Smart cities often rely on technological innovation to improve citizens' safety and quality of life. This paper presents a novel smart mobility system that aims to facilitate people accessing public mobility while preserving their privacy. The system is based on a zero interaction approach whereby a person can use public transport services without any need to perform explicit actions. Operations related to ticket purchase and validation have been fully automated. The system is also designed with the privacy-by-design paradigm in mind, to preserve user privacy as much as possible. Throughout the paper several technical details are discussed as well to describe a prototype version of the system that was implemented. The prototype has been successfully tested in the city of Imola (Emilia Romagna, Italy) in order to prove the system validity on the field.