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Windows 11: TPMs and Digital Sovereignty

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Re: Windows 11: TPMs and Digital Sovereignty

#51

Post by xg15 »

mjevans wrote: post #41
kmeisthax wrote: post #29

Earlier quoted context omitted.

Ok, so instead of Microsoft turning my PC into an Xbox, it's banks asking Microsoft to turn my PC into a credit card reader. This is not materially different. We already know how this works on Android. Attestation requirements and DRM tend to creep beyond their initial scope if implementing them is easy. And those requirements will include not having owner-level control over your machine[0]. If you root Android, you…

I don't really understand why I can't also force my device to _lie_ to any app that demands that. Is it somehow checking the exact combination of my firmware against a database of allowed root certs?

My understanding is that there is something like a system call that a program can use to query the TPM for the current system state. The TPM will then reply with some sort of hash representing the state and also a signature for that hash using a private key stored inside the TPM.

The program (i.e. the netflix app or a browser) can then pass on that data structure to netflix' servers, which will then decide if they permit 4K content or not.

To circumvent this, you'd have to know two things:

1) what kind of hash for a "non-rooted" system netflix is expecting in the first place.

2) the private key to sign the hash with.

To get the former, you'd have to eavesdrop on a connection on a non-rooted device. To get the letter you'd have to extract the key from a TPM, which is likely specifically built to make this hard.

Re: Windows 11: TPMs and Digital Sovereignty

#53

Post by scott00 »

DaiPlusPlus wrote: post #47
Gigachad wrote: post #28

Earlier quoted context omitted.

Seems like a lot of banking and other secure business is moving to mobile first or mobile only, presumably as it's likely the only secure device the user has.

I agree with your assessment: desktop-browser online banking (with US banks in particular) is a depressing experience given how they’re full of ads for credit-card offers and manual (if not broken) OFX/QFX downloads that only contain a fraction of the actual backend txn data that the banks won’t ever share with their (retail-banking) customers… And yet, while lots of banks now use SMS 2FA, none of the banks I use (Ch…

What else is in the backend transaction data?

Re: Windows 11: TPMs and Digital Sovereignty

#55

Post by barbariangrunge »

Gigachad wrote: post #27
AraceliHarker wrote: post #23

One of the reasons why Microsoft and OEMs are promoting TPM is to encourage planned obsolescence, so that users will replace their PCs as often as they replace their smartphones, right? "(Lenovo) said people buy new smartphones every other year but became accustomed used to buying new PCs every six or seven years. The industry needs to do better at motivating people to buy new devices" https://www.cnbc.com/2021/10/05…

Tbh I'd expect the trend of upgrading phones to start to slow down as well as they become "good enough" but there are still pretty big gains being made in cameras. Laptops are just good enough now. If you took the 3 year old M1 internals, and stuck them in the new case and told me it was the 2024 model, I'd not notice anything was off.

Phones are locked down. All you need is a vendor to refuse further software updates after 5 years, after releasing a more resource-draining updates prior to this, and it doesn’t matter how good the old hardware is. People won’t be able to use it

Re: Windows 11: TPMs and Digital Sovereignty

#56

Post by ditmarw »

emily-c wrote: post #42
hlandau wrote: post #39

Earlier quoted context omitted.

Except that it can't actually do that, because x86 DRTM doesn't remove SMM handlers installed by the system firmware, ACPI tables also remain resident and could be changed to contain malicious code, etc.

DRTM does not remove any malicious firmware provided code or data. Traditionally it is merely a measurement mechanism that happens after ExitBootServices which measures platform state in an unforgable manner. Practically the DRTM event can also cause certain chipset registers to get locked or SMM supervisors to get launched depending on the platform. SMM and ACPI tables (on some x86 platforms certain tables are rebui…

Trenchboot overview is good https://trenchboot.org/documentation/Late_Launch_Overview/

Re: Windows 11: TPMs and Digital Sovereignty

#57

Post by blibble »

nly wrote: post #54
jimbob45 wrote: post #4

I have to believe most of us here on HN are in the boat of keeping a W11 partition for work and a Linux partition for everything else at this point.

QEMU emulates UEFI Secure Boot and a software TPM just fine. No need to dual boot.

they can block that extremely easily if they want to

(the article even mentions this)

Re: Windows 11: TPMs and Digital Sovereignty

#58

Post by kmeisthax »

mjevans wrote: post #41
kmeisthax wrote: post #29

Earlier quoted context omitted.

Ok, so instead of Microsoft turning my PC into an Xbox, it's banks asking Microsoft to turn my PC into a credit card reader. This is not materially different. We already know how this works on Android. Attestation requirements and DRM tend to creep beyond their initial scope if implementing them is easy. And those requirements will include not having owner-level control over your machine[0]. If you root Android, you…

I don't really understand why I can't also force my device to _lie_ to any app that demands that. Is it somehow checking the exact combination of my firmware against a database of allowed root certs?

More or less, yes. The exact details vary from system to system: TPMs were built for PCs where firmware and OSes are diverse, so TPM works off boot measurements and hash functions. On phones all the attestation stuff runs on a separate processor with only one kind of firmware and it gets told by the main processor whether or not the user installed a custom ROM (in which case, no attestation for you).

This is because the people in the "need attestation yesterday" camp specifically do not want a system in which device owners can lie about their attestation status, because:

- For streaming video platforms, the whole point of trusting attestation is to prevent owner tampering, because they want to ensure that you aren't retaining any video past your subscription end date

- For banks, they want to protect you from hackers, rather than themselves from you, so an owner override "should" be tolerable. However, banks also work entirely off of risk assessments and probabilities. And the number of owners genuinely overriding their own attestations so they can run custom ROMs is lower than the number of hackers who would attack the override so they can steal credit card numbers. So in practice the attestation is a fraud signal[0], and allowing overrides at all is like allowing hackers to falsify your fraud data.

[0] Specifically a signal that something is NOT fraudulent, since all the correct, unmodified software was run

Re: Windows 11: TPMs and Digital Sovereignty

#59

Post by ldarby »

cyber_kinetist wrote: post #25
ldarby wrote: post #7

Earlier quoted context omitted.

If Windows is required for work then you've already lost. Seriously I'm unable to be productive in Windows (or Mac, I tried). I don't know what the stats are on employers requiring Windows but my current one doesn't (mainly because of a sizable chunk of Mac users, not that there's any support for Linux).

Then how are you going to do the majority of native desktop app/game development (where most of your users use Windows)?

I don't develop or support anything on Windows. Sure that excludes 99.9% (I guess) of career options involving a computer, but I've still found employment that doesn't require Windows. But once either Microsoft finally succeeds at banning Linux from running on desktop PCs (which is basically what this is about), or every single employer requires everyone to run Windows, then I guess I'll switch careers to farming or something.

Re: Windows 11: TPMs and Digital Sovereignty

#60

Post by emily-c »

ditmarw wrote: post #56
emily-c wrote: post #42

Earlier quoted context omitted.

DRTM does not remove any malicious firmware provided code or data. Traditionally it is merely a measurement mechanism that happens after ExitBootServices which measures platform state in an unforgable manner. Practically the DRTM event can also cause certain chipset registers to get locked or SMM supervisors to get launched depending on the platform. SMM and ACPI tables (on some x86 platforms certain tables are rebui…

Trenchboot overview is good https://trenchboot.org/documentation/Late_Launch_Overview/

Thanks :) I wish there was a consolidated list of what kinds of information gets measured that is easy to point to.
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