7 ms·

EME, CDM, AES, CENC, and Keys – Building Blocks of DRM

92 points by jayjohn436 6y ago

shmerl 6y ago
That's a good breakdown of how much effort is spent on unethical application of technology. But advertising DRM on the site: "buy DRM"? That's already disgusting.
- Thorrez 6y ago
  The post was apparently sponsored by them. I've got to at least applaud them for bringing a lot of this info out into the open.
  - jayjohn436 6y ago
    True that.
- bitwize 6y ago
  If you know anyone involved in creative work, you would bite your tongue before saying DRM is unethical. Such people universally, to a man (or woman) believe that unauthorized distribution of their output is unethical because it makes them unable to make money for all their hard work. Inasmuch as DRM prevents this, it is a boon to these people. DRM is a part of life now. Without it, you would not be able to enjoy the rich variety of content available on today's internet.
  - shmerl 6y ago
    Some people in the creative field have sense and don't respect DRM. Check Lexy Alexander's posts on this topic. Check also releases by CD Projekt Red and their DRM-free games store GOG. We need something like this to eventually succeed and disrupt current messed up DRM situation in video too: https://www.gog.com/forum/general/introducing_gogcom_drmfree_movies/post499 https://www.gog.com/forum/general/introducing_gogcom_drmfree... DRM is and will remain unethical, no matter how much its proponents will try to whitewash it with demagoguery, claiming it's "part of life now". And for the reference, DRM doesn't do anything good for creators. It's always a crooked tool, especially when combined with policy laundering that produces stuff like DMCA 1201.
  - ls65536 6y ago
    And if you know anyone who has paid for content that suddenly they had lost access to because of shut down DRM servers or intermittent internet connectivity, then you might be inclined to think a bit differently. Ultimately I think there needs to be a balance here, and most importantly users ought to be made more aware of what they're usually getting when purchasing DRM-protected content: a limited license to consume their paid-for content for a (possibly unspecified) period of time on a specific set of devices under certain circumstances that often lie well beyond their control. I'd like to think that some kind of free market-based approach of consumers choosing to support the content creators who take a more balanced approach to DRM (or just avoid it entirely) would "solve" these problems, but I'm not too hopeful of this ever working out given the enormous knowledge asymmetry between content creators/distributors and consumers about how stuff like this works.
  - account42 6y ago
    > DRM is a part of life now. So is piracy^Wcopyright infringement. > Without it, you would not be able to enjoy the rich variety of content available on today's internet. Why not?
prudhvis 6y ago
Very informative article. Never knew different aspects of the DRM. However i chuckled when I saw the names Ram, Shyam and Hari. Not too often do you see any names besides Alice and Bob.
young_unixer 6y ago
So, the only thing stopping a user from obtaining a clean copy of the content is the fact that the CDM is closed source? What if a CDM vendor leaked the source code? I guess the DRM server would block them after a while, but before they notice, the user would have free access to the content, right?
- deleted 6y ago
  [deleted]
- drudu 6y ago
  You're completely right but the source code doesn't even need to be leaked. Just reverse engineered. How else would we pirate movies from Netflix/Amazon/etc :)
- grishka 6y ago
  DRM is the epitome of security through obscurity.
- ponderingfish 6y ago
  Exactly - which is why the CDM is a contentious topic because you have no way to see what's inside it. Also, technologies such as HDCP, Trusted Execution Environment prevent the decrypted and decoded frames from being leaked. At least, that's the intention. And the CDM vendors are Google, MSFT, and Apple. There's no way they are going to leak their code :) What's really strong is the rotation of decryption keys. Content providers rotate the keys often (at times, in the middle of a movie, and very often during a live stream) to deter people from cracking the key. Cracking DRM can be done and the goal from the other side is to make it hard and expensive. Nothing is impossible :)
  - grishka 6y ago
    IMO it isn't that hard to crack a DRM system. My understanding is that most of the protections are legal, not technical, as in, if you do it, they'll sue the hell out of you and win.
    - 6y ago
palashkulsh 6y ago
I've been trying to understand this drm for some uses for past 6 month. I got few bits and pieces, but this article really put them together in a marvelous fashion. kudos
gok 6y ago
Not sure if the author is here, but the table-of-contents links at the top are broken (all go to the first page)

92 points by jayjohn436 6y ago

That's a good breakdown of how much effort is spent on unethical application of technology. But advertising DRM on the site: "buy DRM"? That's already disgusting.

