JPH08149125A - Communication equipment and communication method - Google Patents

Abstract

PURPOSE: To provide a communication equipment and a communication method in which the leakage of a communication content is surely prevented by dynamically revising a ciphering key without the need for a complicated procedure. CONSTITUTION: A value 11 of an internal timer is rounded at the transmitter side with plural stepwise round widths 13a-13d to obtain plural ciphering keys 14a-14d. Data 12 for round width setting are ciphered by using the ciphering keys 14a-14d and the result is sent as a round width setting ciphering code 16. The receiver side round a value 17 of an internal timer with plural stepwise round widths 18a-18d to obtain plural ciphering keys 19a-19d. A ciphering code 16 for round width setting is decoded by using the ciphering keys 19a-19d to decide the optimum round width. Then data are ciphered and decoded by using the ciphering key obtained by the round width.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device and a communication method for encrypting and transmitting communication data in a wireless or wired network.

[0002]

2. Description of the Related Art FIG. 5 is a diagram showing an example of a wireless or wired communication system. In FIG. 5, a plurality of terminal devices 1
00a, 100b, 100c are connected by a network line 101. Data is transmitted and received between the plurality of terminal devices 100a, 100b, 100c via the network line 101. In the case of a wireless communication system, the network line 101 does not exist.

In order to perform communication in such a communication system while keeping the communication contents secret, the transmitting side encrypts the data according to a predetermined encryption algorithm and transmits the encrypted data. On the other hand, on the receiving side, the received encrypted data is decrypted according to the decryption algorithm corresponding to the above encryption algorithm.

FIG. 6 is a diagram showing an example of a conventional communication method for encrypting and communicating data. In FIG. 6, on the transmitting side, the communication data 22a, 22b, 22c are encrypted using a fixed encryption key 21 according to a predetermined encryption algorithm. Thereby, the encrypted data 23a, 2
3b and 23c are obtained and transmitted to the receiving side.

On the receiving side, the received encrypted data 23
a, 23b, and 23c are decrypted according to a predetermined decryption algorithm using the same fixed encryption key 24 as that of the transmitting side. Thereby, the decrypted data 25a, 25b, 25c are obtained.

As described above, by using the same fixed encryption keys 21 and 24 on the transmitting side and the receiving side, communication data can be encrypted and transmitted / received.

[0007]

However, in the above-mentioned conventional communication method, since the fixed encryption keys 21 and 24 are used for encryption and decryption, the contents of communication data are several kinds such as a command. If the data is stylized, the encrypted data will also be stylized. Therefore, there may be a case where the content of the communication data can be grasped without knowing the content of the encryption key itself.

In order to prevent this, a method of changing the contents of the encryption key at an appropriate time interval is used. However, since such a change is usually performed at a long time interval of several days or months, communication contents may be leaked during that time. Also, when changing the encryption key,
Since it is necessary to notify all terminal devices of the changed encryption key, it is troublesome to change the encryption key frequently.

An object of the present invention is to provide a communication device and a communication method capable of reliably preventing leakage of communication contents by dynamically changing an encryption key without requiring a complicated procedure. It is to be.

[0010]

[Means for Solving the Problems]

(1) First Invention A communication device according to the first invention is a time measuring means for measuring time,
An encryption means for encrypting the transmission data using an encryption key based on the value of the timekeeping means, a transmission means for transmitting the encrypted data obtained by the encryption means, a reception means for receiving the encrypted data, And decryption means for decrypting the encrypted data received by the receiving means using the encryption key based on the value of the timing means.

