JP4751296B2 - E-mail transmission / reception system - Google Patents

Description

  The present invention relates to an electronic mail transmission / reception system, and more particularly to an electronic mail transmission / reception system that transmits and receives electronic mail safely without using specific software.

  With the spread of the Internet, data exchange using e-mail has increased. As a result, various risks are likely to occur. In order to avoid the risk, there is a need for a technology for safely exchanging e-mails.

  Techniques for safely exchanging electronic mail include a method for requesting a password when opening the electronic mail, a method for encrypting the electronic mail, and the like.

  As a technique for encrypting and transmitting and receiving an electronic mail, a method based on S / MIME (Secure / Multipurpose Internet Mail Extensions) and a method described in Patent Document 1 below are known. The method based on S / MIME is a method in which keys are managed on the client side, and an electronic mail is encrypted using a public key encryption method to be transmitted / received.

  In the method described in Patent Document 1 below, a sender issues an email encryption request to a web server, the email is encrypted by the web server, and the recipient of the encrypted email encrypts the same web server. This is a method for decrypting encrypted mail by issuing a decryption request for encrypted mail.

JP 2005-316557 A

  By the way, the method based on S / MIME requires useful management because it requires key management. In addition, there is a restriction that a mail client compatible with S / MIME must be used.

  As described above, the general e-mail encryption method has a problem in that it cannot be easily introduced because there are obstacles to the introduction, such as restrictions on mail clients or the necessity of dedicated client software. .

  The technique described in Patent Document 1 proposes a technique that facilitates the introduction of an electronic mail encryption system. However, there is a risk that information is leaked and security is weak when a sender sends a wrong address or when an e-mail containing an encrypted mail and a password is intercepted.

  Also, data communication for sending and receiving encrypted mail and data communication for sending encrypted mail to a web server and receiving decrypted mail to decrypt the encrypted mail are necessary. This requires about twice as much as e-mail transmission / reception, and there is a problem that the load on the network increases.

  SUMMARY OF THE INVENTION An object of the present invention is to propose an e-mail transmission / reception system that does not require specific client software on the sender side and the recipient side and has enhanced security. Another object of the present invention is to make it easy to install and not to increase the amount of data communication so much that it does not depend on the client environment.

  According to one aspect of the present invention, a first mail server that accepts an e-mail transmission request from a first terminal, locks the received e-mail with a password, and transmits the received e-mail to a second terminal, and used when executing password lock And a web server that publishes the password, wherein the first mail server has a password lock unit that locks the e-mail with a password, and acquires the password and the password. Means for storing necessary information and a destination e-mail address in the first database, the password-locked e-mail, and information necessary for obtaining the password, the e-mail destination Means for transmitting to the second terminal having a mail address, the web server comprising: Necessary for acquiring a login request based on login information from the second terminal and acquiring the password from the second terminal and user management means for permitting login only when the login information is correct Password management means for acquiring and displaying the password from the first database only when the information and the information necessary for acquiring the password stored in the first database match; and An electronic mail transmission / reception system characterized by comprising:

  An encrypted mail server that accepts an e-mail transmission request from the first terminal, encrypts the received e-mail, and transmits the encrypted mail to the second terminal; and a web server that publishes the password used during encryption execution; The encrypted mail server includes a mail encryption means for converting the email into an encrypted file in an executable format, the password, and a password necessary for acquiring the password. A means for storing information and a destination email address in combination in the first database, the encrypted email, and information necessary for obtaining the password are set as the destination email address of the email. Means for transmitting to the second terminal, wherein the web server receives a login request from the second terminal. In addition, user management means for permitting login only when the login information is correct, the information necessary for acquiring the password from the second terminal, and the password stored in the encrypted mail server are acquired. There is provided an e-mail transmission / reception system comprising password management means for acquiring and displaying the password from the first database only when the information necessary for doing so matches.

