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So welcome, everybody, for the talk
replication prohibited, this
talk covers the subject of 3D
printing and the state of physical
security.
Our lovely speaker today is Eric was
true. He just flew in from the States
four days ago, he told me, and he still
jet lagging.
He's a student of computer science
engineering in Michigan, you say.
And please give him a warm round of
applause and enjoy the talk.
Thank you very much.
Thanks, everyone, for coming so early on
the last day.
I'm Eric Wistrom, presenting
research on Replication Prohibited,
which is our research on 3D printed keys
and its impact on high
security locks.
This is joint work with my coauthors,
Ben Burgess and J.L Telamon from
the University of Michigan.
So we're talking about pin tumbler
locks, which I think is appropriate for
this Congress, given that the the theme
is gated communities.
So take take
that what you will. But I see locks as
sort of the the gatekeepers for
the sneaker net of things.
Firewalls are the gatekeepers for the
Internet of things. And that's what these
are for, for this. So
just a brief overview for those that
don't know pin tumbler locks.
Have, you know, these pins in
them that only open
the lock if the correct key is inserted,
if the wrong key is inserted, then
the cuts on that key only lift the
pins to different heights and one or more
of the pins will block the inner plug
from rotating and
the lock will not open.
But if you put it in the correct
corresponding key, then you will be able
to open the lock.
The the pins will be lined up
along the shoreline and broken along the
shoreline. And this allows the inner plug
to turn.
Now, of course, it's important to
remember that that is the secret
information is encoded in these cuts.
If you can ever take a picture or
observe someone having these
these cuts on a key, then you can
figure out how to open the lock.
If that goes to and there
was an attack in 2008 that sort of
generalized this and went a bit further
and said that, you know, you don't have
to just worry about people next to you
and very close to you that can see your
locks. You have to worry about sometimes
people very far away that have telephoto
lenses and cameras that can take pictures
of high resolution
from across from across the entire
courtyards where, you know,
you can sort of see from from some roof
level, there's some keys sitting on a
book that's barely visible by the naked
eye. But you can actually make out the
cuts on this key from this image.
There's some, you know, tricks to
transforming the image so that you can
actually see it straight on rather than
at this weird angle, but nonetheless,
this is possible to do and they
demonstrated this in this work.
Of course, there's also bumpkins, which
is a common attack against pin tumbler
locks that have you
cut a key to the lowest level
and then put it in the lock, give it
a sharp tap.
And this bounces many of the pins
up. And if you turn the key at just
the right time, then maybe the plug will
rotate as the other pins
clear the shoreline just for a split
moment.
And finally, I think one of the most
interesting attacks for pin tumbler locks
comes out of MasterCard systems is unique
to MasterCard systems and the MasterCard
system.
You have multiple keys that can open a
single lock. So say I have my key
that opens my office door at the
University of Michigan and it only opens
that one. But the building manager has a
key that opens every door in in
the building.
And how this is accomplished is there are
actually multiple pins, more than two
pins in each stack.
And and you have different pins that
correspond to each of the different keys.
So my low level change key that opens
just my office door
can can have cuts that correspond to the
red and the green pins, whereas
the master key that opens all the doors
has cuts that correspond to
just the red pins.
And in 2002, Matt Blaze
published this this privileged escalation
or this rice amplification attack
that's unique to Master Kaede Systems,
which I call the blaze attack.
This is an attack that allows a
a an attacker to that has just
changed key, just a low level change key
to query their lock and learn
what the master key to the entire system
is.
And to give you a sense of how this
works, I'll walk through this
illustration. So again, I have my
low level change key that opens just my
office door and it operates these
the red and green pins at the shoreline.
And so what the attacker does is it takes
this key and makes a similar copy
to it that has all of the same cuts
except for one pin.
One pin is different. It raises it to the
to the highest level and the attacker
puts this in the lock and tries to open
it and if and sees if it opens it.
In this case, it wouldn't open the lock
because this red pin is blocking the plug
from rotating.
So the attacker removes it, files it down
and tries it again and continues doing
this until the lock opens.
And because all of the other pins are
still kept at their old position, that
would normally open the lock.
Once the attacker is able to open
the lock. They have learned what the
master cut is for that PIN
position so they can repeat
this for each then iteratively of the
pins in this lock with different blanks
and different different key cuts,
ultimately revealing what
the master key is to this entire
system.
