3D Printed Bump Keys

Getting past a locked door is easy if you have the right tools. It’s just a matter of knowing how to adjust the pins inside to an even level while turning the mechanism at the same time when everything is perfectly in place. That’s the beauty of a bump key. You never have to see the actual key or what it looks like. And with a simple hit to the back of the key, and bumping it just enough, the lock can magically be opened.

Lock picking items like this can be ordered online for a couple of dollars, or as [Jos Weyers] and [Christian Holler] showed in a recent Wired article, alternatively you can print your own at home. The video of these 3D printed keys (which can be viewed below) attempts to prove that a person can unlock a door with plastic, which was a little bit surprising to us because it seems like the edges would break off right away. But as it turns out, a thin plastic bump key can be made and does function. Not sure how long these keys can last though, but sometimes all you really need is a one time use when trying to open a specific, tricky lock.

As the article states, “Weyers and Holler aren’t trying to teach thieves and spies a new trick for breaking into high-security facilities; instead, they want to warn lockmakers about the possibility of 3-D printable bump keys so they might defend against it.” Although this information is geared towards lockmakers, we see our Hackaday readers finding this data useful as well. Organizers of hackerspaces who hold regular lock-picking events might want to print their own keys and teach classes centered around security. The uses for this are boundless in regards to educating the public about how locks truly work.

We searched through Shapeways, i.Materialise, and Thingiverse searching for 3D bump key STL files and came up short handed. So if you decide to create your own version of this, be sure to upload the models somewhere so other people can learn from it!


28 thoughts on “3D Printed Bump Keys

    1. Probably so you can actually have them picked when you lock yourself out. Its not like a home with this lock could not be broken into. Just break a window, or a door jam, etc.

      1. Lol, so it is actually a feature?

        Around here the solution to “lock yourself out” problem is just to have a spare key at some trustworthy place. Indeed locks don’t prevent breaking in, but atleast make it more difficult and cause break-ins to leave clear evidence for insurance.

        1. “Locksmiths” however thieves do.

          the idea of bumping the lock is to open it and reset it without anyone even knowing or to make the advance forensics required to detect bumping .

          Locksmiths drill out the lock because the lock is usually broken or missing the key and requires replacing.

          some locks a Locksmith may require photo id before working on it

    2. It all comes down to price points and distribution deals.
      High quality disc locks exist (Abloy Discloc Pro, Abloy Protec, etc) – and certainly have their uses.
      But, the general public are generally incredibly tight when it comes to paying for locks, padlocks, etc – and will opt for the cheaper/est options available.

      Incidentally, lock manufacturers / designers are fully aware of lock exploits, drilling, bumping, etc – agian, it comes down to price point and target market. If you’re purchasing a $5 padlock, it’s not going to be using anti-bump, anti-drill, anti-pick techniques.
      Quite a few of the big brands (Assa Abloy, Medico, etc) employ people coming from the lockpicking world, and there is quite a bit of cross over.

      NB: Work in lock manufacturing

      1. Because the patents on the original Abloy designs have expired decades ago, why haven’t they replaced the pin tumblers as the most common off-brand design? Is there something about a disc lock that is so much more expensive to manufacture?

    3. It really depends on what are you trying to protect. Same thing with encryption. If you want to hide your porn stash or secure your data in case the PC is stolen, a truecrypt is a good choice. If on the other hand you must hide some data from jewish, american or russian gov. then using TC might not be the best choice (see rubber-hose cryptanalysis).

        1. Jewish? Unacceptable! The bit about Russians and Americans is fine though. Remember kids, using the word “jewish” in a sentence automatically makes you antisemite, even if, as it is the case here, there is actually no negative connotation. Thanks Will for your zeal, spending your days looking for people using the “j” word finally paid off: you nicked one! Everyone, give Will a big pat on the back.

    4. http://goo.gl/vXwzTV

      “The purpose of locks, the locksmith said, is to protect you from the 98% of mostly honest people who might be tempted to try your door if it had no lock.”

      “…locks won’t do much to protect you from the hardened thieves, who can get into your house if they really want to.”

      Unless you have the security level of Fort Knox a standard deadbolt will suffice.

      Not to mention economical opportunity cost, most people will not spend $300 a lock to increase the probability that a burglar will be stopped and give up.

    5. The vast majority of them are very easy to pick. The problem with them is that it is easier to destroy them. That is what theives do. They don’t care about fancy skill. They are looking to steal stuff fast. A drill with an endmill can take the front face of disc detainers off in seconds and the guts can be removed. It takes more time, a modicum of skill, and is easier to thwart similar attacks on traditional locks.

  1. At first I thought that this was completely stupid- a bump key takes very little time to make with a file and the key will last ages. But then I thought about the lock. Bumping with a metal key can damage the pins. Plastic will be softer and hopefully lessen damage.

    1. Good point. The ultimate defense against bumping, along with everything else, is insurance. Bumping leaves very obvious dents on pins and sometimes messes up the lock face. Insurance companies will not fight claims with such obvious evidence. With plastic, it is not likely to leave dents in the brass. Hopefully, probably, it leaves trace evidence.

  2. yeah, good luck finding a 3d printer that can handle those geometries on that scale. not many people will have access to a selective laser sintering machine, and even then, i can’t imagine that those parts are all that strong, like being able to take the abuse of bumping!

  3. I wonder whether you could 3D print a mold, then cast in JB Weld.

    I also wonder about validity of the “disclaimer” typically included with these types of articles, like:

    “Weyers and Holler aren’t trying to teach thieves and spies a new trick for breaking into high-security facilities; instead, they want to warn lockmakers about the possibility of 3-D printable bump keys so they might defend against it.”

    It would take a large increase in the use of bump keys, either real or imagined, to illicit any significant defensive response from lockmakers or consumers. For any increase below that, the info provided is in fact only benefiting a few thieves and spies.

    Let’s assume though that this article and whatever events/publicity that follows, results in 50% of all locks being upgraded. The thieves are hardly inconvenienced, having to try only two locks on average. The lockmakers also make a fortune. The mass populace is on the losing end to some degree, no matter what they choose to do.

    So no, I don’t buy into Weyers and Holler’s altruistic claims. Their actions are of anarchists, or maybe lockmakers…

  4. Funny that they don’t make the software public, since they share enough to infer how to do by hand in – say – blender what the code would do for you. Wouldn’t both trying this with a FFF printer, but it would be fun to experiment doing this with a normal lock.

    Similarly, if one had a photo of a key and its dimensions and a picture of the slot it goes into, you could easily make a plastic reproduction of such a key without any magical software.

    1. I think you are thinking about “burning” a key. You take a blank and flash the edge with a candle, lighter, etc and stick it into the lock and twist it a couple of times. You then file down the cut marks by the pins. Rinse and repeat a bunch and you eventually cut your own key. It is far easier to “carbon copy” a key with an original by doing the same thing holding them together. These are both old old methods though and without a bit of skill ymmv. Sorry if you were shooting for something else, it just reminded me of that. There are a number of “emergency keys” that are credit cards with fold out keys- you may have some luck with them :)

  5. Lockmakers can defeat a proportion of criminals using plastic bump keys by keeping the barrel of the lock heated to plastic melting point. Or using silicone tubing to dispense acetone into the chamber.

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