JP2003186805A - Communication apparatus, and communication method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication apparatus and communication method thereof, which is capable of preventing harassment mails without changing mail addresses. <P>SOLUTION: There are provided a communication I/F for transmitting and receiving electronic mail with a plurality of terminals; a storage part for storing a plurality of mail addresses, IDs corresponding to them, encryption keys, communication encryption keys; an encryption part 211 for outputting the encrypted mail addresses depending on the encryption keys corresponding to the mail addresses, and outputting the IDs corresponding to the mail addresses and encryption IDs depending on the communication encryption keys; an anonymity part 212 for adding an encryption ID and encrypted mail address if the mail address of a transmission source is included in the storage part, and make it distribute by addressing to the mail address of a sending end; a decoding part 231 for decoding the encryption ID and encrypted mail address; an address restoration part 232 for distributing the received electronic mail, if the encryption ID and encrypted mail address are included normally in the electronic mail; and an encryption key changing part 240 for changing the encryption keys in response to the requirements from the terminals. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device for transmitting and receiving electronic mail, and a communication method thereof.

[0002]

2. Description of the Related Art With the spread of computers and the development of communication technology, a communication system is known in which electronic mails are transmitted and received between a plurality of terminals via a communication network such as the Internet. In recent years, mobile terminals, mobile phones, and the like, which can send and receive electronic mail via the above-mentioned communication network, have become widespread.

In the conventional communication system, electronic mails are transmitted and received using mail addresses that specify the sender and the recipient. For example, a mail address is composed of a user name, a delimiter “@”, and a mail server host name. For example, in the communication system described above, the first
An electronic mail including information on the sender's mail address and the recipient's mail address is sent from the terminal to the first mail server via the communication network. The first mail server sends the received e-mail to the second mail server designated by the destination mail address. The second mail server stores the received e-mail in the mailbox corresponding to the destination e-mail address, and when the second terminal accesses the mailbox through a predetermined authentication procedure, the electronic mail is sent in response to the request. Send the mail to the second terminal. Then, the second terminal receives the e-mail sent from the first terminal. Similarly, even with a mobile phone that can connect to the Internet, it is possible to send and receive e-mail by designating the sender's mail address and the recipient's mail address.

By the way, in recent years, there has been known a communication system which uses the above-mentioned electronic mail when answering a questionnaire to an unspecified large number or applying for a prize. However, in the communication system using email as described above, since the email address of the sender is included in the email to be sent, the email address of the user is leaked and abused at the time of the above, and the email address of the sender is used. There is a possibility that a large amount of so-called junk mail such as direct mail or mischievous mail may be sent to the recipient, which is very annoying to the receiving user.

In the past, in order to prevent the above-mentioned troublesome e-mails, it is possible to change the e-mail address being used or to separate the second e-mail address from the second e-mail free of charge.
Use an email server that can use the email address of
Self-defense measures such as sending and receiving electronic mail using the second mail address are taken.

[0006]

However, as described above, when changing the mail address that is normally used, the mail server administrator must perform the changing procedure and the terminal settings used by the user. There is a problem that it takes time and effort to change the. In addition, as described above, when a free second mail address is acquired and an electronic mail is transmitted / received using the second mail address, unsolicited mail is received at the second mail address. If this happens, there is a problem that you must finally change to a different email address and defend yourself against spam.

By the way, as disclosed in Japanese Unexamined Patent Publication No. 2000-174802, a sender's mail address is converted into an anonymous address and an electronic mail is sent to the recipient's mail address. There is known a communication device that restores an anonymous address and sends an electronic mail to the original sender's mail address when receiving all the reply mails.

However, the above-mentioned Japanese Patent Laid-Open No. 2000-17480.
The communication device disclosed in Japanese Patent Publication No. 2 has a problem in that it is necessary to add the above-described function to the mail server used conventionally. In addition, for example, in a mail server currently operating on the Internet, which mail server has sent an e-mail is described in the header area of the e-mail. There is a problem that the mail server name of can be known, and information regarding the sender's mail address is leaked.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a communication device and a communication method thereof capable of preventing unsolicited mail without changing the mail address used conventionally. To provide.

Another object of the present invention is to provide a communication device and a communication method thereof capable of preventing unsolicited mail without changing the function of a conventionally used mail server.

