JPH0895866A - Memory device with duplication/deciphering preventing function - Google Patents

Abstract

PURPOSE: To provide a memory device which holds its storage contents without electric power supply from the outside until the use frequencies exceed a use limit frequency, securely erases them when exceeding the use limit frequency, and can prevent illegal duplication and deciphering. CONSTITUTION: This device is equipped with a use frequency management device 3 which inputs an external power source ON/OFF signal from an external equipment and erases information stored in an EEPROM 1 or RAM through erasure controllers 4 and 5 or a storage holding controller when the frequency of ON/OFF operation reaches a specified limit frequency and a readout control part 2 which inputs a readout address indication from the external equipment to the EEPROM 1 or RAM and erases the information stored in the EEPROM 1 or RAM through the erasure controllers 4 and 5 or storage holding controller when a trap code is read out in response to the indication. By this constitution, ciphered software and a ciphered key stored in the EEPROM 1 or RAM are prevented from illegally being used when the external equipment is a ciphered communication device, and software for trail use is prevented from being copied or deciphered by a provided person when the software is for trial use.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a memory device for holding an encrypted program and an encrypted key for an encrypted mobile / portable communication device (police radio etc.), and a memory for providing a sample software for a computer. The present invention relates to a memory device with copy / decryption prevention function applied to a device.

[0002]

2. Description of the Related Art A conventional memory device provided with a volatile memory that does not have an internal power supply for holding a memory loses its contents when the power supply from the outside is stopped. No software could be included and no limit on the number of times it could be used.

A memory device provided with a volatile memory or an involatile memory having an internal power source for storing data can be preloaded with software, but with a limited number of uses. No information security function was added.

Further, a memory device (Japanese Patent Laid-Open No. 28049/1993) of a system that analyzes an access system to a memory and detects an illegal read for copying / decoding analyzes a program operation and changes a read address. In order to monitor complicated operations and to request complicated processing, a central processing unit (hereinafter referred to as CPU) and an analysis program are required inside the apparatus.

[0005]

The memory device for storing the program / encryption key of the conventional encrypted communication device and providing the free sample software for the computer has the following problems.

(1) In application to an encrypted communication device, a common encryption program and an encryption key are put in a memory device and distributed to users of the communication device. When applied to a computer, the sample software of the computer is put in the memory device and distributed.

In this case, until the memory device is used and the number of times of use is exceeded, the stored contents must be surely held without external power supply. In the case of a memory device provided with a volatile memory that does not have an internal power source, it is impossible to put software in advance and it is impossible to limit the number of times of use.

(2) When the encrypted communication device is lost or stolen, if the power of the communication device (external device) is cut off or the battery of the external device is exhausted, it is not possible to use it to intercept communication. It is necessary to erase the stored contents (use limit number of times: 1).

Further, in the case of providing the sample software, it is necessary to surely erase the stored contents when the number of times of use is exceeded, but as described above, the volatile memory having the internal power source for holding the storage is provided. Or, no memory device provided with a non-volatile memory has a limited number of uses.

(3) In order to copy the contents of the memory device, in order to detect the contents by connecting to a special reading device and read the contents at random, in order to protect the information. Although it is necessary to erase the stored contents, complicated processing is required as described above, which requires a CPU and an analysis program inside. The present invention is intended to solve the above problems.

[0011]

[Means for Solving the Problems]

(1) The memory device with copy / decryption prevention function of the present invention is
An external power supply is turned on from an external device with a specified number of times set in advance
/ OFF signal is input and an erase command is output when the external power ON / OFF count reaches a specified limit number, and an erase control device having a power source that inputs an erase command from the management device and outputs an erase signal , An electrically erasable read-only memory (hereinafter referred to as EEPRO) in which an erase signal is input from the control device to erase stored information and a trap code is stored.
M)) and a read control unit for inputting a read address instruction from the external device and outputting the read address instruction to the memory and outputting an erase command to the erasing device when the information read from the memory is a trap code. Is characterized by.

(2) The present invention uses a random access memory (hereinafter referred to as RAM) in place of the electrically erasable read-only memory in the memory device with copy / decryption prevention function according to the above-mentioned invention (1). In addition, a storage holding control device is used instead of the erasing control device.

[0013]

In the above invention (1), the number-of-uses management device is preset with a specified limit number of ON / OFF of the external power source, and the external power source ON / OFF input from the external device is set.
When the signal reaches the specified limit number of times, the use count management device inputs an erase command to the erase control device, and the erase control device inputs an erase signal to the EEPROM to erase the information stored in the EEPROM.

Therefore, the external device is an encrypted communication device,
When the EEPROM stores the encryption software and the encryption key, if the memory device of the present invention is removed from the encryption communication device for unauthorized use, the EEP
The memory of the ROM is erased, and unauthorized use becomes impossible.

Further, when the external device is a computer and the memory device of the present invention is used to provide the sample software, the EEPROM memory is erased after the use for a predetermined number of times is completed, and the duplication or decoding of the software is prevented. It

If the memory device of the present invention is unused, or the number of times of use is equal to or less than the specified limit number, and the read address is instructed by an external device for the purpose of duplication, the read address is not instructed. Since it is done intentionally, the read control unit may read the trap code. In this case,
The read control unit outputs an erase command to the erase control unit, and the erase control device inputs an erase signal to the EEPROM to output the same EEPROM.
Erase the information stored in the OM. Therefore, it is possible to prevent copying and decoding of the sample software.

In the above invention (2), since the RAM is used instead of the EEPROM in the above invention (1), the information stored in the RAM is retained by constantly supplying electric power from the memory retention controller, Only the information is lost by cutting off this power,
Other functions are the same as in the above invention (1).

