Printing Police Handcuff Keys

Using a 3D printer. Impressive.

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….

EDITED TO ADD (10/12): Additional comments from the author.

Posted on September 16, 2009 at 9:00 AM42 Comments


t3knomanser September 16, 2009 10:02 AM

Handcuffs, of course, are meant to be temporary restraints. The plastic toothpick from a Swiss army knife is just as useful a tool for breaking out of the handcuffs as the key.

Police officers should be trained to recognize them as such, and use them that way. Anyone sufficiently interested in opening a pair of handcuffs will do it.

cowboy_k September 16, 2009 10:14 AM

Very clever, using a photo as the base – wasn’t there something a year or two ago where someone made a “master key” based on a picture of it on the manufacturer’s web site? Can’t find the reference right now, but it seems similar. How long until we see police add this to their list of reasons to ban photography of police officers? (Or am I being cynical?)

Steven Hoober September 16, 2009 10:23 AM

Yeah, I cannot recall the terminology they train to, but on-the-ball police are aware that handcuffs are like any security product we talk about here. They slow you down until someone does something else about it. Handcuffs should therefore never be the only restraint. Prisoners are cuffed to benches, inside locked rooms. They are cuffed to themselves, inside locked police cars, preferably with cages to prevent attacking the guys in front. They should be under some degree of observation so action can be taken if they do get out of the cuffs, etc.

I am not an expert and do not monitor every one of these, but cannot think of a case of a prisoner escaping from restraints or temporary custody (e.g. a police car) or assaulting officers while in restraint, where there was not also some notable procedural violation (everyone thought someone else searched, left alone for half an hour, etc.) which could have easily prevented it.

SoulReaper September 16, 2009 10:33 AM

There is a Scam School video over at Revision3 showing how to easily escape from handcuffs with a paperclip, (a shim?), etc. The key for handcuffs isn’t very complicated. At least US handcuffs, its possible that they are made differently in different places.

Milan September 16, 2009 10:35 AM

I think these Dutch handcuffs are a cut above the sort that are standard issue in North America.

The handcuff ‘keys’ here are really just cylinders with a single flange at the end. Apparently, they had to photograph the keys used by Dutch officers in order to copy them, which suggests that their handcuffs use an actual key, and perhaps something like a pin-and-tumbler lock.

That’s still pickable, of course, but it’s trickier than just manipulating the internal components of standard North American cuffs.

Karl September 16, 2009 10:36 AM

Wow – I always assumed that each pair handcuffs had their own keys (and possibly a “master” key in a cupboard at the police station).

Using the same key on all handcuffs sounds like a strange decision to me: it’s a bit like using he same password everywhere… Convenient, but the resulting security is very fragile. Once the key/password is leaked, the world suddenly looks very different..

Milan September 16, 2009 10:41 AM

From Wikipedia:

“Most modern handcuffs in Canada, the United States, the United Kingdom and Latin America can be opened with the same standard universal handcuff key. This allows for easier transport of prisoners and keeps one out of trouble if one loses one’s keys. However, there are handcuff makers who use keys based on different standards. Maximum security handcuffs require special keys.”

Some higher security handcuffs, with pin and tumbler locks:

paul September 16, 2009 11:01 AM

You so do not want to have individual keys for each set of handcuffs. The denial-of-service risks in all directions would be way too big.

Joe Buck September 16, 2009 11:29 AM

If every set of handcuffs had its own distinct key, the keys would get lost all the time, and you’d have to use hacksaws to get the cuffs off a lot.

Dom De Vitto September 16, 2009 1:04 PM

The security of handcuffs is exclusively in that they can’t be accessed – touched by fingers, or anything else.

That’s a big reason why you’re often handcuffed behind your back, because it aids prisoner control, but also because it prevents bringing the cuffs to the prisoners face, where a pin/needle in the mouth could pick the lock. You could probably just use your teeth to bite and wiggle them over your wrists too….

Clive Robinson September 16, 2009 1:05 PM

Aside from the fact that handcuffs unlike shackles or turnbuckles are ment for temporary restraint they also have a significant failing in a lot of cases.

This failing is that they are a “snap shut” design with a ratchet like closure.

For reliability there needs to be a degree of “mechanical freedom” to ensure they work as desired. This “freedom” is the lockpickers friend and I have seen some handcuffs opened with a soda can ring pull that has had a small fold put in it. I suspect that a metal clip of a cheap ball point pen would work as well.

As I noted some forms of restraint such as turnbuckless are designed in such a way that the mechanical freedom is minimised in the locking process.

