Staying safe and protecting your valuables when away from home should always be a priority. Like most people, you might think that your electronically locked hotel door is secure enough to keep out the unwanted. There’s no physical lock to pick and you need a key card to get in, that’s good, right?
Unfortunately, it’s not. There’s a tiny device out there that can open approximately one third of all hotel doors in seconds.
Using an Arduino microcontroller and a few other components, almost anyone can build a device small enough to fit inside of a dry erase marker. This can then be used to unlock most hotel doors, including the dead bolt, in no time at all.