The embodiment of the invention can verify that a person authorized to use a device through biometric technology is a real person but not a record of some form of a system with the purpose of deceiving. Some embodiment tries to change measured features of a living being to be measured and compares images obtained before the change and after the change to verify the change. In some embodiment, verification of a plurality of stages can be used to increase the difficulty of deceiving safety system, or different levels of safety can be provided according to different level of access of functions of the device.