Thorrez 6y ago
The post was apparently sponsored by them. I've got to at least applaud them for bringing a lot of this info out into the open.
- jayjohn436 6y ago
  True that.
bitwize 6y ago
If you know anyone involved in creative work, you would bite your tongue before saying DRM is unethical. Such people universally, to a man (or woman) believe that unauthorized distribution of their output is unethical because it makes them unable to make money for all their hard work. Inasmuch as DRM prevents this, it is a boon to these people. DRM is a part of life now. Without it, you would not be able to enjoy the rich variety of content available on today's internet.
- shmerl 6y ago
  Some people in the creative field have sense and don't respect DRM. Check Lexy Alexander's posts on this topic. Check also releases by CD Projekt Red and their DRM-free games store GOG. We need something like this to eventually succeed and disrupt current messed up DRM situation in video too: https://www.gog.com/forum/general/introducing_gogcom_drmfree_movies/post499 https://www.gog.com/forum/general/introducing_gogcom_drmfree... DRM is and will remain unethical, no matter how much its proponents will try to whitewash it with demagoguery, claiming it's "part of life now". And for the reference, DRM doesn't do anything good for creators. It's always a crooked tool, especially when combined with policy laundering that produces stuff like DMCA 1201.
- ls65536 6y ago
  And if you know anyone who has paid for content that suddenly they had lost access to because of shut down DRM servers or intermittent internet connectivity, then you might be inclined to think a bit differently. Ultimately I think there needs to be a balance here, and most importantly users ought to be made more aware of what they're usually getting when purchasing DRM-protected content: a limited license to consume their paid-for content for a (possibly unspecified) period of time on a specific set of devices under certain circumstances that often lie well beyond their control. I'd like to think that some kind of free market-based approach of consumers choosing to support the content creators who take a more balanced approach to DRM (or just avoid it entirely) would "solve" these problems, but I'm not too hopeful of this ever working out given the enormous knowledge asymmetry between content creators/distributors and consumers about how stuff like this works.
- account42 6y ago
  > DRM is a part of life now. So is piracy^Wcopyright infringement. > Without it, you would not be able to enjoy the rich variety of content available on today's internet. Why not?

prudhvis 6y ago

Very informative article. Never knew different aspects of the DRM. However i chuckled when I saw the names Ram, Shyam and Hari. Not too often do you see any names besides Alice and Bob.

young_unixer 6y ago

So, the only thing stopping a user from obtaining a clean copy of the content is the fact that the CDM is closed source? What if a CDM vendor leaked the source code? I guess the DRM server would block them after a while, but before they notice, the user would have free access to the content, right?

deleted 6y ago
[deleted]
drudu 6y ago
You're completely right but the source code doesn't even need to be leaked. Just reverse engineered. How else would we pirate movies from Netflix/Amazon/etc :)
grishka 6y ago
DRM is the epitome of security through obscurity.
ponderingfish 6y ago
Exactly - which is why the CDM is a contentious topic because you have no way to see what's inside it. Also, technologies such as HDCP, Trusted Execution Environment prevent the decrypted and decoded frames from being leaked. At least, that's the intention. And the CDM vendors are Google, MSFT, and Apple. There's no way they are going to leak their code :) What's really strong is the rotation of decryption keys. Content providers rotate the keys often (at times, in the middle of a movie, and very often during a live stream) to deter people from cracking the key. Cracking DRM can be done and the goal from the other side is to make it hard and expensive. Nothing is impossible :)
- grishka 6y ago
  IMO it isn't that hard to crack a DRM system. My understanding is that most of the protections are legal, not technical, as in, if you do it, they'll sue the hell out of you and win.
  - 6y ago

palashkulsh 6y ago

I've been trying to understand this drm for some uses for past 6 month. I got few bits and pieces, but this article really put them together in a marvelous fashion. kudos

gok 6y ago

Not sure if the author is here, but the table-of-contents links at the top are broken (all go to the first page)