Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

How encryption for Cinema Movies works

serverless.industries

Post reply on HN
Print view View original

61–70 of 124 posts

Re: How encryption for Cinema Movies works

#61

Post by [deleted] »

kelnos wrote: post #34
codemiscreant wrote: post #24

Earlier quoted context omitted.

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.

Not sure of the GP's core message there, but I think this is kinda the point: even with all this onerous encryption on the cinema releases, high-quality pirated copies still very quickly make it out. So basically they have this very secure scheme for getting movies to theaters, but everything else is full of holes. Makes you wonder if all the effort and cost to secure the theater distribution chain is worth it. If yo…

[deleted]

Re: How encryption for Cinema Movies works

#62

Post by lb1lf »

johnisgood wrote: post #60
gruez wrote: post #8

Earlier quoted context omitted.

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.

I think the question remains, is it still worth it given these holes?

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.

Re: How encryption for Cinema Movies works

#63

Post by Thlom »

kmeisthax wrote: post #45
thaumasiotes wrote: post #31

Earlier quoted context omitted.

> Problem is, the number of people who actually have the password that unlocks the projector is really small[2] > [2] This is also why the 3D era of film made movies way too fucking dark. What is the relationship between these two things?

3D requires inserting an extra device into the image path to split the projector light into polarized halves, otherwise the 3D glasses don't work. Because of how light works, half the light is thrown away. So you either have a darker picture or you jack up the light (which, according to theater owners, means more wear on the projector's light source). Now, in an ordinary scenario, you'd just have the projectionist re…

It's been a few years since I was in the industry, but I don't think this is entirely correct. As far as I remember the polarizer (or for Dolby 3D, the color wheel) was placed on a rail system to be slid in and out of the light path when required (It's possible that cheaper/older versions can't be automated). The polarizer is placed outside of the projector in front of the lens so no password is required to remove it. There is a security step between the projector and the playback server, but that sits on the first PCB the data signal from server hits on the projector (If I remember correctly).

With regards to the projectors light source you are correct, higher illumination means more wear on the XENON lamp in older projectors. If you have the polarizer in front of the lens at all times that would be a problem. With newer laser projectors I don't think higher illumination is a big problem for the longevity of the laser.

In any case, projectionists barley exists anymore and cinema managers knows next to nothing about the technical aspect of the business. Basically everything is automated to such a degree that all the cinema chain management needs to do is to populate the ticketing system, then films, advertisements, trailers and announcements are automatically downloaded, playlists created, distributed to screens and scheduled. Lights, projectors, doors, curtains and so in is also automated.

Re: How encryption for Cinema Movies works

#64

Post by perryflynn »

Animats wrote: post #19

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.

The frames are sent encrypted into the projector. The projector has special hardware for decrypt and decode.

Re: How encryption for Cinema Movies works

#65

Post by perryflynn »

dherls wrote: post #28

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

One movie can be 200G to 1TB large. The chunked encryption allows it to seek the movie without decrypting from the beginning.

Re: How encryption for Cinema Movies works

#66

Post by perryflynn »

jackjeff wrote: post #59

> 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/ I’m surprised they don’t use something like XTS commonly used for disk encryption. It derives a unique key for each…

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.

Re: How encryption for Cinema Movies works

#67

Post by anal_reactor »

john01dav wrote: post #3

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.

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.

Re: How encryption for Cinema Movies works

#68

Post by jasode »

kelnos wrote: post #34
codemiscreant wrote: post #24

Earlier quoted context omitted.

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.

Not sure of the GP's core message there, but I think this is kinda the point: even with all this onerous encryption on the cinema releases, high-quality pirated copies still very quickly make it out. So basically they have this very secure scheme for getting movies to theaters, but everything else is full of holes. Makes you wonder if all the effort and cost to secure the theater distribution chain is worth it. If yo…

>If you're going to allow playback on devices in "adversarial" hands (streaming, home physical media playback), it's going to be incredibly difficult to restrict copying.

Kaleidescape movie players[1][2] are an example of an "adversarial" environment in customers' homes but so far, their DRM is still unbroken by pirates. (10+ years of Strato players deployed out in the wild but still not defeated yet.)

The 4k 100+ GB encrypted files downloaded by Kaleidescape is considered 1 step below the DCP theater releases and are higher quality than Blu-Ray 4k UHD discs. The downloads are often 40+ GB larger than 66 GB discs and downloadable months before physical media is available so the Kaleidescape movies stored on the customers' harddrive are very desirable files to hack and reverse engineer but so far, their DRM protection hasn't been bypassed. Kaleidescape is more locked down than the simple DVD CSS 40-bit encryption.

Sure, a Kaledescape owner could point a video camera at the screen and record it (the "analog hole"[3]) -- but those types of "rips" that suffer generation losses are not considered high quality.

[1] https://www.kaleidescape.com/systems/movie-players-servers/

[2] https://www.kaleidescape.com/news/kaleidescape-taps-nexguard...

[3] https://en.wikipedia.org/wiki/Analog_hole

Re: How encryption for Cinema Movies works

#69

Post by dist-epoch »

kmeisthax wrote: post #12
ddtaylor wrote: post #5

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

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 pr…

> Hollywood is stupid and eroded its own economic advantage by putting everything on streaming

You are making a big assumption that they had a choice, that if a movie was not put on streaming, the consumer would go to the cinema to watch it.

But many consumers don't, if the movie is not streaming, they just don't watch it at all.

Re: How encryption for Cinema Movies works

#70

Post by adrian_b »

cess11 wrote: post #57
adrian_b wrote: post #54

Earlier quoted context omitted.

I do not think that's weird. A 4k movie, even from a Blu-Ray, may look very nice when watched at a normal speed, but if you look at the individual frames in order to distinguish some details during a sequence with fast movements, the quality is very bad and it may be impossible to see the details that you want to see. At the levels of compression that are typical for movies distributed by encoding with H.264, H.265 a…

Where do you live? Where I live only professionals and nerds use movie playback that allows single frame stepping, it's definitely a fringe phenomenon here.

I live in the EU, but any good free movie player should allow stepping through video frames back and forth and also playing with any desired speed in frames per second.

This is not a feature that requires professional tools.

And I do not think that you have to be a pro or a nerd in order to want to see clearly many of the details of the kind "blink and you miss it".

Post reply on HN