addition, the control unit 11 stores the actual data 12 c # l (12 c) for each audit target file in order to store various audit target files received from the client workstations 102 # 1 and 102 # 2 through the network 101. # 2) is written to the data area 12c, while the entry in the directory 12a in the system area includes the file name 1 (file name 2), which is the reference name of the audited file 1, 2,…, Write the attribute information 1 (attribute information 2) including the pointer 1 (pointer 2) to the allocation table 12b specifying the position of the area 12c in association with each other, and further specify with the pointer 1 (pointer 2) A block 12b # 1 (work 12b # 2) starting from the unit 12bb in the allocation table 12b to be allocated has a pointer (unit 12b # 1) indicating the unit order in the block 12b # l (block 12b # 2). Writing unit showing a 12 bb) of. Each unit of the allocation table 12b has a one-to-one correspondence with the storage unit of the decoder area 12c-(class evening). In this way, the files to be audited 1, 2,... Are stored in the storage device S and can be read out at any time through the network 101. For this read, a configuration that authenticates the client workstations 102 # 1 and 102 # 2 is also possible.

Next, the functions of the hash value creating means 11a, the hash value list creating means 11b, the time authentication requesting means 12c, and the auditing means 12d, which are features of the present invention, will be described in order with reference to FIG.

First, the hash creating means 12a obtains, for all the files 1, 2,... To be audited from the system area having the directory 12a and the allocation table 12b, the file names and the attribute information necessary for auditing (creation). Attribute information such as date and time and creator) are extracted as system information for each of the audit target files, and hash values h # 0-1, h # 0-2, ... are created. The technical requirements of the present invention for the procedure for creating a hash value from system information are as follows: For each of the audit target files 1, 2, ..., hash of attribute information necessary for audit written in the system area The point is to create a value, which is not limited to the type of file system or the configuration of its system area.

Then, the hash creating means 12a further outputs the actual data 12c # 1, 12c # 2,... Of the already stored audit target files 1, 2,. Create # 1, h # 2,….

In these hashing procedures, it is possible to use the well-known hash function algorithm MD5, in which case a 128-bit hash value is created. However, other known one-way function algorithms may be used.

The hash value list creating means 11b is provided with the hash value created by the hash value creating means 11a. ヅ Create a hash value list ht that enumerates the hash values h # 0—1, h # 0—2,..., H # 1, h # 2,. At this time, the correspondence between the hash value and the file to be audited as the source, that is, the hash value h # 0—1, h # 0—2,..., H # l, h # 2,… A list of formats in which the correspondence between the system information of target file 1, the system information of target file 2, ..., the actual data of target file 1, the actual data of target file 1, ... It is desirable that The file format of the hash value list ht is arbitrary, but if it is a text file, the processing will be easier. In another configuration, the hash value list enumerates only the hash values, and further creates an index file listing file names 1, aisle names 2,. From…, a hash value table h.t that enumerates the hash value of the system information and the hash value of the actual data for the file to be audited can be specified. A configuration is also possible.

FIG. 3 is an example of a hash value list ht. In the figure, the file name 1 string, hash value h # 0—1 string, hash value h # 1 string, file name 2 string, hash value h # 0—2 string, hash value The character string of h # 2,…, is separated and enumerated by ",".

The time authentication requesting means 1 2 c creates a hash value h # t obtained by hashing the hash value list ht in the same procedure as the hash value creating means 1 1 a, and then converts the hash value h # t It transmits to the time authentication server 103 via the network 101 and requests time authentication. In the communication with the time authentication server 103 at this time, it is desirable to perform strict authentication using a known publicly-known http protocol.

The time authentication server 103 that has received the hash value h # t specifies the date and time of reception and returns the time authentication token tt. As the time authentication token tt, an electronic signature file that can be used conventionally and that includes information specifying the reception date and time may be used. Time authentication using such a digital signature has already been commercialized as a digital time stamp service by Amano Corporation. As another form, a certificate for describing the operation procedure in the binary tree of the hash value having the hash value h # t as a leaf may be used, and a further publicized certificate for specifying the hash value of the root may be used. Such a certificate is described in Patent Document 1 described above. In the present invention, the method of the time authentication token tt does not matter.

