User Authentication Method for Wearable Ring Devices using Active Acoustic Sensing

The ring-type devices currently on the market are not typically equipped with authentication. This paper proposes an automatic and continuous user authentication method using active acoustic sensing with a speaker and microphone mounted on the ring device. The proposed method authenticates the wearer by extracting the fre-quency response of the acoustic signal acquired by the microphone and calculating the similarity between the frequency response of the current wearer and that of a pre-registered individual. It takes advantage of the fact that the ring device is in constant contact with the finger and that the shape and composition of each user’s finger have unique acoustic characteristics. The ring device was created by fixing a flexible piezoelectric element to a 3D-printed ring and was evaluated using seven participants in two states: a relaxing hand and a gripping hand. The average EER was 0.034 for the relaxing hand and 0.027 for the gripping hand.