One more thing to note about all of these
attacks is that you have to find some
piece of metal or some piece of material
that can fit into the keyway of this
lock. Key ways of locks are designed
to be a little bit difficult to get into,
both for to prevent lock picking,
make it harder to get tools into it,
and also to to make it a little bit more
difficult to to get blanks that can
actually fit in these locks.
So for a lot of these attacks, for
bumping, for making unauthorized
duplications and for escalation,
attackers really want to have key
blanks that can fit into these locks.
And for most of the locks that that
we we encounter, this
is very easy. You can just go to, say, a
hardware store and buy
one of these blanks and actually get it
copied from from the dealer.
And there's no control or anything like
that that's going on in
in these open court systems.
One layer above that, there's
duplication, prohibited keys
where you can still buy them
online, things like best keys and
so forth.
And there are manufacturers that sell
them. But you may have a little bit
harder time finding locksmiths that will
duplicate to them or cut to them.
But nonetheless, it's still possible to
find them. They're just more rare.
Finally, there is a step
above duplication prohibited, which is
restricted Kiwi's where the
keyway itself is often patented
or controlled or somehow
specifically and custom designed for
each system by the lock manufacturer.
And this can be system specific in a way
that the lock manufacturer
and the locksmith that deploys it have
some kind of contract where only that
locksmith can buy blanks that fit
that particular keyway and they have some
keycard that authenticates it to to
buying that.
And so you wouldn't be able to buy these
blanks online even if you, you
know, knew what they were.
To to further make this more more
difficult for attackers to find these
blanks, these key designs are often
patented so that if someone actually was
able to manufacture some of these key
highways for popular restricted
highways, then they wouldn't be able to
legally sell them without infringing on
the patent.
So if you're an attacker and you want to
still get access to these blanks, you
have a couple of options at your
disposal, you could try to custom
manufacture it yourself.
You could go to a CMC mill and, you
know, measure out the key that you're
trying to copy and, you know, just
drill this down from from some stock
metal or something like that.
And that certainly is possible for most
Kiwis, although some key ways try to make
this more difficult by having crazy
undercuts and things like that that are
difficult to replicate on CMC
Mills.
But in general, this is going to cost,
you know, some amount of money and take a
fair amount of skill to do in practice.
There's actually a machine that will do
this for you called the Chemex
Easy entry.
And this is a pretty cool device.
You just put in a key that you want to
copy at the top.
It has a little probe that comes out and
measures different parts of the of the
keys thickness and then has a
second part that has a S.A.M.
that cuts the smiley face, Kilink, into
whatever key that you put in the top.
Now, this machine is not cheap.
Last I checked, I think it's about 7000
euro, but it's, you know, something
that could be useful for attackers if
they were, you know, breaking into banks,
I guess.
So finally, there's 3D printing,
this is something that's becoming much
more consumer available.
I've seen several 3-D printers here at
Congress and and
3-D printers are really sort of a
fast, you know, innovating thing that's
going on and rapidly improving
the state and the strength of the
materials that they can print.
3-D printing still requires some amount
of skill, but the tools there are also
improving that.
You can find these these free tools to
model things. And that makes it much
easier than than it used to be.
So one question is, if we print
keys in plastic or in whatever material,
are these printed keys actually strong
enough to use in practice?
To answer this question, our group
performed an experiment on a number of
different ways. We we modeled
several different key ways of keys in
plastic, in acrylic,
in nylon, in several different
materials, including metal.
And we took them all and
put them into locks and tried to break
them off with the most expensive
screwdriver that I have ever purchased in
my life.
It has it has a USB output and
it tells you how many pounds of torque is
being applied to the screwdriver.
And the one redeeming quality of this
screwdriver besides its price
is it had a generous return policy, so.
So we use this tool to measure how
how how much talk we could
take before it snapped off in the lock
and the results surprised us.
We printed these on icemaker
bought using clay, and this
would cost pretty cheap for for each key.
Now, the maker bot itself is not eight
cents, but it's a couple thousand
dollars. But nonetheless, each individual
key that you print off of that is going
to be fairly cheap.
And to our surprise, this key was
strong enough to open most of the
applications that you would come across
if you're using these keys in practice.