(2) Second Invention A communication apparatus according to a second invention is the communication apparatus according to the first invention, further comprising rounding means for rounding the value of the timekeeping means to an arbitrary precision. is there. The encryption means encrypts the transmitted data by using the encryption key based on the value obtained by the rounding means, and the decryption means receives the encrypted data by using the encryption key based on the value obtained by the rounding means. Decipher

(3) Third Invention A communication apparatus according to a third invention is the communication apparatus according to the second invention, further comprising rounding amount determining means for determining a rounding amount. . When transmitting the rounding amount determination data, the encrypting means encrypts the transmitted data using a plurality of encryption keys based on the values rounded by the rounding means to a plurality of levels of accuracy, and rounds the plurality of encrypted data by the rounding amount. The data for determination is transmitted via the transmission means. The decryption unit decrypts the rounding amount determination data received using the plurality of encryption keys based on the values rounded by the rounding unit to a plurality of levels of accuracy when receiving the rounding amount determination data. The rounding amount determination means determines the rounding amount based on the decoding result of the rounding amount determination data by the decoding means.

(4) Fourth Aspect of the Invention A communication method according to a fourth aspect of the present invention encrypts transmission data by using an encryption key based on the value of the clock means at the time of data transmission, and at the time of data reception. , The received data is decrypted by using the encryption key based on the value of the clock means.

[0014]

In the communication device according to the first to third inventions,
At the time of transmitting the data, the transmission data is encrypted using the encryption key based on the value of the time measuring means, and the obtained encrypted data is transmitted. Upon reception, the encrypted data received is decrypted using the encryption key based on the value of the timekeeping means.

In this way, on the transmitting side and the receiving side, the data is encrypted and decrypted by using the encrypted data which are dynamically changed and synchronized with each other. Thereby, even if the communication content is standardized, the encrypted data to be transmitted constantly changes dynamically. Therefore,
It is possible to reliably prevent the leakage of communication contents without requiring a complicated procedure.

Particularly, in the communication device according to the second and third aspects of the invention, the value of the time measuring means is rounded to an arbitrary precision,
When transmitting data, the encrypted data is encrypted using the encryption key based on the rounded value, and when receiving the data, the encrypted data is decrypted using the encryption key based on the rounded value. Be seen.

Therefore, even if there is an error in the value of the clock means on the transmitting side and the receiving side, the decoded data corresponding to the transmitted data can be accurately obtained on the receiving side. Further, in the communication device according to the third aspect of the present invention, when transmitting the rounding amount determination data, the transmission data is encrypted using a plurality of encryption keys based on the value rounded to a plurality of levels of accuracy, The encrypted data is transmitted as rounding amount determination data. Further, when the rounding amount determination data is received, the received rounding amount determination data is decrypted by using the plurality of encryption keys based on the values rounded to a plurality of levels of accuracy. Then, the rounding amount is determined based on the decoding result of the rounding amount determination data.

Thus, before the actual data communication,
By exchanging the rounding amount determination data between the sending side and the receiving side, the minimum rounding that can accurately decrypt the encrypted data when there is an error in the value of the time measuring means between the sending side and the receiving side. The amount can be determined. Therefore, it is possible to perform accurate data communication while surely preventing the leakage of communication contents according to the error of the value of the time measuring means on the transmitting side and the receiving side.

In the communication method according to the fourth aspect of the invention, the transmitted data is encrypted by using the encryption key based on the value of the time measuring means at the time of transmitting the data, and is encrypted based on the value of the time measuring means at the time of receiving the data. The received data is decrypted using the activation key.

As described above, data encryption and decryption are performed on the transmitting side and the receiving side by using the encrypted data which are dynamically changed and synchronized with each other. As a result, even if the communication content is standardized, the encrypted data to be transmitted changes dynamically. Therefore, it is possible to reliably prevent the leakage of communication contents without requiring a complicated procedure.

[0021]

1 is a diagram showing a communication method according to a first embodiment of the present invention. In this embodiment, the value of the internal timer is used as the encryption key on the transmitting side and the receiving side.

On the transmitting side, the value of the internal timer is 199.
When it is 18:00 on October 17, 4th, "19
Transmission data 2 according to a predetermined encryption algorithm using the encryption key 1a having the value of "94101718".
a, 2b, and 2c are encrypted. Thereby, the encrypted data 3a, 3b, 3c are obtained and transmitted to the receiving side.
Further, when the value of the internal timer indicates 19:00 on October 17, 1994, the transmission data 2a, 2b, 2c are transmitted according to a predetermined encryption algorithm using the encryption key 1b having the value "1994101719". Encrypted. Thereby, the encrypted data 4a, 4b, 4c is obtained and transmitted to the receiving side.

