JP2002055932A - Method for updating electronic mail having been sent and its sender and recipient terminal, and recording medium where the same method is recorded as electronic mail sending and receiving program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To delete or update electronic mail which has been sent while protecting the privacy of the user and securing the security. SOLUTION: This is a method for updating electronic mail which has been relayed by one or more mail servers and put in a mailbox on a mail server at a transmission destination, and the electronic mail having been delivered to the terminal device of the recipient can be updated or erased by a sender on condition that the recipient does not recognize its presence yet and that it is confirmed that the sender of the electronic mail is identical with a prior electronic mail. The updating operation is carried out by interpreting a command (unique header information C) embedded between the header and body of the electronic mail sent separately and it is guaranteed that the sender of the electronic mail is the same by authenticating the sender by using an open key.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system for asynchronously exchanging electronic mail among a plurality of terminal devices connected via a network, and to perform an update operation including cancellation of erroneously transmitted data. The present invention relates to a method of updating an already transmitted e-mail, a sender / receiver terminal thereof, and a recording medium on which the method is recorded as an e-mail transmission / reception program.

[0002]

2. Description of the Related Art Electronic mail is an SMTP (Simple Mail).
A protocol such as Transfer Protocol allows data such as text and audio and video to be sent from the sender to the receiver asynchronously. In this case, the data is relayed by some SMTP servers (mail servers) and sent to a mailbox in the destination mail server. The user at the transmission destination can check the contents of the mailbox when he / she likes, and receive the data by an e-mail receiving program called a mailer. In addition, by encrypting the content of the data, the content can not be eavesdropped on a relay mail server, etc.
Can be sent securely.

[0003]

By the way, in the conventional exchange of e-mails, the e-mail once transmitted arrives at the other party's mailbox as it is. The mailbox is typically the owner of that mailbox,
Only the receiving user can access it. Therefore, if the destination is wrong or the wrong content is sent, the other party can be notified by sending an e-mail again indicating the wrong sending.

[0004] Therefore, the recipient of the e-mail must look at the first two e-mails and the correction e-mail in order to know the original contents of the transmission or determine that the e-mail is unrelated to the user. I had to go through. Therefore, it is very annoying for a user who receives many e-mails a day and must read them. on the other hand,
In a system such as e-mail, it is important to protect the privacy and security of the user.

The present invention has been made in view of the above circumstances, and by constructing a mechanism for deleting or updating a transmitted e-mail by using a command embedded in an e-mail to be sent separately later. In this case, the identity of the sender of the e-mail is assured by performing personal authentication using a public key, so that once sent e-mails can be deleted or updated while protecting the privacy and security of the user. It is an object of the present invention to provide a method of updating an already-transmitted e-mail and a method of transmitting and receiving the same, and a recording medium in which the method is recorded as an e-mail transmission / reception program.

[0006]

In order to solve the above-mentioned problems, the invention according to claim 1 has been carried out by one or more mail servers and transmitted to a mailbox in a destination mail server. An e-mail update method, wherein for a new e-mail in which the sender of the e-mail has been confirmed to be the same, the e-mail has arrived at the terminal device of the recipient whose presence is not recognized. An update operation including erasure is permitted in an e-mail.

According to a second aspect of the present invention, in the method of updating an already-transmitted electronic mail according to the first aspect, the update operation interprets a command embedded between a header and a body of the electronic mail to be transmitted separately. It is characterized by performing by doing.

[0010] According to a third aspect of the present invention, in the method of updating an already-transmitted electronic mail according to the first aspect, the personal authentication using a public key is performed to confirm that the sender of the electronic mail is the same. It is characterized by the guarantee.

[0011] According to a fourth aspect of the present invention, the transmission / reception electronic mail relayed by one or more mail servers and sent to a mailbox in the destination mail server or taken in from the mailbox is stored. A sender terminal of the e-mail to be managed, an ID assigning unit that assigns a unique ID to the outgoing e-mail, and an operation unit that obtains a hash value using a one-way hash function of the content of the outgoing e-mail, An encryption unit for encrypting the hash value using a secret key, and a header including a command for performing an update operation of the already-transmitted e-mail is embedded between the mail header and the body of the transmitted e-mail to send the e-mail to the other party. In the case where the operation of the already-transmitted e-mail is not performed with the e-mail transmitting unit that transmits the If you want to update the operation of the e-mail,
An ID of an e-mail to be operated, data obtained by encrypting a hash value of the content of the e-mail to be operated with a secret key of a sender, and a unique header information generation unit for giving an update command are provided.

