JP4439002B2 - Computer with information leakage prevention function and security enhancement program - Google Patents

Description

  The present invention relates to improvement of a computer with an information leakage prevention function and a security enhancement program.

  A security lock password written in a storage device such as a hard disk drive and a low-level program for device control and a security lock password written in a storage means (storage means unique to the computer) storing a low-level program for device control The computer operating system is started by allowing the reading of information from the storage device only when the two match, and after the operating system is started, the user authentication password stored in the computer is The password entered by the user at the logon operation is compared with the authentication means operating on the operating system, and the user can log on only if they match. Unishi was information leakage prevention function with a computer is already known.

The low-level program for device control is generally BIOS (Basic
Input Output System).
The entity is a group of programs used for basic input / output, and is usually stored in a non-volatile storage means (a storage means unique to the computer) mounted on a computer motherboard or the like.

  When starting up the computer, first, the BIOS, which is a low-level program for device control, is started to realize access of the microprocessor to the storage device, and then the operating system stored as a program in the storage device is stored in the computer. In general, various application programs and the like are executed under the management of the operating system.

  In addition, the security lock password written in the storage device and the security lock password written in the storage means (storage means unique to the computer) storing the BIOS are compared when the BIOS is started, and the storage is based on the mismatch. A technology for prohibiting unauthorized use of a storage device including startup of an operating system by restricting reading of information from the device, and further, a computer controlled by the main body of the operating system permitted to start or its application program The authentication means realized by using the microprocessor of this system compares the password for user authentication stored in the computer with the password entered by the user at the logon operation, and A technique of determining whether access users are those appropriate already generalized for over data.

  This type of authentication means is called a logon desktop or the like, and is usually started at the time of starting up the operating system, at the time of logon, or at the time of data or program rewriting processing requiring a high degree of access rights. . The authentication means activated as necessary first performs display processing of a dialog prompting for input of a password, and then compares the password input by the user with the password for user authentication stored in the computer. Based on the password match / no-match determination result, a process for allowing logon or a process for prohibiting logon is selectively executed.

  However, with the authentication means implemented in computers that are currently on the market, even if the user enters the password incorrectly, the user can enter the password over and over again. Your password may be broken.

  Furthermore, an information leakage prevention function of erasing data has also been proposed, but since it takes time to write the erasure data (generally hexadecimal F) itself, when an attacker detects the data erasure process, Data erasure can be stopped halfway, and information can be stolen in another way.

  Further, even if the information itself is encrypted, it is technically possible to extract the encrypted data, and there is a concern that it will be analyzed by the progress of the decryption technique.

  On the other hand, as a technique for operating a security lock password related to a storage device such as a hard disk drive from the BIOS side, a security lock password automatically generated by the BIOS is stored in a storage device such as a hard disk drive and a non-volatile storage means on the BIOS side (in a computer). For example, Patent Document 1 has already proposed a privacy protection system that stores data in each of unique storage means).

  This privacy protection system uses a BIOS to automatically generate a security lock password, and registers it in a storage device such as a hard disk and a non-volatile RAM while keeping the security lock password invisible. It is to become. In short, it is merely an automated setting of the security lock password on the storage device side and the security lock password on the BIOS side (non-volatile RAM side) compared at the time of BIOS startup, and the reliability of the security lock password itself and the storage device There is no configuration for improving security against unauthorized use, and there is a possibility that the security lock password may be broken by inputting a brute force type character string as described above.

JP 2004-78539 A (paragraph number 0009)

  SUMMARY OF THE INVENTION An object of the present invention is to provide a computer with an information leakage prevention function and a security enhancement program that can improve the disadvantages of the prior art and reliably prevent unauthorized use of a storage device.

The computer with an information leakage prevention function according to the present invention uses a security lock password written in a storage device and a security lock password written in a storage means storing a device control low level program as a device control low level program. The computer operating system is started by allowing information to be read from the storage device only when the two match, and the computer authenticates the password for user authentication and the operation at logon. This is a computer with an information leakage prevention function that compares the password entered by the user with the authentication means operating on the operating system and allows the user to log on only when they match. In order to achieve the above objects, in particular,
In the authentication means,
Unauthorized operation detection means for detecting unauthorized access of a user to a computer based on the operation status of the computer at the time of logon operation;
Storage device control means that operates when an unauthorized operation detection means detects unauthorized access, and rewrites the security lock password of the storage device with another security lock password set at a level higher than that handled by the low-level program for device control. When,
And a forced termination control means for shutting down the computer after the operation of the storage device control means is completed.

