JP2008124720A - Information management system, client, server, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a receiver client to acquire information at an arbitrary timing while preventing a server from browsing contents of the information. <P>SOLUTION: Encrypted user information obtained by encrypting user information of a client by a common key 1b of the client and encryption common keys obtained by encrypting the common key by public keys of clients to receive the user information are stored in the server side (s350 to s390). Since the server having no secret keys corresponding to the public keys obtained by encrypting the encryption common keys cannot acquire the common key 1b obtained by decrypting the encrypted common keys, the server cannot browse contents of user information encrypted by the common key. Thereafter, the server returns pertinent encrypted user information and an encrypted common key encrypted by the public key of a client in response to a request from this client (s460). This client can acquire the common key 1b by decrypting the encrypted common key and can acquire the user information by decrypting the encrypted user information by the common key 1b (s240 and s250). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an information management system in which one or more clients are connected to a server so that data communication is possible.

In recent years, when information is transmitted from a specific client to another client via a server, encryption is performed when the information is transmitted so that the information cannot be browsed on this server (patents). Reference 1).
JP 2002-132721 A

  However, with the technology described above, the server simply relays the transmission of information, so if the destination client is not activated, such as when the destination client is not active, the client obtains the information. Can not do it. For this reason, it is desirable to make it possible to obtain information from the client of the transmission destination at an arbitrary timing while preventing the information from being browsed on the server. However, this has not been realized.

  The present invention has been made to solve such a problem, and its purpose is to allow a client as a transmission destination to acquire information at an arbitrary timing while preventing the contents of the information from being viewed on the server. It is to provide a technique for doing so.

In order to solve the above problem, an information management system according to claim 1 is an information management system in which one or more clients are connected to a server so as to be able to perform data communication.
Among these, at least one of the one or more clients encrypts the encrypted user information by encrypting the user information related to the user of the client with the common key of the client. The first encryption unit to be generated and the common key used when the first encryption unit encrypts the user information are encrypted with the public keys of one or more clients to which the user information is to be notified. Thus, the second encryption unit that generates one or more encrypted common keys that are encrypted, the encrypted user information generated by the first encryption unit, and the second encryption unit A client-side transmission means for transmitting the encrypted common key and identification information for identifying the client to the server as a series of information.

  The server includes a storage unit that stores the encrypted user information, the encrypted common key, and the identification information that are transmitted as a series of information from the client in a storage unit in association with each other; When the user information of the specific client is requested by any one of the above clients, the specific client is identified from the encrypted user information stored in the storage unit. The encrypted user information associated with the identification information is specified, and the identification information for identifying the specific client among the encrypted common keys stored in the storage unit is associated with the identification information. A specific method for specifying the encrypted common key that is encrypted with the public key of the requesting client. When, a, the encrypted user information and the encrypted common key that is specified, a server-side transmission means for transmitting to said requesting client by the specifying means.

According to the information management system configured as described above, the encrypted user information and the encrypted common key transmitted from the client are stored on the server side.
Since this encrypted user information is obtained by encrypting the client user information with the common key of the client, the server side that does not have the common key decrypts the user information and browses the contents. I can't.

  The common key obtained by encrypting the encrypted user information is stored on the server side as the encrypted common key encrypted with the client's public key. Since it is necessary, it is not possible to acquire the client's common key on the server side that does not have this. Thereby, the user information of the client is stored on the server side in a state where the contents cannot be browsed.

  After that, the server storing the encrypted user information and the encrypted common key receives a request from the client and returns the corresponding encrypted user information and the encrypted common key. An encrypted common key encrypted with the client's public key is returned. Therefore, this client side can obtain the common key used for encrypting the encrypted user information by decrypting the encrypted common key with the private key of the client itself. User information can be acquired by decoding the user information.

  As described above, with the information management system described above, it is possible to allow a client as a transmission destination to acquire user information at an arbitrary timing while preventing the contents of the user information from being viewed on the server.

  The client-side transmission means in the configuration described above is means for transmitting the encrypted user information, the encrypted common key, and the identification information to the server as a series of information, and these information are recognized as “a series of information” on the server side The information may be transmitted by any method as long as the method is used. For example, a method is conceivable in which each of the above information is continuously transmitted in a predetermined order, and is transmitted with information indicating “a series of information”.

  In addition, the common key used by the first encryption unit of the client for encrypting the user information may be prepared in advance on the client side or may be generated on the client side.

