  Selling train tickets has evolved in the last ten years from queuing in the
railway station, to buying tickets on the internet and printing them. Both
alternatives are still viable options, though they are time consuming or need
printing devices. Nowadays it is essential to offer a service that is as fast
and efficient as possible: mobile phones provide an accessible, affordable and
widely available tool for supplying information and transferring data. The goal
of this project is to design a train ticket contained in a SMS message. While
there are several challenges related to the project, the main one is the
security and how we can digitally sign a train ticket that is contained in 160
characters. The solution offered in this project is the implementation of the
MOVA Signature (from the name of the inventors MOnnerat and VAudenay) that uses
an interactive verification and therefore allows signature of 20 bits (roughly
4 characters).
