Like all good inventions, this one sprouted from frustrated necessity.
“Damnit. I have lived here a long time”, I thought, mentally kicking myself. “I should have a solution to this by now”.
It was late, starting to rain, and I was tired and jet-lagged, lugging two heavy bags, standing on the street outside of my locked apartment. I forgot my keys, and none of the other neighbors were answering.
Directly in front of me was the building’s shared garage door. And few more paces inside was a lockbox with some backup keys to the apartment. If only I could get in to the garage! But I didn’t have the opener with me, and garage door didn’t have an external pinpad.
But what if it could?
The Goal: A Virtual Pinpad
Everyone these days is armed with a smartphone, and I’m no exception. What if I could open the garage door while nearby, with nothing more than my phone?
I started to sketch out a few design goals.
- It has to open the door, securely, without a physical key. The first requirement, perhaps obviously, is that I have to be able to get in without a special key or hardware. It also can be no less secure than existing methods.
- It cannot require modifications to the building. Although I have a garage remote, I don’t have permission to modify the building (e.g. attach or affix a device at or near the garage).
- It cannot require a dependable network connection. Internet of shit is riddled with cute connected products that fail miserably in predictable, less-than-perfect scenarios. Like the fridge that bricks itself when wifi is down. This thing needs to work even without wifi. This can not be internet of shit.
The first idea: “Open Sesame!”
My first idea was a sort of acoustic door lock. It would work something like this:
- Build a microcontroller with a microphone and a garage door opener.
- Train it to listen to a specific pattern of thumps, like a morse code decoder.
- Stash it near the garage.
- When the thunk-pattern is detected, presto! Open the door.
It seemed fun and would be cute. But I quickly ruled it out. The “thunk” mechanism seemed like it would be low security at worst (anyone nearby could hear it), or at best very cumbersome.