JP2010233117A - Electronic mail processor, electronic mail system, and electronic mail encryption method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To implement access control of an attached file after transmission. <P>SOLUTION: An electronic mail processor has: a receiving means for receiving an electronic mail sent from an electronic mail sending/receiving device; a storage means for storing a received electronic mail; a mail analysis means for analyzing whether an attached file is attached to the received electronic mail; an encryption object determination means for determining whether the attached file is an encryption object when an attached file is attached; an attached file encryption means which extracts an attached file from an electronic mail when the attached file is determined as an encryption object, sends the attached file to an encryption device and receives the encrypted file sent from the encryption device; and a replacement means for replacing the attached file attached to the electronic mail with an encrypted file. The encrypted file sent from the encryption device is the attached file which is encrypted by the encryption device and sent to the encryption device by the sending means. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electronic mail processing apparatus, an electronic mail system, and an electronic mail encryption method for automatically encrypting an attached file.

  Since e-mail is transmitted and received through a network that can be freely accessed by third parties, it is important to consider how to prevent e-mails from being intercepted by third parties. Therefore, even if an attached file attached to an e-mail is intercepted by a third party, it is transmitted after being encrypted in order to prevent the contents from being grasped.

  In order to prevent forgetting to encrypt an attached file attached to an e-mail, for example, Patent Document 1 discloses a method for automatically encrypting an attached file.

  However, in the method disclosed in Patent Document 1, since an e-mail including a password for deciphering is also transmitted at the same time, this attachment file is deciphered when intercepted by a third party. There is a danger. In addition, since a password is issued for each electronic document, if transmission and reception are repeated and the number of received attached files increases, password management becomes difficult.

  Further, for example, Patent Document 2 discloses a method in which an encryption method is set for each attached file in accordance with a company security policy, and the attached file is automatically encrypted based on this setting. ing. In this way, stronger encryption can be used for more important attachments.

  However, even if the attached file is encrypted, after transmission, the sender cannot control browsing of the attached file, and cannot manage who is viewing the attached file.

  Therefore, for example, in Patent Document 3, when a user who has received an encrypted attached file decrypts the password, the user cannot obtain a password without sending the user information to a device that has encrypted the attached file. It is disclosed. By doing this, it is possible to know when and who has viewed the encrypted attachment.

  Further, for example, Patent Document 4 discloses a method that allows a sender of an e-mail to set viewing restrictions on the transmitted e-mail after transmission. According to this method, it is possible to control the browsing of electronic mail even after transmission.

JP 2007-324710 A JP 2007-150454 A JP 2007-281622 A JP 2003-114852 A

  However, in the method disclosed in Patent Document 3, a user receives a password for decrypting an attached file, and decryption is performed by the user using this password. For this reason, once the password is received, anyone can decrypt the attached file. In this method, it is impossible to control the browsing of the attached file after transmission.

  In the method disclosed in Patent Document 4, a dedicated mailer must be used.

  Accordingly, the present invention has been made in view of the above problems, and an object thereof is to provide an e-mail processing apparatus, an e-mail system, and an e-mail encryption method capable of performing access control of an attached file after transmission. To do.

  In order to solve the above problems, an electronic mail processing device according to the present invention includes a receiving unit that receives an electronic mail transmitted from a connected electronic mail transmitting / receiving device, and a storage that stores the electronic mail received by the receiving unit. Means, mail analyzing means for analyzing whether an attached file is attached to the e-mail received by the receiving means, and the attached file is attached to the e-mail analyzed by the mail analyzing means When the attached file is determined to be encrypted by the encryption target determining means for determining whether the attached file is to be encrypted, and the encryption target determining means, The attached file is extracted from the electronic mail stored in the storage unit, and the attached file is extracted by the transmitting unit. Attached file encryption means for transmitting to the encryption apparatus and receiving the encrypted file transmitted by the encryption apparatus by the reception means, and attached to the e-mail stored by the storage means Replacement means for replacing the attached file with the encrypted file received by the reception means, and the encrypted file transmitted by the encryption device is transmitted by the encryption device. The attachment file is encrypted and transmitted to the encryption apparatus by the transmission means.

  The electronic mail system according to the present invention is an electronic mail system in which a transmission user terminal, a transmission mail monitoring device, an encryption device, and a database are connected, and the transmission user terminal is a transmission user account input by a transmission user. And a first transmission means for transmitting the transmission user password to the transmission mail monitoring device, wherein the transmission mail monitoring device receives the transmission user account and the transmission user password transmitted by the transmission user terminal. Receiving means, a first storage means for storing the transmission user accounts and the transmission user passwords of a plurality of registered transmission users, and the transmission of the plurality of transmission users stored by the first storage means Of the user account and the sending user password, the first receiving means A second sending means for sending a search screen to the sending user terminal when there is a match with the sent sending user account and the sending user password, wherein the sending user terminal sends the sent mail A second receiving unit configured to receive the search screen transmitted by the monitoring device; the search condition input by the transmission user is transmitted to the transmitted mail monitoring device by the first transmitting unit; The monitoring device receives the search condition transmitted by the transmitting user terminal by the first receiving unit, and stores the list of e-mails transmitted so far by the transmitting user by the first storing unit. And satisfying the search condition received by the first receiving means from the list of e-mails stored by the first storage means Child mail is extracted, a list is created, and the list is transmitted to the transmission user terminal by the second transmission means, and the transmission user terminal receives the list transmitted by the transmission mail device, Input of a first selection for selecting the e-mail from the list by the user, and selection of whether to enable or disable browsing of the attached file attached to the e-mail selected by the first selection The selection information describing the first selection and the second selection is transmitted to the transmission mail monitoring apparatus by the first transmission means, and the database transmits the plurality of transmissions. The encrypted identification number assigned to the encrypted attached file among the attached files attached to the e-mail sent so far by the user is stored. The transmitted mail monitoring device receives the selection information transmitted by the transmission user terminal by the first reception unit, and based on the selection information received by the second reception unit, from the database. The encryption identification number is extracted, the encryption identification number and the selection information are transmitted to the encryption device by the second transmission unit, and the encryption device is transmitted by the outgoing mail monitoring device. The encryption identification number received by the third receiving means based on the selection information received by the third receiving means, having third receiving means for receiving an encryption identification number and the selection information It is characterized in that it is set whether the attached file to which the number is assigned can be browsed or cannot be browsed.