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A memory device with copy / decryption prevention function according to a first embodiment of the present invention will be described with reference to FIG.

In FIG. 1, reference numeral 1 denotes an electrically erasable read-only memory EEPROM for holding information to be stored, and a value which is not used as a program / data by using a validity bit in an empty area which is not normally used. (Trap code) is included.

Reference numeral 6 denotes an external device interface connected to an external device, which monitors an ON / OFF event of an external power source, receives a read address instruction from the external device, and sends read information to the external device.

Reference numeral 2 denotes a read control unit which transmits a read address instruction from the external device interface 6 to the EEPROM 1 and inspects the read information, and in the case where an address is randomly designated for illegal duplication or decoding. EEPROM 1
The trap code output from is monitored by the comparison circuit, and if found, an erase command is output.

Reference numeral 3 denotes a usage frequency management device which receives a power ON / OFF notification from an external device interface 6,
The number of times the power is turned on is defined as the number of times of use, and the specified limit number of times is held in advance. When the number of times of use reaches the specified limit number of times, an erase command is output.

Reference numeral 4 denotes an erasing control device for inputting an erasing command from the read control unit 2 and the usage count management device 3 to erase the information stored in the EEPROM 1. 5 is a device for managing the number of times of use 3, which needs to be operated with the external power supply turned off
And an erasing power supply for supplying power to the erasing control device 4.

Next, the operations of the memory device according to this embodiment when the number of times of use limit and the unauthorized access prevention are activated will be described below. First, when the number of times of use limit operates, the number of times of use limit of this memory device is 1
The case where the present memory device is applied only to the encrypted communication device only once will be described.

When the memory device is removed from the encrypted communication device for the purpose of unauthorized use, or when the normal use is finished and the power is turned off, the external interface 6 senses it and notifies the number-of-uses management device 3. To do.

The number-of-uses management device 3 receiving this notification judges that the use is completed and outputs an erasing command, and the erasing control device 4 which inputs this command stores the encryption software and the encryption key stored in the EEPROM 1. Is erased. Therefore, the communication is not intercepted.

Next, a description will be given of a case in which the number of times of use limit is activated and the number of times of use limit of the present memory device is n, which is applied to the provision of sample software. The external interface 6 detects the number of times the power is turned on or the number of times the memory device is attached, and notifies the number-of-uses management device 3 of this.

The number-of-uses management device 3 that has received this notification accumulates the number of times, judges that the number of times of use by contract has been completed when the number of times of use limit n is exceeded, and outputs an erasing command. EEPRO by the erase control device 4 that has been input
The sample software stored in M1 is deleted. Therefore, this free sample software cannot be copied / decrypted.

Finally, the operation when the unauthorized access prevention operates will be described. When a memory device that has not been used or has been used a number of times is obtained and connected to an external device, the read control unit 2 that has received a read address instruction from the external device interface 6 completes copying / decoding of the EEPROM 1. Since the read operation is performed sequentially or at random in the area, the read controller 2 is not normally used.
The trap code stored in the trap area of ROM1 is read out.

When the trap code is read from the EEPROM 1 and the read control unit 2 senses it, the erase control device 4
Causes the contents stored in the EEPROM 1 to be erased. for that reason,
Even if you try to use it illegally, you will only get fragmented information. The EEPROM 1 has a storage capacity
The less information you have to store, the more likely you are to read the trap code.

A memory device according to the second embodiment of the present invention will be described with reference to FIG. The apparatus of this embodiment shown in FIG. 2 uses a volatile RAM 11 instead of the EEPROM 1 of the apparatus of the first embodiment. Therefore, the first point is that the power of the memory holding power supply 15 is always supplied to the RAM 11 from the memory holding control device 14 for holding the memory.
Unlike the embodiment, in this embodiment, the memory is not erased but lost when the holding power supply 15 is cut off. The operation of each function other than that is the same as that of the first embodiment.

[0032]

According to the memory device with copy / decryption prevention function of the present invention, when an external power ON / OFF signal is input from an external device and the number of ON / OFF times reaches a specified limit number, the erase control device or the storage retention control device is activated. Via EEPROM or R
A number-of-uses management device for erasing the information stored in the AM, and a read address instruction from an external device in an EEPROM or R
When it is input to AM and the trap code is read from it, the EEPROM or RA is sent through the erase controller or the memory retention controller.
By providing the read control unit for erasing the information stored in M, EEPRO when the external device is an encrypted communication device
It is possible to prevent unauthorized use of the encryption software and the encryption key stored in M or RAM, and to prevent the recipient from copying or decrypting the sample software when the sample software is provided.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a memory device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a memory device according to a second embodiment of the present invention.

[Explanation of symbols]

 1 EEPROM 2 Readout control device 3 Number of times management device 4 Erase control device 5 Erase power supply 6 External device interface 11 RAM 14 Memory retention control device 15 Memory retention power supply

Claims (2)

[Claims] 1. An external power source ON / O signal having an external power source ON / OFF signal input from an external device with a preset limit number of times set in advance.
When the number of times of FF reaches the specified limit number of times, a use frequency management device outputs an erase command, an erase command is input from the management device, an erase signal is output, and an erase signal is input from the control device. An electrically erasable read-only memory in which the stored information is erased and the trap code is stored,
And a read control unit for inputting a read address instruction from the external device, outputting the read address instruction to the memory, and outputting an erase command to the erasing device when the information read from the memory is a trap code. / Memory device with decryption prevention function. 2. The memory device with copy / decryption prevention function according to claim 1, wherein a random access memory is used in place of the electrically erasable read-only memory, and a memory retention control device is used in place of the erase control device. A memory device with copy / decryption prevention function characterized by being used.