JP2006190273A - Time of day auditing system and time of day auditing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a time of day auditing system and a time of day auditing method for providing service to improve reliability of the time of day with significant usability. <P>SOLUTION: The time of day auditing system for auditing client's time of day used by the client via a network, comprises a base time of day means 111 for clocking the reliable base time of day calibrated based on the universal time coordinated, a time stamp means 120 for issuing an electronic certification including time stamp information made by adding the reliable time of day information to electronic data or electronic information consisting of a unidirectional function value, a client time of day acquiring means 112 for acquiring at a predetermined timing the time of day information used by the client via the network, and a time of day auditing means 113 for issuing not only the electronic certification relating to the time of day auditing but also the time of day auditing certification 14 over a certain period of time by accumulating the issued electronic certifications. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a time audit system and a time audit method.

  With the spread of the Internet, electronic commerce that performs shopping and transactions via the Internet is actively used. In addition, an increasing number of companies adopt electronic document management that performs internal payment and storage using electronic documents instead of paper documents.

  When such digitization proceeds, it is necessary to prove that the specific electronic information exists at a specific time in the past and that the data has not been falsified thereafter. Stamp technology has been developed, and electronic notary services have also started.

  On the other hand, each company has been asked how accurate the time used on the intranet is. Therefore, in order to respond to such a company's request, a service for distributing Coordinated Universal Time or Japan Standard Time via FM radio waves, a telephone line, GPS, the Internet, or the like has been started.

  However, there is a problem that the distributed time has a risk of being falsified on the route and there is no guarantee that the time is used reliably.

  In view of such circumstances, it is an object of the present invention to provide a time audit system and a time audit method that provide a service that can improve the reliability of time to be used very easily.

  A first aspect of the present invention that solves the above-described problem is a time audit system that audits a client time used by a client via a network, and a reference that records a reliable reference time that is calibrated based on a coordinated universal time Time means, time stamp means for issuing an electronic certificate including time stamp information obtained by adding reliable time information to electronic information consisting of electronic data or a one-way function value thereof, and used by the client via the network The client time acquisition means for acquiring time information at a predetermined timing, the client time acquired by the client time acquisition means is compared with the reference time acquired from the reference time means, and the difference between them is acquired. Time comparison information or a one-way function value indicating the time stamp A time audit system comprising: a time audit means for issuing an electronic certificate related to time audit by outputting to a stage and accumulating the issued electronic certificate and issuing it as a time audit certificate for a predetermined period .

  According to a second aspect of the present invention, in the first aspect, the time auditing unit collects the time audit certificate accumulated during a predetermined period, and the electronic data or the one-way function value is stored in the time stamp unit. The time audit system is characterized in that the electronic certificate obtained by outputting the data is used as a time audit certificate for each predetermined period.

  According to a third aspect of the present invention, there is provided a time audit system according to the first or second aspect, further comprising charging means for charging according to the issued amount of the time audit certificate.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the client is a client PC in an intranet, and the client time is a time used as a standard time in the intranet. There is a time audit system characterized by being.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the client time acquisition unit accesses the client via the network and acquires the client time. In the audit system.

  According to a sixth aspect of the present invention, in any one of the first to fourth aspects, the client time acquisition unit receives the client time via the network and acquires the client time. In the time audit system.

  According to a seventh aspect of the present invention, there is provided a time audit method for auditing a client time used by a client via a network, wherein a reference time means for marking a reliable reference time calibrated based on a coordinated universal time, and an electronic Time stamp means for issuing an electronic certificate including time stamp information obtained by adding reliable time information to electronic information consisting of data or a one-way function value thereof, and time information used by the client via the network Is obtained at a predetermined timing, the client time is compared with the reference time acquired from the reference time means, the difference between the two is acquired, and time comparison information indicating the time difference or its one-way function value is obtained as the time. Output to stamp means and issue electronic certificate related to time audit to make time audit certificate In time supervision method characterized.

