10 ms·

How encryption for Cinema Movies works

230 points by perryflynn 1y ago

6stringmerc 1y ago
Fascinating read and I think an accessible presentation of a lot of the concepts / framework and mechanics of this type of system.
john01dav 1y ago
Even with all of this onerous encryption and DRM, it's not hard to find pirated copies of movies. It makes me think that the sacrifice in ownership rights for the theaters over their equipment isn't worth it.
- ajsnigrutin 1y ago
  Yep, and those pirated copies are DRM free, work everywhere, no HDCP and other crap, no internet connection needed, so they're "better" in that way too (not just price-wise).
  - eastbound 1y ago
    Totally possible that watermark identifies cinemas and showtimes uniquely, and that pirates are due for a lifetime of prosecution. Or that studios will shut down some cinemas, until it stops. For 15 years you let paid options progress. Then fewer people pirate, then you catch the rest. At the beginning you don’t see it putting its clamps; then suddenly you don’t find piracy anywhere.
    - ajsnigrutin 1y ago
      Yes, and those paid options were one subscription that had "everything". Then paid options broke up into 5 different subscriptions, some not allowing more than 2 devices, some having ads in paid plans, some not available in your country, some only having seasons 3 and 5 of the series, some having the series you wanted to watch but remove it half way through, some give you a "buy" button for the media, but then take the movies away after a few months, etc. And people go back to piracy, because the user experience is better.
      - Mindwipe 1y ago
        > Yes, and those paid options were one subscription that had "everything". It really didn't. It's incredible this collective delusion exists when it's not true.
        alabastervlog 1y ago
        It was a lot closer when they still had a streaming + disk option, but even then, they were missing lots (and lots, and lots) of stuff. I think people don't realize how many tens of thousands (maybe into the hundreds, IDK, I wouldn't be surprised) of films there are, let alone how many hours of TV content. This is like when people talk about how everything's on the Web, when it comes to books. 1) This is only even sort-of true if by "on the Web" you mean "piracy sites have an epub/pdf of it", and 2) even then, extremely not close to true, the time from "I'm going to deep-dive this topic" to "... and now I need to go to the library, and possibly a specific library, maybe on another continent" is often not long at all.
        baud147258 1y ago
        > "I'm going to deep-dive this topic" to "... and now I need to go to the library, and possibly a specific library, maybe on another continent" I remember an history professor saying that for a subject he was working on he had to borrow a book from the library of Congress (through the library of his university), where the only publicly available copy in the US was. Of course it was an academic book, so it's not exactly a common situation.
    - kelnos 1y ago
      > For 15 years you let paid options progress. [...] then suddenly you don’t find piracy anywhere. And then they completely ruined it with fragmentation. When all I need to watch everything I wanted to watch was three subscriptions (Netflix, Hulu, and HBO), I was totally fine with the ~$40/mo and reasonably-ok-UX offered. But now it's a mess. I need subscriptions to 7 or 8 different services (which now each cost twice what they used to for an ad-free experience), and the experience is crap. Netflix no longer plays on my Linux/Firefox setup (same thing happened with HBO years ago), and their anti-password-sharing mis-features constantly trigger for me even though I don't share my Netflix password. The Android apps for most of them are glitchy and buggy, and Chromecast has somehow gotten less reliable over time. The irony is that usually I would say more competition is a good thing. I suppose if we had lots of streaming services, but studios were required to license all their content under RAND terms to anyone who asks, we'd have real competition, and streamers would compete on the quality of their platform, lack of ads, etc., and not just on what titles they were lucky enough to be able to license. I do agree that pirating became less popular for a while, but that golden age is over. The piracy scene seems stronger than ever these days.
      - Freak_NL 1y ago
        > Netflix no longer plays on my Linux/Firefox setup […] I know Netflix doesn't support anything beyond 720p or so on Linux, but that never bothered me. Otherwise it just works. Is your Firefox out of date? > The piracy scene seems stronger than ever these days. I hope so. A lot of damage was done. If it wasn't for archive.org a lot of older, regional stuff would not even be accessible. We need piracy if only for the collective digital archives. I refuse to take out more than one subscription. We just hop services.
- gruez 1y ago
  Most pirated copies aren't from theatrical releases; they mostly come out when the titles are available on streaming/blu-ray. DRM might be a failure in other fields, but it's working pretty well in this particular case.
  - deleted 1y ago
    [deleted]
  - johnisgood 1y ago
    I think the question remains, is it still worth it given these holes?
    - lb1lf 1y ago
      It presumably is, as the effort is kept up despite the cost and inconvenience. My guess would be that the plan is mostly to ensure that when a new release premieres in theatres, going to a theatre is the only way to experience it in high quality. It doesn't really matter all that much if the people who waits for it to arrive on Netflix gets a pirated copy; it does matter if the ones forking over $20 to see it in a theatre does, though.
      - sethhochberg 1y ago
        A really important element of this is that much of the burden of maintaining the DRM is on the theaters, and the theaters themselves are the ones who care about protecting the theatrical release period: you might be less likely to pay them for a ticket if you can get a high-quality copy at home before the actual streaming/media release It’s a different dynamic than we typically talk about with DRM. Most of the time DRM is something imposed on a consumer who doesn’t really want it. But in this case, the consumer is the theater and they really do want the protection.
        fmajid 1y ago
        While at the same time dealing with potentially untrustworthy employees and the prisoner's dilemma.
- perryflynn 1y ago