So we rank these four things,
opening a door latch, which is just a
very sort of light spring at a couple
of inch pounds of torque all the
way down to a crash bar where
you're actually physically pulling in one
of those sort of massive crash bars
from the outside with just the key.
And to our surprise, the plane was
actually able to do most of these.
We marked passive.
All of the keys were stronger than
the talk it took to open one of these.
So all of the all of the keys that we
tested were stronger than, say, the
torque it takes to open various padlocks.
We marked it fail if none of them were
strong enough to open any of the tests
of of opening them and we marked it may
fail if some of them passed and some of
them didn't.
So we also tested nylon and acrylic
and these are two different materials,
but they had basically the same results
despite being sort of having different
failure modes and properties.
Nylon is a very stretchy material and
acrylic sort of just snaps off and lock.
And despite being more expensive
and coming from actually a
3D printing service,
these were much weaker than than the play
originally.
And this probably would not be used in
any kind of attack that you would want to
do, we tried Ali
Meid, which is a slightly stronger
plastic that has some sort of aluminum
filings mixed into it.
And and this
was a little bit better, you know, three
dollars per key. So it's still pretty
cheap and it's able to open some of the
weaker components, but it won't
open a crack bar or some of the padlocks
that we had testing on this.
But now you might also had this bad
property that it had the very rough
surface to it. It almost had a sandpaper
like feel to it.
So when you were putting it in and out of
a lock, it felt like you were grinding
down the brass of the lock.
So you might you might actually damage it
ultimately if you use lots of these in
locks and then it might also break off.
Finally, we tested
a couple of medals, several medals,
actually, stainless steel and brass
and bronze as well.
But but it was the same as brass,
which is something that you can
surprisingly print in
three dimensions with with these
services. You can go to these services
and and give them a CAD model and they'll
ship you that same object printed in
whatever metal you want.
You can even printed in gold, I guess, if
you want to match your Apple Watch
or something.
So when
we tested this in practice, the metal
does cost a little bit more.
It's about ten dollars for the stainless
steel or thirty dollars or so, 25 dollars
for the breast of that
amount of metal in in breast.
And this works flawlessly.
This opened everything that we had access
to and then some. It was about half as
strong as the real blanks
that you would buy from, say, a hardware
store. But that's still an order of
magnitude stronger than you need to
to open many of these locks in practice.
And as an anecdote, I've actually been
using a brass printed
key for all of my
opening my office door for the last few
years and haven't had really any problems
with the brass one.
Though I will note that the stainless
steel one is a little bit rough
on the lock, in part because it's
actually stronger than the lock, which is
made out of brass.
So if it's not quite perfectly aligned,
you may actually, you know, break some
of the lock in some ways.
And I believe all of the locks that had
regular stainless steel key use had to be
replaced ultimately.
So.
But what happens when these keys break
off in a lock is kind of important
and how these keys fail.
So I will just, you know, note that the
things like acrylic are things that are
they're very brittle, have these really
bad failure cases that you're turning it,
you're turning it. And then all of a
sudden it breaks.
And now you have this piece of plastic
stuck in this lock and it can be very
difficult to get out if it's play.
I'll note the best thing to do is to
remove the lock from the door, soak
it in acetone for about 12 hours,
then take some rubbing alcohol, mix it
out, put it back in the door and hope
that no one notices your door smells like
paint stripper anymore and move on
with your life.
But things like brass fell much
more gracefully.
They you can actually turn
this and feel as it's as it's
bending and,
you know, in many cases we were able to
turn these keys more than about 90
degrees before they failed completely.
So it's very obvious that this thing is
breaking and not going to open this lock.
And you can feel much before you
would, you know, need to get out your
broken key extractors if
this were to snap off in the lock.
So how do you make these models in the
first place? I mean, have we just punted
the skill to making these models
at all? Well, in some ways, yes.
But the modeling tools are fairly good.
Autodesk Inventor is one of the software
packages we use, has a very fast
learning curve. It took us about a night
to learn and print
working keys despite not having
any background in this kind of
in this area.
SolidWorks is another tool for this, but
those both cost money.
Autodesk has this nice feature that you
can actually put visual basic scripts
in it so you can just put the key cuts
that you want to do and say, well, you
know, this program will execute and cut
the key down to whatever combination you
want, which is handy for
testing
on the free side of things.
