
Custos is using Bitcoin to turn digital pirates against each other - eddyg
https://qz.com/1028528/custos-startup-uses-bitcoin-bounties-to-make-pirates-rat-on-one-another/
======
badosu
> _Custos embeds imperceptible bitcoin private keys in the digital files, with
> different keys for different advance copies of a movie or ebook. (...)

> At the same time, Custos makes a piece of free software that screens movie
> files for these private keys and markets the screener to content pirates.
> Pirates now have an incentive to check pirated movie files in case they
> contain a key. If a key is detected, the pirate can claim the bitcoin
> bounty—usually between $5 and $10—and is free to keep it. But once a bounty
> is claimed, Custos is alerted, and can begin the process of figuring out the
> origin of the leak._

This is really clever! A very interesting social experiment with some game
theory dynamics on the way.

~~~
Blahah
Seems pretty self-defeating. I'd just strip the keys and not claim the bounty.
This whole system depends on pirates wanting $5 more than they want to pirate
the thing, which from my 10 years around release and fxp groups in my younger
days, I can say is barely ever the case.

~~~
codezero
I'm assuming the keys are embedded before it's leaked like a watermark of
sorts. The leaker isn't the pirate in the scenario described _I think_.

~~~
Blahah
Ah! I read the references to pirates as referring to the person sharing the
file online from an original source. But someone just torrenting it or
something makes a lot more sense as the target here.

------
Adverblessly
Maybe I don't understand something?

John Doe, random employee working for Universal Studios leaks an advance copy
of "The Revenge of the Avengers: The Revengers Strike Back" to their contact
XPirateSepirothX for 250$ (or for free because they really want to get back at
their boss for laughing at them).

XPirateSephirothX passes on the watermarked movie to their friendly
neighbourhood reencoder IAmBecomeDeath who notices the watermark strips it,
and reencodes the movie for general consumption.

The pirating public receives an unwatermarked copy and cannot claim any prize.
IAmBecomeDeath, XPirateSephirothX and John Doe have no incentive to claim the
prize because they will implicate themselves in copyright violation.

Are they implying the watermark is impossible to remove? That seems unlikely
to me as pirates can be quite enterprising (and there may be some money on the
line for them as well), so I'd expect them to reverse engineer the process and
figure out how to strip it. Heck, this company is even offering an application
that checks if the watermark is present or not which should at least give the
pirates a measurement on whether their watermark removal method worked (on at
least some version of the watermark detection logic).

Or maybe the plan is to play a constant game of cat and mouse, Custos will
continually switch up their methods for watermarking and so the pirates will
never be sure if they caught and successfully stripped the latest and greatest
version of the watermark, preventing some piracy through uncaught watermarks
and some piracy through fear?

~~~
anilgulecha
> IAmBecomeDeath who notices the watermark strips it, and reencodes the movie
> for general consumption.

Or wants the $$, so claims it, putting down a breadcrumb. (Atleast that's what
the technology in the article is for.)

~~~
horsawlarway
It's not lucrative enough. The product is worth far more than the measly
bounty. Sure, claim that 15 dollars in bitcoin, and _never_ receive another
pre-release copy again, or... strip it and continue business as usual.

This model really only works when most encoders are not aware the tag is there
at all, and don't strip it.

Alternatively (as some other comments suggested) Custos buries additional tags
without revealing them, in which case they act just like all sorts of other
watermarking companies doing the same thing (not terribly effectively).

------
plus
If it is possible to strip the private key, e.g. by re-encoding, then an
intelligent and determined leaker would simply do that before distribution.
They likely won't be tempted to take the reward for themselves, given the
consequences, and by stripping the private key they can prevent anyone else
from claiming it. I suppose this would catch less savvy leakers, though.

Edit: To be clear, I understand that digital watermarking techniques can be
resilient to a simple re-encode, but since Custos is providing the tool to
claim the reward for free to pirates, it should be possible to reverse-
engineer the tool to identify and destroy the watermark.

~~~
dragonwriter
Reading data out of an enclosed file is much less of a problem than altering
that data without damaging the file. All you need for “screening” and
“claiming” is to read out the keys and check if the funds have already been
transferred out on the blockchain and, if not, transfer them out. There's no
alteration to the file content involved.

Destroying the keys requires altering the file while leaving it functional,
which requires more than reverse engineering the tool, because the tool
doesn't need that capacity.

~~~
plus
My point is that if you can identify how the private key is stored in the
video, then it should be possible to develop a strategy to destroy that data
without damaging the integrity of the file. Presumably the key will be hidden
in such a way that it won't be obvious to viewers (that is, it won't be a
_literal_ watermark). If that's true, then it should be possible to destroy
the key without making the video quality noticeably worse, e.g. by selectively
re-encoding certain parts of the video in a certain way that ensures
destruction of the private key. Of course I'm speculating, because I don't
know exactly how the private key is stored in the video, but video quality is
a lot more robust to bit massaging than a hidden digital private key would be.

------
tuxxy
This is neat, but I can't help but feel it's not going to work.

It would work if you encounter a movie that you wanted to watch, decide you
want the money instead, and you report to Custos.

This is not how piracy works.

Instead, a pirate knows the value of the good they have. They know it's worth
more to their reputation in the community than $5-10 dollars. By setting a
bounty on it, you'll just have others willing to pay more to leak it
themselves. This is an experiment, not a business.

