A system and method for efficiently establishing secure mobile device communication for location-aware applications. A beacon device broadcasts encrypted packets. Each of the packets includes an indication of a respective time of broadcast. A mobile computing device, such as a smartphone, receives a packet that is broadcast from the beacon device. The mobile computing device determines the packet corresponds to a particular location-aware application and sends the packet to a server. The server determines an expected latency for the received packet based at least in part on crowdsourcing, which includes latencies of other packets sent from the same location. If the server determines the latency of the received packet is not within an expected range, the server considers the packet to be invalid.