| 摘要 |
PURPOSE:To prevent data which is not ciphered correctly from being written by providing a means which inhibits data from being written on a medium when the detachment of a ciphered polynomial holding part is detected. CONSTITUTION:When the ciphered polynomial holding part 4 is detached, a ciphered normal text generating circuit 3 recognizes the detachment from changes of attachment/detachment state detection lines 7 and 8 and outputs a write inhibition signal 12. A write inhibiting circuit 13 outputs a write indication signal 12 to a write circuit according to a write request signal 15 unless the write inhibition signal 12 is inputted from the ciphered normal text generating circuit 3, but does not output the write indication signal 14 regardless of the state of a write request signal 15 when the write inhibition signal 12 is inputted. When the ciphered polynomial holding part 4 is detached, the ciphered normal text generating circuit 13 recognizes that through the operation of this write inhibiting circuit 13 and inhibits writing operation. |
