JPH03105419A - Fixed disk device - Google Patents

Abstract

PURPOSE:To prevent illicit reading and writing of data by a third person by setting a program which a host device executes to a processor and providing a means which invalidate a data outputted from the host device by the command of the processor. CONSTITUTION:The host device 1 initializes a security device 3 before it uses a fixed device 2 as a file. When the device 1 executes a processing command, a micro processor 6 resets a register circuit 9, prohibits a data read/write circuit as the file from the device 1 to the device 2 and stores cipher data in the prescribed area of EPROM 13. The processor 6 refers data transferred from the device 1 with data which the circuit 9 decides and a decoding circuit 12 executes decoding and sets the state of an interface control circuit 5 to be receivable for releasing lock. Thus, an illicit reading and writing of data can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fixed disk device, and particularly to a security mechanism for preventing unauthorized reading or writing by an outsider.

[Conventional technology]

Conventionally, as shown in Fig. 4, this type of fixed disk device is connected to a higher-level device such as a magnetic disk control unit through an interface such as an SMD type, and receives unit selection data sent from the higher-level device through the same interface. is detected by the unit selector, and when it detects that it has been specified, it further receives data and signals indicating the operation details and commands sent from the higher-level device, and the interface control circuit controls the internal fixed disk device based on the contents. operate the read/write control circuit and servo control circuit of
The read/write circuit and servo circuit are operated to write data sent from the host device through the data read/write head onto the magnetic disk, or to send data read from the magnetic disk to the host device. The above operations were executed unilaterally according to instructions from the host device. [Problems to be Solved by the Invention] The above-mentioned conventional fixed disk devices are designed to unilaterally write data to or read data from a magnetic disk based on commands from a higher-level device. Any command that does not violate the electrical and information rules of the interface specified between the device and the device will be accepted, and data will be exchanged with the host device according to the instructions, so a malicious program can be created by an outsider. There was a drawback that data was exchanged without distinction even in response to commands from the system. For example, they are widely incorporated into fixed disk drives, engineering workstations, and small computers such as personal computers, and these computers are usually installed in locations that are easily accessible to anyone other than authorized computer users. There was a risk that the data stored on the disk could be accessed without permission, destroyed, or stolen due to unauthorized operations. In addition, since there is a risk that the device itself could be taken away with the data on the disk, as shown in Figure 3, these computers do not have disks built into them, but are diskless, and are not connected via a local area network or communication line. , accesses a disk device built in or connected to a computer with higher security, such as a file server or a large host computer, and transfers the necessary programs and data from the disk device to the RAM of these computers before operating. method, or
If the computer is left unattended, such as at night, when the computer is not in use, copy the contents of the fixed disk to a backup medium such as a cartridge magnetic tape device and store it in a safe place such as a safe. Measures are even taken, such as erasing data. [Means for Solving the Problems] A fixed disk device of the present invention includes a microprocessor, a read-only storage circuit for storing programs executed by the microprocessor, and data handled by the microprocessor, and a RAM. and a means for storing a program to be executed by the microprocessor from an EPROM and a host device into the RAM, a means for writing or reading data from the microprocessor to a magnetic disk, and a means for the microprocessor to exchange data with the host device. deciphering the permission information issued by the microprocessor;
Based on this, the fixed disk device has means for accepting or rejecting a data writing or reading command issued from the host device to the magnetic disk.

〔Example〕

Next, the present invention will be explained with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention. In FIG. 1, the host device 1 initializes the security device I113 of the fixed disk device before using the fixed disk device 2 as a file.

Initialization is performed by sending an initialization command from the host device to the interface control circuit 5 via the signal line of the interface 4, for example, the data path line and tag signal line in the case of an SMD interface, and the interface control circuit decodes the command. An initialization command for the security mechanism is transmitted to the microprocessor 6 via the control signal line 10 and the data bus 11.