In the above configuration, when the computer is operated, first, the device control low-level program (BIOS) stored in the storage means unique to the computer is started, and the security lock password written in the storage device and the computer-specific The security lock password written in the storage means is compared.
If they match, the low-level program for device control allows information to be read from the storage device, the computer operating system is started, and the computer enters a wait state waiting for user logon. enter.
When the user inputs a password by the logon operation, the user authentication password stored in the computer and the password input by the user by the logon operation are compared by the authentication unit operating on the operating system.
The authentication means includes an unauthorized operation detection means for detecting unauthorized access by the user to the computer based on the operation status of the computer. The unauthorized access is not detected by the unauthorized operation detection means and is stored in the computer. If the user authentication password matches the password entered by the user in the logon operation, the user is allowed to log on.
On the other hand, when an unauthorized access is detected by the unauthorized operation detection means, the storage device control means operating on the operating system is further activated, and the security lock password of the storage device is handled by the low-level program for device control. Rewrite to another security lock password set at the above level.
Then, when this rewriting work is completed, the forced termination control means operates to shut down the computer.
When the computer that has been shut down is started again, the low-level program for device control stored in the storage means specific to the computer is started first, and the security lock password written in the storage device and the computer-specific The security lock password written in the storage means is compared. At this point, the security lock password of the storage device has already been rewritten with another security lock password. A low-level program prohibits reading information from the storage device.
Therefore, the startup of the computer operating system itself is prohibited, user logon and reading / writing of information to / from the storage device are completely disabled, unauthorized use of the storage device is reliably prevented, and the problem of information leakage is solved. The
In general, the low-level program (BIOS) for device control contains an appropriate password when the security lock password written in the storage device and the security lock password written in the storage means unique to the computer do not match. Although there is a function that prompts the user to re-enter, the level of data that can be handled by the low-level program for device control is lower than the level of data that can be handled by the operating system. Using a low-level program for device control, a password equivalent to a security lock password set at a level higher than that handled by In itself, it is virtually impossible to set.
Therefore, even if various character strings are tried brute force, there is almost no possibility that the password is broken.

  The unauthorized operation detection means can be configured to detect unauthorized access when the number of erroneous input of a password by a user reaches a set value.

  By allowing erroneous input of a password below the set value, it is possible to prevent an accident that an appropriate user inadvertently locks the storage device (makes it inoperable).

  Further, it is desirable that the storage device control means is configured to encrypt and hold the other security lock password.

  By encrypting the security lock password of the storage device, it is possible to reduce the possibility that a third party takes out the security lock password of the storage device from a logged-on computer.

In addition, the low-level program for device control is AT
Handles the security lock password set in the high mode in Attachment-6 (IDE interface implementation method specified by ATA-6), and the storage device control means is AT
It can be configured to handle security lock passwords set in Maximum mode in Attachment-6.

As described above, in the present invention, it is desirable that the level of data that can be handled by the low-level program (BIOS) for device control be lower than the level of data that can be handled by the operating system. A low-level program (BIOS) that handles security lock passwords set in the high mode in AT Attachment-6, and that the storage device control means that operates on the operating system
It should be configured to handle the security lock password set in the maximum mode in Attachment-6.

The security enhancement program of the present invention compares the security lock password written in the storage device and the security lock password written in the storage means storing the low-level program for device control with the low-level program for device control, This is a security enhancement program that runs on the computer operating system that allows the reading of information from the storage device and starts the computer operating system only when the two match. To do
A microprocessor of the computer;
A logon permission means for comparing the user authentication password stored in the computer with the password entered by the user in the operation at the time of logon, and allowing the user to log on only when they match.
Unauthorized operation detection means for detecting unauthorized access of a user to a computer based on the operation status of the computer during logon operation;
Storage device control means that operates when the unauthorized operation detection means detects unauthorized access, and rewrites the security lock password of the storage device with another security lock password set at a level higher than that handled by the low-level program for device control, and,
The storage device control unit functions as a forced termination control unit that shuts down the computer after the operation of the storage device control unit is completed.