Nemo September 16, 2009 1:28 PM

There was great drama several years ago when a very early production run of a certain manufacturer’s cuffs turned out to be openable with the cap from a Bic pen, prompting a recall and upgrade program, and a lot of lingering ill will towards that particular manufacturer in law-enforcement circles.

In the academies, it’s taught again and again that handcuffs are only temporary restraints, and everyone knows that most of them are somewhat vulnerable to being opened. That’s why, in part, most agencies train that the “correct” way to apply handcuffs is with the keyholes facing away from the hands, and with the hands cuffed to the rear.

Of course, in recent years, some manufacturers have been making cuffs with keyholes on each side, supposedly to be “user friendly”; one can’t help but feel they’ve lost the plot, a bit…

Grymoire September 16, 2009 3:16 PM

Some points:

A metal detector will not detect a plastic key.

Handcuffs can be single-locked or double-locked. If single locked, a shim will open the cuffs. If double locked, you usually need a key (some cuffs can be slammed against a surface that causes the lock to jump to the single-lock position).

Blackhat had cuff-escape contests.

. September 16, 2009 3:42 PM

Survival School
Why more Americans are learning to pick locks, bust out of handcuffs,
and avoid surveillance.
By Sara Behunek
Posted Thursday, July 16, 2009 – 2:01pm

It’s a sticky Saturday morning and I’m handcuffed in the back seat of
a Jeep Grand Cherokee parked on the side of a Philadelphia street. On
one side of me is my boyfriend, Bruce, and on the other his best
friend, Nick. Both of them are also cuffed—and like me, sweating like
pigs. I reach into my hair and pull out a bobby pin that within
seconds I’ve fashioned into a simple device I use to jimmy open my
handcuff locks. Our assignment now is to evade 12 professionally
trained trackers in a 25-square-block area for the next eight hours.

It may be hard to believe, but we asked for this. Actually, we paid
for it: $550 apiece.

Today is the final day of a three-day “Urban Escape and Evade” course
offered by onPoint Tactical LLC, a New Jersey-based company that
teaches soldiers, police officers, and, increasingly, civilians urban
survival skills.

AlexP September 16, 2009 5:46 PM

Try to reach for your key and open the Dutch cuffs when you are properly cuffed with your arms above each other on your back. Only very very few are agile enough to do that.

Russell Coker September 16, 2009 11:42 PM

There used to be some variety of handcuff keys used in Auatralia in the early 80’s.

Once when at a youth group visit to a police station we discovered a spare set of handcuffs and put them on a boy. The policeman didn’t have the right key and needed to get one from another station which delayed the visit.

I’m surprised that none of us were shown the inside of a holding cell after that. 😉

Ray September 17, 2009 12:49 AM

Hi there,

nice to see so much interest in my printed key. As many questions arose in these comments, I’ll try to clarify a few details…

First: as many have seen, the dutch handcuff key of course is more complicated than a standard american one. It also normally can’t be bought – they sell replacement keys only to police forces. A silly concept of security for such a relatively simple key, so I simply had to reprap it.

The cuff has a 3 lever chubb lock, which can be picked (more on that later), but you won’t be able to do it with the keholes facing away from your hands. @AlexP: opening with a key can be done even when cuffed correctly, though. Did you notice the extended hot-glue key-head on the picture in blackbag? That’s actually to make this easier…

Then: I didn’t model the key after a photo (even though that could have worked, there actually are good pictures in some police online shops), but used a key for german courtroom handcuffs which are made by the same company. I was pretty sure it will also work on the dutch ones, but before anouncing that in my talk I wanted to be really sure. As the cops on the site did neither want to try my key nor let me even see theirs, I just made a closeup photo to verify they use the same key code as my german version.

And regarding the High-Security Peerless Handcuffs mentioned: their patent is nice, but the implementation fails in one important aspect: the medeco lock doesn’t hold the double lock. You can see that in Part 3 of my presentation at HOPE:

BTW: at the beginning of Part 2 (see related videos…) there’s a comparision of “standard” Keys (and later also a picture of the tubular lock failure handcuff mentioned in an earlier comment). And @Russell: the Australian ones you tried in the 80s are also mentioned there. They all use the same key, but it’s completely different from standard keys. They’re still in use today.

Unfortunately the dutch handcuffs aren’t in my HOPE talk as I reduced it to models used in the US, those who at least understand a bit german can see it in my Berlin version of the talk, “Handschellen Hacken” – downloadable from:
(and there are lots of torrents around for it)

In short: the trick is that by pushing on the bow of the double locked handcuff you can create the needed tension on the lock, so just a normal L-shaped pick (a hook will also do) can be used to lift the 3 disks of the chubb lock to their height, no hobbs hook or similar needed.