For this purpose, the information management system according to claim 1 may be configured like the information management system according to claim 2.
In this information management system, at least one of the one or more clients includes a common key generation unit that generates a common key of the client, and the first encryption unit stores the user information. It is configured to generate encrypted user information that is encrypted with the common key generated by the common key generation means.

  With this configuration, since the first encryption unit can generate a common key used for encrypting user information on the client side, it is not necessary to prepare in advance on the client side.

  In addition, the timing for generating the common key may be any timing. For example, as described in claim 3, prior to transmitting the user information to the server, It may be configured to generate a common key for the client.

  If comprised in this way, another common key will be produced | generated for every session which transmits user information to a server from a client, and the encryption of user information based on it will be performed. Therefore, even if the common key used in any session leaks, the user information whose contents are browsed based on the common key can be limited to the user information encrypted in the session. Thereby, the risk of information leakage as an information management system can be reduced, and damage caused by information leakage can be minimized.

  By the way, the encrypted user information transmitted from the client to the server may be transmitted as it is to the destination client, but the user information finally acquired on the client side is transmitted on the communication path. It is desirable to transmit in a state where it can be confirmed that the file has not been tampered with.

For this purpose, for example, the information management system according to any one of claims 1 to 3 may be configured like the information management system according to claim 4.
In this information management system, at least one of the one or more clients includes a first electronic signature unit that applies an electronic signature to the user information, and the first encryption unit includes the first electronic signature. Encrypted user information is generated by encrypting the user information that has been digitally signed by the means.

  With this configuration, the encrypted user information transmitted from the client to the server is obtained by encrypting the user information to which the electronic signature is applied. It can be confirmed that the user information obtained by decrypting the information has not been falsified based on the electronic signature applied thereto.

  Similarly, the encrypted common key transmitted from the client to the server may be transmitted as it is to the client as the transmission destination, but the encrypted common key finally acquired on the client side is used. It is desirable to transmit in a state where it can be confirmed that the key has not been tampered with on the communication path.

For this purpose, for example, the information management system according to any one of claims 1 to 4 may be configured like the information management system according to claim 5.
In this information management system, at least one of the one or more clients includes a second electronic signature unit that applies an electronic signature to the common key of the client, and the second encryption unit includes the second encryption unit. One or more encrypted common keys are generated by encrypting the common key to which the electronic signature is applied by the electronic signature means.

  With this configuration, the encrypted common key transmitted from the client to the server is an encrypted common key that has been digitally signed. It can be confirmed that the common key obtained by decrypting the key is not falsified based on the electronic signature applied thereto.

  In each of the information management systems described above, communication between the client and the server may be configured as it is (in plain text), but in order to reduce the risk of information leakage as the information management system. Therefore, it is desirable that communication between the two can be encrypted.

For this purpose, the information management system according to any one of claims 1 to 5 may be configured like the information management system according to claim 6.
In this information management system, at least one of the one or more clients can decrypt the encrypted user information, the encrypted common key, and identification information that can identify the client by the server. A third encryption means for encrypting with an encryption key (a common key of the server), wherein the client-side transmission means is encrypted user information encrypted by the third encryption means, the encrypted common key; The identification information is transmitted to the server as a series of information.

  Further, in the server, the storage means transmits the encrypted user information, the encrypted common key, and the identification information that are transmitted as a series of information from the client and encrypted with the common key of the server, respectively. After decrypting with the common key of the said server, it is comprised so that it may memorize | store in the said memory | storage part.

  With this configuration, information transmitted from the client to the server is transmitted in an encrypted state so that it can be decrypted only by the server, so there is no risk of information leakage during communication between the two. Can be reduced.

  As described above, not only data transmission from the client to the server but also data transmission from the server to the client may be similarly encrypted.

According to a seventh aspect of the present invention, there is provided a client including all the means included in the client according to any one of the first to sixth aspects.
According to the client configured as described above, a part of the information management system according to any one of claims 1 to 6 can be configured.

A server according to an eighth aspect is a server characterized by including all the means included in the server according to any one of the first to sixth aspects.
According to the server configured as described above, a part of the information management system according to any one of claims 1 to 6 can be configured.

  A program according to claim 9 is a program for causing a computer system to execute various processing procedures for causing the client according to any one of claims 1 to 6 to function as all means.

The computer system controlled by this program can constitute a part of the information management system according to any one of claims 1 to 6.
A program according to a tenth aspect is a program for causing a computer system to execute various processing procedures for causing the client according to any one of the first to sixth aspects to function as all means.

