Preferred embodiments of the invention relate to a method and device for authenticating a user of a computer and a corresponding system using the method and device. The device is a handheld electronic device having accessible thereto a first authentication code of the user. The handheld electronic device requires a second authentication code for enabling use thereof. In order to authenticate the user to the computer, the handheld electronic device is configured to transmit the first authentication code to the computer over a communication link between the computer and the handheld electronic device.