As described above, even if the transmitted data is the same, the content of the encrypted data dynamically changes depending on the time of encryption. On the other hand, on the receiving side, the value of the internal timer is 1
When it is 18:00 on 17th January, "19941
Received encrypted data 3 according to a predetermined decryption algorithm using the encryption key 5a having the value "01718".
a, 3b, 3c are decrypted. Thereby, the decrypted data 6a, 6b, 6c is obtained. Also, when the value of the internal timer indicates 19:00 on October 17, 1994,
Encryption key 5b having a value of "1994101719"
Is used to decrypt the received encrypted data 4a, 4b, 4c according to a predetermined decryption algorithm. Thereby, the decrypted data 6a, 6b, 6c is obtained.

As described above, by using the value of the internal timer as the encryption key, the encryption key dynamically changes, and at the receiving side, decrypted data that matches the transmitted data can be obtained.

FIG. 2 is a diagram showing a communication method according to the second embodiment of the present invention. In the present embodiment, the value obtained by rounding the value of the internal timer on the transmitting side and the receiving side by the set rounding width is used as the encryption key.

Here, it is assumed that there is a one-hour error between the value 11 of the internal timer on the transmitting side and the value 17 of the internal timer on the receiving side. On the transmitting side, the value 11 of the internal timer is set to a plurality of rounding widths 13a, 13b, 13 set in stages.
It is rounded with c and 13d. The rounding width 13a means rounding the lower 4 digits of the internal timer value 11, and the rounding width 13b
Means rounding the lower 3 digits of the internal timer value 11, rounding width 13c means rounding the lower 2 digits of the internal timer value 11, and rounding width 13d means rounding the internal timer value 11
It means to round the lower one digit of.

When the value 11 of the internal timer indicates 18:05 on October 17, 1994, the rounding width 13a gives the encryption key 14a having the value "941017", and the rounding width 13b gives "9410171". An encryption key 14b having a value of "" is obtained. In addition, rounding width 13c
Encryption key 1 having a value of "94101718" by
4c is obtained, and the rounding width 13d causes "94101718".
An encryption key 14d having a value of "0" is obtained.

Using the plurality of encryption keys 14a, 14b, 14c, 14d thus obtained, the rounding width setting data 12 is encrypted according to a predetermined encryption algorithm. Thereby, a plurality of encrypted data 15a,
15b, 15c and 15d are obtained. These encrypted data 15a, 15b, 15c, 15d are combined and transmitted as the encryption code 16 for setting the rounding width.

On the receiving side, the value 17 of the internal timer is the same as that on the transmitting side.
It is rounded by 8b, 18c and 18d. The rounding width 18a means that the lower 4 digits of the internal timer value 17 are rounded, the rounding width 18b means that the lower 3 digits of the internal timer value 17 are rounded, and the rounding width 18c is the internal timer value 17 of the internal timer value 17. This means that the lower 2 digits are rounded, and the rounding width 18d means that the lower 1 digit of the value 17 of the internal timer is rounded.

When the value 17 of the internal timer indicates 19:05 on October 17, 1994, the rounding width 18a gives the encryption key 19a having the value "941017", and the rounding width 18b gives "9410171". An encryption key 19b having a value of "" is obtained. In addition, rounding width 18c
Encryption key 1 having a value of "94101719" by
9c is obtained, and with the rounding width 18d, "94101719"
An encryption key 19d having a value of "0" is obtained.

Using the plurality of encryption keys 19a, 19b, 19c and 19d thus obtained, the received encryption code 16 for setting the rounding width is decrypted according to a predetermined decryption algorithm. Thereby, the decrypted data 20
a, 20b, 20c, 20d are obtained. By comparing the decoded data 20a, 20b, 20c, 20d with the known data for setting the rounding width, the optimum rounding width can be obtained on the transmitting side and the receiving side.

