Keyless entry via SMS

[Billy’s] work got new keys which he didn’t want to carry around with him. Instead he built this system to unlock the door via text message. It is based around a Spinneret Web Server which drives a servo motor. He’s rigged up a pipe hanger to add some leverage to the lock’s knob. We’re surprised that the servo has enough power to do the job here but the video after the break shows there’s really no problem. On the communication side of things [Billy] set up Twilio to wait for text messages from an approved list of senders, then used an HTML form to issue the unlock commands to the webserver.

[via Make]

15 thoughts on “Keyless entry via SMS

  1. Hey, awesome! And if you use an MVNO as shitty as mine, you can text the door and stand around half an hour waiting for it to unlock!

  2. Huh. I’m surprised that the little servo has enough torque to turn the lock as well.

    The SMS whitelist doesn’t give you amazing protection though. There are sites online which let you spoof a SMS and type in whatever you want as the sender. I guess you’ve got bigger problems though if somebody knows you well enough to know your cell number, your door lock cell number, how to operate it and is malicious :)

  3. For me it is interesting, if it is possible to “override” the servo with the plain old mechanic key if the system would (for some reason) went mad?

  4. not much on security. keep it lan enabled and a wireless router would be more secure, and keep your friends from unlocking your door in the middle of the night or while your away, bad way to get punked.

  5. I’m surprised that servo has enough torque to lock the door. I kind of want to see a vid with it actually unlocking the door. When it’s like this there isn’t as much binding on the bolts of the lock.

  6. It’s not like the servo is connected directly to the knob.

    There is a lever attached to it.

    Notice how the servo horn turns a bit more than the knob.

  7. Is it possible to spoof the phone number in a text messg? I.e. an attacker could send a sms with a false header saying it was from billys phone? shouldn’t he use some sort of encryption/ handshaking

    Ric

  8. @Olek. Yes, you can turn the tumblers and the inside handle on these locks independently. And I love the fact that HAD’s comentariat’s first thought is, ‘How do we break into this dude’s house?’. Splendid.

  9. Whoa. How overly complicated can you make a system? Quite much apparently.

    How about just using a $25 GSM modem from DealExtreme mated to an AVR? Total BOM cost $30 and two potentially failing steps eliminated from the chain of opening the door.

  10. So to avoid carrying a key that unlocks your door instantly, you need to have your phone (not only can you lose it like your keys, but you are more likely to have your phone stolen than your keys, it can run out of battery, you can have poor coverage, the lock is not aesthetically pleasing, consumes energy, it can run out of electricity say if there’s a power cut, …), type and send a text message, and wait (see unlocking in the video) for your device to receive the text before you can get in or out?
    Yet another hack making a fine and perfected solution less practical, just like a binary clock.

  11. i would like to know how the device detects that the door is actually closed? or if there were mechanical failures, will it still reply “door closed” even the mechanical lock malfunctions? thanks for the help Mike

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