  The first mail server or the encrypted mail server may comprise destination confirmation requesting means for sending a request for confirmation of the destination mail address and registration of the password public information to the first terminal by e-mail. . In the first mail server or the encrypted mail server, registration means for storing information related to user registration when the destination mail address of the e-mail is not stored in the second database, user information registration User registration requesting means for transmitting the request to the second terminal by e-mail.

  Further, in order for the first mail server or the encrypted mail server to request the first terminal to approve user information registered in the second terminal, a sender mail address of the electronic mail and Registration means for associating and storing user information in the second database; and when the web server accepts registration of user information from the second terminal, a request for user information approval is sent to the first terminal. You may provide the user approval request | requirement means transmitted with an email.

The electronic mail transmission / reception system of the present invention has the following effects.
(1) E-mail transmission / reception can be performed safely as long as there is no mail client limitation, no dedicated client software is required, and there is only a normal mail client and a web browser. Therefore, the system can be easily introduced.
(2) Even if the sender of the e-mail sends the wrong address, it can be confirmed whether the address is correct by the address confirmation request, and the password is disclosed only when the address is correct. Can reduce the risk of leakage.
(3) If the user login information, the encrypted mail, and the mail containing the information for acquiring the password are not provided, the password lock cannot be released or the encrypted mail cannot be decrypted. Less.
(4) Since the amount of data communication does not increase as much as the amount of data communication for normal mail transmission / reception, there is little problem that the load on the network increases.

  Hereinafter, an embodiment of an e-mail transmission / reception system to which the present invention is applied will be described.

  FIG. 1 is a diagram showing a configuration example of an electronic mail transmission / reception system according to an embodiment of the present invention. The electronic mail transmission / reception system organization A and organization B according to the present embodiment and a network 50 connecting them are provided.

  The organization A transmits a transmission terminal 10 that transmits an electronic mail, receives an electronic mail from the transmission terminal 10, encrypts the electronic mail, for example, and transmits an encrypted mail, and an encrypted mail server 20 Is composed of a mail server 40 that accepts transmission of e-mails and transmits e-mails, and a web server 30 that manages user information and password information used for encryption, each connected via an intra-organization LAN or the like Yes.

  Instead of the encrypted mail server 20, a method of locking an electronic mail with a password may be used.

  The organization B includes a mail server 60 that accepts transmission of electronic mail and transmits the electronic mail, and a receiving terminal 70 that receives the electronic mail, and each is connected via an intra-organization LAN or the like. The mail servers 40 and 60 are connected to a network 50 such as the Internet, and electronic mail is transmitted and received via the network 50. The web server 30 is also connected to a network 50 such as the Internet and can be accessed from the outside.

  FIG. 2A is a diagram showing an example of an internal configuration of the encrypted mail server 20 and a block diagram showing a configuration with a database associated therewith. The encrypted mail server 20 includes a mail receiving unit 201 that receives a mail, an encrypted mail creation unit 202 that encrypts a mail, a password registration unit 203 that registers a password, and a user registration information registration unit that registers user information. 204, a user registration request mail creating unit 205 that creates a mail requesting user registration, a destination confirmation request mail creating unit 206, a message ID notification mail creating unit 207, and a mail sending unit 208. The user information management database DB 80 (second database) and the password information management database DB 90 (first database) are connected.

  The mail receiving unit 201 accepts transmission of an electronic mail from the transmission terminal 10. The encrypted mail creating unit 202 converts the mail body or attached file of the e-mail received from the transmission terminal 10 into an encrypted file in an executable format, and creates a MIME-format mail with the converted file as an attached file. Instead of creating an encrypted mail, a password lock may be performed. The password registration unit 203 generates a unique message ID for each encrypted email, the message ID, the password used when encryption or password lock is performed, and the destination email of the email received from the sending terminal 10 The address is registered in the password information management DB 90, and the message ID, password, and destination mail address are associated with each other.