Computers with this security enhancement program installed
A logon permission means for comparing the user authentication password stored in the computer with the password entered by the user in the operation at the time of logon, and allowing the user to log on only when they match.
Unauthorized operation detection means for detecting unauthorized access of a user to a computer based on the operation status of the computer at the time of logon operation;
A storage device control means that operates when the unauthorized operation detection means detects unauthorized access, and rewrites the security lock password of the storage device with another security lock password set at a level higher than that handled by the low-level program for device control; and ,
The computer functions as a computer including a forced termination control unit that shuts down the computer after the operation of the storage device control unit is completed.
Therefore, when this computer is operated, first, the low-level program for device control stored in the storage means specific to the computer is activated and the security lock password written in the storage device and the storage means specific to the computer are written. Compare with the security lock password.
Here, if they match, the low-level program for device control allows reading of information from the storage device, the computer operating system is started, and the computer waits for user logon. to go into.
When the user inputs a password by the logon operation, the logon authentication means operating on the operating system compares the user authentication password stored in the computer with the password entered by the user during the logon operation.
When the unauthorized operation detection means does not detect the unauthorized access of the user to the computer, and the user authentication password stored in the computer matches the password entered by the user during the logon operation, the logon permission means Will allow the user to log on.
On the other hand, if unauthorized access is detected by the unauthorized operation detection means, the storage device control means is further activated to set the security lock password of the storage device at a level higher than that handled by the low-level program for device control. The security lock password is rewritten, and after the rewriting work is completed, the forcible termination control means operates to shut down the computer.
When the computer that has been shut down is started again, the low-level program for device control stored in the storage means specific to the computer is started and the security lock password written to the storage device and the computer-specific The security lock password written in the storage means is compared. At this point, since the security lock password of the storage device has already been rewritten, they inevitably become inconsistent, and a low-level program for device control is installed in the storage device. Prohibit reading of information from.
Therefore, the startup of the computer operating system itself is prohibited, user logon and reading / writing of information to / from the storage device are completely disabled, unauthorized use of the storage device is reliably prevented, and the problem of information leakage is solved. The

  With this security enhancement program, the microprocessor of the computer may further function as an unauthorized operation detection unit that detects unauthorized access when the number of erroneous password inputs by the user reaches a set value.

  By allowing an erroneous input of a password below the set value, an accident that an appropriate user inadvertently locks the storage device can be prevented.

  Further, the another security lock password can be encrypted and coded in this security enhancement program.

  Encrypting the security lock password of the storage device can reduce the possibility that the security lock password of the storage device is taken out by a third party from a data storage medium storing the security enhancement program.

The computer with an information leakage prevention function and the security enhancement program of the present invention forcibly shut down the computer by rewriting the security lock password of the storage device with another security lock password when unauthorized access to the computer is detected. Thus, the determination process executed by the low-level program for device control at the next startup of the computer, that is, the security lock password stored in the storage means unique to the computer and the security lock password written in the storage device are The result of the judgment process to be compared is forcibly made inconsistent, and access to the storage device by the low-level program for device control is prohibited. In, it can be eliminated reliably prohibited to information leakage and writes information with respect to starting and logon and storage device of the operating system by an unauthorized user.
Moreover, the storage device security lock password is set at a level higher than that handled by the low-level program for device control by the storage device control means operating on the operating system, so the password corresponding to the security lock password is used for device control. It is practically impossible to set a computer using a low-level program, and there is almost no possibility that a password will be broken by brute force password breaking.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings. The security enhancement program to which the present invention is applied can be applied to various computers such as workstations, personal computers, and notebook computers. Here, a case of a laptop computer that is highly likely to be stolen or illegally used is taken as an example. Will be explained.

  For example, as shown in FIG. 1, the security enhancement program 1 of this embodiment is stored together with an installation program in a data storage medium 2 such as a CD-ROM. The security enhancement program 1 is a notebook personal computer according to the installation program. 3 is installed in the hard disk drive 4 as a storage device.