  The electronic mail system in the present invention is an electronic mail system in which a receiving user terminal and an encryption device are connected, and the receiving user terminal includes a receiving user account and a receiving user password input by the receiving user. , Having a first transmission means for transmitting an encrypted identification number of an attached file to be browsed by the receiving user to the encrypting device, the encrypting device including the receiving user account transmitted by the receiving user terminal; A first receiving means for receiving a receiving user password and the encrypted identification number; a first storing means for storing the receiving user accounts and the receiving user passwords of a plurality of registered receiving users; The receiving user accounts and the receiving user passwords of the plurality of receiving users stored by the storage means Among them, there is one that matches the received user account and the received user password received by the first receiving means, and the attachment to which the encrypted identification number received by the first receiving means is assigned. And a second transmission means for transmitting a decryption key for the attached file to the receiving user terminal when the file is viewable, and the receiving user terminal is transmitted by the encryption device. And a second receiving means for receiving a decryption key, wherein the attached file viewed by the receiving user is decrypted with the decryption key received by the second receiving means. It is characterized by

  The electronic mail encryption method according to the present invention includes a reception step of receiving an electronic mail transmitted from a connected electronic mail transmitting / receiving device, a storage step of storing the electronic mail received by the reception step, An email analysis step for analyzing whether an attachment file is attached to the email received by the reception step; and when the attachment file is attached to the email analyzed by the email analysis step, When the attached file is determined to be encrypted by the encryption target determining step for determining whether the attached file is to be encrypted and the encryption target determining step, the information is stored in the storage step. The attached file is extracted from the email and the attached file is extracted. An attached file encryption step of transmitting the encrypted file transmitted by the encryption device and receiving the encrypted file by the receiving means; and the e-mail stored by the storage step Replacing the attached file attached to the encrypted file received by the receiving step, and the encrypted file transmitted by the encrypting device includes: The attachment file is encrypted by an encryption device and transmitted to the encryption device by the transmission step.

  The e-mail encryption method according to the present invention further includes a first transmission step of transmitting a transmission user account and a transmission user password input by the transmission user to the transmission mail monitoring apparatus by the transmission user terminal, A first reception step of receiving the transmission user account and the transmission user password transmitted by the transmission user terminal by the mail monitoring device, and storing the transmission user account and the transmission user password of a plurality of registered transmission users The first storing step, and the transmitting user received by the first receiving step among the transmitting user accounts and the transmitting user passwords of the plurality of transmitting users stored by the first storing step. Match the account and the sending user password A second transmission step of transmitting a search screen to the transmission user terminal when there is a second reception of receiving the search screen transmitted by the transmission mail monitoring device by the transmission user terminal The transmission user terminal transmits a search condition input by the transmission user to the transmission mail monitoring apparatus, and the transmission mail monitoring apparatus performs the first reception step. Receiving the search condition transmitted by the sending user terminal, and storing the list of e-mails sent so far by the sending user by the first storing step by the sending mail monitoring device; The first reception from the list of emails stored in the first storage step by the monitoring device The e-mails that satisfy the search conditions received by the step are extracted, a list is created, and the list is sent to the sending user terminal by the second sending step by the sending mail monitoring device. Sending, receiving by the sending user terminal the list sent by the sending mail device, selecting by the user a first selection for selecting the email from the list, and selecting by the first selection In response to an input of a second selection for selecting whether to allow or prohibit browsing of the attached file attached to the e-mail, the first sending step by the sending user terminal causes the first Selection information describing the selection and the second selection is transmitted to the outgoing mail monitoring device, and the plurality of transmission users are transmitted by the database. An encrypted identification number assigned to the encrypted attached file among the attached files attached to the e-mail sent so far by the user, and the first reception by the sent mail monitoring device The selection information transmitted by the transmission user terminal is received by the step, and the database is based on the selection information received by the second reception step by the second transmission step by the transmission mail monitoring device. The encryption identification number is extracted from the encrypted identification number and the selection information is transmitted to the encryption device, and the encryption device transmits the encryption identification number transmitted by the outgoing mail monitoring device and the encryption information. A third receiving step for receiving selection information, and based on the selection information received by the third receiving step; Serial third the attachments assigned received the encrypted identification number by the reception step of and sets whether the viewing prohibited whether it is viewable.

  In the electronic mail encryption method according to the present invention, the receiving user terminal receives the receiving user account and the receiving user password input by the receiving user, and the encrypted identification number of the attached file viewed by the receiving user. A first transmission step of transmitting the received user account, a received user password and the encrypted identification number transmitted by the receiving user terminal; A first storing step for storing the receiving user accounts and the receiving user passwords of a plurality of registered receiving users; and the receiving user accounts and the receiving of the plurality of receiving users stored by the first storing step. Among the user passwords, the reception user received by the first reception step. When the attached file assigned with the encryption identification number received by the first receiving step is viewable, the decryption of the attached file is decrypted. A second transmission step of transmitting a key to the receiving user terminal, wherein the receiving user terminal receives the decryption key transmitted by the encryption device; And the attached file viewed by the receiving user is decrypted with the decryption key received in the second receiving step.

  According to the present invention, access control of an attached file after transmission can be performed.

It is a figure which shows an example of a structure of the electronic mail system which concerns on embodiment of this invention. It is a figure which shows an example of the processing operation of the electronic mail system which concerns on embodiment of this invention. It is a figure which shows an example of the processing operation of the electronic mail system which concerns on embodiment of this invention. It is a figure which shows an example of the processing operation of the electronic mail system which concerns on embodiment of this invention.

  Next, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing an example of the configuration of an electronic mail system according to an embodiment of the present invention. The transmission user terminal 101, the reception user terminal 102, the e-mail transmission / reception apparatus 110, the e-mail processing apparatus 120, the PDF (Portable Document Format) conversion apparatus 130, the PDF encryption apparatus 140, the database 150, and the transmission e-mail monitoring apparatus 160. Yes.