But as there’s only one key code, it’s much easier to simply print out the key on your 3D printer…

P.S.: You are all right: normally it shouldn’t be a problem, as a police officer should not leave a handcuffed suspect unattended. But reality shows they from time to time rely a little too much on the security of their handcuffs (which for example led to that silly law in Florida…). And I can imagine the dutch ones, with their “government restricted” key, do that even more. Now they should know better…

BF Skinner September 17, 2009 6:05 AM

okay, yeah, keys handcuffs, escape and evasion…relevant to security sure, sure,

but that 3d Printer? is AWESOME…and I want one.

bethan September 17, 2009 7:54 AM

zip ties are a win over cuffs

and 3d printers are extremely cool; saw one in action at NCMEC, used to create 3d renderings of people for identification. so it’s cool and it also has an amazing application.

christopher September 17, 2009 8:29 AM

My father used to teach street-survival courses. I would come along as the practice dummy, and being 6′ 2″ and 200#, it made an impression on the students. My personal highlight was when he would cuff me behind my back and turn to the class to start teaching. I would bring my hands under my legs without making noise, pull a toothpick off the floor, shim the handcuffs, then approach the old man from the rear with the cuff teeth at his throat.

To make the point, he re-cuffed me behind the back, and I shimmed the cuffs again right there.

Nylon zip ties, all I could do is bring my hands to the front. I don’t have a high enough pain threshhold to torque them apart, but it has been done.


David September 17, 2009 8:43 AM

3D printers are neat, but none of the ones I’ve seen produce strong parts. They’re useful for lots of things, but typically not for any application requiring mechanical strength or durability.

Therefore, I’m somewhat surprised that they’d be usable for handcuff keys. Is it just that a handcuff key doesn’t have much stress on it when used, or have 3D printers improved a lot?

Milan September 17, 2009 10:11 AM

“3D printers are neat, but none of the ones I’ve seen produce strong parts.”

Selective laser sintering machines can make strong metal parts.

pegr September 17, 2009 12:57 PM

On a related note, prison guards are often called screws because the cuffs used 100 years ago simply used a recessed screw to engage and disengage. The guards would often be seen screwing or unscrewing a set of cuffs as they managed prisoners.

Ray September 17, 2009 1:46 PM


the machine I used is a RepMan from bitfrombytes, which is a DIY-kit for a reprap like device, but with different electronics, but far from “commercial grade” machines. We had it assembled for about a month in our hacker space when I started thinking about printing keys.

We use ABS which is relatively strong, but of course it breaks at some point. The whole project was pretty much at the limit of what the machine can do, and at the beginning I wasn’t sure if it really will result in a working key. As you can see on the picture on I used some hot-glue to increase the strength of the key’s head (besides making it easier to handle), otherwise it breaks of easily – I meanwhile improved the model to have a thicker ring there.

The critical part of course is the other end, the “code” is in the upper 3 “steps”, but the lowest part has to operate against the spring of the handcuff. When printing with a too low temperature the layers don’t stick good enough to each other to do this, and I also had to make that part as wide as possible. My first working keys were only able to unlock the chubb lock, but you had to shim the handcuff then to actually get it open.

I’m still improving the parameters and also am researching possibilities to improve the stability of printed objects, for example adding a layer of cyanoacylate based super-glue looks promising. This key turned out to be a nice testing object for the parameters and capabilities of a 3D printer…

P.S.: @BenQMember: yes, but that’s a standard key. The key I printed can’t even be bought as a metal original normally…

jl September 17, 2009 3:36 PM

There is now a manhunt underway in the Chicago suburbs for a man police were driving to the courthouse. He was handcuffed, but overpowered the two officers in the police car. Temporary restraints, indeed.

Doug Coulter September 17, 2009 5:18 PM

Take a close look at a zip tie. They’re even easier to “pick” than handcuffs. There’s just a little latch-finger in the block that catches the ripples on the tie, all you have to do is hold it back some way for an instant.

Luckily, I didn’t have to learn this to get out of a restraint, just as a cheap engineer who wanted to reuse them sometimes when my stock of the right size was low. A toothpick or small shim will do it easily on most zip ties.

I hear they hurt more than handcuffs.

Jonadab the Unsightly One September 18, 2009 7:49 AM

Wow – I always assumed that each pair
handcuffs had their own keys

In a word, no. I picked up a set of secondhand handcuffs at a garage sale when I was in junior high, just because I thought they would be an interesting thing to have. If you have half an hour, a patient disposition, and nothing better to do, you can pick them using standard easily obtained items (e.g., an unbent heavy paperclip, or a disassembled ballpoint pen). Of course, if you were handcuffed by police, they wouldn’t generally leave you unwatched for long enough to try it.

