Working handcuff keys printed on a 3D printer

German hacker Ray has shown that he can print working Dutch police handcuff keys from plastic on his 3D printers, and has released the 3D files so you can print your own:

He used a 3D printer to print handcuff keys. And not just any ordinary handcuff key ... no, it's the official handcuff key from the Dutch police! At first the police officers at HAR were a little reluctant to event try out the plastic key he printed. But he found another way to verify the key he printed was the correct one. I guess these officers never thought about wearing keys concealed, especially when talking with Mr. Handcuff himself. Given the megapixel camera's on the market today it was not so difficult to verify the key he printed was the correct one.

At the end of the day he talked the officers into trying the key on their handcuffs and ... it did work! At least the Dutch Police now knows there is a plastic key on the market that will open their handcuffs. A plastic key undetectable by metal detectors....

Printing police handcuff keys ... (via Schneier)


  1. Does this mean that Dutch prisoners will no longer be allowed access to high-resolution digital cameras and 3D printers?

  2. This is how technology evolves. This is how locks get better. The old one becomes obsolete, and new ones must be designed taking current technology into account. Some people do not understand this process, and it causes them fear. The cure for fear is knowledge, not to put your fingers in your ears and pretend the problem (that keys can be replicated) does not exist.

    As it is, the key can already be replicated by conventional means, if someone was able to inspect the original. The only things required would be a bit of mild steel and a file. The method described in the article makes it “easy”, provided your definition of “easy” includes access to a 3D scanner and 3D printer. Better to figure out a new idea now before they become commonplace, hmm? In my opinion, key technology was outdated long ago. Anyone can use a bit of putty and press a key into it to make a reverse reference from which to mould or carve a new copy.

    [I don’t want to create an account, I would rather you read my comments and judge them on their own merits rather than by the association you might make with a particular username over time]

  3. @4 Apoxia

    What would you suggest? That security vulnerabilities just magically cease to exist? This fellow could have easily found the vulnerability and then NOT brought it to the attention of the authorities, instead using it for elicit purposes.

    What, precisely, are you finding fault with?

    ~D. Walker

  4. Hi #6

    I am finding fault with the idea of deliberately creating copies of keys which are used for very serious purposes. Do you honestly believe the police force will instantly acquire excellent new systems to prevent people from exploiting this? Would you be happy if someone copied your house or car key? Would you feel safe working in a prison where a handcuffed criminal could potentially open their cuffs and assault you?

    Or maybe you aren’t concerned because it doesn’t personally affect you and you therefore have nothing to worry about and can instead ruminate on the esoterics of progress and technological advancement.

  5. I don’t know, seems like a white hat hacker for key technology. I doubt he means any harm and I agree with the previous poster that stuff like this helps technology evolve.

  6. @Apoxia I have 2 or 3 prison guards and a few cops in my extended family. Cuffs are easy enough to get out of and have been for some time. This is why a lot of law enforcement organizations have been moving to plastic handcuffs (a very low tech solution, btw), and even those aren’t guaranteed.

  7. #7

    If handcuffs are the only thing keeping police officers safe then they are going to be assaulted. People already have methods for opening up the restraints.

    To pretend that this key drastically alters the risk of assault to police officers is silly. This technology isn’t going to simply disappear tomorrow, and it isn’t so complex other people can’t figure it out independently. The German Hacker is doing the police a favor bringing it to their attention.

    Security through ignorance is bound to fail.

  8. American handcuff keys are a standard. I have one on my keyring.

    Police officers don’t view handcuffs as a way to completely immobilize a suspect, it’s a level of deterrence and a way to slow them down. When someone is handcuffed you still have to keep an eye on them and make sure they aren’t up to funny business.

    Again, I say, they use a standard key in America. It changes nothing. Just because people have access to the key doesn’t make them not work.

    The thing that makes this cool is the 3D printer, obviously.

  9. I believe you can also open handcuffs by sticking something in sideways to open the ratchet mechanism rather than picking the lock. Certainly works for toy versions.

    The moral is, the point of handcuffs is to make it rather more difficult for people to run away, not hold them in itself. For eg, don’t leave people alone and expect them to still be there.

