JP2000013431A - Electronic mail device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic mail device for sending a message with additional file without loading a message transfer device. SOLUTION: An electronic mail device is composed of a network, plural pieces of user terminal equipment 1A, 1B, 1C and 1D connected to that network, and message transfer devices 2A, 2B and 2C. The electronic mail device performs the transmission/reception of message between the network and plural pieces of user terminal equipment 1A, 1B, 1C and 1D through the message transfer devices 2A, 2B and 2C. In the device file preserving devices 3A, 3B and 3C connected to the network are provided separately from the message transfer devices 2A, 2B and 2C. When transmitting the message from the user terminal equipment 1A to the other user terminal equipment 1B while adding a file, the additional file is temporarily preserved in the file preserving device 3A and when the user terminal equipment 1B receiving the message requests the reception of the additional file, the file is received from the file preserving device 3A afterwards.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an electronic mail device for storing a file attached to a message in a file storage device different from the message.

[0002]

2. Description of the Related Art E-mail is widely used and used today because of the convenience of being able to transmit and receive data even when the user is absent and to be able to read when necessary. The e-mail can be attached with various files, which is a big feature. The e-mail device currently used is composed of a network, a plurality of user terminal devices connected to the network, and a message transfer device, and a plurality of user terminal devices are connected via the network and the message transfer device. Can send and receive messages. You can also attach files to emails.
At that time, files generally called binary files such as image data and application data are subjected to binary-text conversion by a specific conversion method, and the converted files are included in the message body.

[0003]

However, application data files of recent years have become large in size,
Due to an increase in transfer load and an insufficient capacity of a storage device of an e-mail device for storing messages, failures such as stopping the e-mail device frequently occur. Further, when the binary-text conversion is performed, the capacity of the data tends to be larger than that of the original file, which promotes the shortage of the capacity of the storage device. Further, when a message containing a data file is sent to a plurality of users at the same time, messages for the number of users are transferred, and there is a problem that the transfer load is further increased. In particular, in the case of simultaneous transmission to a large number of other parties, the load was remarkably increased. The present invention has been made in view of such a problem, and an object of the present invention is to provide an e-mail apparatus that sends an e-mail with an attached file without burdening a message transfer apparatus.

[0004]

In order to solve the above-mentioned problems, the present invention comprises a network, a plurality of user terminal devices connected to the network, and a message transfer device. The e-mail device of the present invention for transmitting / receiving a message between a plurality of user terminal devices is provided with a file storage device connected to a network separately from the message transfer device, and the user terminal device attaches a file to transfer a message to another. When the message is transmitted to the user terminal device, the attached file is temporarily stored in the file storage device, and when the user terminal device that has received the message requests reception of the attached file, the attached file is subsequently received from the file storage device. Further, the user terminal device used in the electronic mail device of the present invention, when transmitting a message with a file attached,
A function to send the file acquirer list, authentication data, and management information of the file storage period to the file storage device together with the attached file, and after receiving the message with the file attached, the file attached to the file storage device And a function that can acquire an attached file if the file storage request is accepted by the file storage device, and the file storage device obtains the file transmitted from the user terminal device. A function to store management information such as a list of possible users, data for authentication, file storage period, etc. and the attached file when they are received, and to authenticate based on the management information if there is a request to acquire the attached file from the user terminal device. User terminal device that has performed the authentication and has obtained the stored management information and attached file Transmitted, and to admit authentication and function of notifying the user terminal apparatus that effect acquisition request, and characterized in that it comprises. With such a configuration, the attached file can be sent to the other party without imposing a load on the message transfer device in the conventional e-mail device.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electronic mail device according to the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of an electronic mail device according to the present invention and a concept of information flow. In the figure, reference numerals 1A, 1B, 1C, and 1D denote user terminal devices connected to a network, and create, transmit, and receive a message with an attached file. 2
A, 2B, and 2C are message transfer devices connected to a network, and are devices that transfer a message created by a user terminal device. Reference numerals 3A, 3B, and 3C denote file storage devices that store files in accordance with a request from the transmitting user terminal device and perform file transfer in response to a file acquisition request from the receiving user terminal device. Although the figure conceptually shows the flow of information, the hardware is connected to the same network in which all user terminal devices, message transfer devices, and file storage devices are connected in a network. I can do it. And
When a message is transmitted from the user terminal device 1A to a plurality of user terminal devices 1B, 1C, and 1D by attaching a file, the message is transmitted to the user terminal device 1B via the message transfer devices 2A and 2B connected to the network.
1C, the user terminal device 1 via 2A, 2C
Sent to D. The attached file is stored in the file storage device 3 once.
A, and the attached file is received from the file storage device 3A when there is a request from the user terminal device 1B, 1C, 1D. In this way, the message to be transmitted and the attached file are sent to the other party via another device.