  According to an eighth aspect of the present invention, in the seventh aspect, an electronic certificate obtained by collecting the time audit certificate for a predetermined period and outputting the electronic data or the one-way function value to the time stamp means The time audit method is characterized in that it is a period time audit certificate for each predetermined period.

  According to a ninth aspect of the present invention, there is provided a time audit method according to the seventh or eighth aspect, characterized in that a charge is made according to the amount of time audit certificate issued.

  According to a tenth aspect of the present invention, in any one of the seventh to ninth aspects, the client is a client PC in an intranet, and the client time is a time used as a standard time in the intranet. There is a time audit method characterized by being.

  An eleventh aspect of the present invention is the time audit method according to any one of the seventh to tenth aspects, wherein the client time is acquired by accessing the client via the network.

  A twelfth aspect of the present invention is the time audit method according to any one of the seventh to tenth aspects, wherein the client time is acquired by receiving an access from the client via the network.

  According to the present invention, it is possible to obtain a time audit certificate in which a third-party organization proves that the time being used is trusted within a predetermined range without providing special equipment. Therefore, there is an effect that even a small business or a private business can easily use it.

  As another aspect of the present invention, a thirteenth aspect of the present invention is an application server for auditing client time information used by a client, and a time stamp for generating an electronic certificate for information acquired from the application server. A time audit center comprising a server, wherein the application server acquires, from the client, reference time means for generating reference time information synchronized with Coordinated Universal Time or Japan Standard Time, and client time information used by the client Generating time comparison information, which is information relating to a difference between the client time acquisition means, the client time information acquired by the client time acquisition means, and the reference time information generated by the reference time means, and is generated for a certain period Summary of the time comparison information A time audit means for sending a one-way function value of the data to the time stamp server, and the time stamp server is time calibrated based on Coordinated Universal Time or Japan Standard Time by an external time calibration center. Time means different from the reference time means proved to be, a one-way function value of the time comparison information acquired from the application server, and time stamp information including time information generated by the time means A time stamp means for creating an electronic certificate and issuing it to the application server, wherein the application server sets the client time at which the client generates the electronic certificate acquired from the time stamp server. Prove that the application server is auditing It is issued to the client as a time audit certificate, time audit center.

  A fourteenth aspect of the present invention is a time audit center including an application server that audits client time information used by a client, and a time stamp server that generates an electronic certificate for information acquired from the application server. The application server includes reference time means for generating reference time information synchronized with Coordinated Universal Time or Japan Standard Time, client time acquisition means for acquiring client time information used by the client from the client, and the client time. Generating time comparison information that is information relating to a difference between the client time information acquired by the acquisition means and the reference time information generated by the reference time means, and generating a one-way function value of the time comparison information as the time stamp server To be sent to And the time stamp server obtains a time calibration certificate when a time unit different from the reference time unit is calibrated by an external time calibration center based on Coordinated Universal Time or Japan Standard Time. An electronic certificate including a one-way function value of the time comparison information received from the time calibration center, stored and acquired from the application server, time information generated by the time means, and time stamp information including the time calibration certificate A time stamp means for creating a certificate and issuing the certificate to the application server, wherein the application server generates the client time at which the client generates the electronic certificate obtained from the time stamp server. Time audit certificate proving that the server is auditing It is issued to the client as a book, time audit center.