In the example of FIG. 2, the transmission data 1 is transmitted using the encryption keys 14a and 14b obtained with the rounding widths 13a and 13b.
Only when 2 is encrypted, the correct decryption data 2 on the receiving side
0a and 20b are obtained. That is, when there is a one-hour difference between the value 11 of the internal timer on the transmitting side and the value 17 of the internal timer on the receiving side, in order to correctly decrypt the encrypted data on the receiving side, On the receiving side, the rounding widths 13b and 18b are determined to be the minimum rounding widths, respectively.

After that, the transmission side encrypts the transmission data using the encryption key 14b with the rounding width 13b,
The reception side decrypts the received encrypted data using the encryption key 19b having the rounding width 18b.

FIG. 3 is a functional block diagram showing the structure of a communication device for executing the communication method of FIG. In the communication device 100 of FIG. 3, the internal timer 31 measures the current time. The rounding width setting means 32 includes a plurality of dividers 32a, 32b, 32c, 32d corresponding to the plurality of rounding widths.
A stepwise rounding width is set in each of the dividers 32a, 32b, 32c and 32d. Dividers 32a, 32b, 3
Each of 2c and 32d rounds the value of the internal timer 31 by dividing the value of the internal timer 31 by the set rounding width. The encryption key setting unit 33 includes the dividers 32a and 32a.
The value rounded by b, 32c, and 32d is set as the encryption key.

During the rounding width setting process, the encryption / decryption unit 35 uses a plurality of encryption keys set in the encryption key setting unit 33 according to a predetermined encryption algorithm to set a preset rounding width. Data is encrypted and a plurality of encrypted data is stored in the transmission buffer 36. The plurality of encrypted data stored in the transmission buffer 36 are combined and transmitted as an encryption code for setting the rounding width.

Further, when the encryption / decryption unit 35 receives the encryption code for setting the rounding width via the receiving buffer 37 during the rounding width setting processing, the encryption / decryption unit 35 sets a plurality of encryption codes set in the encryption key setting unit 33. The received encryption code is used to decrypt the received rounding width setting encryption code according to a predetermined decryption algorithm, and a plurality of decrypted data is stored in the received data storage memory 38.

The optimum rounding width determination unit 39 determines the optimum rounding width by comparing the plurality of pieces of decoded data stored in the received data storage memory 38 with the known data for setting the rounding width, and determines the determined optimum rounding width. Is sent to the encryption / decryption unit 35 and the transmission buffer 36 stores the optimum rounding width data.
To the communication device of the other party via.

After that, the encryption / decryption unit 35 uses the encryption key obtained by the determined rounding width among the encryption keys set in the encryption key setting unit 33 at the time of data transmission, to transmit data. The transmission data stored in the storage memory 34 is encrypted. Also, the encryption / decryption unit 35, when receiving the data, decrypts the received data using the encryption key obtained by the determined rounding width among the encryption keys set in the encryption key setting unit 33. Then, the decoded data is stored in the received data storage memory 38.

The communication device shown in FIG. 3 can be realized by hardware, software, or both hardware and software.

FIG. 4 is a sequence diagram showing communication processing in the communication system using the communication device 100 of FIG.
First, the transmitting communication device transmits an encryption code for setting the rounding width to the receiving communication device (step S1). The receiving communication device performs rounding width setting processing based on the received encryption code to determine the optimum rounding width (step S2),
Rounding width data indicating the determined rounding width is notified to the transmitting communication device (step S3).

After that, the transmission side communication device performs the encryption processing of the transmission data using the encryption key obtained by the determined rounding width (step S4), and the obtained encrypted data is processed by the reception side communication device. (Step S5). The receiving-side communication device performs decryption processing of the encrypted data using the encryption key obtained by the determined rounding width to obtain decrypted data (step S6).

Further, the receiving side communication device performs the encryption process of the transmission data using the encryption key obtained by the determined rounding width (step S7), and transmits the encrypted data to the transmitting side communication device. (Step S8). The transmission-side communication device uses the encrypted data obtained by the determined rounding width to decrypt the received encrypted data to obtain decrypted data (step S9).