  The user registration information registration unit 204 checks whether or not the destination mail address of the e-mail received from the transmission terminal 10 is registered in the user information registration DB 80, and if it is not registered, the user registration that is unique for each user ID is generated, the user registration ID, the destination mail address of the e-mail received from the sending terminal 10 and the sender mail address are registered in the user information registration DB 80, and the user registration ID, the destination mail address and the sender mail address are registered. Associate.

  The user registration ID and the destination mail address are required when the user of the receiving terminal 70 performs user registration, and the user registration ID and the destination mail address can be registered only when the user registration ID and the destination mail address match. The sender e-mail address relates to whether or not the user information registered by the user of the transmitting terminal 10 after the user of the receiving terminal 70 is the user of the receiving terminal 70 after the web server 30 is registered. Used to submit an approval request. The user registration request mail creation unit 205 is activated when the user registration information registration unit 204 registers in the user information registration DB 80 and receives from the transmission terminal 10 to request the user of the reception terminal 70 to register user information. A user information registration request mail (see FIG. 4 to be described later) in which the user registration URL (Uniform Resource Locator) of the web server 30 and the user registration ID are written is created at the destination mail address of the e-mail.

  The destination confirmation request mail creation unit 206 asks the user of the transmission terminal 10 to check whether the destination is correct and to register the password disclosure information in order to have the password public information registered. A destination confirmation request mail (see FIG. 10) is created in which the password public information registration URL of the web server 30, the destination mail address of the email received from the sending terminal 10, and the message ID are written to the sender mail address. The message ID notification e-mail creation unit 207 sends the e-mail received from the transmission terminal 10 to the destination e-mail address in order to notify the message ID, which is information necessary for the user of the receiving terminal 70 to acquire the password. A message ID notification mail (see FIG. 12) describing the login URL and message ID of the web server 30 is created. The mail transmission unit 208 transmits the created encrypted mail, user registration request mail, destination confirmation request mail, and message ID notification mail to the mail server 40. The user information management DB 80 is a database for managing user information, in which a user registration ID, a destination mail address, and a sender mail address are registered from the encrypted mail server 20, and user information is registered from a user of the receiving terminal 70. Approval information is registered from the user of the transmission terminal 10. The password information management DB 90 is a database for managing password information, in which a message ID, a password, and a destination mail address are registered from the encrypted mail server 20, and password public information is registered from a user of the transmission terminal 10.

  FIG. 2B is a diagram illustrating an example of an internal configuration of the web server 30 and a diagram illustrating a configuration of a related database. The web server 30 includes a user information management unit 301, a password information management unit 302, a user approval request mail creation unit 303, and a mail transmission unit 304, and is connected to the user information management DB 80 and the password information management DB 90. Has been. The user information management unit 301 manages user information by receiving a user information registration request or a login request from a user of the receiving terminal 70 or a user information rejection / approval request from a user of the transmitting terminal 10. The password information management unit 302 manages password information by receiving a password public information registration request from a user of the transmission terminal 10 or receiving a message ID input request from a user of the reception terminal 70 and displaying a password. The user approval request mail creation unit 303 is called when the user of the receiving terminal 70 registers user information, and in order to have the user of the transmitting terminal 10 confirm whether the user information is correct, user information management A user approval request mail (see FIG. 7) in which the user approval URL of the web server 30 and the user mail address are described is created in the DB 80 to the sender mail address associated with the user registration ID. The mail transmission unit 304 transmits the created user approval request mail to the mail server 40.

    FIG. 3 is a sequence diagram showing operations in the system. This sequence diagram will be described later with reference to a flowchart showing the flow of processing.

  FIG. 4 is a view showing a display example of the user registration request mail 400. The user registration request mail 400 is transmitted by the encrypted mail server 20 to the user of the receiving terminal 70 whose user information is not registered. The user registration request mail 400 includes a user registration URL 401 and a user registration ID 402 of the web server 30. The user of the receiving terminal 70 that has received the user registration request mail 400 can access the user registration URL 401 based on the described information and perform user registration.

