Use the subway while keeping your hands in your pockets
Alice enters into the subway station and walks in the subway hall named "with electronic ticket only". After few train stations, Alice leaves the subway.
At no point in time, Alice gave a ticket or placed her mobile phone in front of a reader.
How does this work?
By walking in the subway hall, Alice starts the eGo pairing between the eGo compliant device (the subway floor in the hall named "with electronic ticket only" ) and the eGo device (e.g. his watch). The intrabody signal flows from the floor under the alice's shows up to eGo. The eGo pairing done, the subway information system and eGo have a logical channel of communication on which they can exchange data. For instance, the subway information system may access to the Alice' subway electronic ticket into the eGo.
The UWB technology allows long range operations (>10 m) then subway information system and eGo may exchange application data during several seconds. This possible long transaction time budget allows the use of complex cryptographic schemes based on asymetric keys or zero-knowledge principles.
Some subway users may be not equipped with eGo then they have to use another hall equipped with legacy gates. The UWB technology provides a means to localize an eGo device and then its user so, we can detect in a given hall segment who carries an eGo and its associated electronic tickets and who does not carry an eGo in using automatic face tracking (based on a camera).
The "eigenfaces technology for face recognition" may provide a fast solution to identitify people in motion and then people having no electronic tickets may be detected and later on physically controlled.