JP2007251511A - Mail system and mail transmission reception method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mail system and a mail transmission reception method capable of preventing impersonation and eavesdropping through the contrivance that a client possessing an authentication key unit can transmit/receive mail from only a terminal related to the authentication key unit and that the mail is automatically encrypted/decrypted. <P>SOLUTION: The authentication key unit 3 includes authentication information of a mail server 5 and information of private key required for decrypting mail, and a means 10 for asking authentication for a mail server 5 when the authentication key unit is connected to a terminal 1, and the mail server 5 includes a means 6 for acquiring a public key from an address public key conversion DB 4 and an encryption means 7 for using the acquired public key to encrypt transmission mail. The authentication information of the mail server 5 stored in the authentication key unit 3 and the information of the private key required for decrypting mail are set from the terminal 1 by a user. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mail system and a mail transmission / reception method, and in particular, a mail system and a mail transmission / reception method capable of preventing leakage of mail information by limiting users who can send and receive mail to only authorized persons. About.

  In recent years, with the spread of the Internet environment, the use of mail between companies has become common, and important information is often exchanged based on mail. In addition, with the full enforcement of the Personal Information Protection Law, businesses that handle personal information are required to take safety management measures when handling personal information.

  Sending and receiving emails using a general email system has a greater risk of impersonation by users other than the user and eavesdropping on emails on the network, which increases the requirements for email security. .

In addition, as a prior art regarding information leakage prevention from a communication path, for example, a technique described in Patent Document 1 is used. This prior art eliminates the need to flow connection permission information such as a user ID, password, and encryption key on the communication path, thereby preventing information leakage.
Japanese Patent Laid-Open No. 2005-117078

  In general, transmission / reception of mail is an operation by a user, and an arbitrary file can be attached. Further, as described above, the risk of eavesdropping on mail increases with the spread of the Internet. Although it is possible to take measures against eavesdropping by sending an encrypted mail, it is usually left up to the user to decide whether to encrypt the file, so there is a risk that the user forgets to encrypt it. is there.

  In addition, information on users who send / receive emails and password information are often set and saved in email software, so it is important for others when a user leaves the PC that sends / receives emails. There is a risk that an important e-mail is read or an important file is transmitted to a third party.

  An object of the present invention is to provide a mail system and a mail transmission / reception method capable of preventing eavesdropping and spoofing without requiring an operation by a user at the time of mail transmission / reception in view of the above-described points. It is in.

  According to the present invention, the object is to send and receive mail between a terminal device, an authentication key device that is hardware directly connected to the terminal device, and between the terminal device and an external network. In a mail system comprising a mail server that controls transmission / reception, the authentication key device holds authentication information of the mail server and secret key information necessary for decrypting mail, and is connected to the terminal device And a means for authenticating to the mail server, wherein the mail server obtains a public key from an address public key conversion database, and encryption for encrypting outgoing mail using the obtained public key Is achieved.

  Further, the object is to control a terminal device that performs mail transmission / reception, an authentication key device that is hardware directly connected to the terminal device, and mail transmission / reception between the terminal device and an external network. In the mail transmission / reception method in the mail system configured with the mail server, the authentication key device holds the authentication information of the mail server and the secret key information necessary for decrypting the mail, and connects to the terminal device Authentication is performed to the mail server, the mail server obtains a public key from the address public key conversion database, encrypts the outgoing mail using the obtained public key, and the terminal device performs the authentication This is accomplished by decrypting the encrypted received mail using the secret key information in the key device.

  According to the present invention, a client possessing an authentication key device is permitted to send and receive mail only from a terminal device associated with the authentication key device, so that impersonation can be prevented. Since e-mail is automatically encrypted / decrypted, eavesdropping can be prevented.

  Embodiments of a mail system and a mail transmission / reception method according to the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of a mail system according to an embodiment of the present invention. In FIG. 1, 1 is a terminal device, 2 is an authentication key initial setting unit, 3 is an authentication key device, 4 is an address public key conversion DB, 5 is a mail server, 6 is a public key acquisition unit, 7 is a mail encryption unit, 8 is a POP server, 9 is a PC determination unit, 10 is a mail server authentication unit, 11 is an error message output unit, 12 is an authentication key DB, and 13 is a network.

  The mail system according to the embodiment of the present invention shown in FIG. 1 includes a terminal device 1 such as a PC that transmits and receives mail used by a user, an authentication key device 3 that is connected to the terminal device 1, and a mail. The server 5 is configured. The terminal device 1 and the mail server 5 are connected by an in-house LAN or the like. The mail server 5 is connected to a network 13 such as the Internet network, and other terminal devices connected to the network and the terminal device are connected to each other. Control the sending and receiving of emails between them. The above-described authentication key device 3 may be a USB memory, a portable hard disk device that can be directly connected to a terminal device, or the like.

  Although not shown, the terminal device 1 and the mail server 5 constituting the embodiment of the present invention are configured as an information processing device including a storage device such as a CPU, a memory, and an HDD, an input device such as a keyboard and a mouse, and a display device. Various functions to be described later are realized by the CPU executing a program loaded in the memory.