In this way, when the time authentication request means 1 2 c receives the time authentication token tt from the time authentication server 103, the time authentication request means 1 2 c associates the time authentication token tt with the hash value list ht to list the time-authenticated hash values. Create a table htt and save it in the hash value list holding means 14. The present invention uses the format of the time-authenticated hash value table htt. As an example, but not limited to, a single file in which the source value list ht and the electronic signature file for time authentication are embedded using an Adobe PDF file that is already available as a file format that implements the electronic signature function It is also possible. Alternatively, the hash value list ht and the certificate file that can specify the date and time may be separately stored, and a file describing the relation may be created and stored. A series of time-authenticated hash and hash value list ht t by the hash value creating means 1 la, the hash value list creating means 1 lb, and the time authentication requesting means 12 c is, for example, a predetermined time. It may be executed every time (for example, every hour) or may be executed every time the audit target file is newly stored. . _

The auditing means 1 1d uses the file and file name described in the time-authenticated hash value list ht t when verifying the file to be audited at a predetermined timing (such as a specific time every day). With reference to l2, ..., for all files 1, -.2, ....., hash value h # 0—1, h # 0 — Following the same procedure as that for creating 2,..., H # 1, h # 2,…, for each audited file, the system information and actual data of the audited file were re-ashed. Hash values h, # 0—1, h '# 0—2, ... ヽ h, # 1, h, # 2, ...

The hash values h, # 0—1, h, # 0—2,..., H, # 1, h, # 2,. Hash table of hash values Ht hash values h # 0—1, h # 0—2,..., H # 1, h # 2,… one-to-one comparison, missing or falsified audit target files Perform an audit. Needless to say, the predetermined timing includes any request for an audit by an operation of the administrator.

In the audit procedure, first, the authenticity of the time-authenticated hash value list is confirmed using the time-authenticated token tt. Next, the hash values h # 0-1, h # 0-2,... Of the system information are compared with the hash values h, # 0-1, h '# 0-2,. If these match, it can be determined that there is no trace of falsification of the attribute information of the audited file. This is because any unauthorized operation that changes the attribute information of the file to be audited will always change and update the information in the system area.

Then, for each audited file, compare the hash values h # l, h # 2,… with the hash values h, # 1, h, # 2,…. This makes it possible to reliably detect data tampering of the file to be audited. In addition, since the time-authenticated hash value list htt includes the file names 1, 2,..., It is possible to specify a missing file.

Note that the audit report may be displayed on the display unit (not shown) of the storage device S. Alternatively, the information may be reported to a predetermined client workstation 102 via the network 101.

FIGS. 4 and 5 are flowcharts showing a procedure for creating a series of time-authenticated hash value lists ht t by the hash value creating means 1 la, the hash value list creating means 11 b, and the time authenticating means 12 c, respectively. This is a flowchart showing the audit procedure using the Id.

First, the flowchart of FIG. 4 will be described. Step 20 of that flowchart

In steps 1 to 202, each time a file to be audited is newly stored in the storage device S,

Create a hash value (h_ # 1, h # 2—,…) that is a hash of the actual data.

Then, in step 203, it is determined whether or not a predetermined time to be time-authenticated has elapsed. When the predetermined time has elapsed, in step 204, the hash value generation means

.1a generates .. hash values h # 0-1, h # 0-2,... For each of the files to be audited. ing.

In step 205, the correspondence between the hash values h # 0—1, h # 0—2,... ヽ h # 1, h # 2,… and the file name 1, the file name 2,. A hash value list ht listing the hash values h # 0—1, h # 0—2,..., H # l, h # 2,… is created and temporarily stored.

In steps 206 to 208, the time authentication requesting means 11c creates a hash value h # t obtained by hashing the hash value list ht, and then creates the hash value h # t.

# t is sent to the time authentication server 103 via the network 101 to request time authentication, and thereafter, the time authentication token tt is received from the time authentication server 103, and further, the time authentication token tt, the hash value list ht and A time-authenticated hash value list ht t is created and stored in association with

Next, the flowchart of FIG. 5 will be described. In step 301 of the flowchart, the auditing means 11d determines whether it is a predetermined timing to perform an audit.