The computer system controlled by this program can constitute a part of the information management system according to any one of claims 1 to 6.
The above-described programs are provided to clients, servers, and users who use the programs via various recording media and communication lines.

Embodiments of the present invention will be described below with reference to the drawings.
(1) First Embodiment (1-1) Overall Configuration As shown in FIG. 1, the information management system 1 enables one or more clients 10 and a server 20 that are network devices to each perform data communication via a network 100. It is a connected system. Here, each of the client 10 and the server 20 is configured by a known computer system.
(1-2) Storage Request Processing by Client 10 Hereinafter, a processing procedure of storage request processing executed by the client 10 (CPU) will be described with reference to FIG. This storage request process is a process executed to transmit user information related to the user of the client 10 to the client 10 itself or another client 10 via the server 20. This storage request process is started when the client 10 is started and an operation for starting this storage request process is performed.

When this storage request process is activated, a session based on SSL is first established with the server 20 (s110).
Here, first, an HTTPS request is transmitted to the server 20 in order to request the public key certificate of the server 20 (see “1” in FIG. 3), and the public transmitted from the server 20 that has received the HTTPS request. The key certificate is received (see “2” → “3” in the figure). Subsequently, after the public key certificate is authenticated (expiration date and revocation is confirmed), the public key of the server 20 (see “Public Key (S)” in the figure) is acquired from the public key certificate. . Subsequently, a common key of the client 10 (see “common key (1a)” in the figure) is generated and transmitted to the server 20 in a state encrypted with the public key (S) of the server 20 (same as the above). (Refer to FIG. “4” → “5”). The server 20 that has received this decrypts the encrypted common key (1a) with the private key of the server 20 itself (see “secret key (S)” in the figure), so that the client 10 The common key (1a) is acquired (see “5” in the figure).

Thereafter, data communication by the common key encryption method using the common key (1a) of the client 10 is performed between the client 10 and the server 20.
Next, identification information for identifying the user of the client 10 is transmitted to the server 20 (s120). Here, the identification information (see “identification information (1)” in the figure) is transmitted in a state encrypted with the common key (1a) generated in s110 (see “6” in the figure). Upon receiving this identification information, the server 20 side decrypts the encrypted identification information with the common key (1a) of the client 10 and stores it in the storage unit 22 (see “6” → “7” in the figure). . In the present embodiment, the identification information is, for example, information that can be viewed on the server 20 side, such as an ID assigned to the user of the client 10, or information management on the server 20 side. It consists of information that is only used.

  Next, a common key for the client 10 is generated (s130). Here, in addition to the common key (1a) generated in s110 described above, a new common key (see “common key (1b)” in the figure) is generated (see “8” in the figure).

  Next, an electronic signature is applied to user information related to the user of the client 10, and encrypted user information is generated by encrypting the user information with the common key (1b) generated in s130 (s140). . Here, the user information is encrypted with the common key (1b) generated in s130 together with the electronic signature generated based on the user information, and this is generated as encrypted user information (" 9 ”). In the present embodiment, the user information includes information that should not be viewed on the server 20 side, such as personal information of the user of the client 10, for example.

  Next, the encrypted user information generated in s140 is transmitted to the server 20. In this step (s150), the encrypted user information is transmitted after being encrypted with the common key (1a) generated in s110 (see “9” → “10” in the figure). Upon receiving the encrypted encrypted user information, the server 20 decrypts the encrypted user information with the common key (1a) of the client 10, and the encrypted user information obtained in this way is transmitted in s120. The identification information is stored in the storage unit 22 (see “10” in the figure).

  Next, an electronic signature is applied to the common key (1b) generated in s130, and this common key (1b) is used as the public key of the client 10 to which the user information is to be transmitted ("public key ( 1) “Public key (2)”... “Public key (n)”; n is an arbitrary number), and an encrypted common key is generated (s160). Here, the common key (1b) is encrypted with each of the public keys (1) to (n) of the corresponding client 10 together with the electronic signature generated based on the common key, and these are the encrypted common keys. (See “11” in the figure).

  Next, each encrypted common key generated in s160 is transmitted to the server 20. In this step (s170), each encrypted common key is transmitted after being encrypted with the common key (1a) generated in s110 (see “11” → “12” in the figure). Upon receiving the encrypted encrypted common key, the server 20 decrypts the encrypted common key with the common key (1a) of the client 10, and transmits each encrypted common key thus obtained in s120. The information is stored in the storage unit 22 in association with the identification information (see “12” in the figure).

