Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

The GPU, not the TPM, is the root of hardware DRM

mjg59.dreamwidth.org

Post reply on HN
Print view View original

171–180 of 493 posts

Re: The GPU, not the TPM, is the root of hardware DRM

#171

Post by mike_hearn »

jakogut wrote: post #12
MadnessASAP wrote: post #4

I have to wonder A) What does DRM realistically accomplish for the media companies? And, B) How are these DRM schemes actually being defeated? I do occasionally don my pirate hat* and have never had an issue finding what I want at the quality I want within an hour of a episode/movie being released to streaming. That would seem to indicate that these efforts at DRM are actually failing to have any noticeable effect at…

There's always an analog loophole. Even if the OS is unable to access the memory storing the decrypted data, you could always just plug the output of the machine into a capture card and capture the decrypted stream that way. I suppose some monitors and TVs have "features" to cryptographically handshake with the GPU and ensure a secure link, but at some point the data must be decrypted and decoded to be displayed. Thi…

There is no analogue loophole, that's like 15 years behind the curve. Cinavia closed that a long time ago and meant that licensed devices like Bluray players, even TVs, can detect cammed recordings even those cammed in movie theatres.

Of course you can try to play them with hardware that doesn't follow the rules. But there's a finite number of vendors, so that isn't necessarily easy.

Re: The GPU, not the TPM, is the root of hardware DRM

#172

Post by mjw_byrne »

XorNot wrote: post #161
wkat4242 wrote: post #152

Earlier quoted context omitted.

> That's kind of the point. The vast majority of users aren't going to have their laptop stolen at all, if they do it will 99% of the time be by someone who only wants to wipe it and fence it, and attempts to access data are most likely to be by unsophisticated family members who would be defeated by a simple password without any TPM. True, any preboot password method (even fully software) will be sufficient to preve…

No one wants a preboot password though. TPM means the system can boot and then do face login or whatever using the user's password in exactly one place. This is as much as most users will tolerate. And it also means Microsoft account recovery can work to unlock a forgotten password. The whole point is Microsoft don't want user devices to ever be trivially bypassed, regardless of how unlikely that is (probably more li…

"No one wants a preboot password though" - really? Doesn't strike me as particularly inconvenient, especially given the relative rarity of actual bootups these days.

I've been using bog-standard FDE for as long as I can remember. One extra password entry per bootup for almost-perfect security seems like great value to me.

Re: The GPU, not the TPM, is the root of hardware DRM

#173

Post by mike_hearn »

ignoramous wrote: post #165
no_time wrote: post #143

The author is correct in that media DRM is tied to GPU vendors on the field right now. But hardware backed DRM can be so much more invasive beyond that. I have no doubts the long term goal of MS is to have a Windows version of Play Integrity.[0] So total control over everything that happens on your device. Just to give an example of what could happen if this becomes reality: https://en.m.wikipedia.org/wiki/Web_Enviro…

> The author is correct in that media DRM is tied to GPU vendors on the field right now ... hardware backed DRM can be so much more invasive I expect mjg59 to know what they're talking about but like you say, I wonder the same thing about the strength of (what you call) Media DRM v Hardware-backed DRM. GPU vendors have quietly deployed [hardware-based DRM] ... [which] works just fine on [boards] that [don't] have a T…

No, the GPUs have their own hardware RoT that measures the firmware. Modern GPUs are basically parallel computers with their own RAM, bootup sequence, BIOS, operating systems (drivers and firmware together are basically an OS), compiler toolchains, debuggers, sub-drivers and so on.

Re: The GPU, not the TPM, is the root of hardware DRM

#174

Post by mike_hearn »

ChuckMcM wrote: post #52

This is a much more accurate statement than the hate on the TPM. As the article describes, it is the GPU that has its own separate memory space that it can show on the screen without the CPU being involved at all. I expect next generation workarounds will involve virtual GPUs.

If that worked it'd have been done over a decade ago.

The remote server is handshaking cryptographically with the GPU itself, which identifies itself using certificates and keys tied at the factory. You can't emulate such a GPU unless you find a way to steal the keys.

Re: The GPU, not the TPM, is the root of hardware DRM

#175

Post by mike_hearn »

PeterStuer wrote: post #150

But afaik the TPM (or fTPM if no chip is present) is used to establish and restrict trusted access to the replay-protected memory block that the GPU (or other) DRM chain services depend upon to do their thing. IMHO the author does overrestrictively interpret the FSS statement to discredit them.

No, TPM isn't involved with PAVP at any point. Matthew is correct about how it works. This is a typical case where social activists are light years behind the curve and don't really know what they're talking about at all.

