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Trying to extract Widewine key: A journey to failure

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Re: Trying to extract Widewine key: A journey to failure

#21

Post by MikeUt »

azalemeth wrote: post #11

From the repo: >It is my honest opinion that DRM is a malignant tumor growing upon various forms of media, and that people that either implement or enforce implementation are morally repugnant and do no good to society. With that in mind, I was sad to learn in May 2021 that the original extension would soon be rendered obsolete. I really can't agree more. I don't use, and never have, services that require DRM. I buy…

The point of DRM isn't to prevent piracy, but to control manufacturers, who cannot legally break DRM, so they have to comply with whatever the DRM licensing cartel demands.

Prevent screenshots, prevent skipping ads, prevent recording (remember VHS recorders?), enforce region locking.. so many legal activities can be effectively made illegal, since manufacturers cannot both support DRM, and offer these options.

Re: Trying to extract Widewine key: A journey to failure

#22

Post by nyuszika7h »

magila wrote: post #20
siliconc0w wrote: post #19

Earlier quoted context omitted.

"because DRM is fundamentally pointless" I dunno, it gave this person a lot of trouble and the result is maybe a very narrow victory that doesn't practically matter? And this is the lowest level of widevine security - L3 which is basically assumed to be owned. Good luck with L1 which uses trusted compute primitives. DRM has won. And I'm saying this as someone who agrees DRM is a threat to society as we're taking thin…

If you know where to look L1 content can be readily downloaded, including the original 4K streams. As usual the net effect of DRM is to make the paid service inferior to piracy. That's not what I would call "wining".

I don't know why you're being downvoted, you're right. There are plenty of TrustZone exploits that allow extraction of L1 keys.

Re: Trying to extract Widewine key: A journey to failure

#23

Post by nyuszika7h »

step21 wrote: post #14
baybal2 wrote: post #5

Earlier quoted context omitted.

The point of semi-unusable DRMed crap when L1 released keep getting WEB-DLed? Very likely it's not the Shield now which leaks L1, but an actual key recovery because they get the stream even before it gets watermarked in the secure domain. My guess, it's Qualcomm's debugging TZ applets. They cannot really revoke keys because they will take down a giant amount of Snapdragon based handsets for which manufacturers don't…

What's L1? web-dls I have seen are always relatively low resolution, so at least it protects fullhd or 4k.

1080p WEB-DLs are very common if you're in the right places, but even public trackers should have plenty. 4K is slightly less common but does also happen, with frequency depending on the streaming service.

Re: Trying to extract Widewine key: A journey to failure

#24

Post by vladvasiliu »

marcodiego wrote: post #2

Hmmm... Would love if this allows me watch netflix using a fully FLOSSed arm sbc.

I've never really looked long into these things, but now that most GPUs do the actual video decoding, how come it's still not possible to use Linux or any random OS? Isn't the GPU supposed to somehow guarantee that it only sends the decrypted stream to a compliant screen? Isn't this the point of HDCP?

When this was done in software, I understand that open source decoders could have been modified to pipe the clear stream to disk, but now the software basically just hands the encrypted blob to a "trusted" hardware decoder.

Or am I missing something?

Re: Trying to extract Widewine key: A journey to failure

#25

Post by gruez »

step21 wrote: post #14
baybal2 wrote: post #5

Earlier quoted context omitted.

The point of semi-unusable DRMed crap when L1 released keep getting WEB-DLed? Very likely it's not the Shield now which leaks L1, but an actual key recovery because they get the stream even before it gets watermarked in the secure domain. My guess, it's Qualcomm's debugging TZ applets. They cannot really revoke keys because they will take down a giant amount of Snapdragon based handsets for which manufacturers don't…

What's L1? web-dls I have seen are always relatively low resolution, so at least it protects fullhd or 4k.

>so at least it protects fullhd or 4k.

Not really. Popular streaming-exclusive shows often get 1080p versions released within a few hours, and the 2160p versions released within a few days.

Re: Trying to extract Widewine key: A journey to failure

#26

Post by nyuszika7h »

londons_explore wrote: post #4

Every time this is broken, am I right in saying all encrypted media needs to be re-encrypted with the updated version of widevine?

No. Once Google revokes an old version of the CDM, the servers will refuse to issue a license for that version. The license basically contains encrypted keys for the content. If you already saved the decrypted keys for a specific content, you will be able to decrypt it even after the revocation, but you won't be able to get the keys for any new content with that version anymore.

We're not (yet) at the point where actual content keys are rotated frequently, because that sounds like a lot of effort though technologies exist for this already, they're just not in widespread use.

Re: Trying to extract Widewine key: A journey to failure

#27

Post by R0b0t1 »

nyuszika7h wrote: post #22
magila wrote: post #20

Earlier quoted context omitted.

If you know where to look L1 content can be readily downloaded, including the original 4K streams. As usual the net effect of DRM is to make the paid service inferior to piracy. That's not what I would call "wining".

I don't know why you're being downvoted, you're right. There are plenty of TrustZone exploits that allow extraction of L1 keys.

For now, at least. It is possible they fix all issues.

Re: Trying to extract Widewine key: A journey to failure

#28

Post by toxik »

magila wrote: post #20
siliconc0w wrote: post #19

Earlier quoted context omitted.

"because DRM is fundamentally pointless" I dunno, it gave this person a lot of trouble and the result is maybe a very narrow victory that doesn't practically matter? And this is the lowest level of widevine security - L3 which is basically assumed to be owned. Good luck with L1 which uses trusted compute primitives. DRM has won. And I'm saying this as someone who agrees DRM is a threat to society as we're taking thin…

If you know where to look L1 content can be readily downloaded, including the original 4K streams. As usual the net effect of DRM is to make the paid service inferior to piracy. That's not what I would call "wining".

I don’t understand how it can ever be secure unless you let some DRM representatives basically come and do inspections.

Fundamentally, you are going to show a video and play an audio stream. Fundamentally, it can be recaptured perfectly because it must be displayed and played perfectly. There is simply no way around it. DRM can only make life hard for the regular Joes.

Re: Trying to extract Widewine key: A journey to failure

#30

Post by kristofferR »

R0b0t1 wrote: post #27
nyuszika7h wrote: post #22

Earlier quoted context omitted.

I don't know why you're being downvoted, you're right. There are plenty of TrustZone exploits that allow extraction of L1 keys.

For now, at least. It is possible they fix all issues.

Not really, since that would entail breaking playback on current devices/firmwares.

They can only try again next time (for 8K?).

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