B. Configuration and Using
1) To start double-key authentication system: USB key
should be inserted first to set up authentication data, then using
the command “ passwd -D username” to give the permition to
those who can use this double-key authentication.
2) To use double-key authentication system: When an user
wants to log in the system, he should insert his USB key. When
it validated, he inputs his password. The actual autication
process was shown in Fig. 3.