Bluetooth Low Energy Beacons currently provide a great potential for indoor localization to users with smart devices. This paper implements a security concept to mitigate weaknesses of current beacon concepts against forgery and request tracking. The method authenticates beacons with dynamic data by attaching secure signatures. The architecture is especially useful as a many-to-many solution. A test setup shows applicability in a public transportation vehicle to accompany the passenger information system and traveller route planning. A setup on a tram equipped with up to five beacons provided securely authenticated passenger guidance in and around the tram, referencing even a user's device in a pocket.