~~~
simias
You don't "report" to CustOS directly, rather you simply move the money from
one of the CustOS "bounty" private keys into one of your own.

Effectively it does the same thing but I think psychologically it's pretty
different. For one thing you know that the bitcoin transaction will be very
hard to trace (you can't be betrayed by your IP address or something like
that) and you don't really rat anybody, you're just moving bitcoins. If you
don't have any direct relationship with the original leaker (say, you
downloaded the file through bittorent on some private tracker) there's really
no incentive not to claim the bounty. It's free money.

I wonder what happens if a legitimate recipient of one of these copies decides
to claim the bounty without actually leaking anything. Could they be in
trouble? If people accuse them of leaking a copy and they show that they have
control of the coins, will they be off the hook? Do they have to sign
something that forbids them from using the key?

~~~
pavel_lishin
If I were a pirate/leaker/sharer, I would be very tempted to just paste the
key on some completely unrelated forum to lay down a false trail.

~~~
philh
What does that get you? If I understand correctly, I don't think the content
owner finds out who uses the private key. They find out that the key has been
used, which normally means that someone leaked the file to a pirate, and tells
them who leaked.

~~~
simias
Plausible deniability? Since there's an other way for somebody in the wild to
have had access to the key without IP violation you could claim that you never
leaked the file in the first place.

Of course it's one of these smartass "hacker technicalities" that may not hold
much water in a court of law.

~~~
kgwgk
So your defense would be that you didn't leak the file but you did leak the
key?

------
grizzles
It seems like a good way to drive awareness of digital watermarking in the
file sharing community.

------
jakobegger
The big disadvantage with this scheme is that the publisher needs to pay the
reward in advance for every copy they want to protect. That‘s why the rewards
can‘t be big. (The publisher could of course keep the private keys and redeem
unclaimed rewards themselves after some time, only risking currency
fluctuations)

~~~
rtkwe
How much do they have to actually stock though? 50-100k USD ($5-10 over 10000
screeners) is a good bit of money but they'd probably only pay out a tiny
portion of that and compared to the budgets of a large blockbuster it's not
that large of an outlay.

If they can reliably embed multiple private keys into the screener DVDs they
could get by with having fewer account and using the combination of accounts
as the key. Though really if they're able to embed a whole private key in a
way that survives encoding why bother with the bounty, though I guess that
saves them the trouble of having to go find torrents/rips themselves.

~~~
jakobegger
This is a brilliant idea! Since we expect only a handful of leaks, each
screener could contain lets say around 100 bounties of $10, with 200 bounties
total. Then the first leak would be worth $1000, the second leak $500
(expected value) etc, and the studio only needs to pony up $2000 in total. We
are guaranteed to be able to identify the first leak, I'm not sure if we can
identify further leaks (there is probably some kind of trade-off between
payout for the first leak, total amount of bounties, and probability of being
able to identify further leaks, but the mathematics of this is probably not
trivial.

------
0x0
I looked around their web page but I couldn't find the "freely available
bounty hunter tool" they are talking about. Does it exist somewhere or is this
not actually launched yet? They are saying that individuals in pirate circles
are already hunting bounties with this tool...?

------
air7
tl;dr: Scenario: Studio sends 10ks advanced copies of their film to reviewers
before screening. One of them gets leaked. They want to know who leaked it.
Custos embeds a "watermark" in the copies that contains a private key of a
bitcoin wallet containing 5$. Each copy has a different wallet. When anyone
down the pirate chain decides to take the money, Custos knows who the leaking
source was. Benefit over traditional watermarks is that they only have to
monitor the wallets.

IMO this is quite a clever idea because even after pirates start scrubbing the
key off, there will always be an incentive to claim the money, perhaps much
later when someone can get many of them at once. It will seed distrust that'll
be hard to weed out.

~~~
delinka
If cashing out were delayed well past the statute of limitations, it'd be
interesting to see the repercussions.

------
anotheryou
I see no advantage over traditional invisiblee watermarks.

A movie usually just leaks once or twice, these leaks get replicate
everywhere. So if you are looking for a specific movie, just get a pirated
copy from anywhere and check the watermark yourself. It's trivial to check if
there is a leak at all and also trivial to find that leaked version and test
it. No need to throw 15 bucks per copy on it, just let the intern monitor some
torrent trackers.

