1. A method for remotely detecting whether a subject is alive, comprising the steps of: determining a calibration spectral signature for light reflectance from living skin; normalizing the calibration spectral signature values to the calibration reflectance value at a reference wavelength; storing the normalized calibration spectral signature; determining a subject spectral signature of the light reflectance of a region of skin of the subject whose liveness is to be determined; normalizing the subject spectral signature values to the subject reflectance value at the reference wavelength; comparing the normalized subject spectral signature with the normalized calibration spectral signature for at least one wavelength; generating a subject liveness signal based on the comparison of the normalized subject spectral signature with the normalized calibration spectral signature; and emitting the subject liveness signal.