  The authentication key device 3 includes a mail server authentication unit 10 that performs user authentication to the mail server 5, an error message output unit 11 that outputs an error message to the terminal device 1, a PC determination unit 9 that authenticates information of the terminal device 1, and An authentication key DB 12 is provided.

  The mail server 5 is connected to an address public key conversion DB 4 in which a mail address and public key information are associated with each other, and is used to obtain the address of the mail transmitted from the terminal device 1 or the public key of the corresponding address. A key acquisition unit 6, a mail encryption unit 7 that encrypts outgoing mail and decrypts received mail, and a POP server 8 are provided. In the mail server 5, when the mail is transmitted, the mail encryption unit 7 encrypts the mail using the obtained public key and transmits the mail to the network 8.

  In the above description, the mail server authentication unit 10, the error message output unit 11, and the PC determination unit 9 provided in the authentication key device 3 are programs, and the system administrator before the authentication key device 3 is delivered to the user. Etc. are stored. The authentication key DB 12 is set in advance by the user from the terminal device 1 using the authentication key initial setting unit 2 provided in the terminal device 1.

  FIG. 2 is a flowchart for explaining an outline of processing when the user performs transmission / reception of mail using the terminal device 1, which will be described next.

(1) When the user connects the authentication key device 3 to the terminal device 1 that transmits and receives mail, the authentication key device 3 uses the PC determination unit 9 included in the authentication key device 3 in the self-authentication key device 3. It is determined whether or not the information of the terminal device possessed matches the information of the terminal device 1 (steps 201 and 202).

(2) If the determination result in step 202 is abnormal, the authentication key device 3 uses the error message output unit 11 in the authentication key device 3 to display the display unit of the terminal device 1 that the user intends to use An error message is output to the user and the user is notified accordingly. The message in this case is, for example, “e-mail cannot be transmitted / received because it is not the terminal device that issued the authentication key” (step 205).

(3) If the determination result in step 202 is normal, the authentication key device 3 uses the information of the POP server set in the authentication key DB 12 by the mail server authentication unit 10 in the authentication key device 3. Then, the terminal device 1 requests user authentication from the POP server 8 in the mail server 5 and obtains an authentication result (step 203).

(4) The authentication key device 3 determines the authentication result received in the process of step 203. If the determination result is abnormal, the authentication key device 3 uses the error message output unit 11 in the authentication key device 3 to be used by the user. An error message is output to the display unit of the terminal device 1 that is currently informed to the user. The message in this case is, for example, “The mail server is down or busy” (steps 204 and 206).

(5) If the determination result in step 204 is normal, the authentication key device 3 selects whether to transmit mail or receive mail on the display unit of the terminal device 1 used by the user. Display is performed, and the user is allowed to select transmission or reception (step 216).

(6) When the selection of the user in step 216 is transmission, the terminal device 1 transmits mail to the mail server 5 (step 207).

(7) The mail server 5 that has received the mail performs mail encryption processing using the public key, and determines whether the end result is normal. The mail encryption process will be described later (steps 208 and 209).

(8) If the determination result in step 209 is abnormal termination, the mail server 5 notifies the terminal device 1 that the transmission of the mail as an error message has failed, and this notification is displayed on the terminal device 1. (Step 210).

(9) If the determination result in step 209 is normal, the mail server 5 transmits the encrypted mail to the network 13 and notifies the terminal device 1 that the mail has been transmitted normally. This notification is displayed on the display unit of the terminal device 1 (step 217).

(10) When the selection of the user in step 216 is reception, the terminal device 1 repeatedly performs the following processing until reception of all mails is completed (steps 211 and 214).

(11) The terminal device 1 first reads the secret key from the authentication key DB 12 of the authentication key device 3, receives one encrypted mail from the mail server 5, and then uses the read secret key to send a mail. (Steps 212 and 213).

(12) It is determined whether or not the reception of all the mails is completed. If the reception of all the mails is not completed, the process returns to the process from step 212 to continue the reception process of the next mail (step 214).

(13) When the transmission / reception of mail is completed by the above processing, the user removes the authentication key device 3 from the terminal device 1 and ends the mail transmission / reception processing (step 215).

  FIG. 3 is a flowchart for explaining the outline of the processing when the mail server 5 encrypts the mail received from the terminal device 1. Next, this will be described.

(1) The mail server 5 searches the address public key conversion DB 4 using the destination mail address included in the mail received from the terminal device 1 as a search key, acquires the search result, and sets the destination mail address as the destination mail address. It is determined whether there is a corresponding public key (steps 301 and 302).

(2) If it is determined in step 302 that there is a public key, the mail server 5 encrypts the mail and then sends the encrypted mail to encrypt the mail. This process is terminated (steps 303 and 304).

(3) If it is determined in step 302 that there is no public key, an error message is notified to the terminal device 1 that sent the mail, and the user is registered with the public key in the address public key conversion DB 4 The public key registration process is started (step 306).

