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A comment on To Fight Big Tech, We Must Seize the Means of Computation. Parent comment

Re:To Fight Big Tech, We Must Seize the Means of Computation by gruez on Monday October 09, 2023 @07:13PM (#37826640)
>Of course, you could try to open up or bypass the DRM module (e.g., via the GPU driver during hardware accelerated decoding), but that won't work with a TPM module and signed kernel space.

Nope. Thanks to HDCP the data never hits the kernel or the host memory unencrypted. It doesn't even require TPMs or signed kernels.

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Re:To Fight Big Tech, We Must Seize the Means of Computation by choeger on Tuesday October 10, 2023 @01:08AM (#37828697)
That's not true, AFAIK. The DRM module (e.g., widevine) has to negotiate keys with the host and will decrypt the stream for decoding. The HDCP keys are static and independent from the streaming service. That decryption can happen with hardware support but it can also happen in software. I think most streaming services fall back from 4k to FHD or lower if their "security requirements" aren't fully met.

Also, if the DRM module supports hardware decoding, the GPU will need to see a decrypted stream. The GPU memory is in principle accessible to the driver. So if you can manipulate the driver, or setup another kernel module, you might be able to grab that content.

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