There's a 3-D modeling tool called
openside, which is pretty cool.
It's entirely sort of scripting based.
You write out a program that essentially
describes the object that you're trying
to build. So you build, you know, spheres
and rectangular solids and you take
differences and unions of these until you
get the desired shape that you want.
So this is pretty cool for for people
that are used to programing, but
it does take some skill to, you know,
write off this code in the first place.
So what we did to sort of
demonstrate that this is even easier than
using those tools is we made an
automatically generating 3-D
model program.
This program takes a single picture of
the keyway that you're trying to make and
model a model for and produces
that model in in
in CAD, basically from
this image.
You can then take that blank and printed
on a 3D printer or ship it off to
Shapeways or rematerialize or whatever
your 3D printing service that you want to
uses and have
it made for you pretty cheap.
So how this tool works,
first you take an image that can just be
taken from a smartphone that's straight
out of the lock, that has a good view of
the keyway itself that's, you know, sort
of the darkest part of this image.
And the next thing that the tool does is
it tries to threshold this image into
various places so
it tries a threshold it into a black
and white image entirely.
So if things are more than 25
in magnitude out of 255,
then that pixel is black and
otherwise it's white.
And same for all of the other ones.
And so you can see that depending on what
threshold value we choose, we get
different sort of goodness
of our of finding the keyway
mask out of this image.
And 35 seems to be the optimal here.
And once we find
what the keyway mask is,
then we we actually once we find
the optimal threshold, rather, we pull
out this keyway by looking for the
largest blob in this image.
So if we do that for all three of these,
we find that again in 35, we find
the best image here.
Whereas in the other ones we find either
not enough of the keyway or something
that's actually not even related to the
way at all.
But how do we determine that 35 value
automatically, how do we make sure that
that's not, you know, image dependent and
so forth? Well, one thing that we noticed
that that was true across many
different locks and pictures that we took
was that if you looked at the area
of the largest blob
area that you pulled out from an image
after thresholding, there was this large
jump in area right after you had
sort of the optimal keyway mask.
And so you can see that here, that if you
look in the normalizes blob
area, it jumps right after 35,
which is the optimal one for this value.
So that's how we determine
what the what the keyway mask is, we just
go and look for that jump and say the
value before that is the optimal value.
This allows us to pull out the keyway
mask. And we found this to be fairly
robust. We tried some more complicated
things that I won't get into the detail
of for for computer vision sake.
But
we found that this was this was
surprisingly effective in practice.
So once you have this this keyway mask,
we have a program that then takes this
mask and generates some open
CAD code that will essentially
extrude this into a 3D model
and places a bow on it that you can
then, you know, put on a keychain and
carry around with you.
So finally, you get your 3D model of
your key and optionally you
can provide cuts to this this program
so that it can cut it down to whatever,
you know, key that you want to open,
whatever door that you're trying to do.
And if you're trying to do, say, a
privileged escalation attack, maybe you
make, you know, seven copies of this with
different cuts on each one.
So we released this tool as
open source and.
It's available on Kei's Forbes.com
as a demonstration, you can actually go
and try this out, you just upload
a picture and optionally provide the
key cuts that you want on on
whatever key you have.
And it will produce this steel file
that you can download. And then three
different.
So what can you do with these 3D
printed keys? As we said before, there's
these these three main attacks, still
a duplication in bumpkins and privileged
escalation.
But what have people been doing with 3D
printed keys in practice?
Well, there's a number of people that
have have printed keys.
We're not the only ones that do this.
And we're not even the first people to
have publicly done this.
In 2013, there was a couple
of MIT students at DEFCON that printed
Prima's key, which is a moderately
high security key that has actually to
sort of cut
short lines on it that
they replicated using
openness can actually and and
publish this code so that other people
could make Prima's keys
as well.
That was, again, a custom modeling of
just that one keyway.
And they printed it using materials
which after this this all went public in
materials, released the statement that so
that it did not support 3D printing
of high security keys in particular.
They said that it materialized, rejects
any use of its services to promote
activities or to create products which
pose a safety or security risk to others.
Had they known at the time, they would
not have printed these keys.