  It also contains watermarks. So theatres which failed to prevent recording will run into serious issues. See https://dcpomatic.com/forum/viewtopic.php?t=2372 https://dcpomatic.com/forum/viewtopic.php?t=2372
  - deleted 1y ago
    [deleted]
  - thr0w 1y ago
    NexGuard is a wild product.
    - stavros 1y ago
      The flea repellant?
      - thr0w 1y ago
        Nagra's forensic watermarking tech.
  - coppsilgold 1y ago
    If the software to watermark is widely available (as it appears to be) then an adversary has all they need to corrupt any existing watermark. These steganographic watermarks depend on no knowledge of the process. If the method is particularly ingenious (one of the inputs is centrally stored entropy which the extractor references by trialing them all) then knowledge of the process alone may not be sufficient to obtain a high quality result (as too much corruption may be required) but could be used to inform the next step: If you obtain two or more copies of the decrypted content you will be able to diff them and work out what you need to corrupt even without knowledge of the watermarking process. This probably won't work with pirated CAM's or take quite an effort to find the signal in the noise. Edit: After some more research it looks like they don't actually watermark the distributed data (the movie sent to cinemas). The projector inserts its unique watermark during playback. There may be other secret watermarks put in by distributors not mentioned anywhere.
- codemiscreant 1y ago
  There is essentially zero piracy from these digital cinema releases. The pirate copies are generally from once it starts digitally streaming on one of the services including PPV, and when pirate copies exist earlier it is almost always someone with a camera in a theatre making a terrible quality screener. Piracy is inevitable, but in this case their model is much more robust that I would have predicted.
  - tptacek 1y ago
    Most importantly, the industry concerns itself primarily with the new-release window; that high fidelity copies will eventually be widely available doesn't break the model.
    - kelnos 1y ago
      I suppose this would help keep pirated copies from getting out before the theatrical release date (presumably theaters are given these digital releases at least days before their first projection date). But it seems that more and more releases are straight-to-streaming, and/or sometimes simultaneous with the theatrical release. High-quality pirated copies often show up within a day of a streaming release. Sure, many are still theater-only for a week or more after initial release. I get that a big part of their business model for some titles relies on theater ticket sales within the first days or at most weeks after release, but all this DRM just feels like an exhausting, expensive, ultimately-losing game for them. Especially when we consider how theater-going has declined over time, especially recently.
      - plastic3169 1y ago
        There are no high quality pirated versions though. The streaming version and even blu-ray is compressed way heavier than these DCP files. I’d buy these cinema versions of films in a heartbeat if they were availble.
        loeg 1y ago
        1080p/4k as encoded by the streaming sites / blu-ray is sufficiently high quality for virtually all of the viewing public. You're weird (no offense).
- Aurornis 1y ago
  Pirated copies of theatrical releases at the time of release are much more rare, though. The value of protecting releases is extremely high in the narrow window of finalizing production and getting it into theaters or online launch platforms. If there was no DRM and watermarking then these would be pirated constantly before release.
- anal_reactor 1y ago
  Most people are completely fine watching a 720p x264 1GB version half a year after release. Sure, there are some purists who want as good image quality as possible as soon as possible, but that's a tiny minority. I think the actual motivation is that cinemas are becoming less and less relevant in the age of streaming, so they're doing anything they can to protect the little revenue they have, because the only way cinema can make money is to hype a movie to the moon, and then have it shown exclusively in cinemas for some period of time. But with streaming services investing in their own movies, the days of this distribution model are numbered. Having a cinema in 2025 is like having an internet cafe in 2010.
  - yladiz 1y ago
    This really downplays the cinema experience. Yes, many people are fine watching a movie at home while doing something else (the current Netflix model of filmmaking is precipitated on this), and others are fine to watch at home in general, but few people would truly say that their setup is close to what you get in a cinema. The screen is much bigger, the image quality is higher, and the sound system is much better as well, compared to anything short of an actual home cinema setup. It’s not the only reason of course, but it’s one of a few reasons cinemas still sell out for big films like Dune 2, and why people will go out of their way to go watch it in the cinema. Streaming will never fully replace cinemas, even if it dramatically impacts their operating mode, and to argue otherwise is naive.
    - anal_reactor 1y ago
      > but few people would truly say that their setup is close to what you get in a cinema. The opposite is also true. Few cinemas have a setup that imitates the comfort of watching something at home.
- fmajid 1y ago
  Quite often it's industry insiders themselves who release rips from the Blu-Ray screener disks sent for Academy Awards consideration.
ddtaylor 1y ago
How are groups getting the high quality digital dumps of some movies then?
- kmeisthax 1y ago