First, in order to facilitate understanding of the invention, a general configuration and functions of the notebook personal computer 3 will be briefly described.
As shown in FIG. 1, the main part of the notebook personal computer 3 is roughly composed of a microprocessor 5 (hereinafter simply referred to as a CPU 5) as a calculation means, a ROM 6 storing fixed parameters and the like, and a hard disk drive 4 Operating system programs and various application programs read from the computer, as well as the RAM 7 used for temporary storage of calculation data, and the CPU 5 are required to access the hard disk drive 4 prior to the start of the operating system. A nonvolatile RAM 8 that stores a low-level program for device control (hereinafter simply referred to as BIOS), a keyboard 9 and a monitor 10 that constitute a man-machine interface, an interface 11 for external connection, and the like. It is.

  The non-volatile RAM 8 storing the BIOS is fixed to the motherboard 12 of the notebook computer 3 and is inseparable from the notebook computer 3. It is assumed that a security lock password (A) unique to the notebook personal computer 3 is stored in advance in the nonvolatile RAM 8, and the same security lock password (A) is stored in advance in the hard disk drive 4 as a storage device. .

  This security lock password (A) is, for example, a nonvolatile RAM 8 unique to the notebook personal computer 3 as shown in FIG. 3 when the user inputs an arbitrary character string via the keyboard 9 during BIOS setup. And the same value is stored in the hard disk drive 4. Since the setup of the security lock password (A) is managed by the BIOS, what can actually be set is a character string that can be set in the high mode range of AT Attachment-6.

  Here, the operation at the time of starting the notebook personal computer 3 before installing the security enhancement program 1 will be briefly described.

  First, when the user operates the keyboard 9 or the like of the notebook personal computer 3 to perform a starting operation, drive control of the CPU 5 is started according to the BIOS of the nonvolatile RAM 8.

The CPU 5 controlled in accordance with the BIOS performs various initialization processes and the like, and then the security lock password (A) written in the hard disk drive 4 and the security lock password unique to the notebook computer 3 stored in the nonvolatile RAM 8. Compare with (A).
At this time, the CPU 5 can access only the storage area of the hard disk drive 4 in which the security lock password (A) is stored.

  Normally, as shown in FIG. 4, since the security lock password (A) written in the hard disk drive 4 and the security lock password (A) stored in the nonvolatile RAM 8 match, the CPU 5 further stores them in the BIOS. From the hard disk drive 4 by starting the program group for basic input / output, that is, the program group necessary for the CPU 5 to access data other than the security lock password (A) of the hard disk drive 4. Allow reading of information.

However, if the security lock password written in the hard disk drive 4 and the unique security lock password stored in the nonvolatile RAM 8 do not match, the CPU 5 controlled according to the BIOS inputs the security lock password to the monitor 10. Display a prompt message.
Here, when the user again inputs the security lock password from the keyboard 10, the security lock password comparison process is performed in the same manner as described above, and when the input of the proper security lock password is confirmed, the hard disk drive 4 If it is permitted to read the information, and if the input of an inappropriate security lock password is confirmed, the state where the reading of information from the hard disk drive 4 is prohibited is maintained as it is, and only the shutdown operation and the restart operation are performed. Is allowed.
Normally, since the security lock password of the hard disk drive 4 and the security lock password of the nonvolatile RAM 8 match, there is no need for the user to input the security lock password again after the setup of the security lock password by the BIOS is completed.

  Then, only when reading of information from the hard disk drive 4 is permitted, the CPU 5 further reads a part or all of the operating system stored as a program in the hard disk drive 4 into the RAM 7 as an execution target program. The CPU 5 is driven and controlled in accordance with the operating system, that is, the operating system is activated.

On the other hand, a program (hereinafter referred to as a logon desktop) that functions as an authentication means for comparing a user authentication password stored in the notebook personal computer 3 with a password entered by the user into the notebook personal computer 3 by an operation at the time of logon. A part of the program constituting the operating system or one of application programs closely related to the operating system is read into the RAM 7 together with the operating system, and at the time when the operating system starts up or the main part of the operating system is read into the RAM 7 at least. The CPU 5 which is automatically started when the logon desktop program can be executed and operates according to the program is connected to the monitor 10 for the user authentication password. To display a message that prompts you to enter the mode.
This authentication process is not for confirming the consistency between the hard disk drive 4 and the notebook personal computer 3 but for confirming the access authority of the user until he gets tired.
When the user inputs a password for logon from the keyboard 10 in response to the message, the CPU 5 functioning as an authentication means on the operating system, that is, a logon desktop, stores the user authentication password stored in the notebook computer 3 and Only when the passwords input to the notebook computer 3 by the operation at the time of logon are compared and they match, the user can log on, that is, can execute various processing operations using the operating system.