  10. #11

    I didn’t “pretend” that this key drastically increases risk, I do actually know a lot about risk and probability. I have also worked in a prison where people do occasionally get assaulted. I don’t think it is a good idea to make these things available just for the fun of it, or in some attempt to alter a slow-moving and underfunded system that will never be able to keep up with the latest security developments, no matter how hard you might want it to. My reaction is that this is stupid and potentially dangerous.

  11. Considering that I can unlock handcuffs behind my back using a paperclip and carrying on a normal conversation, I am not impressed. What is the point?

  12. I honestly think that the prisoners that could benefit from this are more than likely never going to get this information because it is not posted on a free porn site or are illiterate. Either way just because it was easy for the poster to make the key doesn’t mean it would be easy for your “average” criminal.

  13. @Grimc, @anonymous, @amuderick,

    It’s my understanding that dutch handcuffs cannot be picked with a paperclip, and the key is only sold to “law enforcement”. The standard American key, which can be bought at any S&M shop, will not work. Look at the key– it looks like it fits a four tumbler lock.

  14. This appropriately falls under the category of “grey hat” hacking, which is the most interesting category.

  15. That looks like an easy enough design to replicate without resorting to a slow and costly 3D printer. Anyone in professional need of an unauthorized handcuff key (a petty crook) probably doesn’t have access to a 3d printer, and probably has a much less fussy way of getting/fabricating a key.

    This is a cool proof-of-concept boast, not a serious affront to law enforcement.

    It does suggest a clever Bat man villain escape sequence, however:

    “Ha ha ha! We have evil deeds to perform for the next 5 or 6 hours. Let’s lock our captive in the 3-D printer lab until our return. He’s securely handcuffed. What could possibly go wrong?”

  16. Apoxia: Concern, meet troll!

    The actual potential for security comprises arising from this is neglibible.

    But, you ask, how is this any good?

    Well, it’s a reminder to officers that cuffs should never be relied upon solely as a means of restraining even ‘peaceful’ arrestees, and that anyone using these cuffs needs to be aware of their safety.

    It also means that even though there is glacial-like progression in these environs, when it comes to upgrading equipment, there will be another question to ask when that time comes, and manufacturers will have to address those concerns – ideally with an improved product.

    So while it’s not an instant boost in security or safety, it damned well should lead to one. Progress is progress and improvements are improvements no matter when it happens.

  17. @jerwin

    The paperclip isn’t used to pick the lock, but as Lyndon @13 said, it’s slid into the ratchet mechanism.

  18. Cory you’re so seditious. I bet MI5 has a file on you. I know I have.

    If anyone’s concerned about the policemen, just write to them and advise they add a roll of Duck tape to their belt. Then they can tape up suspects’ fingers, real quick. A new form of abuse – they could then make them do a duck-puppet show.

    I think this is more useful for bent bobbies to get themselves out of a handcuffed jam when they’re double-crossed by their seedy co-villains, or their starry-eyed authority-adoring solicitor lovers.

    Next step is obvious. And real concerning: duplication of your household keys. Didn’t BB cover that?

  19. So, why were the cops reluctant to try the key out in the first place? And, what did Hacker Ray say to persuade them?

  20. If you paint the part with a solvent such as methylene chloride, it will fuse the ABS strands together and make it slightly stronger. It will still be pretty weak but better than the raw part as it comes out of the FDM machine.

  21. The handcuffs in question are so called ‘transportation cuffs’; these restraints are only used for moving arrested citizens from the incident to the police station, and every Dutch police officer carries them.

    These are not meant to be long-term or ultra-secure restraints and, in fact, can be fairly easy picked or broken. But to restrain a single suspect for a brief car ride, they serve their purpose just fine – no plastic lockpick is going to change that, because you actually don’t have the wiggle room to operate the key on your own restraints (and the restraints can be tightened if you are fidgeting.)

  22. most handcuffs can be opened by over-tightening them past the last tooth and inserting a thin piece of plastic between the latch and the teeth. i once got out of handcuffs on a dare using only a q-tip.

  23. Color photo copiers were not permitted earlier for the fear of copying currency notes..till a tracking feature was built in…maybe this will take the same route!

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