JPS6367932A - Ciphering device - Google Patents

Abstract

PURPOSE:To provide a ciphering circuit to a terminal requiring non-ciphering procedure by sending non-ciphering data for a fixed period at the time of establishing a communication line. CONSTITUTION:A timer circuit 1 outputs a trigger signal (b) to a terminal 7 after a prescribed period from the input of a communication line establishing signal (a). Consequently, a switch 2 outputs a switch signal (c). A ciphering circuit 3 ciphers a transmission signal outputted from a terminal 9 and outputs the ciphered signal to a terminal 10 and deciphers a receiving signal obtained from a terminal 11 simultaneously with said ciphering and outputs the deciphered signal to a terminal 12. A selector 4 outputs said transmission signal or ciphering signal to a terminal 13 in accordance with OFF or ON of the signal (c). A selector 5 outputs said receiving signal or deciphered signal in accordance with OFF or ON of the signal (c).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an encoder, and more particularly to an encoder for realizing a method for starting data encryption.

[Conventional technology]

In conventional encrypters, data is encrypted as soon as a communication line is established, and Bypass mode (non-encryption mode) is arbitrarily switched by hand.

[Problem that the invention seeks to solve]

In conventional encryptors, the Bypmms mode must be set by a person, so even if a terminal attempts to communicate only part of the communication data in an unencrypted state, it is not possible.

[Means for solving problems]

The encoder of the present invention includes a timer circuit that starts operating in response to a communication line establishment signal and sends out a trigger signal when a predetermined time has elapsed, and a switch that outputs a switching signal when the trigger signal from the timer circuit is input. and,
an encryption circuit that encrypts a transmitted signal and outputs the encoded signal, decodes a received signal and outputs the decoded signal; and selects and outputs either the transmitted signal or the encrypted signal using the switching signal. The apparatus includes a first selector and a second selector that selects and outputs either the received signal or the decoded signal based on the switching signal.

[Effect]

In the present invention, unencrypted data can be sent for a certain period of time when a communication line is established.

〔Example〕

Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.

In the figure, 1 is a timer circuit that starts multi-operation in response to the i-eye line establishment signal and sends out a trigger signal when a predetermined time has elapsed, and 2 is a timer circuit that sends out a switching signal when the trigger signal from timer circuit 1 is input. 3 is an encryption circuit that encrypts the transmitted signal and outputs the encrypted signal, and also decrypts the received signal and outputs the decrypted signal; 4 is the switching circuit that switches between the transmitted signal and the encrypted signal by the switching signal; A selector that selects and outputs either one, 5
is a selector that selects and outputs either the received signal or the decoded signal according to the switching signal.

Note that 6, 7, . . . , 14 each indicate a terminal.

Next, the operation of the embodiment shown in FIG. 1 will be explained with reference to FIG. 2.

Figure 2 is a time chart used to explain the operation of Figure 1.
(a) shows the communication line establishment signal, (b)
(0) shows the switching signal, (d) shows the output signal of the selector 4, and (e) shows the output signal of the selector 5.

In Fig. 2(d), (a) indicates the plaintext area, and (b) indicates the ciphertext area, and in Fig. 2(e), (c) indicates the plaintext area, and (ii) indicates the non-ciphertext area. shows.

First, the timer circuit 1 starts operating in response to the communication line establishment signal a shown in FIG. 2(a) inputted through the terminal 6, and when a predetermined time has elapsed, the signal is sent to the terminal 7 as shown in FIG. 2(b). Outputs a trigger signal as shown.

Then, the switching device 2 outputs a switching signal C as shown in FIG. 2(e) to the terminal 8 in response to the trigger signal inputted through the terminal 7.

Next, the encryption circuit 3 encrypts the transmission signal inputted through the terminal 9 and outputs the encoded signal to the terminal 10, and at the same time decodes the received signal inputted through the terminal 11 and outputs the decoded signal to the terminal 12. . The transmit signal is input to the selector 4 through the terminal 9, and the encrypted signal is input through the terminal 10t. When the switching signal C input through the terminal 8 is OFF, the transmit signal is selected. Then, it is outputted to the terminal 13 (see FIG. 2(d)), and when the switching signal C is turned ON, the encrypted signal is selected and outputted to the terminal 13 (see FIG. 2(d)). The selector 5 receives the received signal through the terminal 11 and receives the decoded signal through the terminal 12, and when the switching signal C input through the terminal 8 is OFF, the received signal is input to the selector 5. is selected and output to the terminal 14 (see Figure 2 (-)), and when the switching signal C turns ON, the decoded signal is selected and output to the terminal 14 (see Figure 2 (@)). .

〔Effect of the invention〕

As described above, according to the present invention, by allowing unencrypted data to be sent for a certain period of time when a communication line is established, an encrypted line can be provided to a terminal that requires an unencrypted procedure.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a time chart for explaining the operation of FIG. 1...Timer circuit, 2...Switcher, 3...
... Encryption circuit, 4, 5... Selector.

Claims (1)

[Claims] There is a timer circuit that starts operating in response to a communication line establishment signal and sends out a trigger signal when a predetermined time has elapsed, a switch that outputs a switching signal when the trigger signal from this timer circuit is input, and a switch that encrypts the transmitted signal. an encryption circuit that outputs the encrypted signal, decrypts the received signal, and outputs the decrypted signal; and a first selector that selects and outputs either the transmission signal or the encrypted signal based on the switching signal. and a second selector that selects and outputs either the received signal or the decrypted signal based on the switching signal.