  The electronic mail transmission / reception device 110, the electronic mail processing device 120, the PDF conversion device 130, the PDF encryption device 140, the database 150, and the outgoing mail monitoring device 160 are connected to each other via a network such as a LAN (Local Area Network). Yes. The sending user terminal 101 and the electronic mail transmission / reception device 110 may be connected to each other via a local network such as a LAN, or may be connected to each other via a global network such as the Internet. The transmission user terminal 101 and the transmission mail processing device 120 are connected to each other via a global network such as the Internet, for example. The receiving user terminal 102 and the e-mail transmission / reception device 110 may be connected to each other via a local network such as a LAN, or may be connected to each other via a global network such as the Internet. The receiving user terminal 102 and the PDF encryption device 140 are connected to each other via a global network such as the Internet, for example.

  The sending user terminal 101 and the receiving user terminal 102 are an email sending means for sending an email, a sending means for sending information, a sending / receiving means for receiving information, a display means for displaying information, Input means for receiving an input. The transmitting user terminal 101 and the receiving user terminal 102 are information processing apparatuses such as personal computers and mobile phone terminals.

  The e-mail transmitting / receiving apparatus 110 includes e-mail receiving means for receiving e-mail and e-mail transmitting means for transmitting e-mail. The e-mail transmission / reception device 110 is an information processing device such as a workstation or a server, and has a function of receiving e-mail and a function of transmitting e-mail to a destination described in the e-mail.

  The e-mail processing device 120 stores e-mail receiving means for receiving e-mail, transmitting means for transmitting e-mail, receiving means for receiving information, transmitting means for transmitting information, e-mail and information. A storage unit 121, a mail analysis unit 122 that analyzes an electronic mail stored in the storage unit 121, and a cipher that determines whether an attached file attached to the electronic mail stored in the storage unit 121 is an encryption target The encryption target determination unit 123, the attachment file encryption unit 124 that encrypts the attachment file determined to be the encryption target by the encryption target determination unit 123, and the electronic mail stored in the storage unit 121 An attached file replacing means 125 for replacing the attached file with the attached file encrypted by the attached file encryption means 124; Obtain. The email processing apparatus 120 is an information processing apparatus such as a workstation or a server.

  The PDF conversion apparatus 130 includes a reception unit that receives a document file, a transmission unit that transmits the document file, and a PDF conversion unit that converts the document file into a PDF file. The PDF conversion apparatus 130 is an information processing apparatus such as a workstation or a server.

  The PDF encryption device 140 is received by means of receiving information, transmitting means for transmitting information, storage means for storing information, encryption means for encrypting document files, and encryption means encrypted by the encryption means. Encrypted identification information creation means for attaching encrypted identification information to each document file, decryption key creation means for creating a key for decrypting the document file encrypted by the encryption means, and the received account and password are correct An account determination unit for determining whether the file indicated by the received information is viewable or forbidden, and a change in the information stored in the storage unit based on the received information Changing means. The PDF encryption device 140 is an information processing device such as a workstation or a server. The information stored by the storage means includes, for example, access control information. The access control information includes, for example, information about whether the encrypted document file is viewable or prohibited, the user name who can view the encrypted document file, and operations such as printing the encrypted document file Information that indicates whether or not is possible.

  The database 150 includes a receiving unit that receives information, a transmitting unit that transmits information, and a storage unit that stores information. The database 150 is an information storage device such as a database server. The database 150 stores e-mail header information, encryption identification information attached to an attached file encrypted by the PDF encryption device 140, and the like.

  The transmitted mail monitoring device 160 includes a receiving unit that receives information, a transmitting unit that transmits information, a storage unit that stores information, an account determination unit that determines whether the received account and password are correct, and received information And a list creation means for creating a list of information based on the information stored in the storage means, and an extraction means for extracting the information stored in the database 150. The outgoing mail monitoring device 140 is an information processing device such as a workstation or a server. The transmission user performs access control of the attached file via the transmission mail monitoring device 160.

  FIG. 2 is a diagram illustrating an example of a processing operation performed in the electronic mail system according to the embodiment of the present invention when a user transmits mail. First, the e-mail transmitting / receiving apparatus 110 that has received the e-mail transmitted by the transmission user terminal 101 automatically transmits the received e-mail to the e-mail processing apparatus 120 (S101). Here, the e-mail transmitting / receiving apparatus 110 may store the received e-mail and transmit it to the e-mail processing apparatus 120.

  The e-mail processing apparatus 120 that has received the e-mail transmitted from the e-mail transmitting / receiving apparatus 110 stores the received e-mail in the storage unit 121 (S102). The mail analysis unit 122 analyzes the electronic mail stored from the storage unit 121 and determines whether there is an attached file (S104). When there is no attached file (S104, No), the e-mail processing apparatus 120 transmits the e-mail stored in the storage unit 121 to the e-mail transmission / reception apparatus 110, and the e-mail transmission / reception apparatus 110 that has received the e-mail This electronic mail is transmitted to the receiving user terminal 102 described in the transmission destination of this electronic mail (S114), and the process ends. Here, the e-mail processing apparatus 120 notifies the e-mail transmission / reception apparatus to transmit the e-mail, and the e-mail transmission / reception apparatus 110 that has received the notification describes the e-mail in the transmission destination of the e-mail. It may be transmitted to the receiving user terminal 102.

  When there is an attached file (S104, Yes), the mail analyzing unit 122 analyzes the header information of the electronic mail stored in the storage unit 121 and the attached file. The encryption target determination unit 123 determines whether the attached file of the e-mail is an encryption target based on the analysis result by the mail analysis unit 122 and the setting information stored in the storage unit (S105).