  Hollywood is stupid and eroded its own economic advantage by putting everything on streaming. This was already known, but it also makes antipiracy operations much, much harder. Ripping a stream is always going to be easier than getting any unprotected video footage out of a movie theater. The stream is in your own home, you own and can tamper with all the equipment involved in playing it, and the economics of CDNs prevent robust traitor-tracing schemes[0] that could be used to hunt you down. In contrast, movie theaters are public locations, so every one of them is a known entity. The entire supply chain for movie projection is controlled. And that makes traitor-tracing a lot easier. All the hackers pointing out that DRM is fundamentally breakable are ignoring the fact that that only matters iff you're anonymous and untraceable. Otherwise, they won't bother making the DRM stronger, they'll just arrest people until the movies stop leaking. It's the XKCD laptop wrench story[1] in reverse. The crypto nerd imagines DRM to be easily broken trash, but the reality is that the security of the DRM is in the $5 wrench, not the math. Let's play contrast-and-compare. If you want to leak a stream, you need: - A streaming account - Knowhow or software to decrypt the data stream as it's downloaded and played, or, - Knowhow to modify a TV so that you can capture the unencrypted video and audio streams inside the TV The last one isn't done because it's a pain in the ass and the TV scene prefers bit-perfect rips over re-encoded captures. But at some point in the TV, you have to decrypt the video; LCD panels do not natively accept encrypted signals. And that is something you can build hardware to capture. Now let's try leaking a movie. There's a few avenues of attack, roughly corresponding to the traditional movie scene release categories: - You can go to the theater and point a camera at the screen. They actually check for this now, in pretty much any western country you'll get kicked out or arrested for camming a movie. If you don't get caught, they can still narrow you down to a location in the room via your shooting angle, and possibly determine what theater you were at with line frequency hum. That's enough information to narrow down the guy leaking the movie to a handful of customers. Do this enough times and you create a unique fingerprint to catch yourself with. - You can get a job as a projectionist and run the movie projector into another camera directly. That kind of machine is called a telecine, and it used to be one of the higher quality ways to get leaked movies back when they were on film. This is specifically the scenario that all the DRM in the projector is designed to stop. If you do anything to change the light path of the projector, it locks up until the manager comes in and types a password to authorize the change. - You could bribe the manager or owner to telecine the movie for you. Problem is, the number of people who actually have the password that unlocks the projector is really small[2] and traceable. If a telecine leak is traced back to their theater, someone's getting fired at a minimum, jailed in the worst case. - You could break the DCI scheme itself; but you still need to source the files and keys to decrypt the movies. This is the crypto nerd's imaginary scenario. Even then, the files could themselves have steganographically injected information identifying the theater who got that master copy, which you can't strip out merely by having the encryption keys. Again, nobody is giving you those files unless they're too stupid to understand the implications (unlikely) or they have faith that you can strip out the stegotext. It's just way easier to rip a stream than a movie in a theater. And when Hollywood moved to streaming they also made it a lot easier to leak movies. [0] To be clear, traitor-tracing each stream would require a unique encode per account to inject the stegotext; that's computationally unfeasible. Doing one encode per movie theater would still be a struggle, but less so by three orders of magnitude. [1] https://xkcd.com/538/ https://xkcd.com/538/ [2] This is also why the 3D era of film made movies way too fucking dark.
Animats 1y ago
JPEG 2000 for each frame? I wonder what they use for decompression. JPEG 2000 decompressors are really slow. Most couldn't keep up with frame rate without GPU support.
- userbinator 1y ago
  Dedicated hardware, not even regular GPUs. JPEG2000 decompression has a rather complex entropy decoding part which is not easily parallisable.
  - fulafel 1y ago
    Only on the intraframe level - Frames are independent so overall it's "embarrassingly parallel".
    - crazygringo 1y ago
      There's no point to decoding in parallel if you're watching in sequence.
      - dsr_ 1y ago
        If your hardware can only manage 4 frames per second but you need 48, then decoding with 12 sets of hardware in parallel achieves your goal.
        crazygringo 1y ago
        Derp, quite right. Never mind, thanks!
        Animats 1y ago
        Although you still have four frames of latency if you do it that way. All the audio has to be delayed to match. Parallelized decode of JPEG 2000 frames is quite possible, though. The choice of JPEG 2000 is unexpected. Most of the neat features of JPEG 2000 are useless for cinema. Being able to construct a low-rez version from a truncated file isn't useful. Nor is the ability to divide the image into tiles and decompress different tiles at different resolution. (That's used in JPEG 2000 medical and military imagery, where you want to zoom in on the interesting part and see it in lossless mode.) You can have more than RGB or RGBA layers, which the multispectral imagery and prepress people like. Maybe the advantage is that you can have more than 8 bits of color depth.
andreashaerter 1y ago
I also recommend an insightful talk by the author of the article, delivered at a Chaos Computer Club (CCC) event (GPN, Gulaschprogrammiernacht) on this topic. Unfortunately, it's only available in German, but it's definitely worth watching: https://media.ccc.de/v/gpn22-382-kein-kinoerlebnis-ohne-korrektes-zertifikatsmanagement https://media.ccc.de/v/gpn22-382-kein-kinoerlebnis-ohne-korr... „No cinema experience without correct certificate management... A look behind the scenes of a cinema with a digital projector system, how distributors deliver films to cinemas with end-to-end encryption, and how films are protected from piracy. In addition to an overview of projector technology, the presentation will demonstrate the file format and manual decryption of film data.“ Edit: I just realized that the author of the article also delivered the recorded talk, adapted my comment.
jeffbee 1y ago
It's remarkable that they do all this in the context of box office revenues cratering. In 2024 American theaters has less gross ticket sales than they did in 1982, in constant dollars. The whole thing of movie theaters is just over.
- tverbeure 1y ago
  Why does that context matter? It's not as if the use of DRM for movie theater distribution influences whether or not somebody goes to see a movie.
  - jeffbee 1y ago
    No, the other direction. Clearly the problem is that nobody wants their product, not that everyone wants to steal it.
    - tverbeure 1y ago
      Without DRM, even less people would visit a movie theater.
- KaiserPro 1y ago
  Encrypted DCPs have been around since when DVDs were still a revenue generator.
dherls 1y ago
I'm confused why it's encrypted as a JPEG image per frame instead of one AES encrypted video file. Since the same AES key is used for each frame it wouldn't add any additional security imo