  FIG. 5 is a diagram illustrating a display example of the user registration screen 500. The user registration screen 500 is displayed by the web server 30 when the user of the receiving terminal 70 that has received the user registration request mail 400 accesses the user registration URL 401 of the web server 30 described. On the user registration screen 500, the user of the receiving terminal 70 confirms the user registration ID 402 described in the user registration request mail 400 in the input field 501, his mail address in the input field 502, and the password in the input field 503. The user password is entered in the entry field 504, the name is entered in the entry field 505, the company name is entered in the entry field 506, and the telephone number is entered in the entry field 507. When the OK button 508 is pressed, the web server 30 accepts a user registration confirmation screen display request. Detailed user registration processing of the web server 30 will be described later.

  FIG. 6 is a diagram illustrating a display example of the user registration confirmation screen 600. The user registration confirmation screen 600 is displayed by the web server 30 when the OK button 508 is pressed on the user registration screen 500 and the input information is correct. On the user registration confirmation screen 600, the user of the receiving terminal 70 confirms the input content, and presses the registration button 601 if the content is correct. The web server 30 accepts a user registration request when the registration button 601 is pressed. Detailed user registration processing of the web server 30 will be described later.

  FIG. 7 is a view showing a display example of the user approval request mail 700. The user approval request mail 700 is sent to the sender mail address associated with the user registration ID in the user information management DB 80 when the user of the receiving terminal 70 that has received the user registration request mail 400 registers user information (transmission). To the user of the terminal 10 by the web server 30. In the user approval request mail 700, the user approval URL 701 and the user mail address 702 of the web server 30 are described. The user of the transmission terminal 10 that has received the user approval request mail 700 accesses the user approval URL 701 based on the described information and performs user approval.

  FIG. 8 is a diagram illustrating a display example of the user approval information input screen 800. The user approval information input screen 800 is displayed by the web server 30 when the user of the transmission terminal 10 that has received the user approval request mail 700 accesses the user approval URL 701 of the web server 30 described. On the user approval information input screen 800, the user of the transmission terminal 10 inputs his / her mail address in the input field 801 and the user mail address described in the user approval request mail 700 in the input field 802. The web server 30 accepts a user approval screen display request by pressing an OK button 803. Detailed user approval processing of the web server 30 will be described later.

  FIG. 9 is a diagram illustrating a display example of the user approval screen 900. The user approval screen 900 is displayed by the web server 30 when the OK button 803 is pressed on the user approval information input screen 800 and the input information is correct. On the user approval screen 900, the user of the transmission terminal 10 confirms the displayed user registration information and presses the approval button 901 or the reject button 902. The web server 30 receives a user approval request when the approval button 901 is pressed, and receives a user rejection request when the reject button 902 is pressed. Only the user of the receiving terminal 70 approved by the user of the transmitting terminal 10 can log in to the web server 30. Detailed user approval processing of the web server 30 will be described later.

  FIG. 10 is a diagram illustrating a display example of the destination confirmation request mail 1000. The destination confirmation request mail 1000 is transmitted by the encrypted mail server 20 to the user of the transmission terminal 10. The address confirmation request mail 1000 describes the password public information registration URL 1001 of the web server 30, the destination mail address 1002 of the email received from the transmission terminal 10, and the message ID 1003. The user of the transmission terminal 10 that has received the destination confirmation request mail 1000 checks whether or not the destination email address is correct, and then accesses the password public information registration URL 1001 based on the written information if there is no error. Register password public information.