In this way, when s170 is performed, the session established in s110 is released, and the storage request process ends.
(1-3) Transmission Request Processing by Client 10 Hereinafter, a processing procedure of transmission request processing executed by the client 10 (CPU) will be described with reference to FIG. This transmission request process is a process executed to obtain user information of the predetermined client 10 from the server 20. The transmission request process is started when the client 10 is started and an operation for starting the transmission request process is performed.

When this transmission request process is activated, a session based on SSL is first established with the server 20 (s210).
Here, first, an HTTPS request is transmitted to the server 20 to request the public key certificate of the server 20 (see “15” in FIG. 3), and the public transmitted from the server 20 that has received the HTTPS request. The key certificate is received (see “16” → “17” in the figure). Subsequently, after the public key certificate is authenticated (expiration date and revocation is confirmed), the public key of the server 20 (see “Public Key (S)” in the figure) is acquired from the public key certificate. . Subsequently, a common key of the client 10 (see “common key (2a)” in the figure) is generated, and this is encrypted with the public key (S) of the server 20 and transmitted to the server 20 (same as above). (See FIG. 18 “→ 19”). On the server 20 side that receives this, the encrypted common key (2a) is decrypted with the private key of the server 20 itself (see “secret key (S)” in the figure), so that the client 10 The common key (2a) is acquired (see “19” in the figure).

Thereafter, data communication by the common key encryption method using the common key (2a) of the client 10 is performed between the client 10 and the server 20.
Next, a request command for requesting user information of the predetermined client 10 is transmitted to the server 20 (s220). Here, a request command that designates a predetermined client 10 (for example, adds some information in the identification information of the client 10) is encrypted with the common key (2a) generated in s210. Is transmitted to the server 20 (see “20” in the figure).

  Upon receiving this request command, the server 20 first decrypts the request command with the common key (2a) of the client 10, and based on the identification information of the client 10 specified by the request command thus decrypted, the identification is made. The encrypted user information stored in the storage unit 22 in a state associated with the information is extracted. Also, out of the encrypted common key stored in a state associated with the identification information, the encrypted common key encrypted with the public key of the client 10 that is the transmission source of the request command in s220 is extracted. . Then, the identification information, the encrypted user information, and the encrypted common key are returned from the server 20 side in a state encrypted with the common key (2a) of the client 10 ("21" in the figure). (See “26”)

  Thus, after the request command is transmitted, the encrypted identification information, encrypted user information, and encrypted common key are received from the server 20 (s230). Since these identification information, encrypted user information, and encrypted common key are each encrypted with the common key (2a) generated in s210, by decrypting with this common key (2a), These are acquired (see “22”, “24” and “26” in the figure). The encrypted common key acquired here is the common key (1b) encrypted with the public key (2) of the client 10 itself, and the encrypted user information acquired is the common key ( This is the user information encrypted in 1b).

  Next, the encrypted common key received in s230 is decrypted with the private key of the client 10 itself (see “Secret key (2)” in the figure), and the decrypted common key (1b) is added to this. By authenticating based on the attached signature, the common key (1b) is acquired (see “27” in the figure) (s240).

  The encrypted user information received at s230 is decrypted with the common key (1b) acquired at s240, and the decrypted user information is authenticated based on the signature attached thereto. Thus, the user information is acquired (see “28” in the figure) (s250).

When s250 is performed in this way, the session established in s210 is released, and the transmission request process ends.
(1-4) Response Process by Server 20 A response process executed by the server 20 (CPU) will be described below with reference to FIG. This response process is activated when access is received via the network 100.

  When this response process is activated, it is first checked whether the access received prior to the activation is an access requesting establishment of a session based on SSL (s310). Here, prior to the start of response processing, if an HTTPS request for requesting a public key certificate is received, it is determined that the access is for requesting establishment of a session based on SSL. This access occurs at s110 and s210 in FIG.

  If it is determined in s310 that the access is not for requesting establishment of a session based on SSL (s310: NO), a process corresponding to the purpose of the access (other process) is performed (s320). ), This response processing is completed.

  On the other hand, when it is determined in s310 that the access is to request establishment of a session based on SSL (s310: YES), a session based on SSL is established with the client 10 (s330).