Which is funny, given that if you look at
Dematerialize website right now
under their platinum or sorry, their
titanium page, they actually use this
image as on their marketing page to show
you what you can print with with their
service.
So.
More recently, there was this picture
published of the TSA master keys in
some article, for some reason,
I guess the reporter or whoever was being
interviewed thought it would be cool to
flash them keys.
And this picture was published and then
later taken down. But it's the Internet.
So it's, you know, floating around and
here it is here.
So there's that
this this does allow you to you
know, it's high enough resolution that
you can actually figure out the cuts of
each of these keys.
And someone did this and actually modeled
all of the keys and and
modeled this and published this.
Now, I will note that TSA, Masterji,
it sounds pretty bad, but at the end of
the day, the TSA locks were probably not
that high security to begin with.
There were probably ways around them
already. You could probably pick them in
a matter of seconds or just bypass the
lock entirely by opening the zipper with
a big pen or something.
But nonetheless, it's an interesting
sort of experiment and lesson in
when not to show your keys on camera.
And finally, the most recent
study here is a tool called
Photobomb, which is very similar to ours,
which from a single image is able
to produce bump keys of of
that can be printed in plastic.
And this was done
late last year and the tool was never
actually published. That was just talked
about at Lacon, I believe.
And I don't think they've released any of
the code or anything opensource, but
nonetheless, a very cool tool that could
make bunkie's that that worked on some of
these pretty high security locks that
were fairly difficult to bump, even
with metal keys, but sufficient to
work with with plastic.
So
how can we defend against these attacks
besides just shoving superglue in our
locks and giving up?
I think there's a number of different
directions that we can go in with this
with with trying to defend against 3D
printed attacks.
One is to look at non mechanical locks.
So electronic locks are sort of
growing in popularity these days.
No, actually, that does bring in other
kinds of vulnerabilities.
And, you know, now you have now you have
other problems to worry about, like
replay attacks or or any kind of
software vulnerabilities that might exist
in whatever protocols you're using.
But this this will scale pretty
well and it won't have the problem that
a lot of the mechanical locks will have
when it comes to 3D printing attacks.
Sort of slightly related, but a little
bit more on the mechanical side of
things. There are a number of high
security keys that use active keys
and key ways to authenticate
that the right key is in the lock.
So in addition to, say, having very high
tolerances and pin tumblers and things
like that, this these keys,
like the multi lock, can have actual
spring components in the key that sort
of, you know, fold in and then come back
out at different parts in the insertion
process.
And this might be difficult to replicate
with 3D printing, given that most most
of 3D printing at this scale right now
is limited to entirely solid fillers
and can't have these very intricate, fine
features in them.
And finally, I think magnetic locks are
kind of an interesting sort of cool
gadget. But Max is an example
of this. This has magnetic HP-UX
inside of it that actually rotate
physical, mechanical things inside the
lock that have to line up in order
for the lock to open.
This would again be a little bit tricky
to replicate with with 3D printing
alone, although you might be able to do
some kind of inlay thing where you put
magnetic things and be able to
copy a key remotely.
If you had, say, you know, a 3D printer
and a good compass or something, but.
I think one interesting
idea that I haven't really seen proposed
for for defending against 3D
printing is trackways.
So trapped highways are pretty
unknown sort of thing in the
world, but they can be used to
essentially trap a key in
the lock when it's inserted.
So if you have someone, let's say a
contractor or something that goes away
and takes their key with them or
something, and you don't want them to
come back at some point and be able to
access whatever
door that they used to have access to,
you can install a different keyway that's
essentially configured to trap
that key when it's inserted and turned in
lock. And if that happens, you won't be
able to pull the lock the key out of the
lock and the lock will actually have to
be drilled.
But nonetheless, the person will be
stopped from entering that
facility.
And this is useful for for unauthorized
old keys like that.
But it could also prevent privileged
escalation and other attacks that are
enabled by 3D printing, just by
being able to trap all of the
different sort of iterations of the blaze
attack that that might happen during that
process.
So looking forward into the future,
I think there's it's a pretty exciting
time for 3D printing in locks.
We're really just starting to be able to
make these keys that are viable in
practice. And 3D printing is only getting
better. It's only getting higher
resolution and cheaper and more
ubiquitous. And there's more materials
every day, I think.
Recently, I saw that you can now 3D print
in wood,
which is pretty cool.