There are various ways to determine whether or not it is an encryption target. For example, encryption target information describing a file format, an address, and the like to be encrypted is stored in the storage unit 121, and the encryption target determination unit 123 encrypts the attached file based on the encryption target information. It is good to judge whether it is a target. The information to be encrypted includes, for example, the information that the destination is encrypted when the domain is "test.com", the information that is encrypted when the address is " aaa@test.com ", etc. Information is described. On the other hand, the information to be encrypted includes, for example, information that no encryption is performed for the domain “test.com” and information that is not encrypted for the address “ aaa@test.com ”. It may be as described. The encryption target information includes, for example, information that the file format is encrypted if the attached file has a file extension of “.doc”, and conversely, the attachment file has an extension of “.doc”. Information such as not encrypting if it is a child file is described.

  When all the attached files attached to the e-mail are not to be encrypted (S105, No), the e-mail processing apparatus 120 transmits the e-mail stored in the storage unit 121 to the e-mail transmitting / receiving apparatus 110, and this e-mail The e-mail transmission / reception apparatus 110 that received the e-mail transmits this e-mail to the receiving user terminal 102 described in the e-mail transmission destination (S114), and the process ends. Here, the e-mail processing apparatus 120 notifies the e-mail transmission / reception apparatus to transmit the e-mail, and the e-mail transmission / reception apparatus 110 that has received the notification describes the e-mail in the transmission destination of the e-mail. It may be transmitted to the receiving user terminal 102.

  If any of the attached files of the e-mail is to be encrypted (S105, Yes), the attached file encryption unit 124 extracts the attached file to be encrypted from the e-mail stored in the storage unit 121. Extracted and transmitted to the PDF converter 130 (S106). Here, a means for determining the file format of the extracted attached file may be provided, and when the attached file is a PDF file, the attached file may be transmitted to the PDF encryption apparatus 140.

  The PDF conversion device 130 converts the attached file transmitted by the attached file encryption unit into a PDF file. The PDF conversion apparatus 130 transmits the attached file converted into the PDF file format to the attached file encryption unit 124 (S107).

  The attached file encryption unit 124 receives the attached file transmitted from the PDF conversion apparatus 130, and transmits the received attached file to the PDF encryption apparatus 140 (S108).

  The PDF encryption device 140 receives the attached file transmitted from the attached file encryption unit 124, and performs an encryption process on the received attached file (S109). At this time, the PDF encryption device 140 attaches encryption identification information to each encrypted attached file, and stores this encryption identification number information. The PDF encryption device 140 transmits the encrypted attachment file and encryption identification information for each of the encrypted attachment files to the attachment file encryption unit 124 (S110).

  The attachment file encryption unit 124 receives the encrypted attachment file transmitted from the PDF encryption device 140 and attaches the received encrypted attachment file and the electronic mail stored in the storage unit 121. The file is sent to the file replacement unit 125 (S111).

  The attached file replacing unit 125 receives the encrypted attached file and the e-mail transmitted from the attached file encrypting unit 124. The attached file replacing unit 125 replaces the attached file encrypted by the PDF encryption device among the attached files of the received electronic mail with the encrypted attached file (S112). The attached file replacing unit 125 transmits the e-mail with the attached file replaced to the e-mail transmitting / receiving apparatus 110 (S113).

  The e-mail transmission / reception device 110 receives the e-mail transmitted by the attached file replacement unit 125, and transmits the received e-mail to the transmission destination described in the e-mail (S113).

  By doing so, all attachments are automatically encrypted without the user's concern. For this reason, it becomes possible to prevent the user from forgetting to encrypt. In addition, it is possible to specify a file to be encrypted and a transmission destination in advance. For example, for an in-house e-mail, it can be set not to encrypt.

  FIG. 3 is a diagram illustrating an example of a processing operation in the electronic mail system according to the embodiment of the present invention when the transmission user remotely performs access control on the transmitted attached file.

  The sending user connects to the sending mail monitoring device 160 from the sending user terminal 101. There are various ways of connection at this time. For example, it is preferable to use a WEB browser or the like to connect to the outgoing mail monitoring apparatus 160.

  The transmission user inputs recognition information at the transmission user terminal 101 (S201). Various kinds of recognition information can be considered. For example, here, recognition information based on an account given to each user and a password set for the account is considered. Therefore, it is assumed that the sending user has input an account and a password as recognition information.

  There are various ways of setting the account and password. For example, when the sending user obtains an account related to the use of the e-mail transmission / reception device 110, the password is also set, and this account and password are set in the e-mail transmission / reception device 110. When this is done, this account and password may be automatically stored in the outgoing mail monitoring device 160. Here, it is assumed that the transmission user's account and password are stored in the transmission mail monitoring device 160.

  The transmission user terminal 101 transmits the input account and password to the transmission mail monitoring device 160. The outgoing mail monitoring device 160 receives the account and password sent from the sending user terminal 101, and determines whether this account and password are correct (S202). For example, here, account information in which an account and a password for a registered user are described is stored in the outgoing mail monitoring device 160, and the determination is made based on the account information. Like that. In addition, this account information is stored in another device, for example, the database 150 or the outgoing mail monitoring device 160, and at the time of determination, the PDF encryption device 140 reads this account information and makes a determination based on the read account information. You can go.

  If the account or password is incorrect (S202, No), information describing that the account or password is incorrect is sent to the application on the receiving user terminal, and the application that received this information Or the user is informed that the password is incorrect, and the process is terminated. There are various methods for notifying the user. For example, a message indicating that the account or password is incorrect is displayed by the display means of the receiving user terminal. Also, when notifying the user that the account or password is incorrect, the user may be prompted to re-enter the account and password.

  If the account and password are correct (S202, Yes), the outgoing mail monitoring device 160 sends a search screen to the sending user terminal 101 (S203). The transmission user terminal 101 receives the search screen transmitted from the outgoing mail monitoring device 160 and displays the received search screen. The search screen searches for e-mails sent by the sending user so far, and there are various ways of searching. The transmission user may search the electronic mail transmitted to the input transmission destination by inputting the transmission destination from the search screen. Further, when the transmission user inputs a date from the search, an electronic mail transmitted on the input date may be searched. In addition, when the sending user inputs a keyword from the search screen, the input keyword is included in the head information of the email, the content of the email, the file name of the attached file, the content of the attached file, etc. You may make it search mail.

