JPS6130828A - Key distribution device - Google Patents

Abstract

PURPOSE:To distribute simply a different key every time by detecting a key request signal from a station executing ciphering communication, converting a digital pattern corresponding to a station address depending on a random number and transmitting the converted pattern to the station. CONSTITUTION:When an interface 204 gives a key request data from a station executing ciphering communication to a microprocessor 201, it generates a random number R and gives it to a power remainder circuit 203 and gives a digital pattern corresponding to an address of a key request station stored in the memory 202 and an opposite station of ciphering communication to the circuit 203. The circuit 203 converts the digital pattern depending on the random number R and gives the pattern to the microprocessor 201. The microprocessor 201 forms two public key distribution data from the data from the circuit 203 and transmits them to a communication network from the interface 204.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to the delivery of keys in encrypted communications. (Prior art) IEE Transactions on Information is a method for delivering keys used in encrypted communications.・Theo9-(IBEETransactions
on Information Theory)
The public key distribution method described in Vol. 22, No. 6, pages 644-654 is well known as a method that allows key distribution by distributing public information and does not require a secret transmission means. To be more specific, it is as follows: 〇 Stations that perform communication are station 12, station 2. ... It is assumed that there are nine stations N, and all stations 1 and 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. Here, the code pattern corresponding to station k is assumed to be Y. Y
, is created from predetermined positive integers α and p and a secret positive integer X according to the following equation.X 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=Yt (mad p) (
2) However, A (moda) indicates the remainder 9 when A is divided by a. Station 2 creates a key from the public information of station 1 using the following formula.

Key=Y+” (mod p)
(3+ Equation (2) and Equation (3) are the same - number from Equation (1). Here, p t is a large prime number of about 200 digits, α
If we make primordial light, the third party can express αv pt yk (k=1
．． 2t...tr'i) It is stated in the above document that even if the key is known, it requires a lot of calculation and time, and it is impossible to know the key in practice.

(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, with the public key distribution technology described above, the public information does not change. The key between station 1 and station 2 is always the same key, and once the key is decrypted, the communication between station 1 and station 2 is kept secret. The disadvantage is that it disappears. Furthermore, if the public information is changed from time to time, the public information must be collected from each station, and there is a drawback that it is necessary to verify whether the information is correct or not.

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

(Structure of the Present Invention) According to the present invention, there is provided a key delivery device for delivering a key to a station that performs encrypted communication, which comprises a storage means for storing a digital pattern corresponding to an address between the above, and a key request from the above station. request signal receiving means for receiving a signal; random number generating means for generating a random number; and a signal indicating that a key request signal has been received is supplied from the request signal receiving means, and a digital pattern corresponding to an address in between is supplied to the random number. A key distribution device is obtained, which is characterized in that it includes at least a conversion means for converting depending on the conversion means, and a means for transmitting the output of the conversion means to the communication network. The place that holds all the information and distributes the keys all at once is called the center, and the other stations are called station 1, station 2, etc. ...
Let there be 2 stations N. The diagram is as shown in FIG. Assume that the stations to which keys are to be delivered are station 1 and station 2.

FIG. 1 is a diagram for explaining the operation and principle of the present invention.

In the figure, the center has the common information shown in FIG. 3, and the stations have secret information x and t. The common information and secret information are the same as those in the prior art.0 When station 1 performs encrypted communication with station 2, station 1 first requests a key from the center. mod p ) (4
)Zt=Ys (mod p)
Calculate (5) and send to each tube circumference 19 station 2 0 station 1 is Ke
y=Z1 (mod p)
(6), and station 2 calculates Key=Z2 (mod p)
Equation 0 (6) and Equation 9 (7) to calculate (7) are both (
IRX''' (madp).At this time, R is a random number and is changed every time as It can also be used as a primitive root, and the four arithmetic operations on integers can be used as the four arithmetic operations on polynomials. In the following, we will explain only the case of integers to avoid complicating the explanation.

(Embodiment) FIG. 2 is a block diagram showing an embodiment of the present invention. Second
Before explaining the diagram, we will explain an example of the format of data on a communication network.
it (shown in cl. - The membrane shape is shown in FIG. 5(a). It consists of a destination address, a source station address, control information, and data. The control information indicates the type of data. That is, as shown in FIG. 1. Distinguish whether it is key request data, public key distribution data as a response, or other data Figure 5 (bl is the format of key request data) Figure 5 (c) shows the format of the public key distribution data.The address of the other station (referred to as the "secondary station") with which the encrypted communication is to be carried out is entered. Let k be the address of the partner station and the delivery address, and zk:Ys, (mod p) (
81 enters. The primary station is station 1, and the secondary station is station 2.

In FIG. 2, interface 204 passes key request data to microprocessor 201. In FIG. Memory 202
stores the public information shown in FIG. The microprocessor 201 generates a random number Rf and passes it to the exponentiation remainder circuit 203, and passes it to the exponentiation remainder circuit 203 and y stored in the memory 202. The exponentiation remainder circuit 203 is R and ytl
y, from equation (4), Z shown by equation (5), and Zy
is calculated and passed to the -r microprocessor 201. The microprocessor 201 is 2. and Z, create two sets of 7-ormat public key distribution data shown in FIG. A flowchart is shown in FIG. 6. The memory 202 is a ROM or a non-volatile RAM, and the remainder circuit 203 is constructed by, for example, the 1981 IEICE Information and Systems Division National Conference 322 "High-speed multiplication/division method for cryptographic processing". The interface 204, which can be configured with the circuit shown in , is an interface 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. (Refer to Nikkei Electronics November 21, 1983 issue, pages 139-166) 0
Although the embodiments of the present invention have been explained based on integer operations, they may also be based on polynomial operations as described above. Furthermore, although the microprocessor 201 generates random numbers in FIG. 2, the 0 random number may be a natural random number or a pseudorandom number, for which a dedicated random number generator may be used. Also, after the primary station and the secondary station calculate the key, t is determined whether the keys match.

Nippon Telegraph and Telephone Public Corporation technical reference material DCNACN side control level protocol message transfer floor code - DCNA
It is also possible to add a confirmation function similar to P4O10-1983-J pages 145-146.

All these modifications are included within the scope of the present invention.

(Effects of the Invention) As described above in detail, by using the present invention, it is possible to easily deliver a specific key every time, and the effect is extremely large when used in encrypted communication.

[Brief Description of the Drawings] Fig. 1 is a diagram showing an outline of the present invention, Fig. 2 is a block diagram showing an embodiment of the invention, Fig. 3 is public information, Fig. 4 is a schematic diagram of a communication network, FIG. 5 is a diagram showing the format of data transmitted over the communication network, and FIG. 6 is a diagram showing a flowchart of the microprocessor. In the figure, 101 is the center, 102. 103 is a station, 201 is a microprocessor, 202 is a memory, 20
3 indicates a power remainder circuit, and 204 indicates an interface. 0 Figure 2 Figure 3 Figure 4 Figure 5 (α) (b) (C) 6μ

Claims (1)

[Claims] A key distribution device that delivers a key to a station that performs encrypted communication, comprising a storage means that stores a digital pattern corresponding to the address of the station, and a request signal detection unit that receives a key request signal from the station and outputs a detection signal. means, random number generating means for generating random numbers, and converting means for receiving the detection signal from the request signal receiving means and converting a digital pattern corresponding to the address of the station depending on the random number;
A key distribution device comprising at least means for transmitting the output of the conversion means to the station.