this post was submitted on 21 Oct 2024
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Are they breaking Widevine? Are they circumventing it? If the end result is an analog audio signal and (a ton of) RBG on/off signals - why can't I as a normal consumer capture it using some store bought gyzmo?

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[–] [email protected] 37 points 2 weeks ago (2 children)

Basically, media cannot truly be DRM because: (1) it ~has to be converted into data that screens and speakers can display (2) ultimately if it's fetching widevine encryption keys, those keys are somewhere in your device and can be retrieved

So yes, you can do it. A "capture card" is such a "gyzmo" — but often, you can just rip using software, i.e. record the decoded stream

[–] [email protected] 28 points 2 weeks ago (2 children)

To put it another way:

  • If you want to see something it has to be clear (unencrypted)
  • If you want to see something on your computer it has to be on your computer
  • You can control your own computer

Therefore, any media that is viewed on your computer is clear, on your computer, in a realm that you control.

This is also why ad blockers work. You can send me ads, or requests to fetch ads and my computer just ignores them.

Companies will never be able to stop this, cause at some point you can always just intercept the data feed at a hardware level and reconstruct the stream.

[–] [email protected] 13 points 2 weeks ago (2 children)

Companies will never be able to stop this,

If they have their way they will. All the tech bros are pushing for trusted computing platforms.

Imagine a world where most/all computers are as locked down as an iPad. That's what they seem to want.

[–] [email protected] 6 points 2 weeks ago

At some point the electrical signal has to be clear at a hardware level. Companies can make it harder, but if they're streaming any info to a device in your possession someone will be able to extract that clean electrical signal and reproduce an acceptable feed.

[–] [email protected] 5 points 2 weeks ago

TPM isn't inherently bad, it's just a way to cryptographically store keys. TPM overall is great as it gives you a very secure way to store things like encryption keys.

You also don't need TPM to lock down a system. Locked bootloaders have existed for decades and platforms have historically rolled their own encryption modules as they wanted, like your ipad example, or any video game console in the last 20 years, or most mobile phones, etc.

The 'knows enough to be dangerous' crowd has been fearmongering about tpm since it's been introduced, it isn't some magic bullet for vendor locking, since vendor locking is already achieved.

[–] [email protected] 5 points 2 weeks ago (3 children)

I might be asking a dumb question, but why can't the companies host their ads on the server-side? Do the ads have to be on my computer for me to see them? What does being on my computer even mean in this context?

Sorry if this is a stupid question

[–] [email protected] 10 points 2 weeks ago (1 children)

Some do. YouTube switched their ad service so the main video and ads come from the same server. To get around this uBlock now blocks the script on the browser side that shows the ad, then returns a signal that the timer is up.

It's a constant game of cat and mouse to get around ad blockers then block that new method.

[–] [email protected] 2 points 2 weeks ago

I don't think the new strategy of injecting ads directly into the video stream can be defeated in realtime though. It's like how you cannot defeat tv ads...you can blank the screen, or record and restitch without the ads, but the content itself has the ad. YouTube is a bit different where you can theoretically skip ahead, but your device has to tell Youtube that it wants to skip ahead in order to actually even get the video content, and youtube can look at request timestamps to know you didn't see the whole injected ad and just re-inject it in the video stream.

[–] [email protected] 6 points 2 weeks ago* (last edited 2 weeks ago) (1 children)

They do host them on their servers, sort of (if you're asking how ad brokers work that's a bit of a different scope).

Does poo have to be on your desk to smell it?
The post office (website) is telling you (your computer) to go over and pick up a parcel of poo (an ad) that's there for you.
You say no, I don't think I will (adblock/poo block)

[–] [email protected] 1 points 2 weeks ago

That is one hell of an analogy

[–] [email protected] 5 points 2 weeks ago (1 children)

What I mean by "on your computer" is not that it originates on your computer, but that some form of it exists there--namely this is going to be images, text, links, etc that the ad company hosts and a website will normally download temporarily along with the rest of the site's content. Once your computer has that site's information you can do anything you want with it. Importantly what exists on your computer is a local copy of what the ad servers host. If you decide to color ads blue on your computer that only affects your copy. The original ad, and everyone else's copies remain intact.

[–] [email protected] 1 points 2 weeks ago

I think I understand now. Thanks.

[–] [email protected] 5 points 2 weeks ago* (last edited 2 weeks ago)

it's not even hard. It's just to much work, if someone else is doing it for me I thank them with thoughts and prayers (and sometimes I donate money)

Funny enough sometimes I'll download shows that I already paid for (like Max ot Netflix) just becaus VLC is great and my TV is not

[–] [email protected] 17 points 2 weeks ago (1 children)

Absolutely - modern pirates are extracting the digital streams with the DRM removed. However they closely guard the methods of operation because once the exploits or compromised keys are known they can be revoked and they have to start cracking again. They likely have hardware with reverse engineered firmware which won't honour key revocation but still needs to be kept upto date with recent-ish keys.

For example the Blu-Ray encryption protocols are well enough known you can get things working if you have the volume keys. However getting hold of them is tricky and you have to be careful your Blu-Ray doesn't read a disk that revokes the old keys.

For streaming things are a little easier because if you get the right side of the DRM you can simply copy the stream. However things like HDCP and moving DRM into secure enclaves are trying to ensure that the decryption process cannot be watched from the outside. I'm sure their are compromised HDCP devices but again once their keys get leaked they will no longer be able to accept a digital stream of data (or may negotiate down to a sub-HD rate).

[–] [email protected] 1 points 2 weeks ago (1 children)

But cracking ed25519, or RSA , is something that state actors can't do without massive resources... What am I missing here?
Even if I reverse engineer Linux, I can't know the decryption keys for my encrypted data.... Are you saying that HDCP is not "Secured" but "Jumbled up"? If tomorrow the source code for it get released - then "The jig is up"?

[–] [email protected] 3 points 2 weeks ago

In all DRM devices there are private signed certificates that can be used to establish a secure authenticated connection. To get at them you need to crack/hack/file the top of the chip to exfiltrate the certificate. More modern "Trusted Computing" like platforms include verified boot chains so even if you extract the certificate you couldn't use it because you also need to sign the boot chain to ensure no code has been altered.

[–] [email protected] 6 points 2 weeks ago* (last edited 2 weeks ago)
  • HDCP had flaws and keys up to version 2.1 were extracted/reversed. In addition to that there is hdfury device that legally and following HDCP licencing terms downgraded 2.2 to lower 2.x versions to provide compatibility. They got smarter and blocked downgrading in later versions. Blocking HDCP older than that would also break compatibility with devices that don't support versions of the standard newer than late 2012. Add a capture card and you are set.
  • Widevine L1 keys were extracted from a Qualcomm CPU in 2021. They are also stored in Intel CPUs in SGX which had so many flaws over the years I'd be surprised nobody grabbed keys at some point
  • Both audio and video has to be decrypted and analog at some point - you can capture it if you have the hardware and willingness to e.g. grab it at a LCD display ribbon. Not as good/convenient as decrypting it, but it is an option.
[–] [email protected] 5 points 2 weeks ago

I think the reason why regular store bought gizmos won’t let you decrypt it is because content can require HDCP to make sure you don’t gain access to the data. If there were a device at Best Buy that just bypassed this, I think the DMCA and rights holders would come down hard on the seller.

I’ve heard of gizmos from shadier places may be able to decrypt the data but it’s likely because they’re acting outside of the law.