  Here, first, the public key certificate of the server 20 itself is transmitted to the client 10 of the access source (see “2” → “3” in FIG. 3). As described above, the client 10 side that has received the public key certificate transmits the common key (1a) of the client 10 encrypted with the public key (S) of the server 20 (see “ 4 ”→“ 5 ”), and by decrypting this with the private key (S) of the server 20 itself, the common key (1a) of the client 10 is obtained (see“ 5 ”in the figure).

Thereafter, data communication is performed between the server 20 and the client 10 by a common key encryption method using the common key (1a) of the client 10, respectively.
After the SSL-based session is established in this way, the client 10 side transmits the identification information or request command of the client 10 to the common key (1a) or (2a) of the client 10 by s120 or s220 in FIG. Are transmitted in an encrypted state (see “6” and “20” in the figure).

  In this way, the data transmitted from the client 10 with the session established in s330 is checked (s340), and when it is determined that the data is identification information (s340: YES), the identification information thus received is It is stored in the storage unit 22 (s350). Here, the identification information from the client 10 is decrypted with the common key (1a) of the client 10 acquired in s330, and then stored in the storage unit 22 ("6" → "7" in the figure). reference).

  When the identification information is transmitted from the client 10, the encrypted user information and the encrypted common key are sequentially transmitted from the client 10 as described above.

  Next, the encrypted user information transmitted from the client 10 is received (s360), and this is stored in the storage unit 22 in a state in which it is associated with the identification information stored in s350 performed immediately before. (S370). Here, the encrypted user information transmitted from the client 10 is decrypted with the common key (1a) of the client 10 acquired in s320, and the decrypted encrypted user information is stored in the storage unit 22. (Refer to “10” in the figure).

  Since this encrypted user information is encrypted with the common key (1b) of the client 10, if it does not have this common key (b), it is decrypted on the server 20 side and its contents Cannot be viewed.

  Then, the encrypted common key transmitted from the client 10 is received (s380), and these are stored in the storage unit 22 in a state where they are associated with the identification information stored in s350 performed immediately before. (S390). Here, the encrypted common key transmitted from the client 10 is decrypted with the common key (1a) of the client 10 acquired in s330, and the decrypted encrypted common key is stored in the storage unit 22. (Refer to “12” in the figure).

  Note that these encrypted common keys are obtained by encrypting the common key (1b) used for encrypting the encrypted user information described above, and are the public keys (1) to (n) of the client 10, respectively. Since it is encrypted, it cannot be decrypted on the server 20 side that does not have the secret keys (1) to (n) of each client 10. That is, the server 20 does not have the common key (1b) used for encrypting the encrypted user information, that is, the common key (1b) that can directly decrypt the encrypted user information.

When s390 is performed in this way, the session established in s320 is released, and the response process ends.
If it is determined in s340 that the data transmitted from the client 10 is not identification information (s340: NO) and is a request command (s440: YES), the client specified by the request command Ten pieces of identification information are specified, and encrypted user information and an encrypted common key corresponding to the identification information are selected from the encrypted user information and the encrypted common key stored in the storage unit 22 (s450). ).

  Here, first, the encrypted user information stored in the storage unit 22 is selected in association with the identification information of the client 10 specified by the request command. Of the encrypted common keys stored in the storage unit 22 in association with the identification information, the public key (i) specified as the public key of the access source client 10 (i is any one of 1 to n) The encrypted common key encrypted in () is selected.

  Next, the identification information of the client 10 specified by the request command, the encrypted user information selected in s450 and the encrypted common key are transmitted to the access source client 10 ("21" in the figure). (See “26”) (s460).

When s460 is performed in this way, the session established in s320 is released, and the response process ends.
If it is determined in s340 described above that the data transmitted from the client 10 is neither identification information nor request data (s340: NO, s440: NO), the process proceeds to s320, and the data After the processing according to the purpose (other processing) is performed, this response processing ends.
(2) Second Embodiment The information management system in the present embodiment has the same configuration as the information management system in the first embodiment, and only part of the processing procedure is different. Detailed description.

The present embodiment is different from the first embodiment in that the storage request process, the transmission request process, and the response process are configured to transmit a plurality of types of user information to the same or different clients 10, respectively. .
(2-1) Storage Request Processing In the storage request processing in the present embodiment, after s110 is performed as in the first embodiment, as shown in FIG. 4, the process proceeds to s130 without performing s120. In s130, a plurality of common keys for the client 10 are generated. Here, a plurality of common keys (1b_1) to (1b_m) corresponding to a plurality of types of user information (see “user information (1-1) to (1-m)” in FIG. 6) are generated (see FIG. 6). (See “8”).

