JPH0326125A - Remote control system - Google Patents

Abstract

PURPOSE:To prevent the setting of a ciphered key from a device except for a specified center device by re-calling the ciphered key from a remote controller side to the center device and delivering and setting the key. CONSTITUTION:At the time of delivering and resetting the ciphered key by a request from the center side, a center device 1 executes a call to a remote controller 3 through a public telephone network 2. By a response from the remote controller 3, the center device 1 transmits a ciphered key setting request command. When the remote controller 3 accepts the command, a line is disconnected once, thereafter, the re-call is executed from the remote controller 3 to the center device 1, and the ciphered key setting request command is transmitted to the center device 1. The center device 1 sets the ciphered key in response to the command. Thereafter, by using the value of the encoded key set in such a way, the center device 1 releases the guard of the remote controller 3 by transmission and reception of the encoded command with the remote controller 3, and an ordinary command control is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a remote control method for controlling remotely via a public line.

[Conventional technology]

Conventionally, in this type of remote control system, malicious calls have been prevented by using a password input method in which the center side enters a password at the time of access, or a callback method in which the remote control device side calls back in response to a call originating from the center side. This was done using the back method. [Problems to be Solved by the Invention] The conventional password input method described above has the disadvantage that the password can be broken after a finite number of accesses, although it depends on the length of the password. When a password is broken, it is necessary to change it, but if this can be easily changed remotely, there is a risk that the password could be changed by a malicious call. In addition, the callback method accepts control only from a designated center device, and calls are made again even when emergency control is required, so it has the disadvantage of taking too long to control. be. In a remote control method that performs control from a remote location, means for delivering and setting an encryption key value to the remote device by re-calling the center device from the remote control device in response to a request from the center device; means for performing encrypted communication using the value of the encryption key delivered by the means to release the guard of the remote control device and perform command control from the center device; and means for automatically calling the center device from the remote control device to request resetting of the encryption key value when a command error occurs during encryption communication. [Example] Next, the present invention will be explained with reference to the drawings. FIG. 1 shows an embodiment of the remote control method of the present invention.
2 is a communication sequence diagram when the encryption key distribution setting is performed in FIG. 1, and FIG. 3 is an operation sequence diagram of the remote control device when a malicious call in FIG. 1 occurs.

When distributing and resetting an encryption key in response to a request from the center, the center equipment engineer first calls the remote control device 3 via the public telephone network 2, as shown in FIG. In response to the response from the remote control device 3, the center device 1 transmits an encryption key setting request command.

When the remote control device 3 receives this command, it once disconnects the line, then calls the center device l again, and sends an encryption key setting request command to the center device l. The center device 1 sets an encryption key in response to this command.

Thereafter, using the encryption key value set in this way, the center device 1 exchanges encrypted commands with the remote control device 3 to release the guard of the remote control device 3 and return to normal operation. Performs command control.

Next, control when a malicious call for the purpose of password breaking or the like occurs will be explained with reference to FIG.

If a malicious call arrives at the remote control device 3 and an incorrect encryption command is received to find the encryption key, the remote control device 3 will detect a command error, but The communication is disconnected when a specified number of command errors occur. When such communication reaches a predetermined number of times, the remote control device 3 automatically calls the center device 1 to request resetting of the encryption key. In response, the center device l resets the encryption key at the discretion of the maintenance operator. [Effects of the Invention] As explained above, the present invention transmits and sets the encryption key by re-calling the center device from the remote control device side, thereby preventing the encryption key from being transmitted from other than the designated center device. This has the effect of preventing settings. Furthermore, ordinary control commands other than setting the encryption key are performed through encrypted communication using the encryption key, which has the effect of maintaining the security of the device. Furthermore, even in communications for malicious calls to break encryption, if a predetermined number of incorrect encryption commands are received, the remote control device automatically reports this to the center device and resets the encryption key. This has the effect of further increasing security.

[Brief explanation of drawings]

FIG. 1 is a system book diagram showing an embodiment of the remote control method of the present invention, FIG. 2 is a communication sequence diagram when the encryption key distribution setting is performed in FIG. 1, and FIG. FIG. 6 is an operation sequence diagram of the remote control device when a malicious call in the figure occurs. 1... Center device, 2... Public telephone network, 3... Remote control device.

Claims (1)

[Claims] In a remote control method that performs control remotely via a public line, the remote control device re-calls the center device in response to a request from the center device, thereby transmitting the encryption key value and setting it to the remote device. means for performing encrypted communication using the value of the encryption key delivered by the means to release the guard of the remote control device and perform command control from the center device; and means for automatically calling the center device from the remote control device to request resetting of the encryption key value when a command error occurs during continuous encrypted communication. method.