JPS60223248A - Open key delivery system - Google Patents

Abstract

PURPOSE:To secure the certification between counter cipher devices of an open key delivery system by ciphering and delivering open keys to each other to obtain the open keys through decoding of each cipher device, and producing a basic key from those open keys. CONSTITUTION:An open key is ciphered by a cipher key and sent from the remote side. This ciphered open key is supplied to a data ciphering standard arithmetic part 22 via an input register 20. In such a case, a cipher key K is delivered from a key generator 13 via a key register 21. Thus the part 22 performs decoding with the key K to obtain an open key. This open key is selected by a selector 24 via an output register 23 and supplied to the generator 13. A cipher sentence coded by a station of the remote side is supplied to the part 22 via the register 20, and decoded to an original normal sentence by the key K.

Description

[Detailed Description of the Invention] +a) Technical Field of the Invention The present invention relates to an improvement in an encrypted communication method using the data encryption standard (hereinafter referred to as DES) established by the U.S. Department of Commerce Bureau of Standards, which performs public key distribution. .

(b) Background of the Technology With the expansion of online data communication networks, the issue of encrypting communications has become a hot topic. Also, a public key distribution method is often used, which can relieve the burden of key management by distributing the encryption key at the start of encrypted communication using the same transmission path as the data transmission.

A communication system that performs encryption will be explained using the example shown in FIG. 1, taking as an example a case where the host computer 1 encrypts and transmits the data. Plaintext from the host computer 1 is encrypted by the encryption device 2, Modem 3. Transmission line 4
．． The data is sent to the encryption device 6 via the modem 5, decrypted by the encryption device 6, and input into the data terminal 7 as the original plain text.

Encrypted communication is performed in this way.

(C1 Prior Art and Problems In the conventional public key distribution system, for example, the cryptographic device 2 in Figure 1 sends the public key X = M''mod n, the cryptographic device 6 sends the public key Y = MImodn, Encryption device 2
．． In No. 6, the DBS operation unit performs encryption and decryption operations using this basic key with =M''modn as the basic key.

However, M and n are constants, and α and β are secret keys.

In this case, for example, as shown in FIG. 2, an encryption device M8 using a DBS calculation unit is connected in parallel to the transmission line 4, and the encryption device 8 receives the public key X from the encryption device 2. When the public key Z = M'm o d n is sent, the cryptographic device 2 creates a basic key KA = M'' m o d n.At this time, if the cryptographic device 8 creates the basic key KA, the cryptographic device 2
．． Encrypted communication becomes possible within 8 seconds.

However, γ is a secret key.

That is, in the encryption bag W2, the sent cipher text is sent to the encryption device 6.
It is not possible to authenticate the other party because it is not known whether the other party is the original or the one from the encryption device 8.

Conventional public key distribution methods have the disadvantage that authentication cannot be performed as described above.

Td) Object of the Invention In view of the above-mentioned drawbacks, an object of the present invention is to provide a public key distribution system that can provide authentication.

(e) Structure of the Invention The above object is to provide the present invention, in which a public key is encrypted and distributed, each encryption device decrypts the public key to obtain the public key, and generates a basic key from the public key. This is achieved through configuration.

In other words, since a third party does not know the key that encrypts the public key, even if a third party connects an encryption device in parallel to the transmission path, the encrypted public key that is sent to the third party cannot be used. Since the basic key cannot be accessed, and encrypted communication with a third party is not possible, authentication can only be achieved between the parties involved.

(f) Examples of the invention An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a block diagram of an encryption device according to an embodiment of the present invention.

In the figure, 10 is an encryption unit, 11 is a decryption unit, 12 is a key source, 13 is a key generator, 14 is a microprocessor, 15
．． 244! cellz vector, 16.20 is input register, 1
7.21 is the key register, 18°22 is the DBS calculation unit, 1
9.23 indicates the output register.

Since the configurations of encryption devices 2 and 6 in Figure 1 are the same,
The case of the cryptographic device 2 will be explained in FIG.