[0011]

In order to achieve the above object, the communication device of the present invention includes a transmitting / receiving means for transmitting / receiving electronic mail to / from a plurality of terminals connected via a communication network, and transmitting / receiving by the terminal. Storage means for storing a plurality of email addresses related to the email, and address conversion information corresponding to the email address, and the storage means having the same email address as the sender of the email received by the transmitting / receiving means. , The sender's email address is deleted from the email, address conversion information corresponding to the sender's email address is added, and the email address is sent to the recipient's email address. Address conversion means for distribution to the transmission / reception means, and the storage means in the e-mail received by the transmission / reception means If the address conversion information stored is included, in the transmitting and receiving means, and the address inverse transformation means for distributing the address conversion information and said corresponding mail address in the received e-mail,
When the transmission / reception unit receives a change request for changing the address conversion information, the transmission / reception unit changes the address conversion information stored in the storage unit.

According to the present invention, the transmission / reception means connects a plurality of terminals via the communication network and transmits / receives electronic mail. In the storage means, multiple email addresses,
Address conversion information corresponding to the mail address is stored.

The address converting means deletes the sender's mail address from the received electronic mail when the same mail address as the sender's mail address of the received electronic mail is included, and the sender Address conversion processing for adding address conversion information corresponding to the mail address is performed, and the electronic mail subjected to the address conversion processing is delivered to the destination mail address.

When the received e-mail contains the same address conversion information as the address conversion information stored in the storage means, the address reverse conversion means stores the address conversion information stored in the storage means. The received e-mail is delivered to the e-mail address corresponding to the information. The address translation information changing unit changes the address translation information stored in the storage unit in response to a request from the terminal.

Further, in order to achieve the above object, the communication device of the present invention comprises a transmitting / receiving means for transmitting / receiving an electronic mail to / from a plurality of terminals connected via a communication network, and the electronic mail transmitted / received by the terminal. Storage means for storing a plurality of e-mail addresses related to the e-mail address, identification information and an encryption key corresponding to the e-mail address, and a communication encryption key; Encryption that encrypts by the encryption method and outputs an encrypted mail address, and that the identification information corresponding to the mail address is encrypted by a predetermined encryption method based on the communication encryption key and outputs encrypted identification information. And the same mail address as the sender's mail address of the electronic mail received by the sending and receiving means in the storage means. If it is remembered, the sender's mail address is deleted from the electronic mail, the encrypted identification information and the encrypted mail address output by the encryption means are added, and the destination mail address is addressed. An anonymous means to be distributed to the transmission / reception means, and the encrypted identification information is decrypted by a predetermined decryption method based on the communication encryption key to output the identification information, and the encryption corresponding to the output identification information. Decryption means for decrypting the encrypted encrypted email address by a predetermined decryption method based on a key and outputting the email address, and the encrypted identification in the email received by the transmitting / receiving means. If the information and the encrypted e-mail address are included, the decryption means uses the information based on the encrypted identification information and the encrypted e-mail address. When an e-mail address is output and an address restoration unit that distributes the received e-mail to the output e-mail address to the transmission / reception unit, and a change request for changing the encryption key by the transmission / reception unit are received. Has encryption key changing means for changing the encryption key stored in the storage means.

[0016] Preferably, the address restoring means receives the mail address addressed to the mail address only when the mail address decrypted by the decryption means is the same as the mail address stored in the storage means. The transmitted electronic mail is delivered to the transmitting / receiving means.

[0017] Further, preferably, there is a history means for storing the mail addresses of the sender and the recipient of the delivered electronic mail in the storage means as a log, and the address restoration means is the transmission / reception means. When the received email includes the encrypted identification information and the encrypted email address, the source and destination email addresses of the received email are stored in the log. Only when there is, the received electronic mail is delivered to the sending / receiving means to the mail address of the destination.

According to the present invention, the transmission / reception means connects a plurality of terminals via the communication network and transmits / receives electronic mail. The storage means stores a communication encryption key, a plurality of mail addresses, identification information corresponding to the mail addresses, and an encryption key.

In the encryption means, the mail address is encrypted by a predetermined encryption method based on the encryption key corresponding to the mail address and is output as the encrypted mail address,
The identification information corresponding to the mail address is encrypted by a predetermined encryption method based on the communication encryption key and output as encrypted identification information.

In the anonymous means, when the same mail address as the sender's mail address of the electronic mail received by the transmitter / receiver is stored in the storage means, the sender's mail address is deleted from the electronic mail, The encrypted identification information and the encrypted mail address output by the encryption means are added, and the transmission / reception means delivers the mail to the destination mail address.