  On the transmission user terminal 101, the transmission user inputs search conditions such as a transmission destination, a date, and a keyword in order to search for an e-mail attached with an attached file for which access control is desired. The transmission user terminal 101 transmits the input search condition to the transmission mail monitoring device 160 (S204).

  The transmission mail monitoring device 160 receives the search condition transmitted from the transmission user terminal 101, and searches the list of e-mails transmitted so far by the transmission user for an e-mail that matches the received search condition. And create a list of emails that match the search criteria. There are various ways of preparing the list of e-mails sent so far by the sending user. For example, every time the e-mail transmitting / receiving apparatus 110 sends an e-mail, the sent e-mail is recorded. Alternatively, a list may be created based on the stored e-mail. In addition, for example, when encryption is performed by the electronic mail processing apparatus 120, a list of electronic mail in which an attached file is encrypted may be created. The transmitted mail monitoring device 160 transmits a list of emails that match the search condition to the transmitting user terminal 101 (S205).

  The transmission user terminal 101 receives the list transmitted from the transmitted mail monitoring apparatus 160 and displays the received list. The transmission user selects an e-mail to which an attachment file to be subjected to access control is attached from this list, and selects whether the attachment file of the selected e-mail can be viewed or prohibited from being viewed. Selection information indicating selection of an e-mail and selection of whether or not to allow the attachment of the selected e-mail to be browsed is input to the transmission user terminal 101. The transmission user terminal 101 transmits this selection information to the transmission mail monitoring device 160 (S206).

  The transmission mail monitoring device 160 receives the selection information transmitted from the transmission user terminal 101, and extracts from the database 150 the encryption identification information for all the attached files attached to the e-mail indicated by the received selection information. (S207). The outgoing mail monitoring device 160 transmits to the PDF encryption device 140 the selection information for enabling or disabling the browsing of these attached files indicated in the extracted encrypted identification information and the received selection information. (S208).

  The PDF encryption device 140 receives the encryption identification information and the selection information transmitted from the outgoing mail monitoring device 160, and all the attached files with the received encryption identification information are based on the received selection information. Whether or not browsing is possible is set (S209), and the process ends. Setting information that sets whether each attached file can be browsed or prohibited from being browsed may be stored in the PDF encryption device 140 so that it can be identified by the encryption identification number, the database 150, etc. You may make it memorize | store in another apparatus. Then, when the PDF encryption device 140 receives the encryption identification number and the selection information, the PDF encryption device 140 retrieves the stored setting information based on the received encryption identification number and the selection information, and resets the setting information. Good.

  Also, for example, when encrypted by the PDF encryption device 130, all the receiving users are prohibited from browsing, and only the receiving user that the transmitting user wants to permit browsing is allowed to send the transmitting user after transmission. The sent mail monitoring device 160 may be set to allow browsing.

  By doing in this way, the attached file attached to the transmitted electronic mail can be managed even after transmission.

  FIG. 4 is a diagram illustrating an example of a processing operation in the electronic mail system according to the embodiment of the present invention when a user who has received an attached file encrypted by the PDF encryption apparatus 140 views the attached file. .

  When the receiving user terminal 102 gives an instruction to browse the attached file encrypted by the PDF encryption device 140, the application used to view the attached file prompts the user to input authentication information. There are various kinds of authentication information. Here, for example, it is assumed that an account and a password are given in advance to a user who gives a browsing instruction.

  When the user enters an account and password, the application used to view the attachment reads the encryption identification number attached to the attachment, and this encryption identification number, the entered account and password, Is transmitted to the PDF encryption apparatus 140 (S301).

  The PDF encryption apparatus 140 receives the encryption identification number, the account and the password transmitted by this application on the receiving user terminal 102, and determines whether or not the account and the password are correct (S302). There are various ways to make this determination. For example, if account information in which an account and a password for a registered user are described is stored in the PDF encryption apparatus 140, the determination is made based on the account information. good. In addition, this account information is stored in another device, for example, the database 150 or the outgoing mail monitoring device, and at the time of determination, the PDF encryption device 140 reads this account information and makes a determination based on the read account information. May be.

  When the account or password is not correct (S302, No), information describing that the account or password is incorrect is transmitted to the application on the receiving user terminal, and the application receiving this information Or the user is informed that the password is incorrect, and the process is terminated. There are various methods for notifying the user. For example, a message indicating that the account or password is incorrect is displayed by the display means of the receiving user terminal. Also, when notifying the user that the account or password is incorrect, the user may be prompted to re-enter the account and password.

  When the account and password are correct (S302, Yes), the PDF encryption device 140 determines whether the attached file with the encrypted identification number can be viewed based on the received encrypted identification number or is prohibited from being viewed. It is determined whether or not there is something (S203). There are various methods for performing this determination. For example, here, browsing information describing whether browsing is possible or browsing is stored in the PDF encryption apparatus 140 together with the encryption identification information. Make a decision. Further, the transmission user can set whether or not browsing is possible in the outgoing mail monitoring device 160, and this setting information is sent to the PDF encryption device 140, and the PDF encryption device 140 sends the received setting information. The browsing information is rewritten based on this.

  When browsing is prohibited (S303, No), information describing that browsing is prohibited is transmitted to the application on the receiving user terminal, and the application that has received this information indicates that browsing is prohibited based on this information. The user is notified and the process ends. There are various methods for notifying the user. For example, a message indicating that browsing is prohibited is displayed by the display means of the receiving user terminal.

  When browsing is possible (S303, Yes), the PDF encryption apparatus 140 transmits a key for decrypting the attached file to the application on the receiving user terminal 102 (S304). This decryption key may be created and stored at the same time when the PDF encryption apparatus 140 encrypts the attached file, for example. Also, for example, when encrypting an attached file, information on the encryption of the attached file, including the decryption of the attached file, together with the encrypted identification information is created, stored, and determined to be viewable. When this is done, a decryption key may be created.

  The application on the receiving user terminal 102 receives the decryption key transmitted from the PDF encryption device 140, decrypts the attached file using the received decryption key (S305), displays it, The process ends.

  When the PDF encryption apparatus 140 creates a decryption key, it is preferable to record the destination of the decryption key, the date and time when the decryption key was created, and the like. In this way, the transmission user can manage who viewed the encrypted attached file when and after transmission.