Next, a description will be given of a state of information transmission between devices when a file is attached to a message with reference to FIG. Here, a case where the user terminal device 1A transmits a message with an attached file to the user terminal device 1B via the message transfer devices 2A and 2B and the file storage device 3A will be described. First, (1) the transmission-side user terminal device 1A issues a file registration request to a file storage device 3A registered in advance when instructed to attach a file to a message created by the user.
At this time, the transmitting-side user terminal device 1A notifies the file storage device 3A of the capacity of the file to be registered. On the other hand, (2) the file storage device 3A checks the free space of the file storage area and, if the file storage area can be stored, notifies the transmission-side user terminal device 1A of registration permission. (3) The transmitting-side user terminal device 1A that has received the registration permission stores the attached file main body together with file management information such as a file obtainable list created from the destination of the message and authentication data created from the message. Transfer to (4) When all the transfer is completed, the file storage device 3A returns the registration information such as the position information of the file storage area to the transmitting user terminal device 1A and notifies the end of the registration. (5) When the file registration of the file storage device 3A is completed, the transmitting user terminal device 1A creates a storage location of the attached file from the received registration information, and embeds it in the message as the attached file information together with the authentication data. Then, the message is sent to the message transfer device 2A in the same manner as a normal message. (6) The message transfer device 2A that has received the message transfers the message to the message transfer device 2B on the recipient side in the same manner as a conventional electronic mail. (7) The message is received from the message transfer device 2B, and (8) the receiving user terminal device 1B
Confirms the file attachment information in the message, the receiving-side user terminal device 1B requests the file storage device 3A in which the position on the network is described in the file attachment information to acquire the file. (9) In response to the file acquisition request, the file storage device 3A requests authentication data from the receiving user terminal device 1B, and performs authentication using the authentication data of the receiving user terminal device 1B. (10) After being authenticated as a valid file requester, the file storage device 3A transfers the attached file to the receiving user terminal device 1B. (11) When the file transfer ends normally, the receiving user terminal device 1B notifies the file storage device 3A of the normal end and ends the file acquisition.

[0007] Next, for each of the user terminal device and the file storage device, which are components of the electronic mail device,
This will be described with reference to a block diagram and a flowchart showing the internal configuration. FIG. 3 is a block diagram showing a configuration of a plurality of user terminal devices connected to a network. In the figure,
10 is a communication means for directly transmitting and receiving information between the user terminal device and the network by directly connecting to the network;
1 is a registration inquiry means for inquiring of a file storage device whether or not a file can be registered. 12A is a message transmission for creating information necessary for transmitting a message created by a user to a message transfer device and transmitting the message. Means 12B is a message receiving means for receiving a message sent from the message transfer device;
3A is a file transmitting unit for transmitting the attached file to the file storage device together with the file management information. 13B is a file receiving unit for performing an authentication process with the file storage device and receiving the attached file from the file storage device.
Is a message encryption / decryption means for encrypting a message with the recipient's public encryption key and decrypting the message with its own private key; and 15A, a file operation means for managing files such as saving and deleting messages and attached files. , 15B are file storage means for storing a file in a storage device, 16 is a message operation means for creating, changing, and displaying a message, 17 is a user interface for exchanging between a user and a user terminal device, Reference numeral 18 denotes an attached file information generation unit that adds file registration information and authentication data to the message, and 19 denotes an authentication data generation unit that generates authentication data from the message. In such a configuration, when transmitting a message with an attached file, the user terminal device shown in FIG.
The operation is performed as follows according to the flowchart of FIG. S
1: First, when transmitting a message, it is determined whether a file is attached. S if not attached
The process goes to 13 to encrypt the message, and the message is transmitted. S2: If a file is attached, a request for file registration is made to the file storage device. S3: Then, it is determined whether or not the file can be registered. S4: When information indicating that registration is not possible is returned from the file storage device, it is checked whether registration is possible with all other file storage devices. That is, a request for file registration is made to all the other file storage devices, and each answer is determined. If registration is not possible in all file storage devices, the process proceeds to S2. S5: If it can be registered in any of them, the information is added to the user terminal device. S6: After a predetermined time has elapsed, the process proceeds to S2. S7: If registration is possible in S3, a public encryption key of the file storage device is obtained. S8:
Generates the attached file information generation file acquirer authentication data. S9: The attached file information and the file acquirer authentication data are encrypted. S10: attached file information,
Transfer the file acquirer authentication data and attached file to the file storage device. S11: Acquire attached file position information. S12: Add file position information to the message. S13: Encrypt the message. S14: Transfer the message.