  FIG. 4 is a flowchart for explaining the outline of the process in which the user registers public key information in the address public key conversion DB 4 in the process of step 306 in FIG. 3, which will be described next.

(1) When this process is started, the mail server 5 transmits and displays a public key registration form to the terminal device 1 to allow the user to input necessary information. The information to be input includes a destination e-mail address, information on a public key prepared in advance by a user from a key issuing organization, and an expiration date (step 401).

(2) The mail server 5 searches the address public key conversion DB 4 using the input mail address as a search key, and determines whether there is a hit record as the obtained search result (steps 402 and 403). .

(3) If there is no hit record as a search result in the determination in step 403, the information input by the user, here, the destination mail address, the public key information, and the expiration date are registered in the address public key conversion DB 4 (Step 404).

(4) When there is a record hit as a search result in the determination of step 403, the search result and information input by the user are transmitted to the terminal device 1, and it is confirmed whether or not to update the database with the user input information. The screen is displayed, and the user is made to select and input whether to update (step 405).

(5) If the user's selection at step 405 is an update, the address public key conversion DB 4 is updated with the information input by the user as in the process at step 404, and the user's selection is not updated. In this case, the processing here is terminated (steps 406 and 407).

  FIG. 5 is a flowchart for explaining an outline of processing when the user performs initial setting of the authentication key device 3 from the terminal device 1. Next, this will be described.

(1) When this process is started, the terminal device 1 first displays an input screen and allows the user to input various information set in the authentication key device. This input information includes the SMTP server name that is the name of the server used for mail transmission, the POP3 server name that is the server name for mail reception, the POP3 user ID that is the user ID of the user who uses the POP3 server, and its password Is the POP3 password and the private key information paired with the public key (step 501).

(2) The terminal device 1 displays a confirmation screen as to whether or not the entered information can be registered in the authentication key DB 12 of the authentication key device 3, and allows the user to input confirmation (step 502).

(3) It is determined whether or not the confirmation input in step 502 is OK. If the input is not OK, the process returns to step 501 to correct the input information. If the input is OK, the input information Is written in the authentication key DB 12 of the authentication key device 3 and the processing here is terminated (steps 503 and 504).

  Each processing in the above-described embodiment of the present invention is configured by a program and can be executed by a CPU provided in a terminal device or a mail server. These programs are stored in a recording medium such as an FD, a CDROM, or a DVD. It can be stored and provided, or can be provided by digital information via a network.

It is a block diagram which shows the structure of the mail system by one Embodiment of this invention. It is a flowchart explaining the outline | summary of the process when a user transmits / receives mail using a terminal device. It is a flowchart explaining the outline | summary of the process at the time of the mail server encrypting the mail received from the terminal device. It is a flowchart explaining the outline | summary of the process in which a user registers the information of a public key into address public key conversion DB by the process of step 306 of FIG. It is a flowchart explaining the outline | summary of a process when a user performs the initial setting of the authentication key apparatus 3 from a terminal device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Terminal device 2 Authentication key initial setting part 3 Authentication key apparatus 4 Address public key conversion DB
5 Mail Server 6 Public Key Acquisition Unit 7 Mail Encryption Unit 8 POP Server 9 PC Determination Unit 10 Mail Server Authentication Unit 11 Error Message Output Unit 12 Authentication Key DB
13 network

Claims (6)

  A terminal device that performs mail transmission / reception, an authentication key device that is hardware directly connected to the terminal device, and a mail server that controls transmission / reception of mail between the terminal device and an external network In the mail system, the authentication key device holds authentication information of the mail server and secret key information necessary for decrypting the mail, and authenticates to the mail server when connected to the terminal device. The mail server has a means for acquiring a public key from the address public key conversion database, and an encryption means for encrypting the outgoing mail using the acquired public key. A featured mail system.   2. The mail system according to claim 1, wherein the authentication information of the mail server and the secret key information necessary for decrypting the mail held by the authentication key device are set by the user from the terminal device.   The mail system according to claim 1 or 2, wherein the terminal device decrypts the received mail that has been encrypted, using information on a secret key in the authentication key device.   4. The mail system according to claim 1, wherein the authentication key device is configured in a portable hard disk device that can be directly connected to a USB memory or a terminal device.   A terminal device that performs mail transmission / reception, an authentication key device that is hardware directly connected to the terminal device, and a mail server that controls transmission / reception of mail between the terminal device and an external network In the mail transmission / reception method in the mail system, the authentication key device holds the authentication information of the mail server and the secret key information necessary for decrypting the mail, and when connected to the terminal device, the mail Authentication to a server, the mail server obtains a public key from an address public key conversion database, encrypts the outgoing mail using the obtained public key, and the terminal device uses a secret key in the authentication key device A mail transmission / reception method characterized by decrypting an encrypted received mail using the above information.   6. The mail transmission / reception method according to claim 5, wherein the authentication information of the mail server held by the authentication key device and the secret key information necessary for decrypting the mail are set by the user from the terminal device. .

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