JPH0433429A - Code device - Google Patents

Abstract

PURPOSE: To perform highly stable encipherment by receiving enciphered data from a transmitting means and decoding the data into their original data by relying upon a key given from a key distribution center and a random key kept in the recording medium held by a receiving means. CONSTITUTION: A decoding and converting section 104 decodes an enciphered key sent from a host which is a key distribution center by using a terminal key from the IC card 102 held by a user. An enciphering and converting section 105 generates random numbers by enciphering the random key from a memory card 103 held by the user by using the enciphered key decoded by means of the decoding and converting section 104. When the section 104 performs decoding as a receiving means, the section 104 can decode enciphered data into the original data by only inputting the enciphered data in place of input data. Therefore, highly stable encipherment can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an encryption device for encrypting data messages in a computer network.

[Conventional technology]

As a computer network encryption device, IBM SYSTEMJ
The cryptographic device published in OURNAL) is well known. In this encryption device, an encryption key is automatically set between the terminal and the host.

[Problem to be solved by the invention]

In the above-mentioned conventional encryption device, since the encryption key is set within the network, information cannot be stolen from the network line, but there is a drawback that it cannot prevent unauthorized users from using the terminal.

An object of the present invention is to eliminate such drawbacks and provide an encryption device that performs highly secure encryption.

[Means to solve the problem]

The present invention provides a cryptographic device for concealing data on a computer network, comprising: a transmitting means for encrypting the data; and a receiving means for returning the encrypted data sent from the transmitting means to the original data; The transmitting means encrypts data depending on a key given from the key distribution center and a random key stored in a recording medium owned by the transmitting means, and sends the encrypted data to the receiving means. The method is characterized in that it receives encrypted data sent from a transmitting means and restores it to the original data depending on a key given from the key distribution center and a random key stored in a recording medium owned by the receiving means. .

〔Example〕

FIG. 1 is a block diagram showing one embodiment of the present invention. This is an example in which a user performs encryption/decryption at a terminal in a computer network.

This encryption device has an encryption/decryption device 101 for encrypting/decrypting data, and this encryption/decryption device is physically protected so that the inside thereof cannot be opened. There is.

The encryption/decryption device 101 includes a decryption converter 104.
, an encryption conversion unit 105 , and an exclusive OR operation unit 106
is provided.

The decryption conversion unit 104 transfers the encryption key sent from the host, which is the key distribution center, to the IC card 10 held by the user.
Decrypt using the terminal key from 2.

The encryption converter 105 uses the encryption key decrypted by the decryptor converter 104 to convert the memory card 103 held by the user.
Generate random numbers by encrypting the random key from .

The exclusive OR calculation unit 106 performs an exclusive OR operation on the input data (message) and the random number, and outputs encrypted data.

The operation when this terminal communicates with other terminals on the computer network will be explained.

First, the operation when the encryption device performs encryption as a transmission means will be explained. For encryption, first, the decryption conversion unit 104 of the encryption/decryption device 101 receives data and an encryption key sent from the host of the computer network. Here, the encryption key KS is the terminal key KT
is encrypted and sent from the host in the form of E, , (KS). Therefore, the terminal key KT is inputted from the IC card 102 held by the user to the decryption conversion unit 104, decryption conversion is performed using the terminal key KT, and the encryption key KS is obtained.
Enter 5.

Next, a random key RN, which is a random bit string, is input from the memory card 103 held by the user to the encryption conversion unit 105, and this random key RN is encrypted with the encryption key KS to generate a random number R3, and an exclusive logic It is input to the sum calculation unit 106. The exclusive OR calculation unit 106 performs an exclusive OR operation on the input data and the random number R3, and outputs encrypted data. This encrypted data is sent to other terminals in the computer network.

The encryption conversion corresponding to the decryption conversion is, for example, the American Standard Cipher (DB) established by the Federal Bureau of Standards of the US Department of Commerce.
S> can be used.

The random key RN is a long bit sequence stored in the memory card 103, but the output start position is changed each time it is called, so that the output is not the same each time. For example, start from the previous time.

Once all of the bit sequence has been used, instead of starting from the beginning, if you shift the start, it can be treated as a sequence longer than the actual random key length.

Next, when the encryption device performs decryption as a receiving means, the original data can be restored by simply inputting encrypted data instead of input data in the above encryption.

In the above embodiment, the IC card 1 that records the terminal key
02 and the memory card 103 that records the random key are just one example, and these cards may be integrated, or other recording media may be used.

Furthermore, the party to whom encryption/decryption is performed by the terminal in FIG. 1 may be not the terminal but the host. Additionally, both the sender and the receiver may be hosts. In these cases, the contents of the IC card and memory card held by the user are recorded on the host's recording medium.

At this time, you can also encrypt and record it using a key unique to that host just in case. Note that when both the sending and receiving sides are hosts, the name terminal key is inappropriate and should be called a secondary communication key, but the function is the same.

Furthermore, in this embodiment, a plurality of terminal keys for the transmitting side and the receiving side can be prepared and replaced as needed, thereby increasing security.

105 ... Encryption conversion section 106 ... Exclusive OR operation section [Effects of the invention] As explained above, by using the present invention, it is possible to prevent unauthorized users from using the terminal, resulting in high security. Since it can perform encryption, it is highly effective when used in computer networks.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. 101... Encryption/decryption device 102 ・
...IC card 103 ...Memory card 104 ...Decoding conversion unit

Claims (1)

[Claims] (1) An encryption device for concealing data on a computer network, comprising a transmitting means for encrypting data, and a receiving means for returning the encrypted data sent from the transmitting means to the original data, The means encrypts data depending on a key given from a key distribution center and a random key stored in a recording medium owned by the transmitting means, and sends the encrypted data to the receiving means, and the receiving means transmits the data to the transmitting means. A cipher characterized by receiving encrypted data sent from a means and restoring it to the original data depending on a key given from the key distribution center and a random key stored in a recording medium possessed by the receiving means. Device.