Block Diagram. The security system comprises of an Arduino Uno microcontroller and a standard SIM900A based GSM/GPRS modem. The whole system can be powered from any 12VDC/2A power supply unit/battery.

A few months back at the Black Hat Security conference Cody Brocious demonstrated how you can easiy open an Onity hotel room lock, the standard system used in many hotel chains, with an Arduino ...