- Aurornis 1y ago
  I think JPEG 2000 is simply the chosen format for distribution of the video, not for security. JPEG 2000 has some interesting properties for very high quality video storage and transport where bandwidth is not a concern. The traditional encoded video formats we know are less preferred at this scale. JPEG 2000 is resource intensive, though. The decoding hardware is probably either GPU based or using an FPGA implantation from one of the providers who makes hardware for this.
  - userbinator 1y ago
    It's definitely dedicated hardware JPEG2000 decoding.
- KaiserPro 1y ago
  DCPs were designed to be jpeg200 streams with a bunch of audio streams as well. The idea was that they wanted up to 16bit colour (per channel) lossless imagery. The encryption was (or so I recall) was an extra feature.
- perryflynn 1y ago
  One movie can be 200G to 1TB large. The chunked encryption allows it to seek the movie without decrypting from the beginning.
  - 01HNNWZ0MV43FF 1y ago
    But any computer with full disk encryption also has seekable encryption
- Biganon 1y ago
  As per asdcplib's author themselves in another clmment: > Frame-by-frame encipherment, rather than whole stream, better supports random access and the famous tobacco intermissions popular in the EU.
shmerl 1y ago
"Standards that have to be purchased". Someone is just trying to fleece the participants. That's what whole DRM is about most of the time.
- tverbeure 1y ago
  Standards are often cheap. Many tech companies have a subscription to all IEEE papers and standards. The incremental cost of downloading one standard more is in the noise. But even if you don't have a subscription, the price for, say, the 802.11n standard is only $381.
KaiserPro 1y ago
Packaging DCPs used to be a massive faff. (it might still be one) Basically they are a tar[1] of images with a bunch of audio streams for different speaker configurations. depending on the quality settings, they can be encoded for higher colour space (ie 16 bit log per channel) Even with lossless jpeg2000, these packages can be huge. But, back in 2011, the biggest problem was encoding jpeg2000 required hardware to get anything near realtime performance. (I also think there were dedicated DCP packaging machines, but I never actually saw one.) One of my colleagues decided the best way to ship the finalised movie was to open up an NFS port on sohonet and let the technicolor hook the DCP packager directly. it worked, but our CTO diplomatically asked them to stop. [1] not actually but conceptually similar
jackjeff 1y ago
> The video stream is encoded as one single JPEG2000 picture per frame. Each frame is encrypted with the same static AES key. Is this not a problem? It’s not a good idea to reuse the same key to encrypt very similar files. Similar to ECB. See the famous penguin https://words.filippo.io/the-ecb-penguin/ https://words.filippo.io/the-ecb-penguin/ I’m surprised they don’t use something like XTS commonly used for disk encryption. It derives a unique key for each block/frame and allow you to access each individual blocks/frames non sequentially.
- perryflynn 1y ago
  No. They use a unique IV for each frame: > Every Frame is using a unique IV (Initialization Vector), which ensures that the AES Block Cipher generates always different cipher texts and makes brute force harder. This works similar to a Password Salt.
  - jackjeff 1y ago
    Oh thanks. I missed that. I guess that works pretty well too!
NoMoreNicksLeft 1y ago
>Encrypted DCPs use Forensic Watermarks which contain the serial number of the projection system. So if a recorded copy of a movie appears online, the theatre will have to answer serious questions and may never get movies again. Is this not as simple as dumping the same movie from two different projectors, diffing the output, then obfuscating the watermark?
- TheDcoder 1y ago
  To do that you need to figure out what parts are noise (watermark), simply diffing them would just give you a different noise pattern which can still be analyzed depending on how the watermark is encoded.
asdcplib 1y ago
Hi, asdcplib author here (mentioned in the article.) Excellent writeup of DCP and related tech. FYI the colorspace of an SDR DCP MXF file is X'Y'Z' with gamma 2.6 (see SMPTE 428-1.) Other MXF formats (i.e., not cinema) use a wide variety of colorspaces. Despite the huge range of XYZ, DCP image files are usually constrained to code values that fall within P3 (again, SDR.) The HDR applications are more interesting. Upon reading the comments: • DCP is a B2B format. DCP usage is licensed by contract, not EULA. Please keep these important differences in mind when commenting on DRM. • Decrypt, decode, color processing, watermark occurs in FPGA. If you think that sounds hard, remember that all of this tech was originally deployed 20 years ago. Moore's law has made our lives much easier since! • Frame-by-frame encipherment, rather than whole stream, better supports random access and the famous tobacco intermissions popular in the EU.
hbcondo714 1y ago
> 31. May 2024 I’m trying to understand the timeline here; the article was originally written last year and the latest spec is also from 2024 but the article has a link to this HN thread created yesterday?
- baud147258 1y ago
  Maybe the author saw a bunch of hits coming from HN and edited his post to add the link to the discussion? It doesn't seem as if the author themselves posted their article.
  - perryflynn 1y ago
    Yes, I added some notes/improvements while the discussion was happening here. Changelog: https://github.com/perryflynn/serverless.industries/commits/master/src/_posts/2024/2024-05-31-digital-cinema.en.md https://github.com/perryflynn/serverless.industries/commits/...
vitplister 1y ago
Maybe someone with more knowledge could comment on what happened here: https://wikileaks.org/sony/docs/05/docs/Digital%20Cinema/Digital%20Cinema%20Security%20Compromise.pptx.pdf https://wikileaks.org/sony/docs/05/docs/Digital%20Cinema/Dig...
- perryflynn 1y ago
  Well, the DCI system relies on trusted (TPM-ish) hardware. One server vendor has used insecure certificates. So if a AES key for a movie is encrypted / shipped for such insecure certificate the AES key for the movie can be decrypted outside of the actual projector hardware. This is one reason why they use Device lists, if such a issue becomes public, they will just block this specific projector or the whole product line for future movie releases and the leak is contained. Also only movies which got assigned to that projection system are affected. So the damage is low/medium.