In the history means, of the delivered electronic mail,
The mail addresses of the sender and the recipient are stored in the storage means as a log.

In the decryption means, the encrypted identification information is decrypted by a predetermined decryption method on the basis of the communication encryption key and outputted as identification information, and the predetermined on the basis of the encryption key corresponding to the outputted identification information. The encrypted email address encrypted by the decryption method of is decrypted and output as the email address.

In the address restoring means, when the electronic mail received by the transmitting / receiving means includes the encrypted identification information and the encrypted mail address, the mail addresses of the sender and the recipient of the electronic mail are recorded in the log. It is determined whether or not it is stored, and if it is stored, the decryption means outputs the mail address based on the encrypted identification information and the encrypted mail address, and the same mail address as that stored in the storage means is output. Only in this case, the received electronic mail is delivered to the sending / receiving means to the mail address. Then, the encryption key changing means changes the encryption key stored in the storage means when the change request for changing the encryption key is received by the transmitting / receiving means.

Further, in order to achieve the above object, a communication method of a communication device of the present invention is a communication method of a communication device for transmitting and receiving electronic mail with a plurality of terminals connected via a communication network, A plurality of mail addresses relating to an electronic mail transmitted by a terminal and address conversion information corresponding to the mail address are stored, and the stored mail address is a sender mail of the electronic mail transmitted from the terminal. If the same email address as the address is included, the email address of the sender is deleted from the received email,
When address translation information corresponding to the sender's email address is added and delivered to the recipient's email address, and the received email contains the stored address translation information When the change request for changing the address conversion information is received from the terminal, the stored e-mail is delivered to the mail address corresponding to the address conversion information. Change the address translation information.

Further, in order to achieve the above object, a communication method of a communication device of the present invention is a communication method of a communication device for transmitting and receiving electronic mail with a plurality of terminals connected via a communication network, A plurality of mail addresses relating to the electronic mail transmitted by the terminal, identification information and an encryption key corresponding to the mail address, and a communication encryption key are stored, and the stored mail address is transmitted from the terminal. When the same email address as the email address of the sender of the email is included, the email address of the sender is deleted from the received email, and the email address corresponding to the email address of the sender is deleted. The sender's email address is encrypted by a predetermined encryption method based on the encryption key, and the identification information corresponding to the email address is encrypted. Is encrypted by a predetermined encryption method based on the communication encryption key, is added to a predetermined area of the received electronic mail, is delivered to a destination mail address, and the received electronic mail is If the predetermined area contains the encrypted identification information and the mail address, the encrypted identification information is decrypted by a predetermined decryption method based on the communication encryption key, The encrypted mail address is decrypted by a predetermined decryption method based on the encryption key corresponding to the decrypted identification number, and the decrypted email address and the stored identification information are associated with each other. When the email address is the same, the received email is delivered to the email address, and a change request for changing the encryption key is received from the terminal. Case, to change the encryption key to the storage.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an overall schematic diagram for explaining an embodiment of a communication system using a communication device according to the present invention.

As shown in FIG. 1, a communication system 1 using the communication device according to this embodiment has a communication device 2 and a plurality of terminals 3, for example, terminals 3-1 and 3-1. The communication device 2 and the terminals 3-1 and 3-1 are connected via the communication network 4.

FIG. 2 is a block diagram showing an example of the configuration of the communication device shown in FIG. The communication device 2 is, for example,
As shown in FIG. 2, a communication I / F 21, which is a transmitting / receiving means,
Input unit 22, output unit 23, RAM 24, ROM 25, storage unit 26 as storage means, CPU 27, and bus BS
Have. Communication I / F 21, input unit 22, output unit 23,
RAM 24, ROM 25, storage unit 26, and CPU 2
7 is connected by a bus BS.

Under the control of the CPU 27, the communication I / F 21 transmits / receives data such as electronic mail to / from the terminals 3-1 and 3-2 via the communication network 4. For example, communication I /
F21 is a so-called network card.

The input unit 22 generates data according to a user's operation with, for example, a keyboard or a mouse, and the generated data has a predetermined component, for example, the CPU 27.
Output to.

The output unit 23 is, for example, a display or a printer that displays predetermined characters and images to the user, and is, for example, a CRT (Cathode-ray tube displa).
y), liquid crystal displays, laser printers, etc.

The RAM 24 stores data generated by the control processing of the CPU 27. The RAM 24 is used as a so-called working area. ROM25
Stores programs executed by the CPU 27, initial data, various parameters, and the like.

