3D Printing House Keys (and secrets)

Guy releases parametric 3D models for SC1 and KW1 keys, so anyone with a RepRap (~commodity) 3D printer can print keys with an arbitrary code. While nothing special for SC1 or KW1 (those are generic), this is earth-shaking as a development in physical security.

Rather a lot of manufacturers use patent-protected keyways as copy-protection for keys. The patents mean nobody else can sell blanks to a particular cylinder. As a result, it’s “supposed” to be imposible for thieves or college kids to duplicate keys to a building.

If you can just 3D print the keys, that breaks everything. (Yes, the Keyway King and EzEntrie did something similar first, but have major limitations 3D printing doesn’t.)

Still, nobody should be surprised. Lock manufacturers are slowly learning a fundamental truth: secrets tend to become public like water tends to flow downhill. Keeping something secret or protected carries a major cost. Making something public is often free, and may even bring a profit. As a result, everything tends to become public over time.

You can counter this only by cherry-picking the bits that really do need to be secret and focusing your energy there — the key biting or crypto keys or reporters’ sources’ names, for example. Trying to obscure whole systems, particularly with methods (like patents) that convey procedural and not technical security is not gonna fly these days.


“The goal here is to generate working house keys by inputing the key code of the lock into a parametric OpenSCAD model.[…]

I created an SC1 model to start with, but I’ll probably make a KW1 soon.

EDIT: I uploaded a KW1 model as well.

Designing the key model was actually pretty straightforward. I measured a key with a ruler and calipers and created an approximate model of it that is reasonably easy to print. I then got pin depth specifications and parametrically differenced them out of the model. To generate new keys, you can just edit the last line of the file and enter in the key code for your key. If the code isn’t written on the key, you can measure the height of each bit and compare to the numbers in the Root Depth column on the aforementioned pin depth site. Perhaps more nefariously, you could implement something like SNEAKEY to generate key codes without physically measuring the key. “


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