KeysForge will give you printable key blueprints using a photo of a lock

Smartphone photo of lock keyways enough to produce ready-to-print CAD drawings

32c3 Hackers have been gifted with an online web service that can produce blueprints for 3D printed keys from nothing more than a photograph of a lock.

Eric Wustrow

The KeysForge application developed by an academic trio drastically simplifies the complexities in developing keys, allowing amateurs to snap a photo of a lock and have the respective key 3D printed.

University of Colorado infosec assistant professor Eric Wustrow and two colleagues revealed the work at the Chaos Communications Congress in Hamburg last month.

"We made an automatically generating 3D model program [which] takes a single picture of the keyway (lock) and produces a model in CAS (computer assisted design)," Wustrow says, adding that a smartphone photo will suffice.

"You can then take that model and print it on a 3D printer or ship it off to Shapeways or whatever.

The application will attempt to wrangle the image into black and white to distinguish the keyway. It then continues thresholding looking for the largest black blob.

"We found this was surprisingly effective".

The application is useful in sophisticated and targeted attacks using high resolution lenses that were previously shown to be sufficient to allow keys to be replicated using photographs shot at significant distances.

The printed keys are surprisingly effective; the trio measured the strength of keys in various picking applications finding an eight cent 3D-printed key is almost as good as a metal version worth up to US$25, or more than 300 times as expensive.

They tested several dozen keys made from Polylactic acid (PLA), nylon and acrylic, alumide, and metals including stainless steel and brass, using an expensive torque key to measure strength.

It could also help pickers learn master keys more cheaply. In 2007 researcher Matt Blaze demonstrated how pickers could query their locks to replicate the master key.

Master keys are taller triggering the lowest section of the pins, while non-master keys are lower and trigger higher pins.

Pickers would print one section of their key to be too tall while leaving the remainder unaltered. The tall section would be shaved down until the lowest pin is activated allowing the lock to be turned.

That would be replicated in other sections of the key until all the lowest pins are determined, therefore replicating the master key.

Wustrow said such innovations are common in lock picking but less so in lock development.

"We are just starting to make 3D printed keys viable, and this is only going to get better as resolutions become higher and technology more ubiquitous." ®

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