KEYBOARD DEVICE HAVING SECURITY FUNCTION AND METHOD THEREFOR

PROBLEM TO BE SOLVED: To provide a keyboard device having a high security function. SOLUTION: A ciphering/decoding circuit 6 and a ciphering circuit 10 are provided for a main body 1 and the keyboard device 2. The keyboard device 2 waits for the input of user ID and a password from a key 8 with the power supply of the main body 1. When a user ID is inputted and it is transmitted to the main body 1, random numbers for message-compressing the password are transmitted from the main body 1 to the keyboard device 2. The keyboard device 2 message-compresses the password by the random numbers and transmits it to the main body 1. The main body 1 compares the password which is transmitted and message-compressed with the password which is message-compressed inside and certifies a user. An open key is transferred to the keyboard device 2 and a cipher key used for session is transmitted from the keyboard device 2 to the main body 1. Then, session is executed by using the open key hereafter.