[0008] Such a procedure will be described again in an easily understandable manner as follows. First, a message is created by the user in the transmitting-side user terminal device 1A, and an instruction is given to attach a file to the message. The transmitting-side user terminal device 1A checks the file size of the attached file, makes a file registration request to the file storage device 3A registered in advance, and notifies the file size. When the registration permission is obtained from the file storage device 3A, the transmission-side user terminal device 1A stores the file obtainable list from the destination of the message, and the file holding validity period from the user's instruction, for example, the file for one week from registration. Such as holding
The file acquirer authentication data is created, and the attached file is transferred to the file storage device 3A and registered along with information such as the file name and the creator. As an example of the method of generating the file acquirer authentication data, there is a method of generating a one-way hash function based on a message or a method of using a random number. Further, the transfer of the file acquirer authentication data of the file storage device 3A needs to be encrypted in order to cope with eavesdropping and the like. For example, in the case of using the public key cryptosystem, it is conceivable that the generated file acquirer authentication data is encrypted with the public key of the file storage device 3A, and then transferred and decrypted with the secret key. If the registration permission is not obtained from the file storage device 3A, a similar inquiry is made to the other registered file storage devices. Or,
An inquiry is made to another file storage device introduced from the file storage device for which registration permission has not been obtained. If the registration permission has not been obtained from all the file storage devices, the user is notified of the fact and waits for retry. After the file transfer of the file storage device 3A is completed, the transmission-side user terminal device 1A adds the file storage location information and the file acquirer authentication data returned from the file storage device 3A to the message,
The message is transferred to the message transfer device 2A. The file acquirer authentication data requires some encryption, such as using the public encryption key of the receiver, in consideration of eavesdropping on the message transfer path. The description of the file storage location is, for example,
Prepare an appropriate field such as X-Ftp-Source: etc. in the header part of the message and describe it with URL. Thus, the process of the transmitting-side user terminal device 1A ends.

Next, when the user terminal device 1B receives the attached file stored in the file storage device 3A, the user terminal device 1B receives the attached file shown in FIG.
The operation is performed as follows according to the flowchart of FIG. S
1: First, the message is decrypted. S2: Then, a message is displayed on the user terminal device. S3: It is determined whether a file is attached to the message. If not, the process W ends. S4: If the file is attached, the authentication data for the file acquirer and the file position information are acquired from the message. S5: Request file acquisition to the file storage device. S6: Send the attached file name and the acquisition requester name. S7: Obtain a public encryption key of the file storage device. S8: The authentication data for the file acquirer is encrypted and transmitted. S9: Acquire the attached file.

[0010] Such a procedure will be described again in an easily understandable manner as follows. First, the receiving-side user terminal device 1B that has received the message sent in the same manner as the conventional e-mail checks the presence or absence of the attached file from the header of the message. Send an acquisition request to. File storage device 3
After sending the file name, the acquirer name, and the authentication data to A, the file is acquired and saved, and the file acquisition process ends. Since the message containing the authentication data is encrypted with its own public encryption key, the message is first decrypted with the secret key of the receiving user terminal device 12. Next, it encrypts using the public key sent from the file storage device 3A and sends it to the file storage device 3A. Message transfer device 2
The processing performed in A and 2B is the same as the processing performed in the conventional electronic mail. For this reason, even a user terminal device not according to the present invention can receive a message according to the present invention. Also, since the file storage location is described by the URL, the attached file can be obtained by using other software for decrypting and encrypting the authentication data.

