Mobile devices are nowadays widely employed by people all over the world, with almost 3 billion users interacting with smartphones or tablets in their daily life. Such devices are not anymore used for personal communication only, but also for a variety of other applications, ranging from accessing the Internet, storing personal data, making payments, and gaining access to restricted services or areas.
With the rise of the Internet of Things, a growth trend similar to the one characterizing mobile devices in the recent past is now observed for wearable devices such as smartwatch and activity trackers, that is, smart electronic devices equipped with micro-controllers which can be incorporated into clothing or worn on the body as implants or accessories.
Given the types of data must such devices can capture, process, and store, proper secure mechanisms are needed to avoid potentially harmful threats related to security and privacy loss. It is therefore of paramount importance to design workable and effective solutions to implement automatic recognition systems within mobile and wearable devices, with biometric systems certainly representing the most interesting alternative to achieve this goal