The storage unit 26 stores a mail address conversion table,
A communication encryption key, a log, etc. are stored.

Table 1 is a diagram showing a specific example of the conversion table stored in the storage unit.

[0035]

[Table 1]

The storage unit 26 stores a plurality of IDs as a conversion table.
(Identification), the encryption key, and the mail address are stored in association with each other, and, for example, a conversion table as shown in Table 1 is stored.

The ID is a management number assigned to each mail address. The encryption key is an encryption key set corresponding to each ID and email address,
It is used when the CPU 27 performs an encryption process with a predetermined encryption method and a decryption process with a predetermined decryption method. As the encryption method and the decryption method, for example,
DES (Data encryprion standard) or the like is used.
The encryption key is an encryption key used for the above-mentioned predetermined encryption and decryption processing, and has a predetermined bit length.

The mail address is a mail address used for electronic mail, and is, for example, a sender's mail address. For example, the user previously uses the terminal 3
The above-mentioned mail address is registered in the communication device 2 via. The communication device 2 generates an ID corresponding to the mail address and an encryption key, and stores the ID and the encryption key in the conversion table of the storage unit 26.

The communication encryption key is an encryption key used when encrypting an ID and has a predetermined bit length. The log is
The CPU 27 records the data of the process related to the electronic mail. For example, the mail address of the sender, the mail address of the recipient, the processing result, the processing date and time, etc. are recorded in the log.

FIG. 3 is a functional block diagram of the communication device shown in FIG.

The CPU 27 performs various kinds of predetermined data processing. For example, as the function of the CPU 27, as shown in FIG. 3, an address conversion unit 210, a history unit 220, an address reverse conversion unit 230, and an address conversion information changing unit and an encryption key changing unit 240 which is an encryption key changing unit are provided. .

The address conversion unit 210 uses the communication I / F 21.
Based on the source address of the email received by, the source email address is unknown to the destination,
In addition, a predetermined process is performed so that a reply can be made.

For example, the address conversion unit 210 has an encryption unit 211 and an anonymous unit 212. Encryption unit 21
Reference numeral 1 denotes an e-mail address that is encrypted by a predetermined encryption method based on an encryption key corresponding to the e-mail address and outputs the encrypted e-mail address. The ID corresponding to the e-mail address stored in the storage unit 26 is The data is encrypted by a predetermined encryption method based on the communication encryption key stored in the storage unit 26 and output as an encrypted ID.

The anonymous unit 212 stores the same mail address as the sender's mail address of the electronic mail received by the communication I / F 21 via the communication network 4 in the storage unit 2.
It is determined whether or not it is stored in No. 6, and if it is stored, the sender's mail address is deleted from the electronic mail, and the encryption unit 211 assigns the mail address and ID based on the sender's mail address. The encrypted ID and the encrypted mail address output by the encryption process are added to the received electronic mail, and the communication I / F 21 is delivered to the mail address of the transmission destination.

The history section 220 stores the data of the processing result regarding the distribution of the electronic mail in the storage section 26 as a log. For example, the history unit 220 causes the storage unit 26 to store the mail addresses of the sender and the recipient of the delivered electronic mail, the processing result, the processing date and time, etc. as a log.

The address reverse conversion unit 230 uses the communication I / F 2
When the electronic mail received via 1 contains the encrypted ID and the encrypted mail address, the predetermined decryption processing is performed and the mail is delivered to the destination mail address. For example, the address reverse conversion unit 230 uses the decoding unit 2
31 and an address restoration unit 232.

The decryption unit 231 decrypts the encrypted ID by a predetermined decryption method based on the communication encryption key and outputs the ID, and the encryption corresponding to the ID stored in the storage unit 26 is performed. The encrypted email address is decrypted by a predetermined decryption method based on the key, and the email address is output.

The address restoring section 232 is provided for the communication I / F 21.
If the e-mail received in step 1 contains the encrypted identification information and encrypted mail address, the communication I / F
It is determined whether or not the sender's and recipient's mail addresses of the electronic mail received by 21 are stored in the log, and if stored, based on the encrypted identification information and the encrypted mail address. The decryption unit 231 outputs the email address, and only when the email address is the same as the email address stored in the storage unit 26, the received email is delivered to the communication I / F 21 to the email address.