Next, the file storage device will be described. FIG. 4 is a block diagram showing a configuration of a file storage device connected to a network. In the figure, reference numeral 30 denotes communication means for realizing communication with other devices directly connected to the network; 31A, a file receiving means for receiving a file sent from the user terminal device 1;
B is a file transmission unit for transmitting a file to the user terminal device, and 32A is a registration request process for receiving a file registration request from the user terminal device 1, exchanging registration information, and making an inquiry to the file management unit 34 and the storage area management unit 35. Means, 32B an acquisition request processing means for receiving a file acquisition request from the user terminal device 1 and exchanging information for user authentication and acquisition, and 33 an encryption / decryption means for decrypting authentication data and the like. , 34 are file management means for storing and deleting files in accordance with file registration and acquisition requests and updating management information, 35 is storage area management means for grasping and managing the free space of the file storage area, and 36 is file storage. Device.

In such a configuration, when the file storage device registers a file, it operates as follows according to the flowchart of FIG. S1: Send an attached file registration request. S2: Acquire the file size.
S3: Check the free area of the storage area. S4: Determine whether registration is possible. S5: If registration is not possible, it is determined whether there is another file storage device. S6: If there is no other, a notification of the registration load is given, and the process ends.
S7: If any other, an inquiry about registration is made. S8: It is determined from the answer to the inquiry whether registration is possible. If registration is not possible, the process proceeds to S5. S9: If registration is possible, the storage device is recommended to the user terminal device, and the process ends.
S10: If registration is possible in S4, a registration permission is transmitted. S11: Transmit the public key. S12: Acquire the file acquirer authentication data and the attached file information and decrypt them. S13: Receive the attached file. S14: Store the attached file. S15: Register the file acquirer authentication data, the attached file information, and the file storage location information in the management table. S16: Transmit the position information.

The above procedure will be described again in an easily understandable manner as follows. The file storage device 3A stores the file sent from the transmitting user terminal device 1A. Upon receiving the file registration request and the file size from the transmitting user terminal 1A, the file storage area is checked, and if there is sufficient free space for storing the file, registration is permitted to the transmitting user terminal 1A and its own public encryption is performed. Advertise the key. If there is no free space, the file storage device 3A makes an inquiry to the other file storage devices 3B and 3C as to whether there is a free space, and recommends the free file storage device to the transmitting-side user terminal device 2A. If there is no free space in any of the file storage devices, notification of registration rejection is given. Upon receiving the encrypted registration information sent from the transmitting-side user terminal device 1A that has received the registration permission, it decrypts it with its own secret key and adds it to the management table. Further, the attached file main body is received from the transmitting-side user terminal device 1A, stored in the attached-file storage area, and enters a standby state waiting for an acquisition request of the receiving-side user terminal device 1B. In the file storage device,
As the management information, the file name, registration date, retention period, sender, file acquirer list, file acquisition authentication data, and the acquisition status such as the acquirer, acquisition date, etc. are stored in the management table for each file. I do. Also, the deletion information of the file whose retention period has elapsed is retained in the deletion table.

When a file is obtained from the file storage device, the following operation is performed according to the flowchart of FIG. S1: Receive a file acquisition request. S
2: Request file name and acquirer name. S3: Receive file name and acquirer name. S4: Check the management table. S5: It is determined whether or not the file and the acquired name are in the management table. S6: If not, a file transmission non-permission is notified, and the process ends. S7: If there is a file and an obtained name in S5, a public encryption key is transmitted. S8: Receive the encrypted file acquirer authentication data. S9: The file acquirer authentication data is decrypted. S10: Compare with the file acquirer authentication data in the management table.
S11: It is determined whether or not they match. If they do not match, the process moves to S6. S12: If they match, the file is transmitted. S13: Update the acquisition status information in the management table. S14: It is determined whether all the persons who can acquire the file have acquired the file, and if not, the process is terminated. S15: If acquired, delete the file. S16: Add deletion information to the deletion table.