  In this way, the receiving user must always connect to the PDF encryption device 140 in order to view the received encrypted attachment. For this reason, the transmission user can manage when and who viewed the transmitted attachment. Whether the receiving user can browse or not depends on whether the sending user is set to be viewable or prohibited from being browsed, and the sending user can control the browsing of the encrypted attached file.

  In addition, this way, without issuing a password to the receiving user, the decryption key is sent to the application on the sending user terminal, and the application uses the received key to automatically decrypt the password. Can be prevented from being viewed by a third party due to the leakage of.

  In addition, by doing this, it is possible to send an attached file that allows access control using a general-purpose mailer without using a dedicated mailer.

  According to the embodiment described above, the attached file can be encrypted without the e-mail sender being aware of the encryption process. In addition, since the sender of the e-mail can control access to the attached file after transmission, even if he / she makes a mistake in the address, he / she can prohibit viewing without his / her own request.

  In the above embodiment, encryption is performed after converting everything into a PDF file. However, the file format to be converted before encryption is not limited to a PDF file. For files other than document files such as music files, a conversion device that converts the file into a file format suitable for the file and an encryption device that encrypts the converted file may be prepared. If it is a music file, for example, all attached music files are converted into one of the file formats such as WAV format, MP3 (MPeg audio layer 3) format, AAC (Advanced Audio Coding) format, etc. An apparatus may be prepared and an encryption apparatus for encrypting the converted file may be prepared.

  The present invention is useful as an electronic mail system in an environment where confidential documents are handled.

  The present invention has been described above by the preferred embodiments of the present invention. While the invention has been described with reference to specific embodiments thereof, various modifications and changes can be made to these embodiments without departing from the broader spirit and scope of the invention as defined in the claims. is there.

  In the electronic mail processing apparatus according to the present invention, the attachment file encryption unit is stored in the storage unit when the encryption target determination unit determines that the attachment file is an encryption target. The attached file is extracted from the e-mail, the attached file is transmitted to the PDF conversion apparatus by the transmission means, the PDF file transmitted by the PDF conversion apparatus is received by the reception means, and received by the reception means The transmitted PDF is transmitted to the encryption device by the transmission unit, the encrypted file transmitted by the encryption device is received by the reception unit, and the PDF file transmitted by the PDF conversion device is The PDF file is converted to a PDF file by the PDF converter and sent to the PDF converter by the transmission means. The encrypted file transmitted by the encryption device is the PDF file that has been encrypted by the encryption device and transmitted to the encryption device by the transmission means. There may be.

  In the electronic mail processing apparatus according to the present invention, the storage means also stores encryption target information in which a file format to be encrypted is described, and the encryption target determination means is analyzed by the mail analysis means. When the attached file is attached to the electronic mail, it is determined whether the attached file is an encryption target based on the encryption target information stored by the storage means. good.

  In the electronic mail processing apparatus according to the present invention, the storage means also stores encryption target information in which an electronic mail address to be encrypted is described, and the mail analysis means is received by the reception means. The header information of the email is also analyzed, and the encryption target means, when the attached file is attached to the email analyzed by the mail analysis means, the electronic data analyzed by the mail analysis means Based on the transmission destination described in the header information of the mail and the encryption target information stored by the storage means, it may be determined whether the attached file is an encryption target.

  In the electronic mail processing apparatus according to the present invention, the storage means also stores encryption target information in which a file format to be encrypted and an electronic mail address are described, and the mail analysis means is received by the receiving means. The header information of the received email is also analyzed, and the encryption target means is analyzed by the mail analysis means when the attached file is attached to the email analyzed by the mail analysis means. Further, based on the transmission destination described in the header information of the electronic mail and the encryption target information stored in the storage means, it may be determined whether or not the attached file is an encryption target.

  In the electronic mail encryption method according to the present invention, the attached file encryption step is stored in the storage step when the attached file is determined to be encrypted by the encrypted object determining step. The attached file is extracted from the e-mail, and the attached file is transmitted to the PDF conversion apparatus by the transmission step, the PDF file transmitted by the PDF conversion apparatus is received by the reception step, and the reception step The received PDF is transmitted to the encryption device by the transmission step, the encrypted file transmitted by the encryption device is received by the reception step, and the PDF file transmitted by the PDF conversion device is , Converted to a PDF file by the PDF converter, The encrypted file which is the attached file transmitted to the PDF conversion device by the step, and the encrypted file transmitted by the encryption device is encrypted by the encryption device. It may be the PDF file transmitted to.

  In the electronic mail encryption method of the present invention, the storage step also stores encryption target information in which a file format to be encrypted is described, and the encryption target determination step is performed by the mail analysis step. When the attached file is attached to the analyzed email, it is determined whether the attached file is an encryption target based on the encryption target information stored in the storing step. Also good.

  In the email encryption method according to the present invention, the storage step also stores encryption target information in which an email address to be encrypted is described, and the mail analysis step is received by the reception step. The header information of the e-mail is also analyzed, and the encryption target step is analyzed by the e-mail analysis step when the attached file is attached to the e-mail analyzed by the e-mail analysis step. Based on the transmission destination described in the header information of the electronic mail and the encryption target information stored in the storage step, it may be determined whether or not the attached file is an encryption target.

  In the electronic mail encryption method according to the present invention, the storage step also stores encryption target information describing a file format to be encrypted and an electronic mail address, and the mail analysis step is received by the reception step. The header information of the e-mail that has been analyzed, and the encryption target step is analyzed by the e-mail analysis step when the attached file is attached to the e-mail analyzed by the e-mail analysis step Based on the transmission destination described in the header information of the e-mail and the encryption target information stored in the storing step, it may be determined whether the attached file is an encryption target.