The encryption key changing unit 240 performs a predetermined process of changing the encryption key so that unsolicited email does not reach in response to the user's request. For example, when the junk mail is received at the mail address used by the user, the encryption key changing unit 240 changes the terminal 3 operated by the user from the communication network 4 to the communication I / F.
When the request to change the encryption key is received via 21, the ID corresponding to the mail address stored in the storage unit 26 is searched, the encryption key corresponding to the ID is newly generated, and the encryption key is changed. To do.

For example, a mail address encrypted by a predetermined encryption method using an encryption key can be decrypted normally with the same encryption key. By changing the mail address, the mail address encrypted using the encryption key before the change cannot be normally decrypted using the encryption key after the change. For this reason, even if the former encrypted mail address is used, it becomes impossible to reply, and it is possible to prevent unwanted mail.

FIG. 4 is a flow chart for explaining the operation of the communication device shown in FIG. The operation of the communication device 2 having the above configuration will be described with reference to FIG.

In step ST1, the communication I / F 21
Then, the electronic mail is received via the communication network 4. In step ST2, the encryption key changing unit 240 determines, for example, whether or not a request to change the encryption key is included in the electronic mail (ST2). If the change request is included, the storage unit 26 is included. The encryption key corresponding to the sender's mail address of the received e-mail stored in is changed to the newly generated encryption key (ST3), and the process proceeds to step ST10.

When it is determined in step ST2 that the request is not a change request, it is determined whether or not an encrypted ID is included in a predetermined area of the electronic mail received by the communication I / F 21. (ST4). Step S
When it is determined in T4 that the encrypted ID is not included in the electronic mail, step ST5
Go to processing.

In the determination of step ST5, it is determined whether or not the sender's mail address included in the received electronic mail has the same mail address stored in the conversion table of the storage unit 26. In the determination of step ST5, if the sender's mail address is not stored in the storage unit 26, a predetermined error process is performed as an error (ST6). In the error processing, for example, an electronic mail notifying that the address cannot be converted is sent to the sender's mail address, and the process proceeds to step ST10.

If it is determined in step ST5 that the sender's mail address included in the received electronic mail has the same mail address stored in the conversion table of the storage unit, the encryption unit 211 indicates the I corresponding to the sender's mail address stored in the storage unit 26.
D and the encryption key are searched, and the sender's mail address is encrypted by a predetermined encryption method based on the searched encryption key (ST7). Further, the encryption unit 211 encrypts the retrieved ID by a predetermined encryption method based on the communication encryption key (ST8).

The anonymous section 212 adds the encrypted encrypted ID and encrypted mail address to a predetermined area of the received electronic mail, for example, the end of the text area. The communication path information so far described in the header area is deleted from the electronic mail to which the encrypted ID and the encrypted mail address are added.

The electronic mail address subjected to the above processing is delivered from the communication I / F 21 to the destination mail address via the communication network 4 (ST9), and the process proceeds to step ST10. In step ST10, the history unit 220 records the log of the above-described processing in the storage unit 26. For example, the mail address of the sender, the mail address of the recipient, the processing result, the processing date and time, etc. are recorded in the log. Then, the process returns to step ST1.

On the other hand, if it is determined in step ST4 that the electronic mail contains the encrypted ID, the log stored in the storage unit 26 is checked. For example, specifically, the address restoring unit 232 checks the previously transmitted source and destination email addresses stored in the log, and determines whether the email is a reply from the destination email address. Is checked (ST11). That is, it is determined whether or not it was transmitted by a third party.

In the determination of step ST11, the received electronic mail is the one sent by a third party,
That is, when it is determined that the reply is not sent from the destination mail address, error processing is performed (ST
12). For example, in the error processing, an electronic mail stating that the electronic mail is illegal is sent to the sender of the illegal electronic mail to issue a warning, and the process proceeds to step ST10.

In the determination in step ST11, the received electronic mail is not the one sent by a third party,
That is, when it is determined that the reply is made by the destination mail address, the encrypted ID included in the predetermined area of the electronic mail is extracted. The extracted encryption ID is decrypted by the decryption unit 231 using the communication encryption key stored in the storage unit 26 by a predetermined decryption method (ST13).

The encryption key corresponding to the ID stored in the storage unit is searched based on the decrypted ID, and the encrypted mail address is decrypted by the predetermined decryption method based on the retrieved encryption key. Encryption processing is performed, and the mail address of the reply destination, that is, the mail address of the original transmission source is decrypted (ST14). Then, it is determined whether or not the decrypted email address and the email address corresponding to the decrypted ID described in the conversion table stored in the storage unit 26 match (ST15). .