The above procedure will be described again for easy understanding as follows. The file storage device 3A that has received the file acquisition request from the receiving-side user terminal device 1B requests the file name and the acquirer name from the receiving-side user terminal device 1B. When the file name and the acquirer name are received and the corresponding file and the acquirer name are found in the management table, the public key is passed to the receiving user terminal device 1B and the authentication data is requested. The transmitted authentication data is decrypted and compared with the authentication data in the management table. If the authentication data matches, the file is transferred to the receiving-side user terminal device 1B. After the transfer is completed, the acquisition status in the management table is updated and the system enters a standby state. Here, when all the persons who can acquire the list have acquired the file, the file is deleted and the file name, the date of deletion, the source of the file, and the like are recorded in the deletion table.

As described above, since the file attached to the message is stored in a device different from the message, the file is received when the receiving side is convenient without the network being crowded. You can take it. In the present embodiment, the user terminal device and the file storage device are different devices, but may be provided as the same user terminal device.

[0017]

As described above, the present invention can avoid a failure of an e-mail apparatus caused by sending a large-capacity message by separately handling an e-mail message transfer and an attached file. Further, as a secondary effect, there is an effect that confidentiality is improved by performing authentication when acquiring an attached file.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an electronic mail device and a flow of information according to the present invention.

FIG. 2 illustrates a flow of information between devices.

FIG. 3 is a block diagram of a user terminal device.

FIG. 4 is a block diagram of a file storage device.

FIG. 5 is a flowchart showing a file registration processing procedure of the user terminal device.

FIG. 6 is a flowchart showing a file acquisition processing procedure of the user terminal device.

FIG. 7 is a flowchart showing a file registration processing procedure of the file storage device.

FIG. 8 is a flowchart showing a file acquisition processing procedure of the file storage device.

[Description of sign]

 1A, 1B, 1C, 1D User terminal device 2A, 2B, 2C Message transfer device 3A, 3B, 3C File storage device 10, 30 Communication unit 11 Registration inquiry unit 12A Message transmission unit 12B Message reception unit 13A, 31B File transmission unit 13B , 31A file receiving means 14 message encryption / decryption means 15A file operation means 15B, 36 file storage means 16 message operation means 17 user interface 18 attached file information generation means 19 authentication data generation means 32A registration request processing means 32B acquisition request processing means 33 encryption / decryption means 34 file management means 35 storage area management means reference number 12527

Continued on front page F term (reference) 5B089 AA27 AD11 AE08 AF02 CB02 CF00 DD03 DD05 DD07 5K030 GA15 HA05 HB00 HB08 KA02

Claims (3)

[Claims] 1. A network comprising: a network; a plurality of user terminal devices connected to the network; and a message transfer device, wherein a message is transferred between the plurality of user terminal devices via the network and the message transfer device. In an e-mail device that performs transmission and reception, a file storage device connected to the network is provided separately from the message transfer device, and when the user terminal device attaches a file and transmits a message to another user terminal device, An e-mail device wherein the attached file is temporarily stored in the file storage device, and is received from the file storage device when the user terminal device that has received the message requests reception of the attached file. 2. When transmitting a message with a file attached, the user terminal device stores the file acquirable person list, authentication data, and management information of a file storage period together with the attached file in the file storage. A function to transmit to the device and after receiving the message with the file attached, make a request to acquire the attached file to the file storage device, and if the file acquisition request is accepted by the file storage device, the acquisition of the attached file is performed. The electronic mail device according to claim 1, further comprising a function capable of performing the function. 3. The file storage device has a function of storing management information such as a file obtainable person list, authentication data, a file storage period, and the like, and an attached file sent from the user terminal device. If there is a request to acquire the attached file from the user terminal device, authentication is performed based on the management information, and if the authentication is accepted, the stored management information and the attached user file device that has requested acquisition of the attached file are sent to the user terminal device. 2. The electronic mail apparatus according to claim 1, further comprising a function of transmitting the information and notifying the user terminal apparatus that has requested the acquisition if the authentication is not approved.