  A fifteenth aspect of the present invention is a client time information auditing method performed in a time auditing center including an application server and a time stamp server, wherein the application server is synchronized with Coordinated Universal Time or Japan Standard Time. Reference time means for generating reference time information, client time acquisition means, and time audit means. The time stamp server is calibrated based on Coordinated Universal Time or Japan Standard Time by an external time calibration center. And a time stamp means different from the reference time means proved to be performed, and the auditing method includes a client time used by the client by the client time acquisition means of the application server. Obtaining information from the client The time auditing unit of the application server generates time comparison information that is information related to a difference between the client time information acquired by the client time acquiring unit and the reference time information generated by the reference time unit. The time auditing means of the application server sending a one-way function value of data that summarizes the time comparison information generated in a certain period to the time stamp server; and the time stamp means of the time stamp server Creating a digital certificate including a one-way function value obtained from the application server and time stamp information including the time information generated by the time means, and a time stamp means of the time stamp server The electronic certificate with the application. The application server is auditing the client time at which the client generates the electronic certificate acquired from the time stamp server by the time auditing unit of the application server. Issuing to the client as a time audit certificate that certifies the client time information.

According to a sixteenth aspect of the present invention, there is provided a client time information auditing method performed in a time audit center including an application server and a time stamp server, wherein the application server is synchronized with Coordinated Universal Time or Japan Standard Time. Reference time means for generating reference time information, client time acquisition means, and time audit means, and the time stamp server is based on Coordinated Universal Time or Japan Standard Time by an external time calibration center. A time stamp means for receiving and storing a time calibration certificate from the time calibration center when a time means different from the time means is calibrated, and the audit method includes the client time acquisition means of the application server. Client time information used by the client It is information relating to a difference between the step of acquiring from the client and the client time information acquired by the client time acquiring unit and the reference time information generated by the reference time unit by the time auditing unit of the application server. Generating the time comparison information; the time auditing means of the application server sending a one-way function value of the time comparison information to the time stamp server; and the time stamp means of the time stamp server, Creating a digital certificate including a one-way function value obtained from the application server, time information generated by the time means, and time stamp information including the time calibration certificate; and The time stamp means is the electronic Issuing the certificate to the application server; and the application server indicates the client time at which the client generates the electronic certificate obtained by the time auditing unit of the application server from the time stamp server. A client time information auditing method comprising: issuing to the client as a time auditing certificate proving that auditing is in progress;

  As described above, according to the time audit system and the time audit method of the present invention, it is possible to improve the reliability of the time used very easily.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an outline of a time audit system according to an embodiment. As shown in the figure, the time audit center 100 provides a time audit service to the clients 1 such as the client A and the client B. The time audit center 100 includes an application server 110 and a time stamp server 120. It has.

  The application server 110 is a server that communicates with each client 1, a reference time unit 111 that is audited at a reference time 11 that is reliable from the time calibration center 200, and a client time acquisition that acquires the client time 12 from the client 1. Means 112, time auditing means 113 for performing time auditing, and accounting means 114 are provided. Further, the time stamp server 120 issues time stamp information to a one-way function value of electronic data and issues an electronic certificate.

  Here, it is preferable that the reference time 11 recorded by the reference time unit 111 is synchronized with the time information used by the time stamp server 120, and these are periodically calibrated by the time calibration center 200 in this embodiment. Has been. Details of these points will be described later.

  The client time acquisition unit 112 acquires time information used by the client 1 via a network at a predetermined timing, for example, once a day or once a week. It is not limited. For example, the client time acquisition unit 112 accesses the client 1 and acquires time information as the client time 12 by, for example, the network time protocol (NTP). Conversely, access from the client 1 may be accepted and the client time 12 may be acquired. Note that it is not necessary to ensure special security for such time information acquisition.

  Here, the client 1 is not particularly limited as long as it has predetermined time information and can pass the time information to the client time acquisition unit 112 via the network. It may be a set reference clock, or may be a client PC used in an intranet in a company or a web server in the Internet. Generally, an intranet has a time distribution server that distributes the reference time in the intranet, and the time distribution server is synchronized with Japan Standard Time or Coordinated Universal Time by various means. In the embodiment, it is not necessary to acquire time information directly from the time distribution server, and it may be acquired from a general client PC connected to the time distribution server.

