An affordable and safe keyholding lock box.
Find the current revisions of the project here:
This project aims to create a secure lockbox that can be connected to online keyholding services with minimal effort. With a companion app on a desktop, locking up is as easy as running one single command, and uploading the resulting .txt or .png file. Usage of the box is fully private and neither the box nor the controlling software pings out to remote servers. Privacy is a right we take very seriously.
The project has been designed to be as easy to set up as possible. Off the shelf components like the NodeMCU Amica and an SG90 servo have been chosen for their wide availability. The rest is 3d printed for easy customization.
- Secure. No way to break into the box without physically destroying it
- Safe. Is the emergency bigger than the cost of replacing the box? Just force the lid off. (This does destroy the box!)
- Cheap. Only one actuator and no real time clock necessary
- Compatible with all locks based on small physical keys (larger key compatibility coming soon!)
- Based on common off-the-shelf (COTS) and 3d printed parts
- Fully local system, no dependency on the cloud and no telemetry is collected
The box can be updated manually but will not be seeking for the latest updates automatically. Updating the box is not hard, but requires some technical steps. An update utility is in the works. Until then, the version of the control software that matches the firmware of your lock box will be accessible in this repository.
- Print, or have someone print the box and lid.
- Aquire a 9 gram SG90 servo and a NodeMCU Amica (a Lolin does not (yet!) fit the current box design).
- Cut one of the horns of the servo to length. In the locked position it should stick out a little through its slot so it goes inside the lid when locked.
- Flash the MCU.
- Connect the servo to the MCU. Brown to GND, red to 3v3, orange to D4.
- Pull the power wires through the hole in the bottom of the box and connect 5v (red) to Vin and ground (black) to GND. (See the power heading below.)
- Connect to the box' wifi AP and have it connect to your network.
- With everything outside of the box, do a test run.
- Make sure the horn is in a neutral position.
- Lock the box.
- Verify that the horn is now in the correct rotation to stop the lid from lifting off.
- Open the box with the password in the newly created txt file.
- If there are no issues, the assembly can be pushed into the box in a gentle manner. Make sure the side of the MCU with the power wires is on the side of the box with the hole.
Not all 9g servos are the same. If the horn moves too much (only about 90 degrees is necessary) then the open- and closed postion can be adjusted using the controller.
Connect power to the microcontroller. Put the key into the empty partition of the lockbox. Put this lid onto the box. Lock using the controller, send the password away to your platform of choice (Only Emlalock has been verified), and delete it permanently on you local machine. The box can now be safely turned off. It only needs to be turned on again when you have the password. For details on how to use the controller, read the readme
The box may draw 0.4 amps at 5 volts with the servo stalled according to real-world measurements. This should be easily handled by most modern USB devices. Note that some servos may not perform identically to ours, even if they're marketed as 9g SG90.
The box allows dupont cables to come out of the bottom. You can power it with a female USB micro-b to dupont breakout board along with 2 dupont female to female wires; solder your own USB to dupont cable; or even 3d print a USB to dupont adapter.
If you had to abort a session, the electronics can be reset and used in a new box. This can be done by simply connecting the usb port on the microcontroller, listening on the UART (picocom -b 9600 /dev/ttyUSB0 or with the Arduino IDE) and pressing the RESET button on the microcontroller. It will now send data about its status and the password. Use this password with the control software to unlock like normal.
Early versions of the box were controlled with a TCP connection. This is no longer recommended. Use the latest version of the MCU firmware along with the latest version of the control software. Boxes and lids come with their commit hash on the top and bottom. eae25c is a good minimal box but relies on a specially printed locking cam. Later boxes like acaa41 use a horn that comes with the servo that has then be cut to length. Boxes and lids of the same commit hash are guaranteed to be compatible. Some other boxes and lids may be compatible with each other as well, but this is not documented.
This lockbox is an ongoing project. We're on version three of the box, and the second major version of the protocol. The following changes are planned for this version:
- Verify controller functionality on Microsoft Windows (Partially complete)
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Add web-based controller(Scrapped due to technology restraints) - Create a key compartment in the box
- Perform destructive tests on the box
- Add compatibility with other online keyholding platforms (image mode)
A new version will support Bluetooth, opening the way for control right from your browser, or from a mobile app. This version is still several months away. Pull requests are welcomed!