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Comment by siliconc0w | Hacker News Reader

"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 things that the world could otherwise have for free and denying it them so we can instead charge a small % for it. So we're intelligent enough to build this kind of technical sophistication but we are unable/unwilling to figure out a different model for financing it.

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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.

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

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

Broken TZ does not mean the algorithms are broken, only that exploits exist to bypass TZ. Fixing the exploits doesn't break anything about the algorithms for decode / decrypt.

I'm not sure what in my comment you were disagreeing to. Fixing the exploits would entail requiring a software update/breaking unupdatable devices.

Yep. I remember when Blu-ray "required" Windows Vista because it had better DRM APIs then a few months later the studios gave in and allowed playback on XP... which was immediately cracked. Ultimately you have to meet customers where they are which is old devices.

Until current broken devices fall out of use. Eventually, all devices might be secure.

Except that people who exploit L1 just never reveal how they do it, good luck with that.

That's the beauty of the asymmetry against DRM, only a single decoded file (which will always happen) is enough for seeding to everybody.

This seems to be confirmed by the fact that most torrent sites have 4K copies of brand new streaming only content while no publicly known exploits exist.

Since you are running the exploit locally without affecting other peoples machines, I imagine it would be close to impossible to work out what exploit they are using.

Are those actual decrypted copies of the original stream, though? Or did they just re-record the output? For the latter you'd only need to break HDCP, right?

If the end user can't tell then it doesn't matter.

Well but there's likely to be at least a small quality difference, and a considerable a quality per file size difference, because the video would need to be re-encoded.

Yeah. They're WEB-DLs, not WebRips.

Pay NZ$20/mo for Netflix in UHD, or fuck around on pirate sites to make sure none of the people making the series and films I'm enjoying, while hoping that no-one has dropped an entertaining payload in the site ads or the files I'm downloading is "piracy is more convenient"?

The downvotes are for a shit take disconnected from the reality of people who aren't determined not to pay for something.

> piracy is more convenient

It sure is when I can load an entire show on a Plex instance and can sync it on my mobile device without any arbitrary limitation (like how many episodes I can sync, or synced copies that expires after a while which I experienced abroad on Netflix).

Step 1. Pay NZ$20/mo for Netflix in UHD.

Step 2. The content you want is not there or available on any other legal platform for your country.

Step 3. ????

This has nothing with a determination not to pay or to have studios go out of business. This has everything to do with artificially restricting me from being able to watch the content I pay for in a manner which is convenient to me. I have no interest in buying into a proprietary ecosystem of shitty software just to watch a TV series.

Whenever a service provides content in a way which I can access DRM free, I make sure to reward them for it by voting with my wallet. I sometimes also tell them to make sure they understand that one of the factors in my decision to give them money was the fact that they offered the content DRM free. But not because I wanted to re-upload it for free via bittorrent or show it in a cinema to all my friends, but precisely because I wanted to watch it on my computer without having to install crazy whitebox crypto nonsense.

I don't think normalising having to run someone else's crazy whitebox crypto nonsense on your computer is a good idea. Even if most people don't know or care.

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.

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

Oh god, that’s a level of hell I haven’t even imagined. I wonder if the future could ever become as dystopian as that for real. What it would take for that to happen, and how.

I see you've never worked with Oracle...

I don't know, but assume, that the movie studios do this for movie theaters.

Seems to work pretty well, since too my knowledge those are only ever leaked by audience members pointing a hidden camera at the screen (with all the quality issues that entails).

This fundamental gap is known as "the analog hole": https://en.wikipedia.org/wiki/Analog_hole

In theory DRM could be mathematically perfect. However DRM relies on actual implementations both in software and hardware and shares a lot with broader security. Software implementations can have bugs but it’s relatively easy to ship fixes. The hardware level however is where it becomes very difficult to ensure a valid implementation of “secure compute” or “trusted zones” which are key to DRM and general security, particularly from an agent with physical access. It costs money to ship new fixed hardware, if it’s even possible. Then even if a given hardware implementation is correct there are ways to physically glitch the hardware to skip the checks. ESP32 chips had an issue like that where the hardware encryption was correct but simply “glitching” the voltage at the correct time could cause the processor to skip the encryption check entirely [1]. It’s very difficult and costly to make hardware immune to all such attacks. Small seemingly unrelated physical details can become novel ways to break the encryption system (like specter).

Ultimately I’ve come to believe that DRM and it’s cousin of system security is an economic game. So DRM useless in that it will probably be cracked after some time, but that time can translate to revenues or control until that point. It depends on how much money you have to throw at either hardening and cracking systems. It’ll likely become harder (i.e. more expensive) in the future to crack hardware DRM in the future as the technology becomes more sophisticated and classes of vulnerability are discovered and mitigated. But then the cracks become more valuable both for anti-DRM or anti-security.

1: https://raelize.com/blog/espressif-systems-esp32-bypassing-s...

How can DRM ever be perfect? It relies on your computer to be able to decrypt the data so it an never be "mathematically perfect" like regular encryption can be.

Current DRM is all about shoving the decryption part as deep in to a chip as possible and betting on the fact that it is physically too hard to extract that info. So it will always be exploitable with some amount of effort.

