4 ms·

That streaming DRM only works if you give up control of the hardware you own.

by ef4 10y ago

k-mcgrady 10y ago
Sorry, I don't understand. Could you provide more info or a link to something showing this? I can't understand how I'm giving up control of my laptop hardware when I stream a movie on Netflix for example.
- parenthephobia 10y ago
  When you stream a movie on Netflix, either the DRM doesn't work, or you no longer have unrestricted access - from inside the computer - to the pixels on the screen, or the audio being output. i.e. If you try to screenshot the movie, or redirect the audio into a file, you won't be allowed. The video and audio quality may be downgraded if you attach non-HDCP (a DRM system for local video and audio) outputs to your laptop. Sometimes Netflix will simply refuse to stream anything if it isn't sure that the path from the video decoder to the monitor's screen is secure. e.g. https://www.reddit.com/r/apple/comments/3j0vck/whats_hdcp_and_why_cant_i_play_netflix_on_my/ https://www.reddit.com/r/apple/comments/3j0vck/whats_hdcp_an... You don't have permission from Netflix to prevent this. If you're in the US or UK - and many other jurisdictions - it is illegal for you to do so, even if it's very clearly within your fair use (or equivalent) rights. In the future, it's likely that DRM will extended to add and detect watermarks to restricted video and audio output, requiring you (and those around you) to cede full use of any other devices with microphones and cameras that might happen to capture that output.
eridius 10y ago
That's a bogus argument. By that logic, every single commercial app you download and run is "giv[ing] up control of the hardware you own". Hell, even just booting up Windows or OS X qualifies.
- ef4 10y ago
  No, there's a fundamental difference. I'm not talking about running closed source software. Windows will happily execute any general purpose program you care to throw at it. And how could it not, given the principal of Turing equivalence? DRM is different because it's a deliberate attempt to make a non-general computer. One that refuses to execute certain perfectly valid programs. Window and OSX will happily grant the owner the highest level of privileges and let you read or flip any bit in the system. DRM is about creating a privilege level that the owner cannot access.
  - eridius 10y ago
    DRM is not different, you're just confused about what a "program" is. Windows/Linux/OS X defines a program in a specific way (e.g. that matches one or several known formats) and will happily execute programs that conform to that specification. But if you take a C source file that can be compiled into a valid program, Windows/Linux/OS X will not execute that C source file for you, it will only execute the results of compiling it. And DRM is no different. It just happens that the definition of "program" for DRM is different than the definition of "program" for your OS, and the compiler for your DRM computer is the process that takes the un-DRM'd content and wraps it in the DRM. > Window and OSX will happily grant the owner the highest level of privileges and let you read or flip any bit in the system. Not true. At the very least, you cannot muck with kernel memory, and OS X also prevents you from modifying a bunch of files on disk that are crucial for the operation of the system even if you have root access (this is called System Integrity Protection).
    - ef4 10y ago
      > At the very least, you cannot muck with kernel memory You most certainly can. Anyone who has written a device driver has done it. > this is called System Integrity Protection That can be disabled during boot.
      - eridius 10y ago
        If you're writing a device driver, you're operating inside the kernel, effectively modifying the machine itself, rather than merely writing a program that the machine can run. And yes, SIP can be disabled, but OS X isn't granting you the permission do that, the recovery partition is. Once you've booted into OS X you cannot modify SIP. So again, it's more akin to modifying the machine itself.
spacemanmatt 10y ago
Everyone should try this thought experiment: Design a DRM that can't be defeated when the users can run it under any debugger or virtual environment.

That streaming DRM only works if you give up control of the hardware you own.

by ef4 10y ago

That streaming DRM only works if you give up control of the hardware you own.

Sorry, I don't understand. Could you provide more info or a link to something showing this? I can't understand how I'm giving up control of my laptop hardware when I stream a movie on Netflix for example.

parenthephobia 10y ago
When you stream a movie on Netflix, either the DRM doesn't work, or you no longer have unrestricted access - from inside the computer - to the pixels on the screen, or the audio being output. i.e. If you try to screenshot the movie, or redirect the audio into a file, you won't be allowed. The video and audio quality may be downgraded if you attach non-HDCP (a DRM system for local video and audio) outputs to your laptop. Sometimes Netflix will simply refuse to stream anything if it isn't sure that the path from the video decoder to the monitor's screen is secure. e.g. https://www.reddit.com/r/apple/comments/3j0vck/whats_hdcp_and_why_cant_i_play_netflix_on_my/ https://www.reddit.com/r/apple/comments/3j0vck/whats_hdcp_an... You don't have permission from Netflix to prevent this. If you're in the US or UK - and many other jurisdictions - it is illegal for you to do so, even if it's very clearly within your fair use (or equivalent) rights. In the future, it's likely that DRM will extended to add and detect watermarks to restricted video and audio output, requiring you (and those around you) to cede full use of any other devices with microphones and cameras that might happen to capture that output.

eridius 10y ago

That's a bogus argument. By that logic, every single commercial app you download and run is "giv[ing] up control of the hardware you own". Hell, even just booting up Windows or OS X qualifies.

ef4 10y ago
No, there's a fundamental difference. I'm not talking about running closed source software. Windows will happily execute any general purpose program you care to throw at it. And how could it not, given the principal of Turing equivalence? DRM is different because it's a deliberate attempt to make a non-general computer. One that refuses to execute certain perfectly valid programs. Window and OSX will happily grant the owner the highest level of privileges and let you read or flip any bit in the system. DRM is about creating a privilege level that the owner cannot access.
- eridius 10y ago
  DRM is not different, you're just confused about what a "program" is. Windows/Linux/OS X defines a program in a specific way (e.g. that matches one or several known formats) and will happily execute programs that conform to that specification. But if you take a C source file that can be compiled into a valid program, Windows/Linux/OS X will not execute that C source file for you, it will only execute the results of compiling it. And DRM is no different. It just happens that the definition of "program" for DRM is different than the definition of "program" for your OS, and the compiler for your DRM computer is the process that takes the un-DRM'd content and wraps it in the DRM. > Window and OSX will happily grant the owner the highest level of privileges and let you read or flip any bit in the system. Not true. At the very least, you cannot muck with kernel memory, and OS X also prevents you from modifying a bunch of files on disk that are crucial for the operation of the system even if you have root access (this is called System Integrity Protection).
  - ef4 10y ago
    > At the very least, you cannot muck with kernel memory You most certainly can. Anyone who has written a device driver has done it. > this is called System Integrity Protection That can be disabled during boot.
    - eridius 10y ago
      If you're writing a device driver, you're operating inside the kernel, effectively modifying the machine itself, rather than merely writing a program that the machine can run. And yes, SIP can be disabled, but OS X isn't granting you the permission do that, the recovery partition is. Once you've booted into OS X you cannot modify SIP. So again, it's more akin to modifying the machine itself.

spacemanmatt 10y ago

Everyone should try this thought experiment: Design a DRM that can't be defeated when the users can run it under any debugger or virtual environment.