Selling train tickets by SMS

Abstract: 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).