Next, it is checked whether or not there is a common key that is not used for encryption in the subsequent processing among the plurality of common keys generated in s130 (s132).
If it is determined in s132 that there is a common key that is not used for encryption (s132: YES), one of the common keys (1b_j) (1 ≦ j ≦ m) is included. Selected (s134).

  Next, similarly to s120 in the first embodiment, after the identification information is transmitted to the server 20 (s136), the process proceeds to s140, and among the plurality of user information to be transmitted to the client 10, An electronic signature is applied to the user information corresponding to the common key (1b_j) selected in s134, and encrypted user information (j) is generated by encrypting the user information with the common key (1b_j). Is done.

  Thereafter, s150 to s170 are performed, and after s170, the process returns to s132. Thus, s132 to s170 are repeated until there is no common key not used for encryption. As a result, the same number of sets of encrypted user information and encrypted common keys as the common keys generated in s130 are generated (see “9” in the figure), and these are stored on the server 20 side. (Refer to “9” → “10”, “11” → “12” in the figure).

  In this embodiment, as shown in FIG. 7, the case where these data sets contain the common key (1b) encrypted with the public key of a different client 10 is illustrated. This indicates that different clients 10 are defined as transmission destinations of user information included in each data set. Each of these data sets also includes a common key (1b_1) encrypted with the public key of the client 10 that executes this storage request process, so that the client 10 that has executed this storage request process itself Are also defined as user information transmission destinations.

If it is determined in s132 that there is no common key that is not used for encryption (s132: NO), an end notification for notifying that transmission of all user information has ended is transmitted to the server 20. (S138), the storage request process ends.
(2-2) Transmission Request Processing by Client 10 In the transmission request processing in the present embodiment, after s210 to s250 are performed as in the first embodiment, as shown in FIG. Then, it is checked whether or not the encrypted user information and the encrypted common key are received (s252).

  As will be described later, the server 20 sends all the encrypted user information and the encrypted common key set to be transmitted to the client 10 that executes this transmission request process, and then notifies that the transmission of the data set has ended. Is configured to send an end notification for. For this reason, when there is still a data set to be transmitted to the client 10, the identification information, the encrypted user information, and the encrypted common key are further transmitted from the server 20.

If it is determined that the data has been received in s252 (s252: YES), the process returns to s240, and the common key is obtained from the encrypted common key of the data. After this, the process from s240 to s252 is repeated until an end notification is received from the server 20, and if it is determined that the end notification is received in s252 (s252: NO), this transmission request process ends.
(2-3) Response Process by Server 20 In the response process in the present embodiment, after s310 to s390 are performed, as shown in FIG. 4 and FIG. Or whether an end notification has been received is checked (s392).

When it is determined in s392 that the identification information has been received (s392: YES), the process returns to s350, and after this identification information is stored, s360 to s392 are performed.
In this way, s350 to s392 are repeated until an end notification is received from the server 20, whereby the encrypted user information and the encrypted common key data set are stored in the storage unit 22 by the same number (m) as the number of repetitions. (See “9” → “10”, “11” → “12” in FIG. 6).

Thereafter, when it is determined in s392 that an end notification has been received (s392: NO), this response process ends.
If it is determined that the data transmitted from the client 10 is a request command (s340: NO, s440: YES), the storage unit 22 corresponds to the identification information of the client 10 specified by the request command. All data sets to be extracted are extracted (s442).

Next, it is checked whether or not there is a data set that is not referred to in the subsequent processing among the data sets extracted in s442 (s444).
If it is determined in s444 that there is a data set that is not referenced in the subsequent processing (s444: YES), one of the data sets is selected (s446).

  Next, it is checked whether or not the data set selected in s446 includes an encrypted common key corresponding to the identification information of the client 10 specified by the request command (s448).

If it is determined in s448 that the corresponding encryption common key is not included (s448: NO), the process returns to s444.
On the other hand, if it is determined in s448 that the corresponding encrypted common key is included (s448: YES), the process moves to s460, and the encrypted common key determined to be included The identification information and the encrypted user information in the data selected in s446 are transmitted to the access source client 10 (see “21” to “26” in the figure).
(3) Operation and Effect According to the information management system 1 configured as described above, the encrypted user information and the encrypted common key transmitted from the client 10 are stored on the server 20 side together with the identification information (response processing S350, s370, s390).