[0010] According to a fifth aspect of the present invention, sent and received e-mails relayed by one or more mail servers and sent to a mailbox in a destination mail server or received from the mailbox are stored and managed. A receiving terminal of the e-mail to perform, with respect to the fetched e-mail, an operation unit for obtaining a hash value using a one-way hash function, and an encryption unit in a header of the received e-mail using a public key. A decryption unit that decrypts the hash value obtained, and compares the hash value obtained by the arithmetic unit with the hash value decrypted by the decryption unit. And a command execution unit for executing a command embedded in the header.

[0011] With the above configuration, it is possible to provide a mechanism in which only the sender, other than the recipient, can delete and update the mail by using a command embedded in an e-mail to be sent separately later. That is, it is possible to delete or update the contents of the mail sent to the other party by using an electronic mail issued by the same sender. As a result, the recipient of the e-mail receives the corrected e-mail only, or the same as receiving no e-mail when the e-mail is deleted. In order to guarantee that the senders of the two mails are the same, a personal authentication technique using a public key method is used. Commands embedded in e-mail are executed in a mailer that reads mail from a mailbox. The range of operations that can be performed by the command is an electronic mail that matches the sender of the mail and that the recipient has not read (it has reached the mailbox or mailer but the recipient does not recognize the existence of the mail). By limiting to email, security and privacy can be ensured.

According to a sixth aspect of the present invention, there is recorded an e-mail transmission / reception program which is relayed by one or more mail servers and updates an already transmitted e-mail sent to a mailbox in a destination mail server. A computer-readable recording medium, wherein the e-mail transmission program comprises: a step of selecting an e-mail to be updated, a type of update operation from a list of e-mails transmitted in the past; an ID unique to the e-mail; Creating a unique header information consisting of the ID of the e-mail to be operated, the hash value of the e-mail to be operated encrypted with the sender's private key, and the operation command; Embedding the unique header information and sending it as an e-mail to an e-mail server. Characterized in that to execute.

According to a seventh aspect of the present invention, in the recording medium according to the sixth aspect, the electronic mail receiving program extracts the electronic mail from the mailbox and determines the sender from the mail address of the sender. Preparing a sender's public key; decrypting an encrypted hash value in the unique header using the sender's public key; and a mail ID equivalent to the mail ID in the unique header. Calculating a hash value of the email; comparing the hash value obtained by the decryption with the hash value obtained by the calculation; and Executing a command embedded in the unique header information only when the recipient has not read the information.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of the configuration of an electronic mail system for realizing a method for updating a transmitted electronic mail according to the present invention. The present invention is applied to the e-mail transmission software (program) 10 and the e-mail reception software (program) 20 shown in FIG. 1, and is installed in the sender terminal 1 and the receiver terminal 2, respectively. The other mail servers 3, 4, and 5 use existing general systems. Email sending software 10 shown here
The e-mail transmitted / received using the e-mail receiving software 20 can be updated, such as deleted or modified, as described later.

As a prerequisite, a user who uses the present invention in advance has a combination of a public key and a secret key of a public key cryptosystem such as an RSA system, and users who exchange e-mails are required to communicate with each other. It is assumed that the public key is in a known state. These prerequisites are PGP
(Pretty Good Privacy [1]).

FIG. 2 shows an electronic mail transmission software 10.
FIG. 2 is a diagram showing the internal configuration of the sender terminal 1 on which functions have been installed by developing functions. The sender terminal 1 includes an ID assigning unit 11
, An operation unit 12, an encryption unit 13, an e-mail transmission unit 14, a unique header information generation unit 15, and a transmission e-mail storage unit 16.

