JP2009169821A - Leakage prevention system and program for taken-out confidential information - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that a common method of encryption with a password when confidential information is outputted to an external medium such as USB memory so as to be taken out of a company is vulnerable to leakage of the confidential information because code is broken by a brute force method for password cracking, etc. when the encrypted confidential information is lost. <P>SOLUTION: When the confidential information (file) is taken out and decrypted, checking is performed without fail through a decryption server, and a set of site (network location such as host name and IP address), person and takeout time limit authorized for decryption is controlled. Thus, even when the confidential information is lost, decryption is permanently prohibited by letting the takeout time limit registered in the decryption server expire, and leakage of the confidential information is prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a system and a program for preventing leakage of confidential information that is taken out to limit the decryption location of the confidential information encrypted when the confidential information is taken out.

  In order to prevent leakage of confidential information outside the company, there is a method of prohibiting the use of external media, but it is currently necessary to permit the use of the information for business purposes. When taking confidential information out of the office, password encryption is used when outputting to external media such as FD (flexible disk), USB (Universal Serial Bus) memory, and portable HDD (hard disk device). Although the method is general, if the encrypted confidential information is lost, the encryption may be broken by a brute force method of passwords and the confidential information may be leaked.

Patent Document 1 records a file that is encrypted by adding position information that can be decrypted to a confidential information file on a recording medium equipped with GPS (Global Positioning System), whereby a decryption area of the confidential information file is recorded. And a system in which the location of a confidential information file is specified and the file cannot be opened outside the set region.
Japanese Patent Laid-Open No. 2007-241907

  However, in the invention of Patent Document 1, it is necessary to use a dedicated recording medium equipped with GPS, and since the physical position is specified by GPS, the position is specified indoors where the satellite radio waves do not reach. There was a problem that it was impossible to do.

  The present invention can use a generally distributed recording medium, and can identify a network location using a host name or an IP address and decrypt it (network location such as a host name or IP). -The purpose is to provide a system that can prevent the leakage of confidential information by limiting the expiry date of people and exports.

  The system for preventing leakage of confidential information taken out of the present invention includes a person who takes out the confidential information by intervening a decryption server when the confidential information is recorded in a portable memory and taken outside. The network location where information is taken out, the deadline for taking out the confidential information, and the encrypted confidential information are recorded in the portable memory, and the encrypted confidential information recorded in the portable memory is recorded. When decrypting information, a decryption server is always intervened to perform a check process, so that the person who decrypts the confidential information, the network location where the confidential information is decrypted, It is characterized by limiting the time limit for taking out.

  Further, the program of the present invention provides a procedure for connecting to a computer via a network when encrypting confidential information, a person who takes out the confidential information, a network location, and When decrypting confidential information recorded in a portable memory by executing a procedure for checking the deadline and a procedure for performing encryption only when permitted by the check, the computer is connected to the decryption server via a network. And a connection procedure, a person who performs decryption, a network location, a procedure for checking a take-out time limit, and a procedure for performing decryption only when permitted by the check.

  According to the present invention, it is possible to prevent leakage of confidential information by restricting a place where decryption can be performed (network location such as a host name or IP), person, and expiry date, and if confidential information is lost, Alternatively, even if the information is spread, the expiration date of the confidential information registered in the decryption server is expired, so that decryption can be permanently prohibited and leakage of the confidential information can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a system configuration diagram of a system for preventing leakage of confidential information taken outside of an embodiment of the present invention. In FIG. 1, 1 is a system configuration, 2 is an in-house LAN, 3 is outside, 4 is a PC (Personal Computer) (plaintext file output is impossible), 5 is a decryption server, 6 is a decryption password issuing function, 7 is a memory, 8 is a decryption password confirmation function, 9 is the Internet, 10 is a PC that can use the Internet, 11 is a PC that cannot use the Internet, 12 is a mobile phone, 13 issuance of a decryption password, 14 is a decryption password request, and 15 is decryption Indicates password confirmation.

  In the system configuration 1 in FIG. 1, a plurality of PCs (plaintext file output impossibility) 4 and a decryption server 5 are connected by an in-house LAN 2. In addition, the PC 3 available outside the Internet 3 is connected to the decryption server 5 via the Internet connection 9, and the PC 11 unavailable to the Internet outside the company 3 is connected to the decryption server 5 via the mobile phone 12 via the Internet connection 9. .

  The decryption server 5 includes a decryption password issuing function 6, a memory 7, and a decryption password confirmation function 8. When the PC (plain text file cannot be output) 4 records confidential information in a portable memory and takes it out, the PC (plain text file cannot be output) 4 issues a decryption password issuance 13 to the decryption server 5. . When receiving the decryption password issuance 13, the decryption server 5 issues a decryption password using the decryption password issuance function 6, and the issued decryption password is recorded in the memory 7.

  When the memory in which the confidential information taken out of the company 3 is recorded is connected to the Internet-usable PC 10, the self-decryption program is started, the decryption password request 14 is made, and the internet-unusable PC 11 is connected. Confirmation 15 of the decryption password is performed using the cellular phone 12, and the confidential information file is decrypted using the decryption password after confirmation.

  FIG. 2 is a flowchart showing an information encryption procedure according to the embodiment of the present invention. Confidential information is encrypted as usual when it is output to an external medium. Conventionally, when encrypting information, a decryption password is designated. However, in the present invention, the decryption password is not designated, and the following processing is performed.