  Note that there is no particular restriction on the user authentication password, and the security lock password (A) described above may be used as the user authentication password, or a password different from the security lock password (A), for example, The password (B) may be a user authentication password. Since the user authentication password setting operation is managed by the operating system, not the BIOS, theoretically, the password (B) is set in the maximum mode in AT Attachment-6 beyond the range of the high mode in AT Attachment-6. However, because of problems such as workability at the time of logon, usually a simple password (B) is often used. The storage location of the user authentication password (B) may be the nonvolatile RAM 8 or the hard disk drive 4.

  The above is the normal information leakage prevention function before installing the security enhancement program 1, that is, the operation at the time of starting the notebook personal computer 3 provided with a conventional authentication means called a logon desktop or the like.

  As described above, the security enhancement program 1 in the present embodiment is stored in the data storage medium 2 such as a CD-ROM together with the installation program, and this security enhancement program 1 is stored in the hard disk drive 4 that is a storage device of the notebook personal computer 3. By installing, the above-described program constituting the conventional authentication means such as the logon desktop is saved so as not to be deleted or activated, and replaced with the new authentication means 13, that is, the security enhancement program 1 of the present embodiment. It is done.

  That is, this security enhancement program 1 (authentication means 13) is handled in the same manner as a conventional authentication means called a logon desktop or the like, and is read into the RAM 7 together with the operating system when the operating system is started. It is automatically started when the system is started up or when the main part of the operating system is read into the RAM 7 and at least when the security enhancement program 1 can be executed.

  The data storage medium 2 such as a CD-ROM stores an encrypted security lock password (A ′) together with the security enhancement program 1, and the security lock password (A ′) is installed when the security enhancement program 1 is installed. ) Is also stored in the hard disk drive 4. The security lock password (A ') is set by applying the maximum mode in AT Attachment-6, and only the manufacturer's person in charge knows the content.

  FIG. 2 is a functional block diagram showing an outline of the configuration of the authentication means 13 unique to the present embodiment, which is achieved by using the security enhancement program 1 and the CPU 5 stored in the hard disk drive 4 as function realizing means.

  As shown in FIG. 2, the authentication unit 13 includes a dialog control unit 14, a logon permission unit 15, an unauthorized operation detection unit 16, a storage device control unit 17, a forced termination control unit 18, and an AT Attachment-6. The security lock password (A ′) defined in the maximum mode in FIG.

Among these, the dialog control means 14 displays a message prompting the user to input the user authentication password on the monitor 10 at the time of logon operation, that is, at the time when the enhanced security program 1 is started following the startup of the operating system. In addition, it has a function of handing over a password input by the user from the keyboard 10 to the logon permission means 15 in response to this message.
That is, it has the same function as the password input screen of the conventional logon desktop.

The logon permitting means 15 uses the security lock password (A) when the user authentication password stored in the notebook personal computer 3, that is, the security lock password (A) is used as the user authentication password. When a password different from the lock password (A) is used as the password for user authentication, the password (B) is compared with the password delivered from the dialog control means 14, that is, the password entered by the user in the logon operation. Only when the two match, a logon permission signal is output to the operating system, and the logon of the user, that is, the execution of various processing operations using the operating system is permitted.
If the two do not match, the logon permission unit 15 sends an error signal to the unauthorized operation detection unit 16.

The unauthorized operation detection means 16 is for detecting unauthorized access by the user to the notebook computer 3 based on the operation status of the notebook computer 3 during the logon operation. Specifically, the error count register value is initialized to 0 when the enhanced security program 1 is started, and the error count register value is incremented by 1 each time an error signal is received from the logon permission unit 15. Until the count value reaches a set value (for example, 3), the operation of the logon permitting means 15 is permitted and the password retry input by the user is permitted.
When the error count value reaches a set value (for example, 3), the unauthorized operation detection means 16 assumes that the user's unauthorized access to the notebook personal computer 3 has been detected, and causes the storage device control means 17 to Operate.

