A method includes aligning a transmitter and receiver to transmit signals through a body part of a person and transmitting, by the transmitter and through the body part, analog signals of known transmission signal strengths. The method also includes receiving, by the receiver, the analog signals after the analog signals have passed through the body part, and identifying the received signal strengths of the analog signals at the receiver. The method calculates attenuation values between the transmission signal strengths and the received signal strengths to generate an identity signature based on biometry.