  FIG. 11 is a diagram showing a display example of the password public information registration screen 1100. The password public information registration screen 1100 is displayed by the web server 30 when the user of the transmission terminal 10 receiving the address confirmation request mail 1000 accesses the password public information registration URL 1001 of the web server 30 described. On the password public information registration screen 1100, the user of the transmission terminal 10 enters the message ID 1003 described in the destination confirmation request mail 1000 in the input field 1101, the destination mail address 1002 in the input field 1102, and the password used for performing the encryption. Is entered in the input field 1103. When the registration button 1104 is pressed, the web server 30 accepts a password public information registration request. Only when the password disclosure information is registered, the password is disclosed to the user of the receiving terminal 70. That is, even when the user of the transmission terminal 10 sends an e-mail with the wrong destination, the password is not disclosed unless the password disclosure information is registered on the password disclosure information registration screen 1100, so there is no fear of leaking information. The detailed password public information registration process of the web server 30 will be described later.

  FIG. 12 is a view showing a display example of the message ID notification mail 1200. The message ID notification mail 1200 is transmitted by the encrypted mail server 20 to the user of the receiving terminal 70. The message ID notification mail 1200 includes a login URL 1201 and a message ID 1202 for the web server 30. The user of the receiving terminal 70 that has received the message ID notification mail 1200 accesses the login URL 1201 based on the described information, and obtains a password after login.

  FIG. 13 is a diagram illustrating a display example of the login screen 1300. The login screen 1300 is displayed by the web server 30 when the user of the receiving terminal 70 that has received the message ID notification mail 1200 accesses the login URL 1201 of the web server 30 described. On the login screen 1300, the user of the receiving terminal 70 inputs his / her e-mail address in the input field 1301 and the password registered at the time of user registration in the input field 1302. The web server 30 accepts a login request when a login button 1303 is pressed. Detailed login processing of the web server 30 will be described later.

  FIG. 14 is a diagram showing a display example of the message ID input screen 1400. The message ID input screen 1400 is displayed by the web server 30 when the login button 1303 is pressed on the login screen 1300 and the login information is correct. On the message ID input screen 1400, the user of the receiving terminal 70 inputs the message ID 1202 described in the message ID notification mail 1200 in the input field 1401. The web server 30 accepts a password display request when an OK button 1402 is pressed. Detailed password display processing of the web server 30 will be described later.

  FIG. 15 is a diagram illustrating a display example of the password display screen 1500. The password display screen 1500 is displayed by the web server 30 when the OK button 1402 is pressed on the message ID input screen 1400 and the input information is correct. Detailed password display processing of the web server 30 will be described later.

  FIG. 16 is a diagram showing a display example of the password input screen 1600. The password input screen 1600 is displayed when the user of the receiving terminal 70 executes the executable file attached to the encrypted mail. The user of the receiving terminal 70 inputs the password 1501 displayed on the password display screen 1500 into the input field 1601 and presses an OK button 1602, whereby the file containing the original mail text or the original Decrypted into an attached file.

  Hereinafter, the operation of the electronic mail transmission / reception system configured as described above will be described. The description will be made with reference to the sequence diagram of FIG. 3 as appropriate.

  FIG. 17 is a flowchart showing an outline of the mail encryption process of the encrypted mail server 20. The encrypted mail server 20 receives an electronic mail from the transmission terminal 10 (step 1701). The mail body or attached file of the received mail is converted into an encrypted file in an executable format, and a MIME-format mail having the converted file as an attached file is created (step 1702). As described above, it is only necessary to perform password lock.

  Next, it is confirmed whether or not the destination mail address of the e-mail received from the transmission terminal 10 is registered in the user information management DB 80 (step 1703). If not registered, a user registration ID that is unique for each user is generated (step 1704), and the generated user registration ID, the destination mail address of the e-mail received from the transmission terminal 10 and the sender mail address are stored in the user. It registers in the information management DB 80 (step 1705), creates a user registration request mail 400 (step 1706), and sends it to the user of the receiving terminal 70 (step 1707).