DESCRIPTION OF SYMBOLS 101 Sending user terminal 102 Receiving user terminal 110 E-mail transmission / reception apparatus 120 E-mail processing apparatus 121 Storage means 122 Mail analysis means 123 Encryption object determination means 124 Attached file encryption means 125 Attached file replacement means 130 PDF conversion apparatus 140 PDF encryption Device 150 Database 160 Outgoing mail monitoring device

Claims (14)

Receiving means for receiving an e-mail transmitted from the connected e-mail transmitting / receiving device; and
Storage means for storing the e-mail received by the receiving means;
Mail analysis means for analyzing whether an attachment file is attached to the e-mail received by the receiving means;
When the attached file is attached to the email analyzed by the mail analyzing unit, an encryption target determining unit that determines whether the attached file is an encryption target;
When it is determined by the encryption target determination means that the attachment file is an encryption target, the attachment file is extracted from the email stored in the storage means, and the attachment file is transmitted to the transmission means. Attached file encryption means for transmitting the encrypted file transmitted by the encryption apparatus and receiving the encrypted file by the reception means;
Replacement means for replacing the attached file attached to the e-mail stored by the storage means with the encrypted file received by the receiving means;
The encrypted file transmitted by the encryption device is the attached file transmitted to the encryption device by the transmission means encrypted by the encryption device. Processing equipment. The attachment file encryption means extracts the attachment file from the email stored in the storage means when the encryption object determination means determines that the attachment file is an encryption object. The attached file is transmitted to the PDF converter by the transmitting unit, the PDF file transmitted by the PDF converter is received by the receiving unit, and the PDF received by the receiving unit is encrypted by the transmitting unit. Sent to the device, received by the receiving means, the encrypted file sent by the encryption device,
The PDF file transmitted by the PDF conversion device is the attached file that has been converted to a PDF file by the PDF conversion device and transmitted to the PDF conversion device by the transmission means,
The encrypted file transmitted by the encryption device is the PDF file that is encrypted by the encryption device and transmitted to the encryption device by the transmission unit. The electronic mail processing apparatus according to 1. The storage means also stores encryption target information in which a file format to be encrypted is described,
When the attached file is attached to the e-mail analyzed by the mail analyzing unit, the encryption target determining unit determines whether the attached file is based on the encryption target information stored by the storage unit. The e-mail processing apparatus according to claim 1, wherein the e-mail processing apparatus determines whether it is an encryption target. The storage means also stores encryption target information in which an email address to be encrypted is described,
The mail analyzing means also analyzes header information of the email received by the receiving means,
The encryption target means, when the attached file is attached to the e-mail analyzed by the mail analyzing means, the transmission destination described in the header information of the e-mail analyzed by the mail analyzing means 3. The electronic mail processing apparatus according to claim 1, wherein it is determined whether the attached file is an encryption target based on the encryption target information stored in the storage unit. The storage means also stores encryption target information in which a file format to be encrypted and an email address are described,
The mail analyzing means also analyzes header information of the email received by the receiving means,
The encryption target means, when the attached file is attached to the e-mail analyzed by the mail analyzing means, the transmission destination described in the header information of the e-mail analyzed by the mail analyzing means 3. The electronic mail processing apparatus according to claim 1, wherein it is determined whether the attached file is an encryption target based on the encryption target information stored in the storage unit. An email system in which a sending user terminal, a sending mail monitoring device, an encryption device, and a database are connected,
The sending user terminal has a first sending means for sending the sending user account and the sending user password input by the sending user to the sending mail monitoring device,
The transmission mail monitoring device includes a first reception unit that receives the transmission user account and a transmission user password transmitted by the transmission user terminal;
First storage means for storing the transmission user account and the transmission user password of a plurality of registered transmission users;
Among the transmission user accounts and the transmission user passwords of the plurality of transmission users stored by the first storage unit, matches the transmission user account and the transmission user password received by the first reception unit. And a second transmitting means for transmitting a search screen to the transmitting user terminal when there is something to do,
The transmitting user terminal also has a second receiving means for receiving the search screen transmitted by the transmitted mail monitoring device,
The search condition entered by the sending user is sent to the outgoing mail monitoring device by the first sending means,
The transmitted mail monitoring device receives the search condition transmitted by the transmitting user terminal by the first receiving means,
A list of e-mails sent so far by the sending user is also stored in the first storage means,
An e-mail satisfying the search condition received by the first receiving means is extracted from the list of e-mails stored by the first storage means, a list is created, and the list is sent to the second transmission Transmitted to the transmitting user terminal by means,
The transmission user terminal receives the list transmitted by the transmission mail device, and inputs a first selection for selecting the electronic mail from the list by the user, and the selection selected by the first selection. In response to an input of a second selection for selecting whether the attached file attached to the electronic mail can be browsed or prohibited from being browsed, selection information describing the first selection and the second selection is sent to the transmission mail. Transmitted to the monitoring device by the first transmission means;
The database stores encryption identification numbers assigned to the encrypted attachments among the attachments attached to the e-mail sent so far by the plurality of sending users,
The transmitted mail monitoring device receives the selection information transmitted by the transmission user terminal by the first reception unit, and based on the selection information received by the second reception unit, the encryption from the database. Extracting the encryption identification number, and transmitting the encryption identification number and the selection information to the encryption device by the second transmission means,
The encryption device has a third receiving means for receiving the encryption identification number and the selection information transmitted by the outgoing mail monitoring device,
Based on the selection information received by the third receiving means, whether the attached file assigned with the encryption identification number received by the third receiving means is viewable or not viewable. An e-mail system characterized by setting. An e-mail system in which a receiving user terminal and an encryption device are connected,
The receiving user terminal has a first transmitting means for transmitting a receiving user account and a receiving user password input by the receiving user, and an encryption identification number of an attached file viewed by the receiving user to the encryption device. ,
The encryption device includes: a first reception unit that receives the reception user account, a reception user password, and the encryption identification number transmitted by the reception user terminal;
First storage means for storing the receiving user account and the receiving user password of a plurality of registered receiving users;
Of the receiving user accounts and the receiving user passwords of the plurality of receiving users stored by the first storage unit, the receiving user account and the receiving user password received by the first receiving unit match. When the attached file assigned with the encryption identification number received by the first receiving means is viewable, a decryption key for the attached file is transmitted to the receiving user terminal. A second transmission means,