Therefore, when it is determined that the predetermined timing has been reached, in step 302, the hash value creating means 1 la refers to the file names 1, 2,... Described in the time-authenticated hash value list htt, and outputs the hash value h # 0—1, h # 0—2,, h # l, h

Following the same procedure as creating # 2,…, for each of the audited files, the hash value h '# 0—1, h, # 0—2,… ヽ Creates h, # 1, h, # 2,….

Then, in step 303, the authenticity of the time-authenticated hash value—list ht t is confirmed by the auditing means 1 Id based on the time-authentication token ht t. In step 304, the hash values h # 0—l, h # 0—2,… ヽ h # l, h # 2,… listed in the time-authenticated noise value list htt, and the hash for auditing The values h '# 0—1, h, # 0—2, ···, h, # 1, h'# 2,…. In the resulting steps 305, Nono Dzushu value h # 0- 1, h # 0- 2, ... and h '# 0 - 1, h 5 # 0- 2, ... a mismatch is detected between the steps In step 306, an audit report is made on the change in the attribute information of the file to be audited.

In step 307, a mismatch is detected between the hash values h # 1, h # 2,… of the audit target files and h '# 1, h' # 2,…, or the time-authenticated hash value When it is detected that the file to be audited having the file name described in the list htt does not exist, in step 308, the abnormal file to be audited is identified and audited.

(Embodiment 2)

In the first embodiment described above, the hash value creation means 12a extracts attribute information necessary for auditing from the system area for each of the audit target files as system information, and hashes each of the hashed files. After creating the values h # 0-1, h # 0-2,…, the hash values h # 1, h # 2,… are created by hashing the actual data of the file to be audited. However, as an external configuration, for each of the audit target files 1, 2,..., The extracted system information and actual data are combined according to a predetermined rule, and further hashed to form one hash value hh #.

It is also possible to create 1, hh # 2,….

In this case, the hash value list creating means 12b determines the correspondence between the file names 1, 2,... And the hash values hh # 1, hh # 2,. It is configured to create a hash value list hht in a specified format, and the auditing means 12d also determines that the hash values hh # 1, hh # 2,. Audited file 1, newly created in

The configuration is such that the hash values hh, # 1, hh, # 2, ... for 2, ... are audited on a one-to-one basis.

Figure 6 is an example of such a hash value list hht. List of hash values in the figure In the table hht, the character string of the file name 1, the character string of the hash value hLh # 1, the character string of the file name 2, the character string of the hash value hh # 2,… They are listed separately.

(Embodiment 3)

In the first embodiment, the audit target stored in the audit target file storage area 12 Although there is no particular limitation on the case where the file is updated, a write-once configuration that retains the actual data of the audited file that is deleted when the audited file is updated or deleted is more desirable from a security perspective. Even better.

In order to do so, it is necessary to configure a configuration in which information indicating that the file has been erased can be written in the attribute information of the system area 12 a in the file storage area 12 to be audited, and the audit information stored in the file storage area 12 to be audited. When deleting the target file, information indicating that the file has been deleted is added to the attribute information, and the information stored in the data storage area 12c of the location table 12b for the audited file is stored. You can leave it overnight. In this way, even if the file to be audited is deleted due to unauthorized operation, it can be restored.

FIG. 7 is a diagram for explaining the contents of the entry of the directory 12a, to which information indicating that the data has been deleted can be added. The attribute information of the entry shown in the figure includes a flag F indicating that the... Has been deleted. (Embodiment 4)

In the first embodiment described above, the hash value list creating means 11b of the control unit 11 enumerates the hash values of the actual data of all the audit target files stored in the audit target file storage area 12. Although the configuration is such that the hash value list created in this way is created, as another configuration, the hash value list creation means 1 lb may create a history type hash value list. Such a configuration is particularly effective in a storage device S that only creates a new file without erasing the audit target file, and is expected to improve the processing speed.

The history type hash value list here refers to the newly saved audit target file between the time when the hash value list was last created and the time when the hash value list was newly created, that is, Except for the files to be audited that have already been listed in the previous hash value list, this is a file created by listing only the hash values obtained by hashing the actual data. Of course, the latest hash value created from the system information for each newly saved file to be audited is also listed in the historical hash value list each time. Furthermore, the hash value created from the time-authenticated history type hash value list created last time is also described in the new hash value list. This can guarantee the continuity of the history-type hash value list.