~~~
icebraining
I think the difference is that the person who spreads the movie over the
trackers, who is not necessarily the original leaker, now has an incentive to
report it, whereas with regular watermarks they'd simply remove it before
distributing over those public channels.

Of course, it's hard to see such person being in a position to receive many
leaks in the future, after burning the original leaker, so the incentive seems
quite small.

------
bcoates
Calling "Insider gets the master private key list, steals all the bounties" as
the way this turns out.

------
borne0
I don't get it. Any 'damage' to the studio happens when the movie is publicly
leaked, at that point just download the copy yourself and check for a
watermark, telling you where the leak originated without ponying up $5-$10
(which is a paltry sum to begin with).

~~~
Matt3o12_
For this, the company has to first find the leak version. This means they need
people to monitor all kind of sites for this material. With the bitcoin
method, the company only needs to monitor a bunch of bitcoin wallets and, as
soon as a transfer is made, the are aware of the leak immediately (with much
less men power. Furthermore they also don’t need people who have access to
those “private” torrent exchanges).

Furthermore, their response times are pretty awesome (if they are in fact
true):

> Van Rooyen claims once a leaked copy containing a bounty hits the dark web,
> it takes just five minutes on average for the bounty to be claimed and
> Custos and its client to be alerted. On social networks it takes 42 seconds;
> and offline, like if a movie is copied or shared on a DVD or USB drive, it’s
> 28 minutes.

------
mustafabisic1
“You just need a single rotten apple in that group,” he says.

Reminds me of my Primary school teacher :)

Custos did it masterfully.

------
nfriedly
Hah, now some pirate is going to try and figure out how to get all of the
private keys :P

~~~
rtkwe
Beyond just hacking into Custos and stealing them or Custos using a somehow
predictable keygen (not even sure that's really a thing?), in doing that
they'd be tracking down all the leaks which is exactly what Custos and their
customers are wanting.

In reality only a few screeners seem to leak for any given movie.

------
test6554
What's to stop the intended recipient of the movie from intentionally and
unabashedly claiming the bitcoins for themselves.

~~~
et2o
1) It marks them as a "leaker" 2) If you keep claiming the bitcoins, you are
going to stop getting videos sent to you. This could have professional
implications.

~~~
pavel_lishin
You can claim the bounty without leaking the film, though as you point out,
this could prevent you from being sent films in the future.

------
drewbuschhorn
It's a great idea from a game theory perspective, but I think an adversarial
neural network plugin built into vlc as a preencoding step would probably
defeat it pretty quickly with minimal quality loss.

You just can't effectively watermark data intended for human consumption, our
tolerance for intentionally induced noise is too high.

~~~
plus
I don't want to be confrontational, but I really don't understand the point
you're trying to make. Why a neural network, why VLC? I understand that you
are suggesting it would be possible to strip the watermark, but the way you've
said it sounds a lot like "create a GUI interface using visual basic, see if I
can track an IP address"[0]. Which is to say, you've not said what you would
do to defeat it, but how you think it would be implemented... which doesn't
really tell us anything about HOW you think it could be defeated.

>You just can't effectively watermark data intended for human consumption, our
tolerance for intentionally induced noise is too high.

If this were true, steganography[1] would be useless in practice (it isn't).

I would suggest reading up on digital watermarking[2].

[0]
[https://www.youtube.com/watch?v=hkDD03yeLnU](https://www.youtube.com/watch?v=hkDD03yeLnU)
[1]
[https://en.wikipedia.org/wiki/Steganography](https://en.wikipedia.org/wiki/Steganography)
[2]
[https://en.wikipedia.org/wiki/Digital_watermarking](https://en.wikipedia.org/wiki/Digital_watermarking)

~~~
drewbuschhorn
> I don't intend to be confrontational

Of course you do, or you wouldn't end the comment with "I suggest you read up
on."

Stenography is only useful when it's unknown or impractical to investigate
possible payloads, either do to volume of possible hits or lack of knowledge
how to decode the payload out of the source. If you tell an opponent: here is
the decode technique and here is where the message is likely to be, you've
basically defeated your own stenography.

~~~
plus
It is true that my intention was not to be rude. My "I suggest you read up on"
comment was in response to your claim:

>You just can't effectively watermark data intended for human consumption, our
tolerance for intentionally induced noise is too high.

Which is simply not true! That kind of misunderstanding suggests that you are
unfamiliar with the kinds of digital watermarking that are used TODAY, hence
my suggestion that you read up on it. If the comment came off as rude, I
certainly apologize, but I stand by the point I was trying to make.

>If you tell an opponent: here is the decode technique and here is where the
message is likely to be, you've basically defeated your own stenography.

I agree with you on this point 100%. I also made a post to that effect
elsewhere. But that is not the same argument you made in your previous post!