But all of this sort of improvement
of technology is happening on the 3D
printing side.
I don't see an analog happening
in the lock innovation.
And to be fair, locks are fairly old
and have, you know, done
fairly well in in recent
years in history
for the most part.
But I am a little bit concerned
because locks sort of have
this intrinsic property that they're
limited in sort of how small they can get
because the humans that operate them
aren't getting any smaller.
So on the other hand,
the 3D printing tools that we have are
able to get smaller and smaller.
And so at some point I think we'll be
able to do more of these active keyway
attacks and things like that with 3D
printing and moving.
Even beyond that, I think that there's a
lot of room for looking at
different ways that 3D printed materials
could actually actively interact with
the pins in the lock.
Maybe that you could actually make a lock
picking device that actually did a single
pin picking inside of the device
using just something that was
manufactured on a 3D printer.
That's probably a ways out.
But I think that that that sort of, you
know, combination of 3D printing and
meme's like devices would would
be a really interesting future for
the combination of 3D printing and locks.
So with that, I'll
wrap up and be happy to answer any
questions that you have.
Thanks.
Well, thank you for this interesting
talk, Eric, I'm fairly sure that this was
the magic moment for all the lock pickers
present and the highlight of that
Congress.
So if you have any questions, please move
to one of the microphones we have here in
the room.
I was told that we are only using the
four microphones that are down here with
the numbers one, two, three and four.
If you have questions, please move to
the mikes.
Even the Internet is not awake yet.
We don't have any questions from the
Internet.
All right. But we have a question at
microphone number one, please, to ask you
a question.
Does the tool include
taking a picture from a key and then make
it or only the keyway?
So is it able that I can
photograph your key from here?
It only does it from the lock.
So because it's using the outline
of the keyway, if
you were able to take a picture of the
end on view of the key,
then perhaps you could, you know,
Photoshop that to make that the darkest
part of the image and then use that to
upload and maybe you have to mirror it at
some point, but that
would also work.
OK, thank you.
Next question from Michael on the floor,
please.
Thank you for the.
American locks are notorious
for having bad tolerances.
Did you try your findings
with European locks, for example, with
equal locks, which are pretty
much better manufactured
than Chicago or some other
junk?
So we did not try it on on those
particular locks. We did try it on a
number of different ways.
But the latest
ones that we tried it on are not the easy
ones or something like that.
They were Everist and high security.
They were often so
small format, interchangeable cores,
which can be harder to
pick because they have the control shear
and everything. But in general, it's
all in the system.
So any system key,
the 3D printers have enough tolerance and
resolution to print at that sort of
twelve point five miles per.
All right, next question for Mike, number
two, please.
OK, thank you for the interesting talk.
I was noticing that the key ways of
the criminal system seem pretty
overcomplicated.
Is it possible to actually simplify them
by replicating the keys?
So is the question, can you can you
print simpler key ways and not the entire
the whole thing? Yeah, right.
I mean, yeah, they have details that
don't seem to be necessary.
Yeah.
So the short answer is
yes.
And people have discovered this before,
especially with Medco.
There's this surprising property that
there's that actually a straight line
fits through the keyway just fine.
So you can just, you know, stamp out
sheet metal or a credit card or something
like that. You don't have to actually
replicate any of the the squiggles
or anything like that. But on most high
security locks, that's not true.
You will have to get at least, you know,
some corner or something that that
actually comes.
And the key market is a great example of
that. It has this very wide sort of leg
that comes off to the side.
But in general, yes, you could make
something that smaller for
3D printed things you might not want to
because it's stronger if it's thicker
in different areas. And sometimes that's
part of the the keyway design is to make
sort of these these these ridges
and runners that make the key stronger.
Thank you.
All right. Thanks. After I bashed the
Internet, woke up and decided that it
actually does have a question.
Yes. Thank you, Al.
Straight on just the picture
has to be of the of the keyboard.
How sensitive is it?
Yeah, I don't know exactly how many
degrees, but it's not too sensitive as
far as sort of, you know, you can just
walk up. You don't have to stand there
with a protractor or anything or any kind
of guide.
It's a little bit tolerant because it
will actually make a key slightly smaller
for tolerance reasons to fit in the lock.
So you have some leeway there
to sort of figure out if you're at some
SKU or something like that.