  In the flowchart of FIG. 2, the information encryption procedure is started in step S200, the encryption program is started in step S201, and the file to be encrypted is selected in step S202. In step S203, the encryption program requests input of a user ID and password, a network location (IP address, etc.), and a take-out expiration date. In step S204, the encryption program transmits a user ID, a password, a take-out expiration date, and a message digest of the file to be encrypted to the decryption server 5, and in step S205, decryption ID and decryption password are used as information for decryption. Is issued. (The decryption password includes the message digest (or hash value) of the file).

  In step S206, the encryption program outputs a self-decryption program in which information such as a password is embedded (the password is not disclosed to the user). Thereafter, in step S207, the encryption program displays the decryption ID on the screen, and the information encryption procedure is terminated in step S208.

  FIG. 3 is a flowchart showing an information decoding procedure according to the embodiment of the present invention. In the flowchart of FIG. 3, the information decoding procedure is started in step S300, and the self-decoding program is started in step S301. In step S302, the self-decryption program attempts to connect to the decryption server.

  If the connection to the decryption server 5 is possible in step 302, the user ID and password are requested to be input in step S303, the message digest of the user ID, password and decryption file match in step S304, and decryption is performed. If the confidential information to be transferred is within the carry-out expiration date and is the network location registered at the time of encryption, the file is decrypted in step S305. At that time, the decryption server 5 records the user ID and the decrypted file in the memory 7 in step S306. If connection to the decryption server is impossible in step 302, a temporary decryption password input screen is displayed in step 308, and the process proceeds to step 310 in (A).

  If the message digests of the user ID, password, and decrypted file do not match in step S304, or the confidential information to be decrypted is out of the valid period for taking out, or if it is other than the network location registered at the time of encryption, step S309 Stop decrypting the file at.

  FIG. 4 is a flowchart showing a procedure for accessing the decryption server using the mobile phone in the flowchart of FIG. With the decryption password input screen displayed in step S308 of FIG. 3, the user who performs decryption in step S400 accesses the decryption server using a communication device such as a mobile phone that can be connected to the Internet. . After inputting the user ID / password / decryption ID on the screen of the decryption server 5 in step S401, if the information in the decryption server 5 matches the information in the decryption server 5 in step S402 and is within the valid period for taking out, decryption is performed in step S403. The temporary decryption password that can be used for a short period of about one hour based on the password and the current time is displayed on the screen. At that time, in step S404, the decryption server records the user ID and the file to be decrypted. Thereafter, the screen returns to the state where the input screen of the temporary decryption password in step 308 of FIG. 3 is displayed, and the temporary decryption password is input in the self-decryption program, and the confidential information can be decrypted in step S305.

FIG. 1 is a system configuration diagram of a system for preventing leakage of confidential information taken outside of an embodiment of the present invention. FIG. 2 is a flowchart showing an information encryption procedure according to the embodiment of the present invention. FIG. 3 is a flowchart showing an information decoding procedure according to the embodiment of the present invention. FIG. 4 is a flowchart showing a procedure for accessing the decryption server using the mobile phone in the flowchart of FIG.

Explanation of symbols

1 System configuration 2 Internal LAN
3 External 4 PC (Cannot output plain text file)
5 Decryption Server 6 Decryption Password Issue Function 7 Memory 8 Decryption Password Confirmation Function 9 Internet 10 Internet Available PC
11 Internet unavailable PC
12 Mobile phone 13 Decryption password issuance 14 Decryption password request 15 Decryption password confirmation

Claims (8)

  When recording confidential information in a portable memory and taking it outside, a person who takes out the confidential information by intervening a decryption server, a network location where the confidential information is taken out, the confidential information The outside take-out confidential information leakage prevention system is characterized in that the take-out time limit and the encrypted confidential information are recorded in the portable memory.   When decrypting the encrypted confidential information recorded in the portable memory, the person who decrypts the confidential information by performing the check process with the decryption server always intervening, the decryption of the confidential information A system for preventing leakage of confidential information taken outside, characterized by limiting a network-like position where the information is taken out and a deadline for taking out the confidential information. When recording confidential information in a portable memory and taking it outside, a person who takes out the confidential information by intervening a decryption server, a network position where the confidential information is taken out, the confidential information Record the take-out deadline and the encrypted confidential information in the portable memory,
When decrypting encrypted confidential information recorded in a portable memory, a person who decrypts the confidential information by decrypting the confidential information by intervening the decryption server without fail. A system for preventing leakage of confidential information taken outside, characterized by limiting the network location where the data is converted and the deadline for taking out the confidential information.   When decrypting encrypted confidential information recorded in portable memory, the environment for executing the decryption program is not connected to the decryption server over the network, or network connection to the decryption server is prohibited If it is, the person who performs decryption transmits information necessary for decryption to the decryption server using a mobile terminal that can be connected to the network, and obtains a temporary password necessary for decryption. A system to prevent leakage of confidential information taken outside.   5. In the system for preventing leakage of confidential information taken out to the outside according to claim 4, when a temporary password necessary for decryption is obtained from the portable terminal, the password and confidential information are restricted by limiting the expiration date of the password to a short time. A system for preventing leakage of confidential information taken outside, characterized by drastically reducing the risk of leakage in a set.   A system for preventing leakage of confidential information taken outside, characterized by making it impossible to permanently decrypt the confidential information that was taken out from a remote location by expiring the deadline for taking out the confidential information registered in the decryption server .   When encrypting confidential information, a procedure for connecting to a computer via a network to a decryption server, a person who takes out the confidential information, a network location, a procedure for checking the time limit for taking out, and the above A program for executing the procedure to perform encryption only when permitted by the check.   When decrypting confidential information recorded in a portable memory, a procedure for connecting to a computer via a network to a decryption server, a person performing the decryption, a network location, and a procedure for checking the take-out time limit And a program for executing a procedure for performing decryption only when permitted by the check.

Images