  The time auditing means 113 compares the reference time 11 of the reference time means 111 with the client time 12 acquired by the client time acquisition means 112 and audits. FIG. 2 shows the time audit procedure of the time audit means 113. The time auditing means 113 compares the reference time 11 acquired from the reference time means 111 and the client time 12 acquired from the client time acquisition means 112 to acquire the difference between them, and time comparison information 13 indicating these time differences. Is further passed to the time stamp server 120 as a one-way function value 13A. Here, the one-way function value is also called, for example, a hash (HASH) value or a message digest, and is, for example, a fixed-length pseudorandom number generated by an irreversible one-way function such as a hash function. Although the same one-way function value can be obtained from the same data, the original data cannot be reproduced from the one-way function value. The time stamp server 120 receives the one-way function value 13A of the time comparison information 13 from the time audit means 113, and creates the time audit certificate 14, which is an electronic certificate with time stamp information added thereto. The time audit certificate 14 is preferably encrypted and signed by a predetermined procedure.

  Note that such time audit certificate 14 has time information used by the client 1 subjected to time audit when the time audit certificate 14 is created, and the time information is based on Coordinated Universal Time at that time. It proves how much it deviates from the reliable reference time that is calibrated. Therefore, if the client 1 accumulates such a time audit certificate 14, the client 1 continuously receives the time audit, and secures evidence that it is possible to prove how much the time difference has occurred during that period. be able to.

  Such a time audit certificate 14 may be transmitted to the client 1 at the time when the time audit is performed, or may be transmitted collectively at regular intervals. When the data is collected every certain period, an electronic certificate in which time stamp information is added to the electronic data or the one-way function value, for example, a period time audit certificate may be created.

  The charging unit 114 charges the client 1 as a price for the time audit service described above. The charging condition is not particularly limited, but it is preferable to charge according to the number of time audit certificates 14. In this case, the client 1 can select the timing for receiving the time audit, and can pay the price accordingly.

  On the other hand, the time calibration center 200 that performs time calibration of the time stamp server 120 and the application server 110 includes a time calibration unit 210. The time calibration unit 210 is, for example, a master clock to which a time source is supplied from a cesium atomic clock 211. 212 and a time distribution server 213 for time distribution from the master clock 212, and the time distribution server 213 periodically calibrates the time means of the time stamp server 120 and the application server 110. Here, it is assumed that the master clock 212 and the time distribution server 213 are separately audited directly or indirectly with Coordinated Universal Time or Japan Standard Time.

  The time calibration center 200 periodically accesses the time stamp server 120 to calibrate the built-in clock, and also includes the unique ID 102 of the time stamp server 120 and the public key certificate of the public key used by the time stamp server 120. 103 is issued, and a time calibration certificate 201 including a hash value which is a one-way function value of the public key certificate 103 is issued.

  Here, an example of the time stamp server 120 as described above and an example of the time audit certificate 14 issued by the time stamp server 120 will be described in more detail with reference to FIG.

  As shown in FIG. 3, the time stamp server 120 has a unique ID 102 managed by the time calibration center 200, a clock 121, and an electronic certificate creation unit 122. In addition, it has a private key 123 used for encryption when creating the time audit certificate 14 and a public key certificate 103 of a public key that is paired with the private key 123. Further, as described above, the clock 121 of the time stamp server 120 is periodically calibrated at a predetermined timing by the time calibrating means 210 of the time proofing center 200, and receives the time calibration certificate 201 at the time of this calibration. I keep this. Note that the time calibration center 200 acquires the unique ID 102 and the public key certificate 103 from the time stamp server 120 at the time of time calibration, and thereby whether or not the time stamp server 120 has generated an appropriate time audit certificate 14. The issued time audit certificate 14 may be authenticated.