FIG. 8 is a drawing for explaining the structure of the history type hash value list. As shown in the figure, the hash value list hht #X created by hashing the time-authenticated history hash value list htt #X as the parent is listed in the history hash value list ht #Y as the child And hashed the time-authenticated history type hash value list htt # Y The hash value h # Y obtained is described in the history-type hash value table ht # Ζ that becomes the grandchild.

Claims

The scope of the claims

1. It has a storage medium for file storage that has a data storage area and a system area. When a file is stored, the actual data of the file is stored in the data area and the file name is stored. And a network-compatible storage device configured to store attribute information such as node information and creation date and time in the system area in association with each other.

For each of the files to be audited, create a hash value from a part of the above system area and the actual data of the file,

A hash value list including each of the hash values created by the hash value creation means is created,

A hash value created further from the hash value list created by the hash value list creating means is transmitted to the time authentication server via the network, and time authentication is requested. When the authentication token is received, an operation of storing the time authentication token in association with the hash value list is performed at predetermined timings, and

When verifying the files to be audited, hash values are created again by the hash value creation means in the same manner as in the hash value list for all files to be verified, and A method for auditing a storage device, comprising comparing a hash value list stored in association with a time-of-day authentication token with a corresponding hash value, and auditing for missing or falsified files.

2. In Claim 1,

At a predetermined timing, for each of the files to be audited, a hash value is created from a part of the system area, and a hash value is created from the actual data of the file. The method of storage device auditing.

3. In claim 1,

At each predetermined timing, for each of the files to be audited, a hash value is created by combining a part of the system area and the actual data of the file according to a predetermined rule. The method of storage device audit.

4. In any one of claims 1 to 3,

Information indicating that the file has been erased can be written in the attribute information of each file stored in the system area. When deleting the file to be audited, the information indicating that the file has been erased is included in the attribute information. In the above-mentioned area A method of auditing a storage device, characterized by leaving the actual data remembered.

5. In any one of claims 14 to 14, when creating the hash value list,

A method for auditing a storage device, comprising: creating a history type hash value list further including a hash value created from a hash value list created last time.

6. It has a storage medium for storing a file that has a data area and a system area. When storing a file, the actual data of the file is stored in the data area, while the file name and A network-compatible storage device o, ヽ-'■,' one 'which is configured to store path information and attribute information such as creation date and time in the system area in association with each other.

For each of the files to be audited, a hash value creating means for creating a hash value from a part of the system area and actual data of the file; and a hash value creating means for creating the hash value by the hash value creating means. A hash value list creating means for creating a hash value list including each of them,

A hash value created further from the hash value list created by the hash value list creation means is transmitted to the time authentication server via the network to request time authentication, and when a time authentication token is received from the time authentication server, A storage device comprising time authentication request means for storing the time authentication token and the above-mentioned list of hash values in association with each other.

7. In Claim 6,

The above-mentioned node value creating means creates a hash value from a part of the system area for each of the files to be audited, and further creates a hash value from the actual data of the file. Storage device.

8. In Claim 6,

The above-mentioned nose value creating means is configured to combine a part of the above-mentioned system area with actual data of the file in accordance with a predetermined rule for each of the files to be audited, and then create a hash value. Storage device.

9. In any one of claims 68,

In the storage medium, information indicating that the file has been deleted can be written in the attribute information of each file stored in the system area, and the file is to be stored as the audit target. A storage device of a write-once type configuration in which when deleting a file, information indicating that the file has been deleted is added to the attribute information, and the actual data stored in the data area is left.

10. In any one of claims 6 to 9,

The storage device, wherein the hash value list creating means creates a history type hash value list further including a hash value created from a hash value list created last time.

11. In any one of claims 6 to 10,

When verifying the files to be audited, all the files to be verified are processed by the hash value generating means in the same manner as in the hash value table. A storage device further comprising an auditing unit that compares the hash value with a corresponding hash value in a hash value list stored in association with the time authentication token, and audits for missing or falsified files.