Re: The GPU, not the TPM, is the root of hardware DRM

#176

Post by mike_hearn »

mjg59 wrote: post #139
cryptonector wrote: post #137

> Now, TPMs are sometimes referred to as a TEE, and in a way they are. However, they're fixed function - you can't run arbitrary code on the TPM, you only have whatever functionality it provides. But TPMs do have the ability to decrypt data using keys that are tied to the TPM, so isn't this sufficient? Well, no. First, the TPM can't communicate with the GPU. The OS could push encrypted material to it, and it would ge…

How would the GPU verify it's speaking to a real TPM? You'd need to bake the full set of legitimate EK cert CAs into it somehow (charitably let's say that's a signed blob that the driver pushes in at startup), but that's still going to be a terrible user experience because you won't get media playback if your machine has a TPM that's too new or from too niche a vendor.

Right, and more to the point there's nothing special about a TPM design-wise. It's actually a very odd kind of chip that only really exists due to the unique political and market requirements of the PC industry. If you look at vertically integrated platforms like Apple's, or the games consoles, or smartphones, there's no TPM. There are subsystems that do similar things, but none of them follow the TPM design specs.

Even Intel abandoned it when designing SGX. SGX doesn't involve a TPM at any point.

So for a GPU vendor there's no reason to introduce the additional complexity of handshaking with a TPM. Blowing a private key into some eFuses at the factory is relatively easy, add a RAM encryption engine on top and you're already providing better security than what a TPM provides.

Re: The GPU, not the TPM, is the root of hardware DRM

#177

Post by jasomill »

santoshalper wrote: post #41
soerxpso wrote: post #38

Earlier quoted context omitted.

Microsoft doesn't sell hardware. Why would they be incentivized to make you buy new hardware? Unless you're alleging that their hardware partners pushed for it, in which case there would likely be logs of communications that are pretty illegal.

They do sell some PCs, but their market share is very low, and I can't imagine it's a significant part of their revenue. They definitely wouldn't bother slowing down Windows 11 adoption to sell a few more Surface Books.

About 1.9% ($4.706 billion) of Microsoft's FY 2024 revenue was from devices "including Surface, HoloLens, and PC accessories" (and not including Xbox hardware).

About 9.5% ($23.244 billion) was from Windows "including Windows OEM licensing and other non-volume licensing of the Windows operating system; Windows Commercial, comprising volume licensing of the Windows operating system, Windows cloud services, and other Windows commercial offerings; patent licensing; and Windows Internet of Things."

Compared to FY 2023, devices revenue decreased 15% and Windows revenue increased 8%.

Source: https://www.microsoft.com/investor/reports/ar24/

Re: The GPU, not the TPM, is the root of hardware DRM

#178

Post by bjoli »

watermelon0 wrote: post #155
Rohansi wrote: post #92

Earlier quoted context omitted.

Requiring TPM can actually benefit multiplayer video games because it introduces a secure way to identify hardware being used by cheaters. Right now everything being used by games is easily spoofed by cheats so cheaters just need to get a new account to continue cheating after being banned.

Such restrictions usually mean that you can't play games via Windows VM or on Linux directly. Additionally, there are cheats using video capture cards, which cannot practically be prevented.

Wait what? I don't game, so this is new to me. Do you have more info? That seems pretty cool.

Re: The GPU, not the TPM, is the root of hardware DRM

#179

Post by dataflow »

AnthonyMouse wrote: post #131
adgjlsfhk1 wrote: post #130

Earlier quoted context omitted.

imo sms 2fa is great since it is sufficient to stop automatic mass account stealing.

So is an authenticator app. Also, SMS isn't , because attackers often get access to the SMS network itself (see e.g. Salt Typhoon) in which case they can do automatic mass account stealing because they can see all the totally unencrypted SMS codes. The security of SMS really is that bad.

> attackers often get access to the SMS network itself (see e.g. Salt Typhoon)

"Often"?

Re: The GPU, not the TPM, is the root of hardware DRM

#180

Post by BlueTemplar »

Rohansi wrote: post #92
osy wrote: post #26

> I'm going to be honest here and say that I don't know what Microsoft's actual motivation for requiring a TPM in Windows 11 is. It is quite obvious: to force people to buy a new PC. TPM provides no added security value for the vast majority of users[1] but it is a convenient hardware that has only started to become standard (fTPM) in PCs built in the last ~8 years so it provides an excuse for Microsoft to declare co…

Requiring TPM can actually benefit multiplayer video games because it introduces a secure way to identify hardware being used by cheaters. Right now everything being used by games is easily spoofed by cheats so cheaters just need to get a new account to continue cheating after being banned.

This only matters for a tiny minority of video games, and even a small minority of multiplayer video games : for instance this is not going to be something I'm worried about if I play couch co-op / split screen multiplayer with friends only.
Post reply on HN