| 摘要 |
PURPOSE:To hold the secrecy with high reliability without disturbing a job where the ciphering data is written onto a recording medium, by forming a ciphering polynomial holding part and a normal sentence polynomial holding part independently of each other and realizing a loadable/unloadable structure of the normal sentence polynomial holding part to a magnetic disk device. CONSTITUTION:The normal sentence data 1 on the information to be recorded onto a recording medium is converted into the ciphering data 9 via a ciphering normal sentence circuit 8 based on a ciphering polynomial stored in a ciphering polynomial holding part 3. The data 9 is recorded onto the recording medium. While the ciphering data 10 read out of the recording medium is converted into a normal sentence via the circuit 8 based on a normal sentence polynomial stored in a normal sentence polynomial holding part 6 and then delivered as the normal sentence data 2. Therefore the secrecy can be held with high reliability when only the part 6 is fetched from the main body of a magnetic disk device and stored separately. |