There is also a trick you can use to get out of them without picking them, but only if the person who puts them on you is careless, and not everyone can do it. If you clench your fists in a certain manner while the cuffs are being put on, it makes your wrists about 10% bigger around. If the cuffs are not applied too tightly, and depending on your hand bone structure, some people are then capable of just slipping out of the cuffs.

One more: if you have long arms and legs and a short back, and your hands are cuffed behind you, and you have room to move around a bit (e.g., an open floor, rather than a chair), you can easily slip your arms under your backside and around your legs (one at a time) and get your hands in front of you. This takes about twenty seconds to do, however, and is extremely obvious to anyone who might be paying even a modicum of attention to watching you.

The security of handcuffs is exclusively
in that they can’t be accessed – touched
by fingers, or anything else.

That’s incorrect. They absolutely can be manipulated with the fingers, provided your arms aren’t parallel. In a typical police custody situation, you wouldn’t have time to do anything, which brings me to my point: the security of handcuffs lies in the fact that they are not the sole measure.

Handcuffs don’t by themselves control a prisoner. Handcuffs make it easier for police (or whoever, I guess) to control a prisoner.

you’re often handcuffed behind your back,


because it aids prisoner control, but also
because it prevents bringing the cuffs to
the prisoners face, where a pin/needle in
the mouth could pick the lock.

The mouth is not really dextrous enough. The eyes are more the issue: it’s hard to see what you’re doing behind your back.

You could probably just use your teeth to
bite and wiggle them over your wrists too….

Not necessarily. Handcuffs are generally made of metal, steel if they’re good ones, and the ratcheting mechanism is one-way (unless you open them with a key or pick). The wrist is narrower than the base of the hand, so in the general case no amount of biting and wiggling is going to get the cuffs off.

Breaking them (the part that links the two cuffs together, usually a very short chain) is theoretically possible, but (in the absence of a tool and good leverage) you’d have to be some kind of serious body builder or something. And then they’d put you in heavy-duty manacles next.

There was great drama several years ago
when a very early production run of a
certain manufacturer’s cuffs turned out
to be openable with the cap from a Bic pen

Most cuffs are, if you’re patient and can see what you’re doing. It usually takes a few minutes, though. If there was a big drama about a certain model, it was probably because they were too easy to pick, not because it was possible.

Try to reach for your key and open the
Dutch cuffs when you are properly cuffed
with your arms above each other on your
back. Only very very few are agile enough
to do that.

More to the point, try fumbling with a key behind your back while the police are actively marching you to the cruiser, to your cell, or wherever. They don’t handcuff you and then leave you in a field unobserved for an hour to do whatever you want.

In short, I don’t think it matters that normal civilians can get their hands on keys for police handcuffs. It makes a sensational headline, because most people don’t understand the issues involved, but in actual practice I don’t think it’s significantly relevant to the usefulness of the cuffs.

Clive Robinson September 18, 2009 12:29 PM

@ Doug Coulter,

“A toothpick or small shim will do it easily on most zip ties.”

Or the pin on a lapel badge or safety pin etc

However it can be made quite difficult to do with two zip ties.

Put the first around the wrists semi losely with the “zip lock” on the little finger side of the wrist about equidistant between the wrists. Then put a second zip tie around the first zip tie but between the wrists. Pull this tight and both zip locks will disapear up betweenthe wrists away from the face making it very difficult to get at the zip lock latches.

“I hear they hurt more than handcuffs.”

They can do but not as much as my favourit restraint “Dental Floss”.

Yup a couple of loops around somebodies wrists to keep them a little more controlable, then tie their thumbs together behind the first knuckle joint.

There are two ways to do this the “handcuff knot” or wrap five or six turns reasonably tightly around the thumbs, then take the lose ends and wrap a few times around the first turns between the fingers putting a half hitch in every couple of turns to keep the tension and finish with a reef or other non slipping knot.

The advantage to this is that if you get the tension right then you cannot get your teeth in to undo it and unless you don’t mind losing your thumbs you will not be able to break the dental floss (oh and no muscules to worry about either).

Oh and the other advantage is that you can keep a persons hands behind their back simply by putting a loop around the thumb restraint and up around the neck, most people find that keeping still is prefreable to choking themselves.

As you may have guessed the latter part of the restraint is considered an illegal practice in a war. Likewise using head covering with draw strings liable to “get caught” in other restraints. But hey, whatever gets the job done 😉

averros September 20, 2009 4:41 AM

I always carry a set of keys to different padlocks and handcuffs with me… but, then, I’m kinky.

So are the police… but they don’t subscribe to the “safe, sane, consensual” creed.

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