230 points by perryflynn 1y ago

Fascinating read and I think an accessible presentation of a lot of the concepts / framework and mechanics of this type of system.

john01dav 1y ago

Even with all of this onerous encryption and DRM, it's not hard to find pirated copies of movies. It makes me think that the sacrifice in ownership rights for the theaters over their equipment isn't worth it.

ajsnigrutin 1y ago
Yep, and those pirated copies are DRM free, work everywhere, no HDCP and other crap, no internet connection needed, so they're "better" in that way too (not just price-wise).
- eastbound 1y ago
  Totally possible that watermark identifies cinemas and showtimes uniquely, and that pirates are due for a lifetime of prosecution. Or that studios will shut down some cinemas, until it stops. For 15 years you let paid options progress. Then fewer people pirate, then you catch the rest. At the beginning you don’t see it putting its clamps; then suddenly you don’t find piracy anywhere.
  - ajsnigrutin 1y ago
    Yes, and those paid options were one subscription that had "everything". Then paid options broke up into 5 different subscriptions, some not allowing more than 2 devices, some having ads in paid plans, some not available in your country, some only having seasons 3 and 5 of the series, some having the series you wanted to watch but remove it half way through, some give you a "buy" button for the media, but then take the movies away after a few months, etc. And people go back to piracy, because the user experience is better.
    - Mindwipe 1y ago
      > Yes, and those paid options were one subscription that had "everything". It really didn't. It's incredible this collective delusion exists when it's not true.
      - alabastervlog 1y ago
        It was a lot closer when they still had a streaming + disk option, but even then, they were missing lots (and lots, and lots) of stuff. I think people don't realize how many tens of thousands (maybe into the hundreds, IDK, I wouldn't be surprised) of films there are, let alone how many hours of TV content. This is like when people talk about how everything's on the Web, when it comes to books. 1) This is only even sort-of true if by "on the Web" you mean "piracy sites have an epub/pdf of it", and 2) even then, extremely not close to true, the time from "I'm going to deep-dive this topic" to "... and now I need to go to the library, and possibly a specific library, maybe on another continent" is often not long at all.
        baud147258 1y ago
        > "I'm going to deep-dive this topic" to "... and now I need to go to the library, and possibly a specific library, maybe on another continent" I remember an history professor saying that for a subject he was working on he had to borrow a book from the library of Congress (through the library of his university), where the only publicly available copy in the US was. Of course it was an academic book, so it's not exactly a common situation.
  - kelnos 1y ago
    > For 15 years you let paid options progress. [...] then suddenly you don’t find piracy anywhere. And then they completely ruined it with fragmentation. When all I need to watch everything I wanted to watch was three subscriptions (Netflix, Hulu, and HBO), I was totally fine with the ~$40/mo and reasonably-ok-UX offered. But now it's a mess. I need subscriptions to 7 or 8 different services (which now each cost twice what they used to for an ad-free experience), and the experience is crap. Netflix no longer plays on my Linux/Firefox setup (same thing happened with HBO years ago), and their anti-password-sharing mis-features constantly trigger for me even though I don't share my Netflix password. The Android apps for most of them are glitchy and buggy, and Chromecast has somehow gotten less reliable over time. The irony is that usually I would say more competition is a good thing. I suppose if we had lots of streaming services, but studios were required to license all their content under RAND terms to anyone who asks, we'd have real competition, and streamers would compete on the quality of their platform, lack of ads, etc., and not just on what titles they were lucky enough to be able to license. I do agree that pirating became less popular for a while, but that golden age is over. The piracy scene seems stronger than ever these days.
    - Freak_NL 1y ago
      > Netflix no longer plays on my Linux/Firefox setup […] I know Netflix doesn't support anything beyond 720p or so on Linux, but that never bothered me. Otherwise it just works. Is your Firefox out of date? > The piracy scene seems stronger than ever these days. I hope so. A lot of damage was done. If it wasn't for archive.org a lot of older, regional stuff would not even be accessible. We need piracy if only for the collective digital archives. I refuse to take out more than one subscription. We just hop services.
gruez 1y ago
Most pirated copies aren't from theatrical releases; they mostly come out when the titles are available on streaming/blu-ray. DRM might be a failure in other fields, but it's working pretty well in this particular case.
- deleted 1y ago
  [deleted]
- johnisgood 1y ago
  I think the question remains, is it still worth it given these holes?
  - lb1lf 1y ago
    It presumably is, as the effort is kept up despite the cost and inconvenience. My guess would be that the plan is mostly to ensure that when a new release premieres in theatres, going to a theatre is the only way to experience it in high quality. It doesn't really matter all that much if the people who waits for it to arrive on Netflix gets a pirated copy; it does matter if the ones forking over $20 to see it in a theatre does, though.
    - sethhochberg 1y ago
      A really important element of this is that much of the burden of maintaining the DRM is on the theaters, and the theaters themselves are the ones who care about protecting the theatrical release period: you might be less likely to pay them for a ticket if you can get a high-quality copy at home before the actual streaming/media release It’s a different dynamic than we typically talk about with DRM. Most of the time DRM is something imposed on a consumer who doesn’t really want it. But in this case, the consumer is the theater and they really do want the protection.