It can depend on online keys that can be changed by the rightsholder at will.

"The Internet is the ultimate dongle" - John Carmack

You still have to deliver the new keys to the clients. As long as the client can decrypt the file, the client can also decrypt and dump it to storage. And if the top pirates keep their methods secret, you can change the keys all you want and not know how they are extracting them each time.

The DRM implementation and algorithm could be "perfect" in a mathematical sense, but as you point out they tend to rely on a PUF in the silicon hardware. Currently very hard to extract but not completely so. However, say a system had a quantum based PUF then it could be unclonable due to QM. Such a system could still be potentially cracked by causing issues in the processor itself like with the ESP32s. Which was my point, since there's a physical system to work in it'd be impossible in a practice to make perfect. Hence it boils down to economics.

It doesn't boil down to economics at all. Even if you push a googolplex dollars into perfecting it. If you wanted you can still relatively easily snoop the electrical signals that control an LCD to reconstruct the video. This is not possible to encrypt and never will be.

It could only be described as "mathematically perfect" in the sense that without the decryption key, the encrypted data is no more useful than random bytes.

But DRM fundamentally needs to have the decryption key available at the end user's device - which at least in my opinion, makes it better described as "provably mathematically impossible".

DRM is always pointless because the content has to be converted to analog form at some point. So, it gets decrypted in the DistrustZone, decompressed, then encrypted again before it goes over HDCP to your display, which then decrypts it to show it on the screen. Couldn't you capture the LVDS signal that the display panel receives? And even if you don't do that, isn't every version of HDCP cracked already so you could use a capture card instead?

The last bastion of DRM is forensic watermarking (so they can trace the leaked video back to your device) and key revocation (so your device won't play any new content). These techniques are so complex that they aren't used much.

So they trace the ripped video file to a particular throwaway account that was registered with a prepaid card, then what? And if you're determined enough, you could as well rip multiple copies on behalf of multiple accounts and average out the pixel colors.

The idea is to revoke the device, not the account.

> you could as well rip multiple copies on behalf of multiple accounts and average out the pixel colors.

Can you show that this can reliable get rid of the fingerprinting? This particular method could be countered by only including the fingerprint info in a few random frames, then you'd be able to retrieve the account info of all the accounts that participated in ripping. I don't think finding a method to counter any sort of fingerprinting is as easy as "just averaging the pixels".

It's my understanding that most schemes actually use very low frequency encoding with a large amount of error robustness built in (probably involving Haar wavelets) in order to maximize the probability that it survives re-encoding. Still, these schemes are not faultless: if you have two devices, and are knowledgeable enough to break the DRM twice for the same content, you're probably smart enough to take the md5 and shasum of the resulting bitstreams and diff them. Any discrepancy results in signal processing transforms until they have the same hashes...

If they can get the content key out of TZ, they don't even need the per-device key, and TZ based decoder anymore.

They just straight decrypt any files, which were at some point laying in the open on CDNs.

I believe, sooner or later it will come to the point when the only way left for DRMed content to work will be to have each stream individually encrypted, and watermarked at the backend at an enormous computational expense.

You'd ideally do this for 3+ devices and just majority vote on every framelocked frame; take the mean average if there isn't a median.

Isn't it also incompatible with the distribution model? Because personalizing video for every customer is hard to scale for companies that rely on reducing cloud costs

The watermarking is done during playback, not distribution.

I took conradev to mean "the model of distributing the same content to everyone via traditional (passive) CDN".

Movie theater watermarking is done during playback, but if Netflix was going to do watermarking, it would have to be done prior to delivery of streamed bits or it would be susceptible to the same "it's just software" attacks as any other local software-only approach to DRM.

Is Widevine L1 "just software"? If its key distribution can somehow remain uncracked for years then maybe it could also do client-side watermarking.

It's mostly done for review copies of content where only a handful of reviewers have the content.

Watermarking is the kind of DRM I'm 100% okay with.

Please, sell me a watermarked but DRM-free video file that I can use with any player on any device. If I share it, you'll know it was me, but otherwise I have complete freedom. Win-win.

> DRM is a threat to society as we're taking things that the world could otherwise have for free

But someone needs to pay to create those things in the first place. Payment for work after the fact is the basic incentive.

I think if DRM didn't exist piracy would be just as rampant (i.e. not very, since for the average joe it seems more convenient to just go on netflix or amazon prime or whatever) and people would still get paid.

People are against DRM not because they don't want to pay for content, but because they want to be able to play the content they pay for. And not in breach of the license they have been sold.

I have every interest in participating in the content market and paying people to make content. I have no interest in having to buy special proprietary hardware or run special proprietary code on my computer just to do it.

>we're taking things that the world could otherwise have for free and denying it them so we can instead charge a small % for it

Are we? Where are the studios making feature-length movie-quality content and putting it on YouTube to be supported by ad money? There isn't even an equivalent to TV in that form factor. All of the new content that requires any sort of production budget (actor salaries, non-trivial special effects) is on platforms with subscription fees and DRM to require those subscription fees because we can't have these things for free.

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