The ID assigning section 11 assigns a unique ID (mail ID) for each mail to the transmission electronic mail. Arithmetic unit 1
Reference numeral 2 has a function of obtaining a hash value by using a one-way hash function of the content of the transmitted e-mail. Encryption unit 13
Encrypts the hash value using a public key method such as RSA. The e-mail transmitting unit 14 embeds a header including a command for performing an update operation of the already-transmitted e-mail (e-mail deletion, replacement of e-mail, etc.) between the mail header and the body of the transmitted e-mail, and sends the e-mail to the other party. send an email. The unique header information generation unit 15 assigns only the mail ID to the embedded header information when not performing the operation on the already-transmitted e-mail. A data in which the hash value of the content of the e-mail to be operated is encrypted with the secret key of the sender and an update command are added. The transmission electronic mail storage unit 16 has a function of storing and managing the generated transmission electronic mail.

FIG. 4 shows an example of an electronic mail source. An electronic mail usually includes a mail header A and a mail body B. In general, an e-mail is transmitted with the mail subject and the mail address of the sender at the same time as the mail text. Information such as the subject and the sender's mail address is added as a mail header A before the mail body B in a standardized form. In the present invention, the mail body B and the mail header A
Is embedded in the header information C. The unique header information C includes an ID unique to a mail, a mail ID to be operated, data obtained by encrypting a hash value of an e-mail to be operated with a sender's public key, and commands such as deletion and update. Details will be described later.

FIG. 3 is a diagram showing the internal configuration of the receiver terminal 2 by developing its functions. The receiver terminal 2 includes an arithmetic unit 21
, A decryption unit 22, a command execution unit 23, and a received e-mail storage unit 24.

The arithmetic unit 21 has a function of obtaining a hash value for an electronic mail fetched from a mailbox using a one-way hash function. The decryption unit 22 has a function of decrypting the encrypted hash value in the header of the received e-mail using the public key. The command execution unit 23 compares the hash value obtained by the operation unit 21 with the hash value decrypted by the decryption unit 22, and only when a match is found, the command embedded in the header of the received e-mail. With the ability to perform The received e-mail storage unit 24 has a function of storing and managing the received e-mail.

Hereinafter, the operation of the embodiment of the present invention shown in FIGS. 1 to 4 will be described in detail. First, in the e-mail transmission software 10, the user selects an e-mail from a list of e-mails transmitted by the user in the past, and selects what kind of operation (erasing or updating) he wants to perform. In the case of updating, write the contents to be updated in the mail text. Next, the unique header information is created by the unique header information generation unit 15 described above. The content of the header is an e-mail ID unique to each mail
, The mail ID of the e-mail to be operated, the hash value to be operated, which is encrypted with the sender's secret key, and the command to be operated.

The e-mail transmission software 10 transmits to the mail server 4 the header information of a general e-mail, the unique header information created earlier, and the mail text as one e-mail. The mail server 4 transmits the e-mail to the mail server 5 having the mailbox of the user (recipient) of the transmission destination by SMTP. Here, it is transmitted via the relay mail server 3.

The e-mail receiving software 20 takes out the e-mail addressed to itself from the mailbox in accordance with the instruction of the recipient. Then, it processes the unique header information in the received e-mail. An e-mail having no unique header information (e-mail sent from a general mailer) or a mail having only a mail ID are presented as they are to the recipient. Other emails are controlled according to the following procedure.

That is, the e-mail receiving software 2
0 determines the sender from the sender's email address,
Prepare the sender's public key. (The sender's public key is obtained in advance from the preconditions). Then, the encrypted hash value in the header is decrypted using the sender's public key. Further, the hash value of the mail having the ID in the header is calculated. Then, check whether the hash values match,
If they match, it proves that the e-mail was sent from a legitimate sender. If they do not match, it is an unauthorized email, and that fact is presented to the recipient.

FIG. 5 shows an operation conceptual diagram for confirming the identity of the sender. Here, it is shown that the same sender of the e-mail is assured by performing personal authentication using a public key. That is, the hash value of the email encrypted with the sender's private key is
Decryption is performed using the sender's public key, a hash value of the e-mail corresponding to the mail ID in the unique header information is calculated, and it is confirmed that the sender is the same user by confirming a match between the two.