      - fmajid 1y ago
        While at the same time dealing with potentially untrustworthy employees and the prisoner's dilemma.
perryflynn 1y ago
It also contains watermarks. So theatres which failed to prevent recording will run into serious issues. See https://dcpomatic.com/forum/viewtopic.php?t=2372 https://dcpomatic.com/forum/viewtopic.php?t=2372
- deleted 1y ago
  [deleted]
- thr0w 1y ago
  NexGuard is a wild product.
  - stavros 1y ago
    The flea repellant?
    - thr0w 1y ago
      Nagra's forensic watermarking tech.
- coppsilgold 1y ago
  If the software to watermark is widely available (as it appears to be) then an adversary has all they need to corrupt any existing watermark. These steganographic watermarks depend on no knowledge of the process. If the method is particularly ingenious (one of the inputs is centrally stored entropy which the extractor references by trialing them all) then knowledge of the process alone may not be sufficient to obtain a high quality result (as too much corruption may be required) but could be used to inform the next step: If you obtain two or more copies of the decrypted content you will be able to diff them and work out what you need to corrupt even without knowledge of the watermarking process. This probably won't work with pirated CAM's or take quite an effort to find the signal in the noise. Edit: After some more research it looks like they don't actually watermark the distributed data (the movie sent to cinemas). The projector inserts its unique watermark during playback. There may be other secret watermarks put in by distributors not mentioned anywhere.
codemiscreant 1y ago
There is essentially zero piracy from these digital cinema releases. The pirate copies are generally from once it starts digitally streaming on one of the services including PPV, and when pirate copies exist earlier it is almost always someone with a camera in a theatre making a terrible quality screener. Piracy is inevitable, but in this case their model is much more robust that I would have predicted.
- tptacek 1y ago
  Most importantly, the industry concerns itself primarily with the new-release window; that high fidelity copies will eventually be widely available doesn't break the model.
  - kelnos 1y ago
    I suppose this would help keep pirated copies from getting out before the theatrical release date (presumably theaters are given these digital releases at least days before their first projection date). But it seems that more and more releases are straight-to-streaming, and/or sometimes simultaneous with the theatrical release. High-quality pirated copies often show up within a day of a streaming release. Sure, many are still theater-only for a week or more after initial release. I get that a big part of their business model for some titles relies on theater ticket sales within the first days or at most weeks after release, but all this DRM just feels like an exhausting, expensive, ultimately-losing game for them. Especially when we consider how theater-going has declined over time, especially recently.
    - plastic3169 1y ago
      There are no high quality pirated versions though. The streaming version and even blu-ray is compressed way heavier than these DCP files. I’d buy these cinema versions of films in a heartbeat if they were availble.
      - loeg 1y ago
        1080p/4k as encoded by the streaming sites / blu-ray is sufficiently high quality for virtually all of the viewing public. You're weird (no offense).
Aurornis 1y ago
Pirated copies of theatrical releases at the time of release are much more rare, though. The value of protecting releases is extremely high in the narrow window of finalizing production and getting it into theaters or online launch platforms. If there was no DRM and watermarking then these would be pirated constantly before release.
anal_reactor 1y ago
Most people are completely fine watching a 720p x264 1GB version half a year after release. Sure, there are some purists who want as good image quality as possible as soon as possible, but that's a tiny minority. I think the actual motivation is that cinemas are becoming less and less relevant in the age of streaming, so they're doing anything they can to protect the little revenue they have, because the only way cinema can make money is to hype a movie to the moon, and then have it shown exclusively in cinemas for some period of time. But with streaming services investing in their own movies, the days of this distribution model are numbered. Having a cinema in 2025 is like having an internet cafe in 2010.
- yladiz 1y ago
  This really downplays the cinema experience. Yes, many people are fine watching a movie at home while doing something else (the current Netflix model of filmmaking is precipitated on this), and others are fine to watch at home in general, but few people would truly say that their setup is close to what you get in a cinema. The screen is much bigger, the image quality is higher, and the sound system is much better as well, compared to anything short of an actual home cinema setup. It’s not the only reason of course, but it’s one of a few reasons cinemas still sell out for big films like Dune 2, and why people will go out of their way to go watch it in the cinema. Streaming will never fully replace cinemas, even if it dramatically impacts their operating mode, and to argue otherwise is naive.
  - anal_reactor 1y ago
    > but few people would truly say that their setup is close to what you get in a cinema. The opposite is also true. Few cinemas have a setup that imitates the comfort of watching something at home.
fmajid 1y ago
Quite often it's industry insiders themselves who release rips from the Blu-Ray screener disks sent for Academy Awards consideration.

