Portable devices, methods, and systems for controlling access to computers and other secure systems such as systems protecting secure premises, by processing data supplied by the individual seeking access to the system and data supplied by the system to which the prospective user seeks access, to determine whether access by the individual is to be authorized or enabled. In one embodiment the invention provides a device for providing a code that may be used to access a system such as a computer or security system. The device comprises an output device and at least one processor. The processor processes data representing a biometric characteristic of a prospective user of the system and a signal provided by the system, and, depending upon a result of the processing, provides to the output device a code that may be used to access the system.