JPH0362333B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Technical Field of the Invention The present invention relates to a data line terminating device installed at each end of a communication path and a data terminal device connected to the data line terminating device and transmitting data. Public key distribution method (Public Key Distribution method)
The present invention relates to an encryption device that encrypts signals sent from the data terminal device using PKDS (PKDS), and reduces the time occupied by communication channels necessary for public key distribution without using particularly expensive dedicated arithmetic circuits. This invention relates to a key generation method for a cryptographic device.

(b) Prior art and problems When transmitting data between computer systems using a communication channel, or when transmitting data by connecting a terminal device to a computer system via a communication channel, the information to be transmitted must be encrypted. may be used to transmit data. In this case, there is a key required to encrypt/decrypt information, and it is necessary to exchange the key between the encryption devices installed at both terminal stations. One of these key exchange methods is a public key distribution method. A key generation method for a cryptographic device that performs key distribution using a conventional public key distribution method will be described with reference to FIG.

FIG. 1 is a diagram illustrating a key generation method using a public key distribution method. Data sent from the data terminal device 1 is encrypted by the encryption device 2, converted into a signal suitable for transmission over a communication channel by the data line termination device 3, and sent out. The signal reaching the data line termination device 4 is converted into the original encrypted data, enters the encryption device 5, is decoded, and is sent to the data terminal device 6. Data sent from the data terminal device 6 is transmitted in the same manner as described above. Here, the cryptographic device 2 generates a private key α using the public key distribution instruction as a trigger. Then, the public key X is calculated.
In other words, it is the operation of X=M〓(mod n), which means that M is α
This is an operation of multiplying and dividing by n. This is a one-way function and it is very time consuming and difficult to calculate α from X. Therefore, even if this X is leaked, it is extremely difficult to break the encryption, so X is called a public key. Then, this X is sent to the encryption device 5 via the communication path.
Deliver to. When the cryptographic device 5 receives this X, it generates a private key β and calculates the public key Y by Y=M〓(mod n)
and delivers the public key Y to the cryptographic device 2. When the cryptographic device 2 receives this Y, it calculates the common key K. That is, K=Y〓(mod n)=M〓〓(mod n)
becomes. When the cryptographic device 2 receives the public key Y, it sends an affirmative response to the cryptographic device 5, and the cryptographic device 5 also calculates the common key K. That is, K=X〓(mod n)=M〓〓
(mod n). A method for performing encryption/decryption using this common key K is a public key distribution method.
Here, the time required to calculate M〓(mod n) and M〓(mod n) to obtain public keys X and Y is M, α,
If n is about 100 bits, it will take several seconds to about 10 seconds if executed by a microprocessor. Therefore, the time required for one public key distribution is about 10 to 20 seconds, which is not practical because the communication channel occupancy time is very large. Therefore, in order to increase the speed of public key calculation, a dedicated
They use LSI or combine general-purpose high-speed processors with innovative calculation methods. But exclusive
LSIs and high-speed processors are expensive and have the disadvantage of being used less frequently and are not economical.

(c) Purpose of the Invention In order to eliminate the above-mentioned drawbacks, the purpose of the present invention is to provide a key generation method for a cryptographic device that does not require the use of expensive dedicated arithmetic circuits and shortens the time required to occupy a communication path for public key distribution. It is about providing.

(d) Structure of the Invention The structure of the present invention is to generate a plurality of private keys in a cryptographic device that encrypts/decrypts information transmitted via a communication furnace using a public key distribution method, and to generate a plurality of private keys. A table is provided in which a plurality of public keys corresponding to the above are calculated and stored, and public keys from the table are distributed between the cryptographic devices according to predetermined instructions, and the public keys based on the distributed public key and the public key are shared between the cryptographic devices. The key calculation result is controlled to be stored in the table corresponding to the private key of the table, and the calculation of the public key and the common key is performed by referring to the table during the processor's idle time. It is something to control.