ddtaylor 1y ago

How are groups getting the high quality digital dumps of some movies then?

kmeisthax 1y ago
Hollywood is stupid and eroded its own economic advantage by putting everything on streaming. This was already known, but it also makes antipiracy operations much, much harder. Ripping a stream is always going to be easier than getting any unprotected video footage out of a movie theater. The stream is in your own home, you own and can tamper with all the equipment involved in playing it, and the economics of CDNs prevent robust traitor-tracing schemes[0] that could be used to hunt you down. In contrast, movie theaters are public locations, so every one of them is a known entity. The entire supply chain for movie projection is controlled. And that makes traitor-tracing a lot easier. All the hackers pointing out that DRM is fundamentally breakable are ignoring the fact that that only matters iff you're anonymous and untraceable. Otherwise, they won't bother making the DRM stronger, they'll just arrest people until the movies stop leaking. It's the XKCD laptop wrench story[1] in reverse. The crypto nerd imagines DRM to be easily broken trash, but the reality is that the security of the DRM is in the $5 wrench, not the math. Let's play contrast-and-compare. If you want to leak a stream, you need: - A streaming account - Knowhow or software to decrypt the data stream as it's downloaded and played, or, - Knowhow to modify a TV so that you can capture the unencrypted video and audio streams inside the TV The last one isn't done because it's a pain in the ass and the TV scene prefers bit-perfect rips over re-encoded captures. But at some point in the TV, you have to decrypt the video; LCD panels do not natively accept encrypted signals. And that is something you can build hardware to capture. Now let's try leaking a movie. There's a few avenues of attack, roughly corresponding to the traditional movie scene release categories: - You can go to the theater and point a camera at the screen. They actually check for this now, in pretty much any western country you'll get kicked out or arrested for camming a movie. If you don't get caught, they can still narrow you down to a location in the room via your shooting angle, and possibly determine what theater you were at with line frequency hum. That's enough information to narrow down the guy leaking the movie to a handful of customers. Do this enough times and you create a unique fingerprint to catch yourself with. - You can get a job as a projectionist and run the movie projector into another camera directly. That kind of machine is called a telecine, and it used to be one of the higher quality ways to get leaked movies back when they were on film. This is specifically the scenario that all the DRM in the projector is designed to stop. If you do anything to change the light path of the projector, it locks up until the manager comes in and types a password to authorize the change. - You could bribe the manager or owner to telecine the movie for you. Problem is, the number of people who actually have the password that unlocks the projector is really small[2] and traceable. If a telecine leak is traced back to their theater, someone's getting fired at a minimum, jailed in the worst case. - You could break the DCI scheme itself; but you still need to source the files and keys to decrypt the movies. This is the crypto nerd's imaginary scenario. Even then, the files could themselves have steganographically injected information identifying the theater who got that master copy, which you can't strip out merely by having the encryption keys. Again, nobody is giving you those files unless they're too stupid to understand the implications (unlikely) or they have faith that you can strip out the stegotext. It's just way easier to rip a stream than a movie in a theater. And when Hollywood moved to streaming they also made it a lot easier to leak movies. [0] To be clear, traitor-tracing each stream would require a unique encode per account to inject the stegotext; that's computationally unfeasible. Doing one encode per movie theater would still be a struggle, but less so by three orders of magnitude. [1] https://xkcd.com/538/ https://xkcd.com/538/ [2] This is also why the 3D era of film made movies way too fucking dark.

Animats 1y ago

JPEG 2000 for each frame? I wonder what they use for decompression. JPEG 2000 decompressors are really slow. Most couldn't keep up with frame rate without GPU support.

userbinator 1y ago
Dedicated hardware, not even regular GPUs. JPEG2000 decompression has a rather complex entropy decoding part which is not easily parallisable.
- fulafel 1y ago
  Only on the intraframe level - Frames are independent so overall it's "embarrassingly parallel".
  - crazygringo 1y ago
    There's no point to decoding in parallel if you're watching in sequence.
    - dsr_ 1y ago
      If your hardware can only manage 4 frames per second but you need 48, then decoding with 12 sets of hardware in parallel achieves your goal.
      - crazygringo 1y ago
        Derp, quite right. Never mind, thanks!
      - Animats 1y ago
        Although you still have four frames of latency if you do it that way. All the audio has to be delayed to match. Parallelized decode of JPEG 2000 frames is quite possible, though. The choice of JPEG 2000 is unexpected. Most of the neat features of JPEG 2000 are useless for cinema. Being able to construct a low-rez version from a truncated file isn't useful. Nor is the ability to divide the image into tiles and decompress different tiles at different resolution. (That's used in JPEG 2000 medical and military imagery, where you want to zoom in on the interesting part and see it in lossless mode.) You can have more than RGB or RGBA layers, which the multispectral imagery and prepress people like. Maybe the advantage is that you can have more than 8 bits of color depth.

andreashaerter 1y ago

I also recommend an insightful talk by the author of the article, delivered at a Chaos Computer Club (CCC) event (GPN, Gulaschprogrammiernacht) on this topic. Unfortunately, it's only available in German, but it's definitely worth watching: https://media.ccc.de/v/gpn22-382-kein-kinoerlebnis-ohne-korrektes-zertifikatsmanagement https://media.ccc.de/v/gpn22-382-kein-kinoerlebnis-ohne-korr... „No cinema experience without correct certificate management... A look behind the scenes of a cinema with a digital projector system, how distributors deliver films to cinemas with end-to-end encryption, and how films are protected from piracy. In addition to an overview of projector technology, the presentation will demonstrate the file format and manual decryption of film data.“ Edit: I just realized that the author of the article also delivered the recorded talk, adapted my comment.

jeffbee 1y ago

It's remarkable that they do all this in the context of box office revenues cratering. In 2024 American theaters has less gross ticket sales than they did in 1982, in constant dollars. The whole thing of movie theaters is just over.

tverbeure 1y ago
Why does that context matter? It's not as if the use of DRM for movie theater distribution influences whether or not somebody goes to see a movie.
- jeffbee 1y ago
  No, the other direction. Clearly the problem is that nobody wants their product, not that everyone wants to steal it.
  - tverbeure 1y ago
    Without DRM, even less people would visit a movie theater.
KaiserPro 1y ago
Encrypted DCPs have been around since when DVDs were still a revenue generator.

dherls 1y ago

I'm confused why it's encrypted as a JPEG image per frame instead of one AES encrypted video file. Since the same AES key is used for each frame it wouldn't add any additional security imo

