The work that I am reporting on is work that we recently started with a Luxembourgish company, itrust. Together with this company we are working on the design of a security architecture and security protocols to enable location-based services. The general architecture of the system consists of a satellite and a local user device, such as a mobile phone. This user device helps you to use location-based services offered by a service provider. Because the service provider needs to be sure about your location, we have also introduced a location verifier. You receive the data from the satellite, calculate your location and forward the data and the calculated location to the location verifier. In some way, the location verifier then validates your location and returns a certificate. Then you can use this certificate to convince the service provider that you are really at the location where you claim to be.