If it is determined in step ST15 that they do not match, error processing is performed (ST16). For example, in the error processing, an electronic mail stating that the reply mail address is incorrect is sent to the sender, and the process proceeds to step ST10.

If it is determined in step ST15 that they match with each other, the received e-mail is communicated to the mail address with which it is determined that they match with each other via the communication I / F 21. It is distributed via the network 4 (ST16), and the process proceeds to step ST10.

The terminals 3-1 and 3-1 are operated by the user, for example, and send and receive electronic mail via the communication network 4. The terminals 3-1 and 3-1 are, for example, personal computers having a communication function. Also, the terminals 3-1 and
2 is a mobile terminal or PDA that can send and receive e-mail
It may be a (Personal digital assistant) or a mobile phone.

The hardware configuration of the terminals 3-1 and 3-1 is almost the same as the configuration of the communication device 2, and only the differences will be described.
Description of the same components will be omitted. Storage unit 26
Stores application programs having a predetermined function, data, and the like.

FIG. 5 is a schematic diagram for explaining the operation of a communication system including the communication device shown in FIG. The operation of the communication system including the communication device having the above configuration will be described with reference to FIG. 5, FIG. 1, and FIG.

User A has a mail address A, and user B has a mail address B. It is assumed that the user A knows the email address B of the user B in advance. Further, it is assumed that the user B does not know the mail address A. It is assumed that the user A wants to send an electronic mail without the user B knowing the mail address A.

At step ST101, the user A
Operates the terminal 3-1 to access, for example, a mail server (not shown) to send an electronic mail to the communication device 2 via the mail server and the communication network 4.
For example, the email has a header area 510 and a body area 520 as shown in FIG.

The terminal 3-1 displays the header area 510 in the
The sender's mail address A and the mail address of the communication device (hereinafter also referred to as the center) 2 are described. A desired text is written in the text area 520. In a predetermined area of the body area 520, for example, the body end portion 521, the mail address B of the transmission destination is described.

In step ST201, the communication device 2 receives the electronic mail transmitted from the terminal 3-1 via the communication network 4 via the communication network 4 by the communication I / F 21. In the communication device 2, the above address conversion process is performed.

That is, the destination mail address is extracted from the end 521 of the body of the electronic mail, the ID and encryption key corresponding to the mail address A stored in the storage unit 26 are searched, and the ID is the communication encryption key. The encrypted mail address A of the sender is encrypted by the encryption key corresponding to the mail address A, and the encrypted ID and the encrypted mail address are written in the end portion 521 of the body of the electronic mail.

At this time, the mail address B written at the end 521 of the text is deleted. Then, the header area 510
In this field, the mail address of the communication device is described as the transmission source, and the mail address B where the transmission destination is the original transmission destination is described. Then, the electronic mail is delivered to the mail address B.

In step ST301, user B
The terminal 3-2 operated by, for example, accesses a mail server (not shown), performs a predetermined authentication process, and then receives an electronic mail addressed to the mail address B. At this time, the user B is the email address A of the user A.
The email address A cannot be known because is encrypted.

At step ST302, the user B
Does not know the mail address A when sending an e-mail for reply to the user A,
An electronic mail for reply is sent to the communication device (center) 2.

Specifically, for example, the terminal 3-2 operated by the user B cites the text area 520 of the received electronic mail as shown in FIG. An email is sent. At this time, only the encrypted ID and the encrypted mail address at the end 521 of the body may be quoted.

In step ST202, the communication device 2 receives the e-mail via the communication network 4 by the communication I / F 21. Then, the communication device 2 performs the above-described predetermined process. For example, the received e-mail is subjected to predetermined processing based on the encrypted ID and the encrypted e-mail address, the ID and the e-mail address A are decrypted, and it is checked whether or not the e-mail address A is normal. In this case, the electronic mail is transmitted from the communication device (center) 2 to the mail address A.

In step ST102, the terminal 3-1 operated by the user A, for example, accesses a mail server (not shown) to perform a predetermined authentication process, and then receives an electronic mail addressed to the mail address A. To be done. The user A can send an e-mail to the e-mail address B without receiving the e-mail address A, and can receive a reply e-mail.

Then, for example, when unsolicited mails are frequently received from the user B, a change request for changing the encryption key corresponding to the mail address A is transmitted to the communication device 2, and the communication device 2 The encryption key corresponding to the mail address A of the communication device 2 is changed in response to the request.

