What kind of special knowledge or equipment do piracy groups have?
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?
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
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.
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?
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).
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"?
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.
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.
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.