| 摘要 |
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. |