By doing so, for example, even if user B sends a reply e-mail in which the former encrypted mail address is quoted, the encryption key has been changed, so that the communication device 2 has the old one. I cannot decrypt the encrypted email address normally. Therefore, spam mail can be prevented.

As described above, according to the present embodiment, the communication I / F 21 for transmitting and receiving electronic mail with the plurality of terminals 3 connected via the communication network 4, and the terminal 3
Based on the encryption key corresponding to the mail address, and a storage unit 26 for storing a plurality of mail addresses relating to the electronic mails transmitted and received by the user An encryption unit 211 that outputs an encrypted mail address by performing encryption with a predetermined encryption method, encrypts an ID corresponding to the mail address with a predetermined encryption method based on a communication encryption key, and outputs an encrypted ID. If the same mail address as the sender's mail address of the electronic mail received by the communication I / F 21 is stored in the storage unit 26, the sender's mail address is deleted from the email and encrypted. Part 2
Add the encrypted ID and encrypted email address output by 11 to send the communication I to the destination email address.
/ F21 based on the communication encryption key, the anonymous section 212 to be delivered, the history section 220 to store the source and destination email addresses of the delivered email as a log in the storage section 26, and the encryption ID. A decryption unit 231 that decrypts the encrypted email address with a predetermined decryption method based on the encryption key corresponding to the output ID and decrypts the encrypted email address with a predetermined decryption method, and outputs the ID.
If the email received by the communication I / F 21 includes the encrypted ID and the encrypted email address, it is determined whether the email addresses of the sender and the recipient of the email are stored in the log. If it is stored, the decryption unit 231 outputs the email address based on the encrypted ID and the encrypted email address. Only when the email address is the same as the email address stored in the storage unit 26, the email is sent. An address restoration unit 232 that causes the communication I / F 21 to deliver the received e-mail to the address,
Since the encryption key changing unit 240 that changes the encryption key stored in the storage unit 26 in response to a request from the terminal 3 is provided, for example, when sending a mail to a person who is unknown in the identity, that person It is possible to prevent unsolicited emails from.

Further, by sending and receiving electronic mail via the communication device without modifying the conventional infrastructure (mail server), anonymous mail can be sent using the mail address that has been used conventionally. it can. Further, it is possible to prevent direct mail that is regularly sent.

The present invention is not limited to this embodiment, and various suitable modifications can be made. For example, in the present embodiment, the encryption key corresponding to the email address is stored in the storage unit, the email address is encrypted using the encryption key, and the email is added to the email. However, the present invention is not limited to this. . For example, a random character string corresponding to a mail address may be stored in the storage unit, and the character string may be attached to an electronic mail, or a nickname or the like may be used. It is difficult to guess the sender's mail address, and it is sufficient if the sender's mail address is stored in the storage unit in association with the mail address. When an unsolicited email arrives, the correspondence with the mail address stored in the storage unit may be changed to create a new correspondence.

[0083]

As described above, according to the present invention, it is possible to provide a communication device and a communication method thereof capable of preventing unsolicited mail without changing the mail address used conventionally. Further, according to the present invention, it is possible to provide a communication device and a communication method thereof capable of preventing unsolicited mail without changing the function of a conventionally used mail server.

[Brief description of drawings]

FIG. 1 is an overall schematic diagram for explaining an embodiment of a communication system using a communication device according to the present invention.

FIG. 2 is a block diagram showing an example of the configuration of the communication device shown in FIG.

3 is a functional block diagram of the communication device shown in FIG. 1. FIG.

FIG. 4 is a flowchart for explaining the operation of the communication device shown in FIG.

5 is a schematic diagram for explaining an operation of a communication system including the communication device shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Communication system, 2 ... Communication device, 3 ... Terminal, 4 ... Communication network, 21 ... Communication I / F, 22 ... Input part, 23
... output section, 24 ... RAM, 25 ... ROM, 26 ... storage section, 27 ... CPU, 210 ... address conversion section, 211 ...
Encryption section, 212 ... Anonymous section, 220 ... History section, 230 ...
Address reverse conversion unit, 231, ... Decoding unit, 232 ... Address restoration unit, 240 ... Encryption key changing unit, 510 ... Header area, 520 ... Body area, 521 ... Body end, BS ... Bus.