  The storage device control means 17 operates when the unauthorized operation detection means 16 detects the unauthorized access of the user to the notebook personal computer 3 and uses the security lock password (A ′) stored in the hard disk drive 4 in an encrypted state. Decrypt and instantly rewrite the security lock password (A) stored in the hard disk drive 4 to the security lock password (A ′).

The forced termination control means 18 is activated when the operation of the storage device control means 17 is completed and the rewrite of the security lock password is completed, and shuts down the notebook computer 3.
Since the purpose of shutting down the notebook personal computer 3 is to end the processing on the operating system and start the booting process from the BIOS again, the shutdown in this case is a concept including rebooting.

FIG. 6 is a flowchart showing the processing operation of the CPU 5 that is driven and controlled according to the security enhancement program 1.
Next, referring to FIG. 6, the processing operation of the CPU 5 functioning as the dialog control means 14, the logon permission means 15, the unauthorized operation detection means 16, the storage device control means 17, and the forced termination control means 18 in the authentication means 13 will be described. To do.

  When the security enhancement program 1 is started following the startup of the operating system, first, the CPU 5 functioning as the dialog control unit 14 of the authentication unit 13 prompts the user to input a user authentication password required for logon. Is displayed on the monitor 10 (step S01). This is the same as the conventional logon desktop.

  When the user inputs a password for logging on from the keyboard 10 in response to this message, the CPU 5 functioning as the dialog control means 14 temporarily stores the password in the RAM 7 (step S02).

  Since the CPU 5 functioning as the logon permitting means 15 can freely access the RAM 7, in effect, the process of step S02 has completed the transfer of the password from the dialog control means 14 to the logon permitting means 15.

  Next, when the CPU 5 functioning as the logon permission means 15 uses the user authentication password stored in the notebook personal computer 3, that is, the security lock password (A) as the user authentication password, the security lock password (A ), And when a password different from the security lock password (A) is used as the password for user authentication, the password (B) is entered by the user through the password passed from the dialog control means 14, that is, the logon operation. Compare with the password (step S03).

  If the two match, the processing operation of the CPU 5 in accordance with the security enhancement program 1 is completed, and the user logon, that is, the execution of various processing operations using the operating system is permitted (step S06). ). Conceptually speaking, the CPU 5 functioning as the logon permission means 15 outputs a logon permission signal to the operating system and permits the user to log on, that is, to execute various processing operations using the operating system.

  As described above, in the case where the password for logging on is appropriately input by the user and the processes in step S01, step S02, and step S03 are performed without any trouble, the authentication unit 13 in the present embodiment also uses the conventional logon desktop. Will perform the same function.

  On the other hand, when the mismatch of the user authentication password is confirmed in step S03, the CPU 5 functioning as the unauthorized operation detection means 16 increments the error count register value of the initial value 0 by 1, and this error count value is set. It is determined whether or not a value (for example, 3) has been reached (step S04).

If the error count value does not reach the set value (for example, 3), the CPU 5 permits the execution of processing relating to the password retry input (step S02), and stores the password newly input by the user and the notebook personal computer 3. The comparison process with the user authentication password that has been performed is repeatedly executed (step S03), and if the password mismatch is confirmed again, the value of the error count register is incremented by 1 again, and this error count value is set to the set value. It is determined whether or not (for example, 3) has been reached (step S04).
That is, until the error count value reaches a set value (for example, 3), the operation of the logon permitting means 15 is permitted, and the password retry input by the user is permitted.

  In this manner, when the retry process of step S02 to step S04 is repeated, and in the determination process of step S03, if the match between the password input by the user and the user authentication password is confirmed, the logon permission unit The CPU 5 functioning as 15 assumes that the previous password input is simply due to an erroneous operation of a user having an appropriate access right, and that the user himself has an appropriate access right. Thus, user logon, that is, execution of various processing operations using the operating system is permitted (step S06).

  On the other hand, if it is confirmed that the value of the error count register exceeds the set value (for example, 3) in the determination process of step S04 while the retry process of steps S02 to S04 is repeated, an unauthorized operation is detected. The CPU 5 functioning as the means 16 permits the operation of the storage device control means 17 on the assumption that a user who does not have the use authority for the notebook personal computer 3 is attempting unauthorized access.