  Next, a unique message ID is generated for each encrypted e-mail (step 1708), the generated message ID, the password used when executing the encryption, and the e-mail destination e-mail received from the sending terminal 10 are generated. The address is registered in the password management DB 90 (step 1709), a destination confirmation request mail 1000 is created (step 1710), and transmitted to the user of the transmission terminal 10 (step 1711). Next, a message ID notification mail 1200 is created (step 1712) and transmitted to the user of the receiving terminal 70 (step 1713). Finally, the encrypted or password-locked mail is transmitted to the user of the receiving terminal 70 (step 1714).

  FIG. 18 is a flowchart showing an overview of the user registration process of the web server 30. When the user of the receiving terminal 70 accesses the user registration URL 401 described in the user registration request mail 400, the web server 30 displays the user registration screen 500 (step 1801). User registration information from the user of the receiving terminal 70 is received (step 1802), and pressing of an OK button 508 is received (step 1803). When the OK button 508 is pressed (from here, the web server 30 and the receiving terminal 70 communicate with each other by SSL (Secure Socket Layer)), whether the input user registration ID is registered in the user information management DB 80, or user information It is confirmed whether the destination e-mail address associated with the user registration ID registered in the management DB 80 is the same as the input e-mail address, and whether the input password and the confirmation password are the same (step 1804). If the input information is invalid as a result of this confirmation processing, an input invalid message is displayed (step 1805), and the user registration screen 500 is displayed again. If the input information is correct, the user information confirmation screen 600 is displayed (step 1806), and the pressing of the registration button 601 is accepted (step 1807). When the registration button 601 is pressed, it is confirmed whether user information has already been registered in the user information management DB 80 (step 1808). If registration has not been performed, the user information input to the user information management DB 80 is registered (step 1809), a user approval request mail 700 is created (step 1810), and the user information management DB 80 is associated with the user registration ID. To the sender mail address (addressed to the user of the transmission terminal 10) (step 1811). If registered, a registered message is displayed (step 1812).

  FIG. 19 is a flowchart showing an outline of the user approval process of the web server 30. When the user of the transmission terminal 10 accesses the user approval URL 701 described in the user approval request mail 700, the web server 30 displays the user approval information input screen 800 (step 1901). User approval information from the user of the transmission terminal 10 is accepted (step 1902), and pressing of an OK button 803 is accepted (step 1903). When the OK button 803 is pressed, the input user mail address is registered in the user information management DB 80 or the sender mail address associated with the user mail address registered in the user information management DB 80 is input. Whether it is the same as the approver's e-mail address (step 1904). If the input information is invalid as a result of the confirmation, an input invalid message is displayed (step 1905), and the screen returns to the user approval information input screen 800. If the input information is correct, the user approval screen 900 is displayed (step 1906), and a request for pressing the approval button 901 or the reject button 902 is accepted (step 1907). It is determined whether either the approval button 901 or the reject button 902 is pressed (step 1908). If the reject button 902 is pressed, the information on the user to be approved registered in the user information management DB 80 is in a rejected state. (Step 1909). When the approval button 901 is pressed, it is confirmed whether or not the information on the approval target user registered in the user information management DB 80 has already been approved (step 1910), and if approved, an approved message is displayed. (Step 1911). If not approved, the information on the approval target user registered in the user information management DB 80 is updated to the approval state (step 1912).

  FIG. 20 is a flowchart showing an outline of the password public information registration process of the web server 30. When the user of the transmission terminal 10 accesses the password disclosure information registration URL 1001 described in the destination confirmation request mail 1000, the web server 30 displays the password disclosure information registration screen 1100 (step 2001). Password public information from the user of the transmission terminal 10 is accepted (step 2002), and pressing of the registration button 1104 is accepted (step 2003). When the registration button 1104 is pressed, the entered message ID is registered in the password information management DB 90 or the destination email address associated with the message ID registered in the password information management DB 90 is entered. It is confirmed whether it is the same as the address and whether the input publication deadline is valid (step 2004). If the input information is invalid as a result of the confirmation, an input fraud message is displayed (step 2005), and the screen returns to the password public information registration screen 1100. If the input information is correct, the disclosure information of the disclosure target password information registered in the password information management DB 90 is updated (step 2006).