Claims (6)

[Claims] 1. A transmission / reception unit for transmitting / receiving electronic mail to / from a plurality of terminals connected via a communication network, a plurality of mail addresses relating to electronic mail transmitted / received by the terminals, and address conversion information corresponding to the mail addresses. And a storage unit that stores the same email address as the sender's email address of the email received by the sending and receiving unit, the storage unit storing the Deleting the mail address, adding address conversion information corresponding to the sender's mail address, and causing the sending and receiving means to deliver to the sending recipient's mail address, and the address received by the sending and receiving means. If the email contains the address conversion information stored in the storage means, When the receiving means receives the address reverse conversion means for distributing the received electronic mail to the mail address corresponding to the address conversion information, and the change request for changing the address conversion information by the transmission / reception means. Is an address translation information changing unit that changes the address translation information stored in the storage unit. 2. A transmission / reception unit for transmitting / receiving an electronic mail to / from a plurality of terminals connected via a communication network, a plurality of mail addresses related to the electronic mail transmitted / received by the terminal, and identification information corresponding to the mail addresses. And a storage means for storing an encryption key and a communication encryption key, the mail address is encrypted by a predetermined encryption method based on an encryption key corresponding to the mail address, and an encrypted mail address is output. Encryption means for encrypting the identification information corresponding to a mail address by a predetermined encryption method based on the communication encryption key and outputting encrypted identification information, and transmitting the email received by the transmission / reception means When the same mail address as the original mail address is stored in the storage means, the sender of Anonymous means for deleting the mail address, adding the encrypted identification information and the encrypted mail address output by the encryption means, and delivering the mail to the sending / receiving means to the destination mail address, and the encrypted identification information. Is decrypted by a predetermined decryption method based on the communication encryption key, and the identification information is output, and the encrypted encryption is performed by the predetermined decryption method based on the encryption key corresponding to the output identification information. If the decryption means for decrypting the encrypted email address and outputting the email address, and the email received by the transmission / reception means includes the encrypted identification information and the encrypted email address, The decryption means outputs the email address based on the encrypted identification information and the encrypted email address, and the output email address is output. Address recovery means for distributing the received e-mail to the transmission / reception means, and, if the transmission / reception means receives a change request for changing the encryption key, the encryption stored in the storage means. A communication device having encryption key changing means for changing a key. 3. The address restoring means receives the received mail addressed to the mail address only when the mail address decrypted by the decryption means is the same as the mail address stored in the storage means. The communication device according to claim 2, wherein an electronic mail is delivered to the transmitting / receiving unit. 4. A history means for storing the source and destination mail addresses of the delivered electronic mail as a log in the storage means, wherein the address restoring means receives the email received by the transmitting / receiving means. If the email contains the encrypted identification information and the encrypted email address, only if the source and destination email addresses of the received email are stored in the log 4. The communication device according to claim 2, wherein the received electronic mail is delivered to the sending / receiving means to a destination mail address. 5. A communication method of a communication device for transmitting and receiving e-mail to and from a plurality of terminals connected via a communication network, the method comprising: a plurality of e-mail addresses relating to e-mail sent by the terminal; The corresponding address translation information is stored, and if the stored email address includes the same email address as the sender's email address of the email sent from the terminal, the received email is received. The email address of the sender is deleted from the email, the address translation information corresponding to the email address of the sender is added, and the email is delivered to the email address of the recipient. If the stored address translation information is included in the mail address, the mail address corresponding to the address translation information is stored. It addressed less, and distributes the received electronic mail, from the terminal, when receiving a change request to change the address conversion information to a communication method to change the address translation information that the storage. 6. A communication method of a communication device for transmitting and receiving e-mail to and from a plurality of terminals connected via a communication network, the method comprising: a plurality of e-mail addresses relating to e-mail sent by the terminal; Corresponding identification information and encryption key and communication encryption key are stored, and the stored email address includes the same email address as the sender email address of the email sent from the terminal. In this case, the sender's email address is deleted from the received electronic mail, and the sender's email address is determined by a predetermined encryption method based on an encryption key corresponding to the sender's email address. And the identification information corresponding to the mail address is encrypted by a predetermined encryption method based on the communication encryption key, It is added to a predetermined area of the received email and delivered to the destination email address, and the predetermined area of the received email includes the encrypted identification information and the email address. In this case, the encrypted identification information is decrypted by the predetermined decryption method based on the communication encryption key, and the predetermined decryption is performed based on the encryption key corresponding to the decrypted identification number. When the encrypted email address is decrypted by the encryption method and the decrypted email address and the email address corresponding to the stored identification information are the same, the received email is A communication method in which the stored encryption key is changed when a change request for changing the encryption key is received from the terminal by delivering to the mail address.