Next, the CPU 5 functioning as the storage device control means 17 decrypts the security lock password (A ′) stored in the hard disk drive 4 in an encrypted state, issues a Security Set Password command to the hard disk drive 4, and hard disk drive 4 is immediately rewritten with another security lock password (A ′) (step S05).
As mentioned above, the security lock password (A ')
This is a sufficiently long irregular character string of 32 bytes or less set by applying the maximum mode in Attachment-6, and this security lock password (A ′) is poured into the hard disk drive 4 in the maximum mode.

In this way, the security lock password on the hard disk drive 4 side is changed from the security lock password (A) that can be handled on the BIOS defined in the high mode in AT Attachment-6 to the AT.
When the security lock password (A ′) that cannot be handled on the BIOS specified in the maximum mode in Attachment-6 is rewritten, the CPU 5 functioning as the forced termination control means 18 issues a shutdown command to the operation system. Then, the power supply of the notebook personal computer 3 is shut down (step S07).

  Normally, the shutdown operation is performed in the process of step S07 only when an inappropriate user who does not have the authority to use the notebook computer 3 performs an unauthorized logon operation. It is reasonable to think that an attempt will be made to restart and read data from the hard disk drive 4.

  When the notebook personal computer 3 is restarted under such circumstances, the drive control of the CPU 5 is first started in accordance with the BIOS of the nonvolatile RAM 8 as described above.

  Then, the CPU 5 controlled according to the BIOS compares the security lock password (A ′) written in the hard disk drive 4 with the security lock password (A) unique to the notebook computer 3 stored in the nonvolatile RAM 8. As shown in FIG. 5, the two are inconsistent, and the CPU 5 controlled according to the BIOS displays a message prompting the monitor 10 to input the security lock password. This is a general function of the BIOS.

  At this point, it is possible to input a certain security lock password from the keyboard 9, but as described above, what can be handled at the BIOS level is limited to the range of passwords defined in the high mode in AT Attachment-6. Since the security lock password (A ') set in the maximum mode in AT Attachment-6 cannot be handled, the password entered by the user at the BIOS level is the security lock password no matter what password is entered. It does not match (A ′).

  Therefore, the BIOS does not start a program group required for reading information from the hard disk drive 4, and a so-called hard disk lock state in which reading and writing of information to and from the hard disk drive 4 is prohibited is maintained. Only a startup operation and a password re-input operation are allowed. As long as reading of information from the hard disk drive 4 is prohibited, it is naturally impossible to start up an operating system stored as a program in the hard disk drive 4.

Even if an unauthorized user performs password analysis in a brute force format using software that can issue AT Attachment-6 commands freely, a hard disk drive tester, etc., AT
In the Attachment-6 specification, if an incorrect input is repeated five times for a password request, all command inputs continue to be ignored until the power is turned on again. If an attempt is made, an unauthorized user is required to repeatedly turn on / off the power every five input operations.
For this reason, it is very difficult to investigate all 30 half-width alphanumeric characters (case sensitive), and password analysis is virtually impossible.

Therefore, it is possible to cope with the brute force type password attack that has been a problem until now, and after erasing data by turning off the power while erasing data, the hard disk drive Unauthorized operations such as reading encrypted data from 4 and analyzing the encryption can also be prevented with a high probability.
In addition, since the operation for locking the hard disk drive 4, that is, the rewriting and shutdown operation of the security lock password of the hard disk drive 4 is completed almost instantaneously, the operation of the security tool (the security enhancement program for rewriting the security lock password) The lock can be completed without the attacker noticing (operation 1).
In the case of a security system that requires processing time for self-destruction processing, such as hard disk drive initialization or dummy data writing, this process is likely to be detected by an attacker and blocked. The security tool of the embodiment (security enhancement program 1) is almost free from such concerns.

  On the other hand, even if a legitimate user inputs an incorrect password and locks the hard disk drive 4, the data itself in the hard disk drive 4 is not erased, so the security lock password (A ') is set. If the hard disk drive 4 is unlocked by the manufacturer's unlocking machine, the original use environment can be restored, which is effective for data preservation.