First, when the public key X is sent from the key generator 13, the selector 15
selects this and manually inputs it to the DBS calculation unit 18 via the manual register 16.

At this time, the key generator 13 generates the encryption key KH=M'm o d
n is created and sent to the DBS calculation unit 18 via the key register 17. However, ε is a secret key for authentication, which is held by the opposite encryption device 2.6.

The DBS calculation unit 18 inputs the public! ! Using X as the encryption key, encrypt it as X and send it to the other station.

On the other hand, the other station encrypts the public key Y using an encryption key and transmits it as Y, so this encrypted public key Y is input to the DBS calculation unit 22 via the input register 20.

At this time, since the encryption key K is sent from the key generator 13 via the key register 21, the DBS calculation unit 22 decrypts it with this encryption key K, receives the public key Y, and sends it to the selector via the output register 23. 24 and input to the key generator 13.

The key generator 13 generates a basic key K from the public key Y, α, and n, and this basic key K is sent to D via the key register 17゜21.
It is input to the BS calculation section 18.22.

Next, the plain text sent from the host computer l in FIG. is sent to the other station via.

On the other hand, the ciphertext encrypted with basic@1K at the other station is input to the DES calculation unit 22 via the input register 20, decrypted with the basic key K, and becomes the original plaintext, which is output to the output register 23.
is selected by the selector 24 and sent to the host computer 1 shown in FIG.

The above control is performed by the computer 14.

Also, from the key source 12, constant M and n secret key α.

An authentication key ε is given to the key generator 13.

In this case, a third party connects the encryption device 8 in parallel to the transmission path 4 as shown in Figure 2, and even if he receives the encrypted public key X from the encryption device 2, he does not know the encryption key. Therefore, the public key Since there is no basic key K
A cannot be created and encrypted communication cannot be performed.

Therefore, since encrypted communication is only possible with the encrypting device 6 shown in FIG. 1, it is possible to provide authentication between the opposing encrypting devices 2 and 6.

(g) Effects of the First Invention As explained in more detail, the present invention has the effect of providing authentication between opposing cryptographic devices using the public key distribution method.

[Brief explanation of drawings]

Figure 1 is a block diagram of an example of a cryptographic communication system, Figure 2 is a block diagram for explaining that authentication cannot be achieved using the conventional public key distribution method, and Figure 3 is a block diagram of an example of a cryptographic communication system according to the present invention. FIG. 2 is a block diagram of the device. In the figure, 1 is a computer, 2, 6.8 is a cryptographic device, 3.5
is a modem, 4 is a transmission line, IO is an encryption unit, 11 is a decryption unit, 12 is a key source, 13 is a key generator, 14 is a microprocessor, 15.24 is a selector, 16.20 is an input register, 17 , 21 is the key register, 18.22 is D
BS Computing Department, Procedural Amendment (Voluntary) May 11, 1939 60.5.2, Commissioner of the Japan Patent Office+, qt tl indication No. 1923-1939 Showa 3-7 Permanent Application No. 1, IIJ 7 3 Supplement. Leap II with each thing f1 QfJ person address Kanayo prefecture Kawasaki Yamanaka) 6) 1 me 1.・j・1 (address 1015 in i and a brief description of the drawings - 8 Contents of the amendment As shown in the attached sheet (1) The claims column of the specification is amended as follows. ``The public key is encrypted. They are distributed to each other, and each encryption device decrypts it to obtain the public key, and the public (2) same *sg
The 11th to 13th lines of page i are corrected as follows. The floor invention was based on the data encryption standard established by the U.S. Department of Commerce Bureau of Standards (
(3) rKJ on page 5, line 13 and @line 14 of the same book is corrected to rKbJ. (4) Correct rKJ on page 6, line 15 and line 18 of the same book to rKbj. (5) On page 7, line 15 of the same book, [Compounding section J is amended to read "compounding section."

Claims (1)

[Claims] A public key distribution system characterized in that a public key is encrypted and distributed, each encryption device decrypts it to obtain a public key, and generates a basic key from the public key.