The electronic mail receiving software 20 executes the command contained in the unique header information only when the hash values match and the mail to be operated has not been read by the recipient. In the case of deletion, the e-mail specified by the unique header information is deleted. In the case of update, the body of the target e-mail is replaced with the body of the e-mail in which the command is embedded, and presented to the user as new mail.

FIG. 6 is a flowchart showing a mail reading process by the mail receiving software 20.
Here, first, the e-mail receiving software 20
A connection is made to the mailbox (step S61), and it is checked whether or not there is an e-mail addressed to the user (step S62). Then, the e-mail is fetched one by one, and it is checked whether or not unique header information is embedded (steps S63, S64). Further, the operation command is checked (step S65), and if the command is present, it is checked whether or not there is a target e-mail specified by the unique header information and unread (step S65). S66). If the unique header information is not embedded or if there is no command, it is added to the received mail list as a normal electronic mail (step S70).

Here, as shown in FIG. 5, only when the target electronic mail is present and unread, the hash value of the target electronic mail is calculated and the hash value of the header is decrypted. Perform comparison (steps S67, S68, S
75). If a match is obtained, the process proceeds to the command processing. If a comparison is not obtained, an error mail is added to the list of received mails of the user (step S69).

In the command processing (step S7)
1) If the operation command indicates deletion, the target electronic mail is deleted (step S72). If the operation command indicates update such as correction, the target electronic mail is updated according to the instruction (step S73). Then, the content of the received mail list of the user is updated, and the process returns to the step S61.

As described above, according to the present invention, it is possible to provide a mechanism in which only the sender can delete and update the mail by a command embedded in an e-mail to be sent separately later, in addition to the receiver. That is, it is possible to delete or update the contents of the mail sent to the other party by using an electronic mail issued by the same sender. As a result, the recipient of the e-mail receives the corrected e-mail only, or the same as receiving no e-mail when the e-mail is deleted. In order to guarantee that the senders of the two mails are the same, a personal authentication technique using a public key method is used. The command embedded in the e-mail is executed in e-mail receiving software for reading the e-mail from the mailbox. The range that can be operated by the command is that the sender of the mail matches and the recipient is unread (it has reached the mailbox or the e-mail receiving software 20 but the recipient does not recognize the existence of the mail) ), Security and privacy can be ensured.

Note that the sender terminal 1 in FIG.
The receiving terminal 2 in FIG. 3 includes an assigning unit 11, a calculating unit 12, an encrypting unit 13, an e-mail transmitting unit 14, a unique header information generating unit 15, and a transmitting e-mail storing unit 16. Although the description has been made assuming that the operation unit 21, the decryption unit 22, the command execution unit 23, and the received e-mail storage unit 24, these are all installed in the transmission and reception terminals 1 and 2 as software programs, and The function is realized by a system, here, a transmitting / receiving terminal. Here, the “computer system” includes an OS and hardware such as peripheral devices.

The "computer system" is a WW
If the W system is used, a homepage providing environment (or display environment) is also included. The “computer-readable recording medium” refers to a floppy (registered trademark) disk, a magneto-optical disk, an RO
M, a portable medium such as a CD-ROM, and a storage device such as a hard disk built in a computer system. Further, the “computer-readable recording medium” refers to a volatile memory (RAM) inside a computer system that becomes a server or a client when a program is transmitted through a network such as the Internet or a communication line such as a telephone line. And those holding programs for a certain period of time.

The above program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the "transmission medium" for transmitting a program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. Further, the program may be for realizing a part of the functions described above. further,
What can realize the above-mentioned function in combination with a program already recorded in the computer system, that is, a so-called difference file (difference program) may be used.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes a design and the like within a range not departing from the gist of the present invention. It is.

[0035]

As described above, according to the present invention, it is possible to delete or update an e-mail once transmitted while securing protection and security of the privacy of the user. It is possible to make up for the drawback of a system that sends and receives data asynchronously, such as electronic mail, and the drawback that update and cancellation cannot be performed. For many users, e-mails may receive more than a hundred e-mails a day. Among them, by reducing incorrect e-mails and correction e-mails, the load on users is reduced, and e-mails are used. The efficiency of information exchange can be increased.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of the configuration of an e-mail system that implements a method for updating a transmitted e-mail according to the present invention.