A program A is stored in the read-only memory 7 as shown in FIG.
is stored. When the power is turned on to the fixed disk device or when the host device initializes the system, the microprocessor executes program A from address O of the read-only storage device using the clear signal generated thereby.
Make sure that it is executed.

The function of program A is to start the microprocessor, receive program B as data from the host device, and send it to RA.
A function to store program B in a predetermined area of RAM, reset the register circuit, and ignore file write/read commands from the host device to the fixed disk device. Includes a function to jump to B.

The security mechanism is initialized when the fixed disk device is powered on and the microprocessor is started, or when a processing command is executed from the host device, the microprocessor 6 resets the register circuit. , prohibits data writing/reading as a file from the host device to the fixed disk device, then requests transfer of program B to the host device, and stores it in a predetermined area of RAM. Furthermore, the security calculation constant al l b2+C3
＋・・・・・・ is requested to the higher-level device and EPROM1 is transferred.
Store it in the designated area of 3. Furthermore, data indicating completion of initialization of the initial status display area of the RAM is stored. This completes the initialization of the security mechanism and jumps to program B. The function of program B is to jump in from program A and wait until the unlock command is executed from the host device. A function that detects an unlock command, requests the transfer of encrypted data to a host device, and stores the encrypted data in a predetermined area of RAM or a register for calculation of a microprocessor. Furthermore, in this embodiment, the program jumps to the program F transferred from the host device as encrypted data, reads the aforementioned constants al l b2 1... from the EPROM, and
- = f (al, a3, a3, ...
...Function to perform calculations on i. Furthermore, compare X- with the constant X transferred from the higher-level device,
Includes a function that releases the security lock of the fixed disk device if x"=x, and does not release the security lock if X-=X. The security mechanism initialization is completed, the program jumps to program B, and the command to release the lock is executed from the host device. When the fixed disk device is in a state where it is in a security lock state and the data as a file device from the host device is In order to release this lock and enable data writing/reading as a normal file device, the host device must execute the following security lock release command: The lock is unlocked as shown below. When program B detects the unlock command, it requests the transfer of encrypted data to the host device and stores it in a predetermined area of RAM or a calculation register of the microprocessor. In the embodiment, a program F and a constant X are used as an example of encrypted data, and the program F is stored in RAM and the constant
is temporarily stored in the microprocessor's arithmetic register. Once the above is completed, the microprocessor will run program B.
Jump to program F and set the constant a1 r
b2 + a3 r """ is read from the EPROM and X − = f (at r &z + as r ”
...Perform the operation of l. Furthermore, this X' is compared with X of the encrypted data transferred from the host device, and if X-=X, the security lock is released, and if X-=X, the lock is not released as a security verification mismatch is excluded. Here, the unlocking operation in the fixed disk device involves the microprocessor setting predetermined data in the register circuit 9, the decoding circuit 12 decoding the data, and the host device fixing the state of the interface control circuit. The objective is to enable a fixed disk device to accept commands for writing/reading data to/from files that are executed on the disk device. Once the security lock is released, this state remains until the lock command is executed again from the higher-level device or the fixed disk device becomes logically unusable as a file device due to power being cut off, etc. It is possible to write and read data from a host device in the same way as a normal fixed disk device. In order to eliminate the need for data writing/reading from the host device to the fixed disk device and to lock the fixed disk device for security, the host device must perform a security check.
When a lock command is issued and the microprocessor of the fixed disk device detects this, it erases the encrypted data (program F) stored in RAM and the constant X stored in the microprocessor's register, and then resets the register circuit. and prevents the interface control circuit from accepting data write/continue output commands from the host device. Also, even if you turn off the power to the fixed disk device instead of issuing the security lock command from the host device, the R
The program F on the AM and the constant X stored in the register of the microprocessor will volatilize and be lost as well, so simply turning on the power again will not restore the unlocked state. [Effects of the Invention] As explained above, the present invention provides a microprocessor, a program executed by the processor, a read-only storage circuit for storing data handled, a RAM, and an EF.
By having means for the ROM and the processor to exchange data with the host device, and means for invalidating the write or read commands of data issued from the host device based on commands from the processor, The fixed disk device itself has a security function, which has the effect of preventing unauthorized data writing/reading by third parties. Fixed disk devices are widely used and built into small computers such as EWS and personal computers, but these computers are usually installed in locations that are easily accessible to third parties and cannot be easily accessed by unauthorized users. There is a risk that stored data may be accessed without permission, destroyed, or stolen. Furthermore, since many of these computers and fixed disk devices are small and lightweight, there is a risk that the fixed disk itself, along with the data written therein, may be taken away and deciphered in some cases.