  Further, since the security lock password (A ′) for locking the hard disk drive 4 is encrypted and embedded without being known by the user, it cannot be easily found and read, and the administrator can always read the contents. Since it can be changed, the security level can be maintained.

  As described above, the embodiment using a hard disk drive as the storage device has been described. However, the storage device may have any configuration as long as it can store the security lock password together with the original data and program.

  The activation timing of the authentication means 13 (security enhancement program 1) will be described when the operating system starts up or when the main part of the operating system is read into the RAM 7 and the program 1 can be executed. However, when logging on again with the operation system running (when the workstation operator changes), or when rewriting data or programs that require high access rights, the authentication means 13 (security It can be easily implemented from the above description that the strengthening program 1) is activated.

It is the functional block diagram shown about the outline of the structure of the notebook personal computer of one Embodiment to which this invention is applied. It is the functional block diagram shown about the outline | summary of the structure of the authentication means achieved by using the security enhancement program stored in the hard disk drive of a notebook personal computer, and CPU of a notebook personal computer as a function implementation means. It is the conceptual diagram shown about the setup operation of a security lock password. It is the conceptual diagram which showed the memory | storage state of the password in the condition where the hard disk drive is used appropriately. It is the conceptual diagram which showed the state where starting of an operating system was prohibited by rewriting of a security lock password. It is the flowchart shown about the outline of the processing operation of the microprocessor drive-controlled according to a security enhancement program.

Explanation of symbols

1 Security enhancement program 2 Data storage medium 3 Notebook computer (computer)
4 Hard disk drive (storage device)
5 Microprocessor 6 ROM
7 RAM
8 Non-volatile RAM (storage means unique to the computer)
9 Keyboard 10 Monitor 11 Interface 12 Motherboard 13 Authentication means 14 Dialog control means 15 Logon permission means 16 Unauthorized operation detection means 17 Storage device control means 18 Forced termination control means A, A 'Security lock password

Claims (7)

The security lock password written in the storage device and the security lock password written in the storage means storing the low-level program for device control are compared with the low-level program for device control. The computer allows the information to be read from the storage device and starts the computer operating system. In a computer with an information leakage prevention function that is compared by an authentication means operating on the operating system and that allows the user to log on only when both match.
In the authentication means,
Unauthorized operation detection means for detecting unauthorized access of the user to the computer based on the operation status of the computer during a logon operation;
A storage device that operates when the unauthorized operation detection means detects unauthorized access, and rewrites the security lock password of the storage device with another security lock password set at a level higher than that handled by the low-level program for device control Control means;
A computer with an information leakage prevention function, comprising: a forced termination control means for shutting down the computer after the operation of the storage device control means is completed.   2. The computer with an information leakage prevention function according to claim 1, wherein the unauthorized operation detection means detects unauthorized access when the number of erroneous input of a password by a user reaches a set value.   3. The computer with an information leakage prevention function according to claim 1, wherein the storage device control means encrypts and holds the another security lock password. The low-level program for device control is AT
The security lock password set in the high mode in Attachment-6 is handled, and the storage device control means is configured to handle the security lock password set in the maximum mode in AT Attachment-6. A computer with an information leakage prevention function according to claim 2 or claim 3. The security lock password written in the storage device and the security lock password written in the storage means storing the low-level program for device control are compared with the low-level program for device control. A security enhancement program that operates on a computer operating system that allows the reading of information from the storage device and starts the computer operating system,
A microprocessor of the computer;
A logon permission means for comparing the password for user authentication stored in the computer and the password input by the user to the computer during the logon operation, and allowing the user to log on only when they match.
Unauthorized operation detection means for detecting unauthorized access of the user to the computer based on the operation status of the computer at the time of logon operation;
A storage device that operates when the unauthorized operation detection means detects unauthorized access, and rewrites the security lock password of the storage device with another security lock password set at a level higher than that handled by the low-level program for device control Control means, and
A security enhancement program that functions as forced termination control means for shutting down the computer after the operation of the storage device control means is completed.   6. The security enhancement program according to claim 5, wherein the microprocessor of the computer is caused to function as the unauthorized operation detection means for detecting unauthorized access when the number of erroneous input of a password by a user reaches a set value.   7. The security enhancement program according to claim 5, wherein the another security lock password is encoded and coded.

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