Aurornis 1y ago
I think JPEG 2000 is simply the chosen format for distribution of the video, not for security. JPEG 2000 has some interesting properties for very high quality video storage and transport where bandwidth is not a concern. The traditional encoded video formats we know are less preferred at this scale. JPEG 2000 is resource intensive, though. The decoding hardware is probably either GPU based or using an FPGA implantation from one of the providers who makes hardware for this.
- userbinator 1y ago
  It's definitely dedicated hardware JPEG2000 decoding.
KaiserPro 1y ago
DCPs were designed to be jpeg200 streams with a bunch of audio streams as well. The idea was that they wanted up to 16bit colour (per channel) lossless imagery. The encryption was (or so I recall) was an extra feature.
perryflynn 1y ago
One movie can be 200G to 1TB large. The chunked encryption allows it to seek the movie without decrypting from the beginning.
- 01HNNWZ0MV43FF 1y ago
  But any computer with full disk encryption also has seekable encryption
Biganon 1y ago
As per asdcplib's author themselves in another clmment: > Frame-by-frame encipherment, rather than whole stream, better supports random access and the famous tobacco intermissions popular in the EU.

shmerl 1y ago

"Standards that have to be purchased". Someone is just trying to fleece the participants. That's what whole DRM is about most of the time.

tverbeure 1y ago
Standards are often cheap. Many tech companies have a subscription to all IEEE papers and standards. The incremental cost of downloading one standard more is in the noise. But even if you don't have a subscription, the price for, say, the 802.11n standard is only $381.

KaiserPro 1y ago

Packaging DCPs used to be a massive faff. (it might still be one) Basically they are a tar[1] of images with a bunch of audio streams for different speaker configurations. depending on the quality settings, they can be encoded for higher colour space (ie 16 bit log per channel) Even with lossless jpeg2000, these packages can be huge. But, back in 2011, the biggest problem was encoding jpeg2000 required hardware to get anything near realtime performance. (I also think there were dedicated DCP packaging machines, but I never actually saw one.) One of my colleagues decided the best way to ship the finalised movie was to open up an NFS port on sohonet and let the technicolor hook the DCP packager directly. it worked, but our CTO diplomatically asked them to stop. [1] not actually but conceptually similar

jackjeff 1y ago

> The video stream is encoded as one single JPEG2000 picture per frame. Each frame is encrypted with the same static AES key. Is this not a problem? It’s not a good idea to reuse the same key to encrypt very similar files. Similar to ECB. See the famous penguin https://words.filippo.io/the-ecb-penguin/ https://words.filippo.io/the-ecb-penguin/ I’m surprised they don’t use something like XTS commonly used for disk encryption. It derives a unique key for each block/frame and allow you to access each individual blocks/frames non sequentially.

perryflynn 1y ago
No. They use a unique IV for each frame: > Every Frame is using a unique IV (Initialization Vector), which ensures that the AES Block Cipher generates always different cipher texts and makes brute force harder. This works similar to a Password Salt.
- jackjeff 1y ago
  Oh thanks. I missed that. I guess that works pretty well too!

NoMoreNicksLeft 1y ago

>Encrypted DCPs use Forensic Watermarks which contain the serial number of the projection system. So if a recorded copy of a movie appears online, the theatre will have to answer serious questions and may never get movies again. Is this not as simple as dumping the same movie from two different projectors, diffing the output, then obfuscating the watermark?

TheDcoder 1y ago
To do that you need to figure out what parts are noise (watermark), simply diffing them would just give you a different noise pattern which can still be analyzed depending on how the watermark is encoded.

asdcplib 1y ago

Hi, asdcplib author here (mentioned in the article.) Excellent writeup of DCP and related tech. FYI the colorspace of an SDR DCP MXF file is X'Y'Z' with gamma 2.6 (see SMPTE 428-1.) Other MXF formats (i.e., not cinema) use a wide variety of colorspaces. Despite the huge range of XYZ, DCP image files are usually constrained to code values that fall within P3 (again, SDR.) The HDR applications are more interesting. Upon reading the comments: • DCP is a B2B format. DCP usage is licensed by contract, not EULA. Please keep these important differences in mind when commenting on DRM. • Decrypt, decode, color processing, watermark occurs in FPGA. If you think that sounds hard, remember that all of this tech was originally deployed 20 years ago. Moore's law has made our lives much easier since! • Frame-by-frame encipherment, rather than whole stream, better supports random access and the famous tobacco intermissions popular in the EU.

hbcondo714 1y ago

> 31. May 2024 I’m trying to understand the timeline here; the article was originally written last year and the latest spec is also from 2024 but the article has a link to this HN thread created yesterday?

baud147258 1y ago
Maybe the author saw a bunch of hits coming from HN and edited his post to add the link to the discussion? It doesn't seem as if the author themselves posted their article.
- perryflynn 1y ago
  Yes, I added some notes/improvements while the discussion was happening here. Changelog: https://github.com/perryflynn/serverless.industries/commits/master/src/_posts/2024/2024-05-31-digital-cinema.en.md https://github.com/perryflynn/serverless.industries/commits/...

vitplister 1y ago

Maybe someone with more knowledge could comment on what happened here: https://wikileaks.org/sony/docs/05/docs/Digital%20Cinema/Digital%20Cinema%20Security%20Compromise.pptx.pdf https://wikileaks.org/sony/docs/05/docs/Digital%20Cinema/Dig...

perryflynn 1y ago
Well, the DCI system relies on trusted (TPM-ish) hardware. One server vendor has used insecure certificates. So if a AES key for a movie is encrypted / shipped for such insecure certificate the AES key for the movie can be decrypted outside of the actual projector hardware. This is one reason why they use Device lists, if such a issue becomes public, they will just block this specific projector or the whole product line for future movie releases and the leak is contained. Also only movies which got assigned to that projection system are affected. So the damage is low/medium.