As described above, before the actual data communication,
By exchanging rounding width setting data between the transmitting side and the receiving side, the optimal rounding width is set according to the error in the value of the internal timer in the transmitting side communication device and the receiving side communication device. Data is encrypted and decrypted using the encryption key with the set rounding width. Therefore, it is possible to reliably prevent the leakage of communication contents and absorb the error in the value of the internal timer to perform accurate data communication.

[0044]

According to the first to fourth aspects of the invention, on the transmitting side and the receiving side, the data is encrypted and decrypted by using the encrypted data which are dynamically changed and synchronized with each other. Since the encrypted data constantly changes dynamically, it becomes difficult for a third party to decrypt the encrypted data. Therefore, it is possible to reliably prevent the leakage of communication contents without requiring a complicated procedure.

In particular, according to the second and third inventions, the value of the time measuring means is rounded to an arbitrary precision, and the encryption key based on the rounded value is used. Even if there is an error in the value of the means, the error can be absorbed, and the encrypted data can be accurately decrypted on the receiving side.

According to the third aspect of the invention, since the minimum rounding amount that enables accurate data communication is determined before the actual data communication, the values of the timekeeping means on the transmitting side and the receiving side are determined. Accurate data communication can be performed while surely preventing leakage of communication contents according to the error.

[Brief description of drawings]

FIG. 1 is a diagram showing a communication method according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a communication method according to a second embodiment of the present invention.

3 is a functional block diagram showing the configuration of a communication device for executing the communication method of FIG.

FIG. 4 is a sequence diagram showing communication processing in a communication system using the communication device of FIG.

FIG. 5 is a block diagram showing a communication system including a plurality of terminal devices connected by a network.

FIG. 6 is a diagram showing a conventional communication method using a fixed encryption key.

[Explanation of symbols]

1a, 1b, 5a, 5b, 14a, 14b, 14c, 1
4d, 19a, 19b, 19c, 19d Encryption keys 2a, 2b, 2c, transmission data 3a, 3b, 3c, 4a, 4b, 4c, 15a, 15
b, 15c, 15d Encrypted data 6a, 6b, 6c, 20a, 20b, 20c, 20d
Decoded data 11,17 Internal timer value 12 Rounding width setting data 13a, 13b, 13c, 13d, 18a, 18b, 1
8c, 18d Rounding width 16 Encryption code for setting rounding width 31 Internal timer 32 Rounding width setting unit 33 Encryption key setting unit 35 Encryption / decryption unit 39 Optimal rounding width determination unit 100 Communication device

Claims (4)

[Claims] 1. A time measuring means for measuring time, an encrypting means for encrypting transmission data by using an encryption key based on a value of the time measuring means, and transmitting the encrypted data obtained by the encrypting means. A communication device comprising: a transmitting means; a receiving means for receiving encrypted data; and a decrypting means for decrypting the encrypted data received by the receiving means using an encryption key based on the value of the timekeeping means. 2. A rounding means for rounding the value of the time counting means to an arbitrary precision is further provided, wherein the encryption means encrypts the transmission data using an encryption key based on the value obtained by the rounding means, 2. The communication device according to claim 1, wherein the decryption means decrypts the encrypted data received using the encryption key based on the value obtained by the rounding means. 3. A rounding amount determining means for determining a rounding amount is further provided, wherein the encryption means is based on a value rounded by the rounding means to a plurality of stages of accuracy when transmitting the rounding amount determining data. The transmission data is encrypted using a plurality of encryption keys, the plurality of encrypted data is transmitted as rounding amount determination data via the transmitting unit, and the decryption unit receives the rounding amount determination data, The rounding amount determining means decrypts the received rounding amount determination data using a plurality of encryption keys based on the value rounded to a plurality of levels of precision by the rounding means, The communication device according to claim 2, wherein the rounding amount is determined based on a result of decoding the data. 4. When the data is transmitted, the data is encrypted by using the encryption key based on the value of the time measuring means and is transmitted, and when the data is received, the received data is transmitted by using the encryption key based on the value of the time measuring means. A communication method characterized by decoding.