  The electronic certificate creation means 122 creates time stamp information 104 in which the time information obtained from the clock 121 is added to the one-way function value 13A obtained from the time audit means 113, and the time stamp information 104 is stored with the secret key 123. A digital signature 105 that is encrypted and signed is created and output as a time audit certificate 14. Therefore, the time audit certificate 14 includes the time stamp information 104 and the electronic signature 105, and further includes the public key certificate 103 of the time stamp private key and the time calibration certificate 201. Note that the time audit certificate 14 is not limited to this, and may be any certificate that includes at least the time stamp information 104 and the electronic signature 105.

Another configuration of the present invention includes the following. A time audit center comprising an application server that audits client time information used by a client, and a time stamp server that generates an electronic certificate for information acquired from the application server,
The application server includes a reference time means for generating reference time information synchronized with Coordinated Universal Time or Japan Standard Time,
Client time acquisition means for acquiring client time information used by the client from the client;
Generating time comparison information that is information related to a difference between the client time information acquired by the client time acquisition means and the reference time information generated by the reference time means; A time audit means for sending to the time stamp server,
The timestamp server is
Time means proved by an external time proofing center that time is calibrated based on Coordinated Universal Time or Japan Standard Time,
A time stamp means for creating an electronic certificate including a one-way function value obtained from the application server and time stamp information including the time information generated by the time means, and issuing the electronic certificate to the application server; Have
The application server issues the electronic certificate acquired from the time stamp server to the client as a time audit certificate that proves that the application server is auditing the client time generated by the client. Time Audit Center. Time audit center configured as above.

In addition, a client time information auditing method performed at a time audit center including an application server and a time stamp server,
The application server includes reference time means for generating reference time information synchronized with Coordinated Universal Time or Japan Standard Time, client time acquisition means, and time audit means.
The time stamp server has time means proved to be time calibrated based on Coordinated Universal Time or Japan Standard Time by an external time proofreading center, and a time stamp means.
The audit method is:
The client time acquisition means of the application server acquires client time information used by the client from the client;
The time auditing unit of the application server generating time comparison information that is information relating to a difference between the client time information acquired by the client time acquiring unit and the reference time information generated by the reference time unit; ,
The time auditing means of the application server sending a one-way function value of the time comparison information to the time stamp server;
The time stamp means of the time stamp server creates a digital certificate including time stamp information including the one-way function value of the time comparison information acquired from the application server and the time information generated by the time means;
The time stamp means of the time stamp server issues the electronic certificate to the application server;
The time audit means of the application server uses the electronic certificate acquired from the time stamp server as the time audit certificate that proves that the application server is auditing the client time generated by the client. A method for auditing client time information comprising the steps of issuing to a client. A method for auditing client time information configured as described above.

The application server communicates with a time stamp server having a function of issuing an electronic certificate and audits client time information used by the client,
A reference time means for generating reference time information synchronized with Coordinated Universal Time or Japan Standard Time,
Client time acquisition means for acquiring client time information used by the client from the client;
Generating time comparison information that is information related to a difference between the client time information acquired by the client time acquisition means and the reference time information generated by the reference time means; A time audit means for sending to the time stamp server,
Obtaining an electronic certificate created by the time stamp server and including a one-way function value of the time comparison information, and the application server auditing the client time generated by the client. An application server that issues to the client as a time audit certificate that proves An application server configured as described above.

In addition, the client is audited by a time audit center including an application server that audits client time information used by the client and a time stamp server that generates an electronic certificate for information acquired from the application server. ,
Means for sending the client time information to the application server of the time audit center;
A time audit certificate that is an electronic certificate created by the time stamp server from the time audit center;
The time audit certificate is obtained by the time stamp server according to a unilateral function value of time comparison information which is information related to a difference between the client time information and the reference time information, and an external time calibration center. An electronic certificate created including time stamp information including time information generated by time means certified to be time calibrated based on time or Japan Standard Time,
The client wherein the client time information is audited by verifying the time audit certificate, and a deviation from the reliable reference time information is proved. Client with the above configuration.

