  Digitisation is often viewed as beneficial to a user. Whereas traditionally,
people would physically have to identify to a service, pay for a ticket in
cash, or go into a library to access a book, people can now achieve all of this
through a click of a button. Such actions may seem functionally identical to
their analogue counterparts, but in the digital case, a user's actions are
automatically recorded. The recording of user's interactions presents a problem
because once the information is collected, it is outside of the control of the
person whom it concerns. This issue is only exacerbated by the centralisation
of the authentication mechanisms underpinning the aforementioned services,
permitting the aggregation and analysis of even more data. This work aims to
motivate the need and establish the feasibility of the application of a
privacy-enhancing digital token management service to public transit. A
proof-of-concept implementation is developed, building upon a design proposed
by Goodell and Aste. This implementation was optimised for the public transport
use case. Its performance is tested in a local environment to better understand
the technical challenges and assess the technical feasibility of the system in
a production setting. It was observed that for loads between one and five
requests per second the proof-of-concept performs comparably to other
contactless payment systems, with a maximum median response time less than two
seconds. Due to hardware bottlenecks, reliable throughput in our test
environment was limited to five requests per second. The demonstrated
throughput and latency indicate that the system can feasibly compete with
solutions currently in use. Yet, further work is needed to demonstrate their
performance characteristics in an environment similar to that experienced in
production.