FIG. 2 is a diagram showing the internal configuration of a transmission part of the transmission / reception terminal device according to the present invention, in which functions are developed.

FIG. 3 is a diagram showing an internal configuration of a receiving portion of the transmitting / receiving terminal device of the present invention, in which functions are developed;

FIG. 4 is a diagram showing an example of an e-mail source used in the present invention.

FIG. 5 is a diagram showing an operation concept for confirming the identity of a sender used in the present invention.

FIG. 6 is a flowchart showing a processing procedure by the electronic mail receiving software of the embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sender terminal, 2 ... Receiver terminal, 3 ... Relay mail server, 4 ... Outgoing mail server, 5 ... Received mail server, 1
0: E-mail transmission software (program), 11
... ID assigning unit, 12 ... calculating unit, 13 ... encrypting unit, 14 ...
E-mail transmission unit, 15: unique header information generation unit, 20
... E-mail receiving software (program) 21 ... Calculation unit, 22 ... Decryption unit, 23 ... Command execution unit

Claims (7)

[Claims] 1. A method for updating a sent e-mail that has been relayed by one or more mail servers and sent to a mailbox in a destination mail server, wherein the sender of the e-mail is the same. In response to a new e-mail that has been confirmed, the e-mail sent to the terminal device of the receiver whose receiver does not recognize the existence of the new e-mail is permitted to perform an update operation including deletion of the e-mail. Update method. 2. The method according to claim 1, wherein the updating operation is performed by interpreting a command embedded between a header and a body of the e-mail to be transmitted separately. 3. The method according to claim 1, wherein the sender of the e-mail is assured by performing personal authentication using a public key. 4. A sender of an e-mail that is relayed by one or more mail servers and sent to or received from a mailbox in a destination mail server and stores and manages transmitted and received e-mails. An ID assigning unit for assigning a unique ID to the outgoing e-mail; an operation unit for obtaining a hash value using a one-way hash function of the contents of the outgoing e-mail; An encryption unit for encrypting a value; and an e-mail transmission unit for transmitting an e-mail to the other party by embedding a header including a command for performing an update operation of the already-transmitted e-mail between a mail header and a body of the e-mail When the operation of the already-transmitted e-mail is not performed, only the mail ID is added to the embedded header information, and the operation of updating the already-transmitted e-mail is performed. And a unique header information generation unit for providing an ID of an e-mail to be operated, data obtained by encrypting a hash value of the content of the e-mail to be operated with a secret key of a sender, and an update command. An e-mail sender terminal, characterized in that: 5. A recipient of an email relayed by one or more mail servers and sent to or received from a mailbox in a destination mail server for storing and managing sent / received emails. A terminal for calculating a hash value using a one-way hash function with respect to the fetched e-mail; and a cipher in a header of the received e-mail by using a prepared key of a sender. A decryption unit that decrypts the encrypted hash value, and compares the hash value obtained by the arithmetic unit with the hash value decrypted by the decryption unit. A command execution unit for executing a command embedded in a header of the mail, and a receiver terminal for the electronic mail. 6. A computer-readable recording medium in which an e-mail transmission / reception program for updating an already transmitted e-mail sent to a mailbox in a destination mail server relayed by one or more mail servers is recorded. The e-mail transmission program may include a step of selecting an e-mail to be updated, a type of an update operation from a list of e-mails transmitted in the past, an ID unique to the e-mail, and an ID of the e-mail to be operated
Creating a unique header information consisting of a hash value of the e-mail to be operated encrypted with the sender's private key and an operation command; and A step of embedding information and transmitting it as a single e-mail to the mail server; and a recording medium recording an e-mail transmission program for causing a computer to execute the steps. 7. An electronic mail receiving program, comprising: extracting an electronic mail from the mailbox, defining a sender from a sender's mail address, and preparing a sender's public key; Decrypting an encrypted hash value in the unique header using a key; calculating a hash value of an email corresponding to a mail ID in the unique header; Comparing the obtained hash value with the hash value obtained by the calculation, and the hash value matches, and only when the recipient has not read the operation target email, the unique header information 7. The recording medium according to claim 6, wherein an electronic mail receiving program for causing a computer to execute the embedded command is executed.