A time audit system for auditing a client time used by a client via a network,
Issuing an electronic certificate that includes time stamp information in which reliable time information is added to electronic information consisting of electronic data or its one-way function value, and a reference time means that ticks a reliable reference time that is calibrated based on Coordinated Universal Time Time stamp means, client time acquisition means for acquiring time information used by the client via the network at a predetermined timing, client time acquired by the client time acquisition means, and reference acquired from the reference time means Compares the time and obtains the difference between the two, outputs the time comparison information indicating the time difference or the one-way function value thereof to the time stamp means, issues an electronic certificate relating to time audit, and issues the electronic certificate Time auditing means for storing certificates and issuing them as time audit certificates for a certain period of time Time supervision system characterized by comprising. Time audit system configured as above.

  Further, in the time audit system, the time audit means collects the time audit certificates accumulated during a predetermined period and outputs the electronic data or the one-way function value to the time stamp means. A time audit system characterized in that a certificate is a period time audit certificate for each predetermined period. Time audit system configured as above.

  Furthermore, the time audit system can be a time audit system characterized in that it comprises a charging means for charging according to the issued amount of the time audit certificate.

  Furthermore, the time audit system is characterized in that the client is a client PC in an intranet, and the client time is a time used as a standard time in the intranet. can do.

  Further, the time audit system may be a time audit system in which the client time acquisition means accesses the client via the network and acquires the client time.

  Furthermore, the time audit system may be a time audit system in which the client time acquisition unit receives the client time via the network and acquires the client time.

Another time audit method is a time audit method for auditing a client time used by a client via a network.
Issuing an electronic certificate that includes time stamp information in which reliable time information is added to electronic information consisting of electronic data or its one-way function value, and a reference time means that ticks a reliable reference time that is calibrated based on Coordinated Universal Time A time stamp means for acquiring time information used by the client via the network at a predetermined timing and comparing the client time with a reference time acquired from the reference time means. Time comparison information indicating the time difference or a one-way function value thereof is output to the time stamp means, and an electronic certificate relating to time audit is issued to obtain a time audit certificate. It can be a method.

  Further, in the time audit method, the time audit certificate is collected for a predetermined period, and the electronic certificate obtained by outputting the electronic data or the one-way function value to the time stamp means is used for the period time audit for each predetermined period. The time audit method can be characterized by being a proof.

  Furthermore, it is possible to provide a time auditing method characterized by charging according to the amount of time audit certificate issued.

  Further, the time audit method is a time audit method characterized in that the client is a client PC in an intranet, and the client time is a time used as a standard time in the intranet. be able to.

  Furthermore, the time audit method may be a time audit method in which the client time is acquired by accessing the client via the network.

  Furthermore, the time audit method may be a time audit method characterized in that the client time is acquired by receiving an access from the client via the network.

It is a figure which shows the schematic structural example of the time audit system which concerns on one Embodiment of this invention. It is a figure which shows an example of the time audit procedure of the time audit means in one Embodiment of this invention. It is a figure explaining the time stamp server and electronic certificate in one Embodiment of this invention.

Explanation of symbols

1 Client (Client A, Client B)
11 Reference time 12 Client time 13 Time comparison information 13A One-way function value 14 Time audit certificate 100 Time audit center 102 Unique ID
DESCRIPTION OF SYMBOLS 103 Public key certificate 110 Application server 111 Reference time means 112 Client time acquisition means 113 Time audit means 114 Billing means 120 Time stamp server 200 Time calibration center 210 Time calibration means

Claims (4)

