MATTHEW D2.2 Report on Privacy Algorithms and their Implementation

At a high-level perspective, MATTHEW intends to enable new applications and services on
mobile platforms using multiple roots of trust. In that respect, the privacy of users is considered
as being a critical asset and therefore MATTHEW considers this problem from the design phase
on. Dealing with multiple roots of trust enables the possibility of transfers of credentials from
one secure element to another. Of course, the meaning of the term credential may differ
depending on the considered application. Therefore operating multiple roots of trust lays
the ground for a notion of mobility for credentials, which may be stored and used within
different secure elements as users interact with their devices in their daily life. This document
explores privacy algorithms suitable for realizing the project’s goals. It considers, in particular,
how attribute-based credentials (ABCs) help us realizing the advanced ticketing use case (Use
Case 3) that aims at providing anonymity for tickets in public transport. The results are
compelling, as presented protocols allow for highly efficient ticket presentations. Moreover,
it gives a thorough discussion of these approaches, of their efficiency, of the realization of
transferability in both the single-use and the long-term ticketing use cases and of ways to
implement them efficiently.