Simple RFID Door Lock System

Group entry hacks are a favorite for hacker social groups. Why use old fashioned keys when you can use newfangled electronic keys? If you are looking to build a simple RFID-based security system to secure your important stuff, this project from is a good place to start. In it, [Joe Roberts] outlines the process of building a simple RFID-triggered mechanism for their office door.

It’s a pretty simple setup that is composed of an RFID reader, a Rasperry Pi and a Neopixel ring. When someone places an RFID card against the reader hidden behind a poster by their front door, the reader grabs the code and the Pi compares it with a list of authorized users. If the card is on the list, the Pi triggers the door lock using a signal line originally designed to work with an intercom system. If the user isn’t on the list, a laser is triggered that vaporizes the interloper… well, that’s perhaps in the next version, along with an API that will allow someone to open the door from the company chat application.

At the moment, this is a clean, simple build that uses only a few cheap components, but which could be the basis for a more sophisticated security system in the future.

23 thoughts on “Simple RFID Door Lock System

  1. So far I’ve not seen anyone implement a card reader in the most obvious (and possibly most secure) place: in the door mat. Have the RFID chip inserted into the authorized person’s shoe, and when they walk up to the door, they’re checked and admitted. And it won’t be as easy for someone to get the code in the wild.

    1. So they have to wear a specific pair of shoes? When transferring an insert would be annoying compared to just leaving something on your keychain or in your wallet…

      Better to use a Nordic Bluetooth or something these days, they have AES, and since it’s longer range wireless you don’t need a visible sensor

      1. Longer range… Like the door already opens when you’re within 10 meter of the door? That’s a big window of time for some perpetrator to push you aside and enter the building himself…

    2. Add a second factor with the embedded certificate calling up that user’s required (tap) dance sequence?
      Third with singing the matching tune to the dance?

      But seriously, certainly interesting. Stand here, here or here for an authorized entry. Stand there if you’re being forced to provide entry and need to be met by security.

  2. “I might also add a front-end that shows who is in the office, based on their card login – although this may be slightly Orwellian.”

    You could co-ordinate pulling up their staff photo along side of a webcam on the reader and the entry (live, and snapshot). Scrolling sets of images: staff photo, reader & entry.
    And then you add recognition software to monitor it for you.

    1. It should be done like in Harry Potter: a big “painting” asking you for password and the AI behind it will also recognize you. And perhaps your authenticating token. And perhaps a secret hand gesture. And perhaps a certain hat with a hidden pattern. And a banknote with a certain serial number. And a sample of spit, blood and urine to identify by DNA and past known viral infections, so you’ll deny access for the clones. And i have no more ideas.

  3. What always drives me nuts about this kind of article is that the hardest part — the part that actually opens the lock, is never specified. In this case it’s just tossed off as “we repurposed an intercom buzzer.” Well, THAT helps a lot! Finding, sizing, and reliably implementing RFID door locks is 90% about the lock and only about 10% about the electronics.

    1. having installed these systems, 100 percent this. the reader is usally done and configured in about half an hour, the lock assembly takes longer to cable, test, and fit for reliability. (alot of shimming and cutting and testing and crying….so much crying….)

      The short list:
      -actuated bolts are good (make sure you get the kind that its failure state is open, fire codes being what they are)

      -Magnets are cool, but also a terrifying mess to install and get to latch properly. (A great deal of thought needs to go into making sure their power supply is up to snuff)

      -stuff that fits into the door, instead of the frame, are going to be a royal pain to cable up. You are either going to have to live with the wires being duct taped to the inside of the door, or buy long, expensive drill bits and hope ya don’t mess it all up.(or fish around for long periods of time if its a metal door) stress point at the door hinge often causes issues in these setups.

      -do a thorough inspection of the door closer beforehand, far, far too many of them take up all of the real estate inside the top of the door/door frame and will cause you alot of grief doing the install.

      -Make sure the door is in good condition beforehand! alot of grief can be caused by trying to shim up your latching system, not getting it to fit, and finding out later the door itself is crooked or loose.

  4. I’m already working on a Pi based MQTT broker that talks to a network of Feather Huzzahs and accepts infra-red as an input. I’ve taken several programmable Harry Potter wands and ‘trained’ them with the appropriate IR code from the Pi starter kit. I use the feathers to activate my props through the feather relay boards. There’s no reason why I couldn’t use this setup for a door. hehe Leave the wand in a holder next to the door and include an audio input component. After all, “It’s leviOsa, not levioSA!” ~JKRowling

    The same could be done with interactive wands from Ollivander’s wand shop at Universal Studios. Those are a different animal, are relatively short in range, and would require the integration of something like the Playstation Eye, in order to function. It would be considerably more accurate for the movements.

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