JPS63124125A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To obtain a magnetic disk device that can hold the secrecy of a high degree by using a ciphering/holding circuit which can be attached to and detached from a ciphering circuit and holds a ciphering polynomial. CONSTITUTION:The normal sentence data on the information to be recorded is inputted to a terminal 1 and then ciphered by a ciphering circuit 5 based on a ciphering polynomial held by a ciphering polynomial holding circuit 3. The ciphered normal sentence data is outputted through a cipher output terminal 6 and recorded onto an attachable/detachable recording medium. While the data read out of the recording medium and ciphered is inputted to the circuit 5 through a cipher input terminal 7 and turned into normal sentences based on a polynomial held by the circuit 3. These normal sentences are outputted through a normal sentence output terminal 2. In such a way, the normal sentences are ciphered and vice versa by the circuit 5 based on the polynomials held by the circuit 3. Thus it is impossible to read out the information ciphered and recorded on the recording medium in the form of normal sentences as long as the circuit 3 is detached from the circuit 5 via a connecting part 4 and stored. As a result, the secrecy of a high degree can be held.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic disk device that uses a removable flexible medium, and particularly to a removable flexible medium that encrypts information input in plain text and records it on the medium. This invention relates to a magnetic disk device using.

[Conventional technology]

Conventional removable visible media encryption magnetic disk drives that encrypt information entered by subordinates and record it on a removable recording medium do not have a fixed circuit to hold the polynomial for encryption. It is not removable from the magnetic disk drive.

[Problem that the invention seeks to solve]

As mentioned above, in a magnetic disk device that uses a conventional removable flexible medium and inputs information in plain text and encrypts and records it, the encrypted polynomial holding section is not removable.
Although secrecy can be maintained between magnetic disk drives with different encryption polynomials, there is a drawback that secrecy cannot be maintained between magnetic disk drives with the same encryption polynomial.

An object of the present invention is to provide a magnetic disk device that can maintain a high degree of confidentiality by eliminating the drawbacks of the conventional encrypted magnetic disk device using a removable flexible medium as described above.

[Means for solving problems]

The magnetic disk device of the present invention has an encryption circuit that inputs plaintext information and outputs information encrypted according to an encryption polynomial, and inputs encrypted information and outputs information encoded in plaintext according to the encryption polynomial. A magnetic disk drive using a removable flexible medium having a removable flexible medium includes an encryption holding circuit that is detachably attached to the encryption circuit and holds the encryption polynomial.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the main parts of an embodiment of the present invention, and is a circuit diagram showing functions related to encryption and decryption of input/output information in blocks.

In FIG. 1, 1 is a plaintext input terminal to the encryption circuit 5;
Similarly, 2 is a plaintext output terminal, 6 is a cipher output terminal, and 7 is a cipher input terminal. 3 is an encryption holding circuit for holding a polynomial for encrypting plaintext;
It is configured to be detachable from the encryption circuit 5.

In the magnetic disk drive having the above-described configuration, when plaintext data of information to be recorded on a medium (not shown) is input from the plaintext input terminal 1, the data is stored in the encryption polynomial holding circuit 3 in the encryption circuit 5. The data is encrypted according to the encryption polynomial, outputted from the encryption output terminal 6, and recorded on a removable recording medium. Further, the encrypted data read from the recording medium is transferred from the encryption input terminal 7 to the encryption circuit 5.
The encryption circuit 5 performs encryption and plain text conversion operations by performing operations such as 0 or more in which the input data is input into the encrypted polynomial and is converted into plain text according to the polynomial held in the encrypted polynomial holding circuit 3, and this is sent out from the plain text output terminal 2. Encrypted polynomial holding circuit 3
This is done according to the polynomial held in the medium, so by removing the encrypted polynomial holding circuit 3 from the encrypting circuit 5 at the connection part 4 and storing it, the information encrypted and recorded on the medium can be read out as plain text. can be made impossible.

〔Effect of the invention〕

As explained above, according to the present invention, by removing the encrypted polynomial holding unit from the encrypting circuit and storing it,
Since it is impossible to read out the information encrypted and recorded on the medium as plain text, this has the effect of making it possible to maintain a high degree of confidentiality.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. 1...Plaintext input terminal, 2...Plaintext output terminal, 3...
- Encrypted polynomial holding circuit, 4... Connection section, 5... Encryption circuit, 6... Encryption output terminal, 7... Encryption input terminal. 22X Kaya l figure

Claims (1)

[Claims] A removable flexible device having an encryption circuit that inputs plaintext information and outputs encrypted information according to an encryption polynomial, and inputs encrypted information and outputs plaintext information according to the encryption polynomial. A magnetic disk device using a medium, comprising an encryption holding circuit that is detachably attached to the encryption circuit and holds the encryption polynomial.