| 摘要 |
PURPOSE:To efficiently protect a program by providing a protect means equipped with an identifying means to judge coincidence between an inputted password and a cryptographic key. CONSTITUTION:An identifying means 10 provided at a protect means 11 is equipped with a NAND gate circuit 21 inputting outputs from respective shift registers 20 of a password input means 8 and plural OR gate circuits 22 inputting outputs from respective cryptographic key memories 24 of a mask means 9, and a coincidence circuit 27 is composed of the plural OR gate circuits 22 and the NAND gate circuit 23. When cryptographic key information stored in the mask means 9 is coincident with the information of the password, a coincidence signal is outputted from the protect means 11, a switching means 7 is driven, and a ROM part 4 and an external circuit OUT are connected through an internal bus 6. Thus, stored program information can be efficiently protected with simple circuit configuration. |