(e) Embodiments of the Invention The present invention does not perform the exponentiation operations M〓(mod n) and M〓(mod n), which require a lot of time in public key distribution, using a cryptographic device. By using the idle time of the microprocessor installed in the computer to execute the process, store it in a non-volatile memory, and distribute it as appropriate, the time occupied by the communication channel can be shortened. Also, by sending multiple public keys in one delivery, it is possible to generate multiple common keys for multiple private keys.

FIG. 2 is a diagram for explaining the control method of the present invention, and FIG. 3 is a diagram for explaining a table according to an embodiment of the present invention. This will be explained using FIGS. 2 and 3. The operations of the data terminal devices 1 and 6 and the data line termination devices 3 and 4 are similar to those shown in FIG. The cryptographic device 7 stores private keys α ₁ , α ₂ , ...αn using random numbers generated by a built-in microprocessor or random number generation circuit in the private key area of table A consisting of non-volatile memory as shown in FIG. Store as shown. Also, encryption device 8
are secret keys β ₁ , β ₂ …βn using random numbers generated by a built-in microprocessor or random number generation circuit.
is stored in the secret key area of table B configured in non-volatile memory as shown in FIG. Based on the random numbers, that is, the private keys α ₁ to αn, the microprocessor of the cryptographic device 7 calculates the public keys X ₁ , X ₂ , . . . are stored corresponding to secret keys α ₁ , α ₂ , ...αn. Furthermore, the microprocessor of the cryptographic device 8 calculates public keys Y ₁ , Y ₂ , ... Yn based on the random numbers, that is, the private keys β ₁ to β n during idle time when it is not operating, and stores them in the public key area of table B. Key β ₁ , β ₂ ,...βn
Store correspondingly. For example, when the cryptographic device 7 receives a public key distribution instruction according to a predetermined procedure, it reads public keys X ₁ , X ₂ , . . . Encryption device 8 receives the delivered public key
X _{1 ,} X _{2 ,} . . . Then, the public keys Y ₁ , Y ₂ , . . . Yn are read from table B and delivered to the encryption device 7. The cryptographic device 7 stores _the delivered public keys Y ₁ , Y _{2 ,} . When the cryptographic device 7 receives the public keys Y ₁ , Y ₂ , . . . Yn, it sends an acknowledgment to the cryptographic device 8 and completes the public key distribution operation. Therefore, the occupation of the communication path can be very small since it only takes the time to send a plurality of public keys to each other. The microprocessor of the cryptographic device 7 uses the free time to retrieve the other party's public key from the table 4.
Y ₁ , Y ₂ , ...Yn and secret keys α ₁ , α ₂ , ...αn are read out sequentially, common keys K ₁ , K ₂ , ...Kn are calculated, and table A
The private keys α ₁ , α ₂ , ... αn are stored in the common key area of . Also, the microprocessor of the cryptographic device 8 uses the free time to retrieve the other party's public key from table B.
_{X 1 , X 2 ,} ...
The private keys β ₁ , β ₂ , ...βn are stored in the common key area of Until the common keys K ₁ , K ₂ , . Further, switching of the common keys K ₁ , K ₂ , . . . Kn can be performed by an instruction from the cryptographic device 7 or 8.

(f) Effects of the Invention As explained above, the present invention does not require the use of an expensive dedicated arithmetic circuit, and is capable of public key distribution that requires only a short time for occupying a communication channel. Multiple public keys can be distributed.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining a key generation method using a public key distribution method, FIG. 2 is a diagram for explaining a control method of the present invention, and FIG. 3 is a diagram for explaining a table according to an embodiment of the present invention. 1 and 6 are data terminal devices, 2, 5, 7, and 8 are encryption devices, and 3 and 4 are data line terminal devices.

Claims (1)

[Claims] 1. A cryptographic device that encrypts/decrypts information transmitted via a communication channel using a public key distribution method, generates multiple private keys, and calculates multiple public keys corresponding to the multiple private keys. A table is provided in which public keys are stored, and a public key is distributed between the encryption devices from the table according to predetermined instructions, and the distributed public key and the calculation result of a common key based on the public key are stored in the secret of the table. A cryptographic device characterized in that it is controlled to store keys in the table in accordance with the keys, and to perform calculations on the public key and the common key by referring to the table during idle time of processor operation. Key generation method.