  FIG. 21 is a flowchart showing an overview of the password display process of the web server of the web server 30. When the user of the receiving terminal 70 accesses the login URL 1201 described in the message ID notification mail 1200, the web server 30 displays a login screen 1300 (step 2101). The login information from the user of the receiving terminal 70 is accepted (step 2102), and the depression of the login button 1303 is accepted (step 2103). When the login button 1303 is pressed (from here, the web server 30 and the receiving terminal 70 communicate with each other via SSL), it is confirmed whether or not the input mail address is registered in the user information management DB 80 (step 2104). If not registered, an unregistered message is displayed (step 2105), and the screen returns to the login screen 1300. If it is registered, it is confirmed whether or not the user information for the input mail address registered in the user information management DB 80 is in an approved state (step 2106). If it is not in an approved state, an unapproved message is displayed (step 2107). If it is in the approval state, it is confirmed whether or not the password for the input mail address registered in the user information management DB 80 is the same as the input password (step 2108). If they are not the same, a password fraud message is displayed (step 2109), and the screen returns to the login screen 1300. If they are the same, the message ID input screen 1400 is displayed (step 2110). The input of the message ID from the user of the receiving terminal 70 is accepted (step 2111), and the press of the OK button 1402 is accepted (step 2112). When the OK button 1402 is pressed, it is confirmed whether or not the input message ID is registered in the password information management DB 90 (step 2113). If not registered, a message ID invalid message is displayed (step 2114), and the screen returns to the message ID input screen 1400. If it is registered, it is confirmed whether or not the expiration date for the input message ID registered in the password information management DB 90 is after the current time (step 2115). If it is not after the current time, a password disclosure end message display is displayed (step 2116). If it is after the current time, a password display screen 1500 is displayed (step 2117).

  In the above embodiment, user information can be changed, or user information once approved can be rejected. It is also possible to make a password once published private or change the publication deadline.

  As described above, the electronic mail transmission / reception system according to the present embodiment has the following advantages.

(1) There is no restriction on mail clients, no dedicated client software is required, and if there is a normal mail client and a web browser, it is possible to send and receive e-mails safely, so that it can be easily introduced. .
(2) Even if the sender of the e-mail has sent the wrong address, it can be confirmed whether the address is correct by the address confirmation request, and the password can be disclosed only if it is not incorrect, so the risk of information leaking Less.
(3) If the user login information, the encrypted mail, and the mail containing the information for acquiring the password are not provided, the encrypted mail cannot be decrypted, and the risk of information leakage is reduced.
(4) Since it does not increase as much as the amount of data communication for normal mail transmission / reception, an increase in network load can be suppressed.

  The present invention can be used as an electronic mail system.