But in general, you know, just taking it
straight on and eyeballing it
seems to be good enough.
Thank you. Next question from Mike
Namath, right?
Yeah. Did you notice
that any lock manufacturer is
for traditional mechanical locks, so no
active components trying to do
something to prevent 3D printing?
Of course, I haven't seen
anything concrete from the manufacturers.
I know they have mentioned that
they're aware of these attacks, that
they're interested in looking into
defenses. But I haven't seen anyone that
made any specific changes
that are locks yet. But
given that, it probably takes some time
to actually, you know, make these changes
in practice, I don't really fault them
for, you know, not coming out right away.
But nonetheless, these these printed 3D
printed keys have sort of been a long
time coming, I think, in the last few
years, and they're just getting more
popular. So I think it would be kind
of foolish for for manufacturers to
ignore that.
But I haven't seen anything yet.
All right. I see someone at Mike No.7.
I'm not 100 percent sure it's open, but
you can try.
All right.
Have you tried to make a negative form
and fill this up with some kind of resin
with carbon or fiber in it?
Are you make a 3D printing
of the negative form and then build
the key as the positive while filling
up with some fluids?
Yes, so that's actually how
the metal 3D printed
keys are manufactured by the service
that that makes them.
Brath is done with essentially a lost
wax casting where the wax is printed,
a plaster mold is put around it and then
melted, the wax melted out and then
molten brass poured in.
Stainless steel is printed
in a slightly different process with
you have this sort of sintered stainless
steel and glue resin that you print
the positive of. And they say it has the
consistency and structural integrity of
a sandcastle
at that point, that they then put in an
oven and fill the rest
with bronze, which then replaces the
glue so that you have an all metal
key at the object or whatever you're
printing at the end of that process.
We haven't tried doing that ourselves,
but that's certainly what the
services are doing for some of the more
complicated materials.
And it seems to work quite well.
Brass has a really high resolution, as
you can see here. This is a 3D printed
brass key and the replication prohibited
is part of the 3D model and
shows up when you print this.
All right, we have another question from
the Internet, thank you, have two
brief questions.
First of all, as have you
also looked at a rotating cylinder
logs and have you ever used
abscessed material?
I printed a key
on an ABS commercial machine,
and it was, I believe, not as strong as
the play, but it was sort of comparable
as far as that goes.
It was it was still able to open
many of the locks.
And what was the first question?
Have you ever looked at rotating disc
cylinder locks?
Oh, detaining Justin?
No, I haven't looked at that specifically
for 3D printing.
I think a lot of these would extend
to that.
But there's probably different tolerances
in sort of the Z direction that you can
get for some of these printers.
Part of the tricks here can be sometimes
to figure out what angle
or what orientation you want to print the
key on, because some of these printers
will have better resolution in the X Y
direction and the Z direction or vice
versa.
So you have to sort of play around and
find what the what the actual tolerances
there. But I haven't I haven't personally
played around with that.
Kind of like another question from Mike
number before ask away.
Okay. Um, you've
been tried you've been testing a few
locks. Right.
So do you think that in the future
will we'll see more like
locks that with hardening steel
or that have challenge response
authentication systems?
Because from an emergency services point
of view, it's quite important to be able
to just drill them open.
Yeah.
I mean, a huge important
part of of of of LOCKSS that they have
to always work, right? If you run of a
battery or something like that, then
that's a problem.
A lot of electronic locks have solved
that by having the key provide
the battery so that, you know, you know,
you now have a battery that's external
and you can replace that.
But still, that's kind of finicky because
maybe your battery runs out, you don't
have an extra one and so forth.
I think that it's likely
in the short term that people will go
more toward the active ways for at least
the high security locks.
It's still expensive to do that.
It's expensive to manufacture that and
expensive to make in practice.
So it will probably be reserved only for
the high security locks.
And most of the homeless will sort of
have the same same problems that they
always did.
It will be interesting to see which
institutions adopt these higher security
locks. If universities say, for example,
that traditionally heavily used,
say, MasterCard systems will
move toward higher security locks or
moved completely away from MasterCard
systems to avoid some of these these
problems, but I don't know have what
will happen in the future.
OK.
Another question from the Internet,
is it possible to use a metallic core
and print the key around it?
