The invention relates to an arrangement and a method for reliably identifying
a user in a computer system. The method utilizes a mobile station for communicating
with the system. The method comprises generating a first one-time password in the
mobile station by utilizing a known algorithm on the basis of the identification
number of the user, subscriber-specific identifier, device-specific identifier
of the mobile station, and time. The password obtained and the subscriber-specific
identifier of the user are encoded and transmitted to an authentication server
of the computer system, comprising identifying the user on the basis of the subscriber-specific
identifier, searching a database for the personal identifier number of the user
and the device-specific identifier of the mobile station associated with the user,
generating a second password at the authentication server by utilizing the same
predetermined algorithm on the basis of the personal identification number of the
user, subscriber-specific identifier, device-specific identifier of the mobile
station and time, comparing the first and the second passwords with each other
at the authentication server, and if the passwords match, enabling the telecommunication
connection between the mobile station and the computer system.