A time audit center comprising an application server that audits client time information used by a client, and a time stamp server that generates an electronic certificate for information acquired from the application server,
The application server is
A reference time means for generating reference time information synchronized with Coordinated Universal Time or Japan Standard Time,
Client time acquisition means for acquiring client time information used by the client from the client;
Generating time comparison information that is information relating to a difference between the client time information acquired by the client time acquisition means and the reference time information generated by the reference time means; Time audit means for sending one-way function values of the collected data to the time stamp server,
The timestamp server is
Time means different from the reference time means proved to be time calibrated based on Coordinated Universal Time or Japan Standard Time by an external time proofing center;
Time stamp means for creating an electronic certificate including a one-way function value acquired from the application server and time stamp information including time information generated by the time means, and issuing the electronic certificate to the application server And
The application server issues the electronic certificate acquired from the time stamp server to the client as a time audit certificate that proves that the application server is auditing the client time generated by the client. Time Audit Center. A time audit center comprising an application server that audits client time information used by a client, and a time stamp server that generates an electronic certificate for information acquired from the application server,
The application server is
A reference time means for generating reference time information synchronized with Coordinated Universal Time or Japan Standard Time,
Client time acquisition means for acquiring client time information used by the client from the client;
Generating time comparison information that is information related to a difference between the client time information acquired by the client time acquisition means and the reference time information generated by the reference time means; A time audit means for sending to the time stamp server,
The timestamp server is
A time calibration certificate is received from the time calibration center and stored when the time means different from the reference time means is calibrated by an external time calibration center based on Coordinated Universal Time or Japan Standard Time,
Creating an electronic certificate including a one-way function value of the time comparison information acquired from the application server, time information generated by the time means, and time stamp information including the time calibration certificate; And a time stamp means for issuing
The application server issues the electronic certificate acquired from the time stamp server to the client as a time audit certificate that proves that the application server is auditing the client time generated by the client. Time Audit Center. A method for auditing client time information performed at a time audit center including an application server and a time stamp server,
The application server includes reference time means for generating reference time information synchronized with Coordinated Universal Time or Japan Standard Time, client time acquisition means, and time audit means.
The time stamp server has time means different from the reference time means proved to be time calibrated based on Coordinated Universal Time or Japan Standard Time by an external time proofing center, and time stamp means. And
The audit method is:
The client time acquisition means of the application server acquires client time information used by the client from the client;
The time auditing unit of the application server generating time comparison information that is information relating to a difference between the client time information acquired by the client time acquiring unit and the reference time information generated by the reference time unit; ,
The time auditing means of the application server sends a one-way function value of data that summarizes the time comparison information generated in a certain period to the time stamp server;
The time stamp means of the time stamp server creates a digital certificate including time stamp information including the one-way function value of the time comparison information acquired from the application server and the time information generated by the time means;
The time stamp means of the time stamp server issues the electronic certificate to the application server;
The time audit means of the application server uses the electronic certificate acquired from the time stamp server as the time audit certificate that proves that the application server is auditing the client time generated by the client. A method for auditing client time information comprising the steps of issuing to a client. A method for auditing client time information performed at a time audit center including an application server and a time stamp server,
The application server includes reference time means for generating reference time information synchronized with Coordinated Universal Time or Japan Standard Time, client time acquisition means, and time audit means.
The time stamp server receives a time calibration certificate from the time calibration center when a time unit different from the reference time unit is calibrated by an external time calibration center based on Coordinated Universal Time or Japan Standard Time. A time stamp means for storing,
The audit method is:
The client time acquisition means of the application server acquires client time information used by the client from the client;
The time auditing unit of the application server generating time comparison information that is information relating to a difference between the client time information acquired by the client time acquiring unit and the reference time information generated by the reference time unit; ,
The time auditing means of the application server sending a one-way function value of the time comparison information to the time stamp server;
An electronic certificate in which the time stamp means of the time stamp server includes a one-way function value of the time comparison information acquired from the application server, time information generated by the time means, and time stamp information including the time calibration certificate The steps of creating
The time stamp means of the time stamp server issues the electronic certificate to the application server;
The time audit means of the application server uses the electronic certificate acquired from the time stamp server as the time audit certificate that proves that the application server is auditing the client time generated by the client. A method for auditing client time information comprising the steps of issuing to a client.

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