  Since this encrypted user information is obtained by encrypting the user information of the client 10 with the common key (1b) of the client 10 (storage request processing s140), the server that does not have the common key (1b) On the 20th side, the user information cannot be decoded and browsed.

  Then, the common key (1b) obtained by encrypting the encrypted user information is the server 20 side as an encrypted common key encrypted with the public keys (1) to (n) of the client 10 to which the user information is to be transmitted. However, since the secret key of the client 10 is necessary to decrypt it, the server 20 side that does not have the secret key cannot obtain the common key (1b) of the client 10 . Thereby, the user information of the client 10 is stored on the server 20 side in a state in which the contents cannot be browsed.

  Thereafter, the server 20 storing the encrypted user information and the encrypted common key receives the request from the client 10 and returns the corresponding encrypted user information and the encrypted common key (s460 of the response process). This encrypted common key is encrypted with the public key of the requesting client 10. Therefore, the client 10 side can acquire the common key used for encrypting the encrypted user information by decrypting the encrypted common key with its own secret key. The user information can be acquired by decrypting the information (s240 and s250 in the transmission request process).

  As described above, in the case of the information management system 1 described above, the client 10 serving as the transmission destination receives the user information at an arbitrary timing (start timing of transmission request processing) while preventing the server 20 from browsing the contents of the user information. Can be acquired.

  In the above embodiment, since the common key (1b) is generated on the client 10 side for each storage request process, it is not necessary to prepare the common key (1b) on the client 10 side in advance.

  In particular, in the above embodiment, another common key is generated for each session in which user information is transmitted from the client 10 to the server, and user information is encrypted based on the common key. Therefore, even if the common key used in any session leaks, the user information whose contents are browsed based on the common key can be limited to the user information encrypted in the session. Thereby, the risk of information leakage as the information management system 1 can be reduced, and damage caused by information leakage can be minimized.

  In the above embodiment, the encrypted user information and the encrypted common key transmitted from the client 10 to the server 20 are encrypted after applying an electronic signature to each of the user information and the common key. . Therefore, on the client 10 side as the transmission destination, the user information and the common key obtained by decrypting the encrypted user information and the encrypted common key are not falsified based on the electronic signature applied thereto. Can be confirmed.

Moreover, in the said embodiment, it is comprised so that data communication may be implement | achieved between the client 10 and the server 20 by the common key encryption system based on SSL. Therefore, since data from one side is transmitted between the client 10 and the server 20 in a state that can be decoded only by the other side, not only user information but also identification information on the communication path between the two. You can't even browse. This can reduce the risk of information leakage during communication between the two.
(4) Modifications The embodiment of the present invention has been described above. However, the present invention is not limited to the above embodiment, and can take various forms as long as they belong to the technical scope of the present invention. Needless to say.

  For example, in the above-described embodiment, when the client 10 transmits the identification information, the encrypted user information, and the encrypted common key to the server 20 in the storage request process, each is sequentially transmitted as separate data. (S120 to s170 of the same process).

  However, the order of these data is not particularly limited as long as the data can be recognized on the server 20 side as a series of information. In this case, it is sufficient to check whether or not the data to be transmitted first is received in s340 of the same process.

  In addition, the transmission of each data may be configured to be transmitted by another method as long as it is a method that can be recognized on the server 20 side as a series of information. For example, each piece of data is transmitted with information indicating that it is a “series of information”, and the server 20 that has received the data recognizes that it is a “series of information”. In addition, it may be configured to store data by response processing.

  As a specific configuration for this, in response processing, after establishing a session in s330, processing for collecting data transmitted from the client 10 within a certain period of time, a series of information from the collected data The process of specifying “identification information, encrypted user information, encrypted common key” and the process of associating them with each other and storing them in the storage unit 22 is performed, and then the response process is terminated. That's fine.

  Moreover, in the said embodiment, what was comprised so that the common key (1b) might be produced | generated by the client 10 side for every memory | storage request | requirement process was illustrated. However, this common key (1b) may be prepared in advance on the client 10 side.

Moreover, in the said embodiment, what was comprised so that data communication might be implement | achieved between the client 10 and the server 20 by the common key encryption system based on SSL was illustrated. However, as for the communication between the client 10 and the server 20, as long as the data from the client 10 can be decrypted only by the server 20, the encryption mode is limited to the encryption based on SSL. Absent.
(5) Correspondence with the Present Invention In the embodiment described above, s140 in FIGS. 2 and 4 is the first encryption means and the first electronic signature means in the present invention, and s160 in the figure is the second in the present invention. S120, s136, s150, and s170 are the client side transmission means and the third encryption means in the present invention, and s130 is the common key generation means in the present invention. is there.

