JPS6130829A - Key distribution device - Google Patents

Abstract

PURPOSE:To attain ciphering communication with high safety by storing a predetermined digital pattern to each station specific to the own station and executing ciphering communication and obtaining a key depending on an output of a random number generating means. CONSTITUTION:The 1st digital pattern determined to each of stations executing ciphering communication and the 2nd digital pattern specific to the own station are stored in a RAM214. When a key change request is received from a terminal station 211, a microprocessor 213 generates a random number R and gives the information of the RAM214 and a random number R to a power remainder circuit 215, which converts the information in the RAM214 depending on the random number R and transmits a key distribution data converting the own station pattern to an opposite station. On the other hand, the circuit 215 converts the key distribution data transmitted from the opposite station based on the data converted from the pattern of the opposite station to obtain a key of the ciphering communication.

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to the delivery of keys in encrypted communications. Infomesh 1 ~ Theory (IBEETransactions
on Information Theory) 22
The public key distribution method described in Volume 6, pages 644-654 is well-known as a method that allows secure distribution by transmitting public information and does not require a secret transmission method. Then it becomes as follows.

Stations that perform all communications are 19 stations 2. ...Assume that there are two stations N, and that money amount 1 and station 2 are trying to share a key when performing encrypted communication. As public information, a table of code patterns corresponding to each station is made public as shown in FIG. 3. Here, it is assumed that the code pattern corresponding to station k is tY. Y
, is created from predetermined positive integers α and p and a secret positive integer C according to the following equation.

xk(1) Yk=α (mod p) Xk is a number known only to the station.

At this time, station 1 creates a key from the public information Y of station 2 using the following formula.

Key=Y2 (mod p) (2
1 However, A (moda) indicates the remainder # when dividing ^ by a. Station 2 creates a key from the public information of station 1 by using the following formula.

K, ey=Y1 (mod p)
(31 Equation (2) and Equation (3) are the same number from Equation (1) 0 Here, if pi is a large prime number of about 200 digits and α is a primitive element, the third party will be α, p, Yk (k =1,2...
+N), it takes a lot of calculation and time to know the Key, and the above literature shows that it is practically impossible to know the Key.

(Problems with the Prior Art) If the same encryption key is always used, once the encryption key is decrypted, it will no longer be possible to keep it secret, so it is safer to change it from time to time. However, the above-mentioned public key distribution technology has the disadvantage that the key between station 1 and station 2 will always be the same unless the public information is changed.In addition, if the public information is changed from time to time, the public information from each station will always be the same. must be collected,
There is a drawback that it is necessary to confirm whether or not the information is correct.

(Object of the Invention) An object of the present invention is to provide a key distribution device that eliminates the above-mentioned drawbacks.

(Structure of the Invention) According to the present invention, a first digital pattern determined for each station that performs encrypted communication and a second digital pattern unique to the own station are used.
means for storing a digital pattern, a random number generating means for generating a random number, and outputting the second digital pattern to the random number generating means to output the first digital pattern corresponding to the other station, the output of the random number generating means, and the output of the random number generating means. There is obtained a key distribution device characterized by comprising means for obtaining a key for encrypted communication with a partner station from a second digital pattern unique to the own station.

(Operation/Principle of the Present Invention) It is assumed that the target communication network consists of N stations.Each station has a secret positive integer corresponding to its own station in addition to the public information shown in FIG. The secret positive integer corresponding to station k is expressed by formula (1)
is Xk at Currently, the station conducting encrypted communication is station 1.
Assume that it is 2nd station 2.

FIG. 1 is a diagram showing the operation and principle of the present invention. In the figure, station 1 obtains public information Y, random number R1, and prime number p from Zl ”Y,'(rnod p )
(31 as the starting point and sends it to station 2. Station 2 similarly calculates 'bl = Y2 (mod p) from public information Y, random number R8, and prime number p.
(4) is calculated and sent to station 1. The station engineer converts Z2 sent from station 2 into the public information Y2, the random number 几, and the secret positive integer X.
.

From “l X+ KEY = (Y! Zl) (mod p)
Calculate (5) and use the key 0 as well as station 2 and station 1.
2 sent from the public information Y, the random number R52, and the secret positive integer X2, R2X2 KEY'''(Y+ Z+) (mod p)
Calculate (6) and use it as a key. Equation (5) 9 Equation (6)
Both results include KEY = α (R + "z) x + xt (mOdp) (0 random number R'l + R2 equal to 7° under the condition of equation (1), so K
EY is different every time.

