JPH0248752A - Storage device with security protecting function - Google Patents

Abstract

PURPOSE:To reduce overhead on a CPU, and to let a storage device have a security protecting function by stopping a refresh operation by the instruction of the CPU. CONSTITUTION:When the use of the storage part is finished, after the CPU 1 issues a storage erase instruction to an expanded storage device 10, it executes the succeeding CPU instruction immediately, and an operating system carries on other processing without waiting for the completion of the storage erase instruction. On the other hand, when the expanded storage device 10 receives the storage erase instruction from the CPU 1, a flip flop 8 stops the refresh operation of a refresh control part 5. Therefore, the contents of the storage part 3 is broken, and besides, a storage control part 4 stops the control of a read operation and a write operation. Thus, the security protecting function can be obtained without increasing the overhead on the CPU.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a storage device that can prevent unauthorized access and provide security.

[Conventional technology]

In recent years, with the development of computer usage technology, the information stored in Miko computers has come to include a large amount of highly important information that requires confidentiality protection. on the other hand,
In order to use computers efficiently, it is common for many users to use one computer at the same time, and a security protection function prevents unauthorized access to individual user information from an unspecified number of users. is an important technology.

Therefore, various functions are provided for the purpose of security protection and are used in various situations, and one of them is a function to erase the storage area that the user has finished using.

Traditionally, this feature indicates that the user has finished using it! &!
! This was accomplished by the operating system that identified this issue executing a large number of CPU instructions to erase the contents of the user area.

[Problem to be solved by the invention]

The security function of the conventional storage device described above is
It is necessary to execute the U instruction, which increases overhead. In particular, as storage capacity continues to increase, the problem of overhead becomes more and more serious.

[Means to solve the problem]

A storage device having a security function according to this invention is a CPU.
It has a refresh operation stop means for stopping the refresh operation in response to a command from.

[Effect]

By having the refresh operation stop means, the present invention can reduce the overhead on the CPU.

〔Example〕

The figure is a block diagram showing a clear information processing device equipped with an embodiment of a storage device having a security protection function according to the present invention.

In the figure, 1 is a CPU, 2 is an MMU, 3 is a storage section that stores information from an unspecified number of users, 4 is a storage control section that controls the storage operation of this storage section 3, and 5 is a storage section of the storage section 3. 6 is an AND gate, T is a refresh timing generator that outputs a refresh signal, and 8 is an extended storage device shown below, which is set to the logic "0" state in the normal operating state, and the storage 9 is a two-socket flop that is set to the logic "1" state during the erase operation state; 9 is a timer/carrier that outputs a timer signal after the refresh time interval required by the memory element used in the memory section 3 has sufficiently elapsed; 10 is the storage section 3.storage control section 4. Refresh control unit 5. This is an extended storage device composed of an AND gate 6, a refresher tie blow generator 7, 7, a flip-flop 8, and a timer counter 9.

Next, the operation of the storage device having the security function with the above configuration will be explained. First, the operating system executed on the CPU checks whether the extended storage device 10 can be used in response to a request from a user program, and if it can be used, transfers control to the user program. This user program performs processing using the extended storage device 10, but at this time, the flip-flop 8 is in the logic rOJ state, indicating that it is not in the memory erasing state. The output signal of logic "0" from the 7-lip flop 8 is input to the timer counter 9, so the timer counter 9 is in an inactive state. On the other hand, the inverted output signal of the clip 70 tube 8 is input to the storage control section 4 and the other input terminal of the AND gate 6. Therefore, AND gate 6 opens,
The refresh signal output from the refresh timing generator T passes through the AND gate 6 and is input to the refresh controller 5. Therefore, the refresh control unit 5 performs a normal refresh operation. (9) The storage control section 4 performs various control operations by inputting the inverted output signal of the flip-flop 8, and can perform normal read and write operations.

When the normal read and write operations of the storage unit 30 are completed, the operating system is notified of this fact.

Next, when the operating system is notified that the use of the storage unit has ended or when it recognizes that the execution of the user program has ended, it executes a memory erase command, which is one of the CPU commands. Therefore, after the CPU 1 issues a memory erase command to the extended storage device 10, the CPU 1 immediately erases the memory from the subsequent CPU.
Since the U instruction is executed, the operating system can continue other processing while waiting for the memory erase instruction to complete. - When the extended storage device 10 receives a memory erasing command from the CPU 1, the flip-flop 8 is not in the logic "1" state and indicates that the memory erasing operation is in progress. The inverted output signal of the flip 70 tube 8 is input to the storage control section 4 and the other input terminal of the AND gate 6. In preparation for this, the AND gate 6 is closed, and the refresh signal output from the refresh timing generating section T is transmitted to the refresh control section 5, thereby stopping the 5-line refresh operation of the refresh control section.

Therefore, the contents of the storage section 3 are destroyed. Further, the storage control section 4 stops controlling the read operation and the write operation upon input of the inverted output signal of the 7-lip flop 8. Also, the timer counter 9 is set to the logic “1” of the flip-flop 8.
” operation is started by inputting the output signal, and after a sufficient refresh time interval required by the memory element used in the memory unit 3 has elapsed, a reset signal to the flip-flop 8 is outputted. When the reset signal of the timer counter 9 is input, a returns to the logic "0" state. Therefore, the extended storage device 10 returns to its normal operating state.

〔Effect of the invention〕

As explained in detail above, according to the storage device having the security function according to the present invention, the refresh operation stops during the memory erasing operation state, and after a certain period of time, the contents of the storage section are destroyed and the subsequent Since it is possible to prevent the previous memory contents from being read by the user program, the CP
This has the effect of realizing a security function without increasing the overhead on U.

[Brief explanation of the drawing]

The figure is a block diagram showing the configuration of a clear information processing device including an embodiment of a storage device having a confidential image @ function according to the present invention. 1...CPU, 2...MMU, 3@...Storage section, 4...Storage control section, 5...Refresh control section, 6. Company-AND gate, T- ---Refresh timing generator, 8...7 lips, 70 lips, 9
...-timer counter. L-1111111

Claims (1)

[Claims] What is claimed is: 1. A storage device that uses a memory element that requires refresh processing and has a security protection function, characterized in that the storage device includes a refresh operation stop means that stops the refresh operation in response to a command from a central processing unit.