Sorry, can you repeat to use a metallic
core and print a plastic
key around this core?
A metallic core and a
key around the core, it would
be difficult to do that.
It is so I have seen people
on 3D printers sort of print
some base layer of plastic, then print
and play something else, say even
a PCB or some kind of electronic or
a battery or something or a magnet even,
and then print the rest of the player.
Maybe on top of that,
I don't know that you would be able
to do that with the thickness of these
keys. They're fairly thin.
I mean, the actual especially
with all of the key ways, sort of wiggles
and and so forth,
it's kind of hard to get an actual very
thick part that you could put something
metal in.
One thing that you can do, however, is
you can sort of leave out a gap in the
back of the key and then insert
a tension wrench there instead.
And so now you have, you know, all the
strength of attention and the plastic
key is just operating
the PIN tumblers and and raising them to
the right height.
All right, the brave person waiting for
quite some time at Magic number eight.
How do you actually get the dimensions of
the key from the picture?
Yeah, so in the
tool that we use,
the dimensions are assumed
to be in sort of a standard
small format, interchangeable core, so.
From that, most of those are standardized
to a specific height, so you can just
sort of take the top to the bottom and
you know what that height is for more
complicated locks you might
try. And something that we tried to do
early on was detect the circle
around the lock out of the mortise.
And then if you knew how big that was,
either by measuring it or entering it
in or knowing, you know, the standard
sizes of Martz's, then you would be able
to scale that image based off of that.
All right, Mike, number four, please.
I'm quite excited.
I haven't been thinking that line
that it's possible to do that with a 3D
printing, and
I want to look from a different angle,
like the one who wants to protect
himself against any threat
with reasonable means
financially.
What would you do?
In my case,
I think you'd have to define reasonable,
you know, financial means.
But, you know, if you're if
you're running a master kid system,
then I think you would probably want to
either upgrade to a higher security lock
or a different kind of master key system.
I know Yale has a,
I think, Biaggio lock that
has actually two different ways.
One that one, that's for
the master key and one that's for the
change key. And so then these privileged
escalation attacks are not a problem
for that kind of system.
I don't know the relative cost of that
offhand, but I know that MIT has
moved to those locks almost exclusively.
I guess they maybe had a problem with
students being part of the escalation or
something like that.
But I don't know many other universities
that have done that in recent years.
I think that's a good compromise for that
particular attack. But again, it depends
on your threat model, right? If you're
concerned about people copying your keys,
then maybe you want to go with something
that's just restricted and so has active
components to it, like a multi lock or
something like that.
Or if you're concerned about bumping or
picking, then you can find bump resistant
locks or something like that as well.
So.
I may add one
more question.
I've seen some people using
no locks on these
not so good or so,
no pads.
I mean, they're kind of an electronic
lock, right? It's it has many of the
problems, but it has a limited interface.
So it's a little bit better than say
something that's, you know, talking to
your smartphone or something like that
as far as the attack surface goes.
But it still has the problems of, you
know, if it runs out of a battery,
there's no backup or something like that.
It can be difficult to to get in
and reliability problems there
and can also be hard to weatherproof them
in some locations.
And no pads in particular
have this problem that if you only ever
enter correct combinations on the number
pad, the correct buttons were down more
than the incorrect ones.
And so you don't have this side channel
for learning on.
What the correct combination is so.
All right, the Internet is curious and
has many questions this morning.
Yes, yes, yes.
Have you looked at Kramnik or EPOXI like
materials for keys, sorry,
Carmac or EPOXI like materials
for kids.
I have not I don't know that you can
print any epoxy, but
maybe you could do some kind of, you
know, mold based thing on
and use that instead.
Play, I think was fairly good in
part because it has this sort of sweet
spot between being flexible and rigid.
Nylon was was way too flexible and
just sort of like a rubber rubber band
inside the lock.
And acrylic was way too brittle
and sort of didn't have any give to it
and just snapped off. So I'm finding that
sweet spot is, I think, pretty important.
All right. Any other questions?
You have another 10 to 15 minutes to ask
the hell out of the speaker.
Now, that is here and you can get your
hands on him.
So any other questions?
It does not seem to be the case, and
even the Internet is satisfied, at least
for now.
So please give another warm round of
applause to speak, Eric.
Thank you.