(Embodiment) FIG. 2 is a block diagram showing an embodiment of the present invention. Before explaining FIG. 2, the format of data flowing on a communication network will be explained. FIG. 4 is a diagram showing an example of the format. In the figure (, 1 is the general form of data, and 0 is composed of a destination address, a source station address, control information, and data. 0 Control information indicates whether the data is for key distribution or not, and if it is for key distribution, the station that takes the initiative (The station that takes the initiative is called the primary station, and the partner station is called the secondary station.) Figure 2(b) shows the key distribution data, and the data part KZ , is entered.However, this applies when the originating station is station 1.If the originating station is station 2, z2 is entered.

In FIG. 2, R, AM 214 holds public information and private information shown in FIG. The communication partner station is station 2, the own station is station 1, and station 1 is the primary station. When the microprocessor 213 receives a key change request from the terminal 211, it generates a random number R,t-, passes the public information y, , y, of R8 and R,AM 214 to the exponentiation remainder circuit 215, and calculates the exponentiation remainder. The circuit 215 calculates zl and Y:'(mod
p) is calculated and output. Microprocessor 213 passes the Z8 to interface 216 and Yz (mo
d p ) t Stored in RAM 214 . The interface 216 sends to the z, ft station 2. On the other hand, the Inter-7 Ace 216 receives Zz'! shown by equation (4) sent from the station 2. i' receive microprocessor 21
Pass it to 3. The microprocessor 213 has Z, KRAM
y stored in 214, (mod p)1
Multiply as p @ modulus 7, multiplication result A and secret positive integer X,
is sent to the exponentiation remainder circuit 215. The power remainder circuit 215 calculates and outputs A (modp)ft. The microprocessor sets the output as a key in the encoder/decoder 212. Thereafter, the key is used for encrypted communication until the key is changed again.

The exponentiation remainder circuit 215 can be constituted, for example, by a circuit shown in 1988 IEICE Information and Systems Division National Conference 322 ``High-speed multiplication and division method for cryptographic processing''. The interface 216 interfaces with a communication network, and is determined once the communication network is specified. For example, if the communication network is Ethernet, the interface consists of a controller and a transceiver (see Nikkei Electronics, November 21, 1983 issue, pages 139-166). The operation of the encoder/decoder uses a commercially available cryptographic chip, and the operation of the microprocessor 213 is shown in a flowchart in FIG. (a) shows the operation until transmitting zl when station 1 is the primary station, and (b) shows the operation 1 from receiving the key distribution data to setting the key in the encoder/decoder 212. . The actual program is stored in ROM217.

In the above explanation, all operations on integers have been used to simplify the discussion, but it also holds true for operations on polynomials modulo a prime number, that is, p is a primitive polynomial Mc
x) With tα as the primitive element, the polynomial was performed by a log processor, but the 9 generated externally was converted into Nippon Telegraph and Telephone Public Corporation technical reference material r DCNA function control level and message transfer protocol ~DCNA PSO40-1983-
Verification functionality similar to that described in J pages 145-146 may be added; all such modifications are within the scope of the present invention.

(Effect of the invention) As explained in detail above, if the present invention is used, the random number R3
With R7, you can set a different key to the entire encryptor/decryptor each time, allowing highly secure encrypted communication, which is extremely effective.

[Brief explanation of drawings]

Fig. 1 shows the operation and principle of the present invention, Fig. 2 shows an embodiment of the invention, Fig. 3 shows public information, and Fig. 4 (act (b)) shows the information on the communication network. Figure 5 is a diagram showing an example of the format of flowing data, and a diagram showing the operation of the microprocessor 213. ,
215 is a power remainder circuit, 216 is an intern ace, 2
Figure 4 (a) (, b)

Claims (1)

[Claims] a storage means for storing a first digital pattern determined for each station performing encrypted communication and a second digital pattern unique to the own station; a random number generating means for generating a random number; and a random number generating means for generating a random number; means for transmitting a pattern as key distribution data to a partner station depending on the output of the random number generating means; and the first digital pattern and the random number generating means that receive the key distribution data from the partner station and correspond to the partner station. A key distribution device comprising means for obtaining a key for encrypted communication with a partner station from the output and the second digital pattern unique to the own station.