  2 and 4, s350, s370 and s390 are storage means in the present invention, s450 in FIG. 2, s442 and s446 in FIG. 5 are specifying means in the present invention, and s460 in FIGS. It is the server side transmission means in this invention.

  Also, the common keys 1a and 2a passed from the client 10 to the server 20 in s110, 210, and 330 in FIG.

Conceptual diagram showing the configuration of the information management system The flowchart which shows the process performed by each of the client and server in 1st Embodiment The block diagram which shows the flow of each data in 1st Embodiment The flowchart (1/2) which shows the process performed by each of the client and server in 2nd Embodiment The flowchart (2/2) which shows the process performed by each of the client and server in 2nd Embodiment Block diagram showing the flow of each data in the second embodiment (1/2) Block diagram showing the flow of each data in the second embodiment (2/2)

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Information management system, 10 ... Client, 20 ... Server, 22 ... Memory | storage part, 100 ... Network.

Claims (10)

An information management system in which each of one or more clients is connected to a server so that data communication is possible,
At least one of the one or more clients is
First encryption means for generating encrypted user information obtained by encrypting user information related to a user of the client with a common key of the client;
The first encryption means encrypts the common key used when encrypting the user information by encrypting each of the public keys of one or more clients to which the user information should be notified. A second encryption means for generating the encrypted common key,
The encrypted user information generated by the first encryption unit, the encrypted common key generated by the second encryption unit, and identification information that can identify the client are sent to the server as a series of information. A client-side transmission means for transmitting,
The server
Storage means for storing the encrypted user information, the encrypted common key, and the identification information transmitted as a series of information from the client in a storage unit in association with each other;
When the user information of the specific client is requested from any one of the one or more clients, the specific client among the encrypted user information stored in the storage unit The encrypted user information associated with the identification information to be identified is specified, and the identification information for identifying the specific client among the encrypted common keys stored in the storage unit A specifying means for specifying the encrypted common key associated with the encrypted common key encrypted with the public key of the requesting client;
An information management system comprising: server-side transmission means for transmitting the encrypted user information and the encrypted common key specified by the specifying means to the requesting client. At least one of the one or more clients is
A common key generating means for generating the common key of the client;
The first encryption unit is configured to generate encrypted user information obtained by encrypting the user information with a common key generated by the common key generation unit. 1. The information management system according to 1. At least in any one of the one or more clients,
The common key generation unit is configured to generate a common key of the client prior to transmitting the encrypted user information and the encrypted common key by the server side transmission unit. The information management system according to claim 1 or 2. At least one of the one or more clients is
A first electronic signature means for applying an electronic signature to the user information;
The said 1st encryption means is comprised so that the encryption user information formed by encrypting the said user information to which the electronic signature was given by the said 1st electronic signature means may be produced | generated. The information management system according to any one of 1 to 3. At least one of the one or more clients is
A second electronic signature means for applying an electronic signature to a common key used when the first encryption means encrypts the user information;
The second encryption means is configured to generate one or more encrypted common keys obtained by encrypting the common key that has been digitally signed by the second electronic signature means. The information management system according to any one of claims 1 to 4. At least one of the one or more clients is
Third encryption means is provided for encrypting the encrypted user information, the encrypted common key, and identification information that can identify the client with an encryption key (server common key) that can be decrypted by the server. ,
The client-side transmission unit is configured to transmit the encrypted user information encrypted by the third encryption unit, the encrypted common key, and the identification information to the server as a series of information. And
In the server,
The storage means transmits the encrypted user information, the encrypted common key, and the identification information, which are transmitted as a series of information from the client and encrypted with the common key of the server, respectively by the common key of the server. The information management system according to any one of claims 1 to 5, wherein the information management system is configured to be stored in the storage unit after being decrypted. All the means with which the client in any one of Claim 1 to 6 is provided. The client characterized by the above-mentioned. All the means with which the server in any one of Claim 1 to 6 is provided The server characterized by the above-mentioned.   A program for causing a computer system to execute various processing procedures for causing the client according to any one of claims 1 to 6 to function as all means.   A program for causing a computer system to execute various processing procedures for causing the client according to any one of claims 1 to 6 to function as all means.