It is a figure which shows the example of 1 structure of the email transmission / reception system by one embodiment of this invention. 2A is a configuration diagram showing an internal configuration diagram of the encrypted mail server and a related database, and FIG. 2B is a configuration diagram showing an internal configuration diagram of the web server and a related database. It is a sequence diagram which shows the process in the system by this Embodiment. It is a figure which shows the example of a display of a user registration request mail. It is a figure which shows the example of a display of a user registration screen. It is a figure which shows the example of a display of a user registration confirmation screen. It is a figure which shows the example of a display of a user approval request mail. It is a figure which shows the example of a display of a user approval information input screen. It is a figure which shows the example of a display of a user approval screen. It is a figure which shows the example of a display of a destination confirmation request mail. It is a figure which shows the example of a display of a password public information registration screen. It is a figure which shows the example of a display of message ID notification mail. It is a figure showing the example of a display of a login screen. It is a figure which shows the example of a display of a message ID input screen. It is a figure which shows the example of a display of a password display screen. It is a figure which shows the example of a display of a password input screen. It is a flowchart which shows the outline | summary of the mail encryption process of an encryption mail server. It is a flowchart which shows the outline | summary of the user registration process of a web server. It is a flowchart which shows the outline | summary of the user approval process of a web server. It is a flowchart which shows the outline | summary of the destination registration process of a web server. It is a flowchart which shows the outline | summary of the password display process of a web server.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Sending terminal, 20 ... Encrypted mail server, 30 ... Web server, 40 ... Mail server, 50 ... Network, 60 ... Mail server, 70 ... Receiving terminal, 80 ... User information management DB, 90 ... Password information management DB, DESCRIPTION OF SYMBOLS 201 ... Mail receiving part, 202 ... Encrypted mail preparation part, 203 ... Password registration part, 204 ... User registration information registration part, 205 ... User registration request mail preparation part, 206 ... Destination confirmation request mail preparation part, 207 ... Message ID Notification mail creation unit, 208 ... mail transmission unit, 301 ... user information management unit, 302 ... password management unit, 303 ... user approval request mail creation unit, 304 ... mail transmission unit.

Claims (5)

A first mail server that accepts an e-mail transmission request from the first terminal, password-locks the received e-mail and sends it to the second terminal; a web server that publishes the password used when executing the password lock; An email sending and receiving system comprising:
The first mail server includes password lock means for locking the e-mail with a password, the password, information necessary for acquiring the password, and an electronic device addressed to the second terminal from the first terminal. a means for storing the first database and a destination mail address of the mail in the set, the destination mail address of the electronic mail and information necessary to obtain the said password locked email passwords Means for transmitting to the second terminal,
The web server accepts a login request based on login information from the second terminal, and acquires user management means for permitting login only when the login information is correct, and the password from the second terminal. Addressed to the second terminal, information necessary for obtaining the password stored in the first database, information necessary for obtaining the information and the destination mail address of the second terminal An e-mail transmission / reception system comprising password management means for acquiring and displaying the password from the first database only when the destination e-mail address of the e-mail matches. An encrypted mail server that accepts an e-mail transmission request from the first terminal, encrypts the received e-mail, and transmits the encrypted mail to the second terminal; and a web server that publishes the password used during encryption execution; An e-mail transmission / reception system comprising:
The encrypted mail server includes a mail encryption means for converting the electronic mail into an encrypted file of an executable format, the password, information necessary for obtaining the password, and the second from the first terminal. Means for storing in the first database in combination with the destination mail address of the e-mail addressed to the terminal of the e-mail and the information necessary for obtaining the encrypted e-mail and the password. Means for transmitting to the second terminal having a destination email address,
The web server accepts a login request from the second terminal, permits user login only when the login information is correct, information necessary for acquiring a password from the second terminal, and The destination mail address of the second terminal, the information necessary for obtaining the password stored in the encrypted mail server, and the destination mail address of an e-mail addressed to the second terminal And a password management means for acquiring and displaying the password from the first database only when they match, an e-mail transmission / reception system comprising: The first mail server or the encrypted mail server further comprises destination confirmation requesting means for sending a request for confirmation of the destination mail address and registration of the public information of the password to the first terminal by e-mail. The e-mail transmission / reception system according to claim 1 or 2, characterized in that:   In the first mail server or the encrypted mail server, a registration means for storing information relating to user registration when the destination mail address of the electronic mail is not stored in a second database, and a request for user information registration The e-mail transmission / reception system according to any one of claims 1 to 3, further comprising: a user registration request unit that transmits the e-mail to the second terminal. In order for the first mail server or the encrypted mail server to request the first terminal to approve the user information registered in the second terminal, the sender mail address and user information of the e-mail Registration means for associating and storing in the second database,
The web server comprises user approval request means for sending a user information approval request to the first terminal by e-mail when registration of user information is received from the second terminal. Item 5. The electronic mail transmission / reception system according to Item 4.

Images