Methods, systems, and devices are described for warless communications. An apparatus may identifying a living person by recording a heat image of a person's facial area and detecting a local heat inhomogeneity in a predetermined detection range of the heat image in order to identify the living person. Identifying the living person may include detecting a heat pattern in a predetermined detection range and comparing the detected heat pattern to a heat reference sample. The predetermined detection range may be detected based on a heat image geometry, using pattern matching, by comparing the heat image to a white light image of a living person, or by masking the heat image.