The receiving user terminal has second receiving means for receiving the decryption key transmitted by the encryption device;
An e-mail system characterized in that the attached file viewed by the receiving user is decrypted with the decryption key received by the second receiving means. A receiving step of receiving an email sent from the connected email sending and receiving device;
Storing the e-mail received by the receiving step;
An email analysis step of analyzing whether an attachment is attached to the email received by the reception step;
When the attached file is attached to the e-mail analyzed by the mail analyzing step, an encryption target determining step for determining whether the attached file is an encryption target;
When it is determined by the encryption target determination step that the attachment file is an encryption target, the attachment file is extracted from the email stored in the storage step, and the attachment file is extracted by the transmission step. An attached file encryption step of transmitting to the encryption device and receiving the encrypted file transmitted by the encryption device by the receiving means;
Replacing the attached file attached to the e-mail stored by the storing step with the encrypted file received by the receiving step;
The encrypted file transmitted by the encryption device is the attached file transmitted to the encryption device by the transmission step, encrypted by the encryption device. Encryption method. The attached file encryption step extracts the attached file from the e-mail stored in the storing step when it is determined by the encryption target determining step that the attached file is an encryption target. The attached file is transmitted to the PDF converter by the transmitting step, the PDF file transmitted by the PDF converter is received by the receiving step, and the PDF received by the receiving step is encrypted by the transmitting step. Sent to the device, and received by the receiving step, the encrypted file sent by the encryption device,
The PDF file transmitted by the PDF conversion device is the attached file that has been converted to a PDF file by the PDF conversion device and transmitted to the PDF conversion device by the transmission step,
The encrypted file transmitted by the encryption device is the PDF file that is encrypted by the encryption device and transmitted to the encryption device in the transmission step. 9. The e-mail encryption method according to 8. The storing step also stores encryption target information in which a file format to be encrypted is described,
In the encryption target determining step, when the attached file is attached to the e-mail analyzed in the mail analyzing step, the attached file is determined based on the encryption target information stored in the storing step. 10. The e-mail encryption method according to claim 8 or 9, wherein it is determined whether or not it is an encryption target. The storing step also stores encryption target information in which an email address to be encrypted is described,
The mail analysis step also analyzes header information of the email received by the reception step,
In the encryption target step, when the attached file is attached to the email analyzed in the email analysis step, the destination described in the header information of the email analyzed in the email analysis step 10. The e-mail encryption method according to claim 8, wherein whether or not the attached file is an encryption target is determined based on the encryption target information stored in the storage step. The storing step also stores encryption target information in which a file format to be encrypted and an email address are described,
The mail analysis step also analyzes header information of the email received by the reception step,
In the encryption target step, when the attached file is attached to the email analyzed in the email analysis step, the destination described in the header information of the email analyzed in the email analysis step 10. The e-mail encryption method according to claim 8, wherein whether or not the attached file is an encryption target is determined based on the encryption target information stored in the storage step. A first transmission step of transmitting a transmission user account and a transmission user password input by the transmission user to the transmission mail monitoring device by the transmission user terminal;
A first reception step of receiving the transmission user account and the transmission user password transmitted by the transmission user terminal by the transmission mail monitoring device;
A first storage step of storing the transmission user account and the transmission user password of a plurality of registered transmission users;
Among the transmission user accounts and the transmission user passwords of the plurality of transmission users stored in the first storage step, matches the transmission user account and the transmission user password received in the first reception step. A second transmission step of transmitting a search screen to the transmission user terminal when there is something to do,
A second receiving step of receiving the search screen transmitted by the transmitted mail monitoring device by the transmitting user terminal;
In the first transmission step by the transmission user terminal, the search condition input by the transmission user is transmitted to the transmission mail monitoring device,
Receiving the search condition transmitted by the transmitting user terminal by the first receiving step by the transmitted mail monitoring device;
The first storing step by the transmitted mail monitoring device also stores a list of emails transmitted so far by the transmitting user,
Extracting e-mails that satisfy the search conditions received by the first receiving step from the list of e-mails stored by the first storing step by the outgoing mail monitoring device, creating a list,
By the second transmission step by the transmitted mail monitoring device, the list is transmitted to the transmission user terminal by the second transmission step,
The sending user terminal receives the list sent by the sending mail device, and inputs the first selection for selecting the e-mail from the list by the user, and the selected by the first selection. Receives an input for a second selection that selects whether to allow or prohibit viewing the attachment attached to the email,
In the first transmission step by the transmission user terminal, the selection information describing the first selection and the second selection is transmitted to the outgoing mail monitoring device,
The database stores an encrypted identification number assigned to the encrypted attached file among the attached files attached to the email sent so far by the plurality of sending users,
The selection information transmitted by the transmission user terminal is received by the first reception step by the transmitted mail monitoring device,
Based on the selection information received by the second reception step, the encryption identification number is extracted from the database by the second transmission step by the transmission mail monitoring device, and the encryption identification number and the selection are extracted. Sending information to the encryption device;
The encryption device includes a third reception step of receiving the encryption identification number and the selection information transmitted by the outgoing mail monitoring device,
Based on the selection information received in the third receiving step, whether the attached file assigned with the encryption identification number received in the third receiving step is viewable or not viewable. An e-mail encryption method characterized by setting. The receiving user terminal has a first transmission step of transmitting the receiving user account and the receiving user password input by the receiving user, and the encrypted identification number of the attached file viewed by the receiving user to the encryption device,
The encryption device receives a reception user account, a reception user password, and the encryption identification number transmitted by the reception user terminal, a first reception step;
A first storing step of storing the receiving user account and the receiving user password of a plurality of registered receiving users;
Of the receiving user accounts and the receiving user passwords of the plurality of receiving users stored in the first storing step, match the receiving user account and the receiving user password received in the first receiving step. When the attached file assigned with the encryption identification number received in the first receiving step is viewable, a decryption key for the attached file is transmitted to the receiving user terminal. A second transmission step,
The receiving user terminal includes a second receiving step of receiving the decryption key transmitted by the encryption device;
An e-mail encryption method characterized in that the attached file viewed by the receiving user is decrypted with the decryption key received in the second receiving step.

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