If the security mechanism of the present invention is used, even if the entire device is taken away, it will be difficult to write/continue writing to the disk unless the encrypted data is known.
Internal register circuit 9, decode circuit 12, microprocessor 6, interface control circuit 5, RAM 8,
If the read-only memory 7 is composed of an integrated LSI or the like, even if you try to disassemble the circuit and partially operate it to unlock it, the operation will be performed by a minute and volatile program. This method is almost impossible. Here, changes such as increasing the number of encrypted data for security check, making the calculations of program F more complicated, increasing the degree of security guarantee, or simplifying and making handling easier are also possible. This method is convenient because it can be easily performed by computer users because the system and programs are supplied from the host device. As a result of the above, the security of fixed disk devices built into or connected to small computers installed in locations easily accessible to third parties, such as personal computers, engineering workstations, and off-site computers, is guaranteed by fixed disk measures. , the handling has become extremely easy, and troublesome security assurance work that is not normally performed, such as copying the contents to a removable medium such as a magnetic tape or floppy disk at night and storing it in a safe, or installing it in a security guaranteed area. This eliminates the need to transfer files to the magnetic disk drive of the file server you are currently using, then erase the contents of your own computer's fixed disk drive, and then do the reverse when you start up your computer the next morning, for example. These tasks require a lot of time to transfer files via file coveys, LANs, etc., so conventionally, for example, these tasks were required before and after computer processing tasks, and certain operators were asked to do so before the start of work. There were labor problems, such as coming to work early to perform this work, and having to work overtime after the end of the work day. There was also a decline in service, such as a reduction in computer service time. According to the present invention, these problems can be solved at the same time.
It brings great benefits not only in terms of security but also in terms of operation. In addition, engineering workstations (EWS) used for CAD such as LTI design handle a large amount of data, so each EWSl is equipped with a fixed disk device with a capacity of several hundred bytes to IG bytes. If you copy and store the contents on a cartridge magnetic tape device with a capacity of 100 MB per volume, you will have to write on several to 10 cartridge tapes, and even if you write each volume in 30 minutes, it will be between numbers and numbers. This is not practical because it is time consuming and requires manual labor to change the tape. This is especially true when using a floppy disk device with a small capacity (approximately 1MB capacity). Furthermore, even if files are transferred from the EWS to a file server via a communication means such as Ethernet, the data transfer speed of Ethernet is at most IM bytes/second, and in reality it is several hundred bytes/second depending on the service speed of the communication support software. Since the speed decreases to about seconds, it takes a lot of time to send and receive large amounts of data files to and from the refile server.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the internal functions of the fixed disk device of the present invention, Figures 2 and 3 are memory allocation diagrams showing the storage locations of programs and data used by the processor next to the security machine, and Figure 4 is a conventional FIG. 2 is a block diagram showing the internal functions of a fixed disk device.

Claims (1)

[Claims] A microprocessor, a read-only memory circuit, RAM, and EPROM that store programs that execute the processor and data to be handled, and a
means for storing a program executed by the processor in M; writing data from the processor to a magnetic disk;
or means for reading data, means for the processor to exchange data with a host device, and means for invalidating a command to write or read data from the host device based on a command from the processor. A fixed disk device comprising: