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Remote Attestation

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Re: Remote Attestation

#91

Post by matejdro »

Cider9986 wrote: post #64

GrapheneOS has an implementation of this with their Auditor app. You can use their service or you can use another Android. No freedom lost, just security gained. https://attestation.app/about There's also Android's hardware attestation API which apps can use to verify integrity in a more secure and privacy-respecting way than Google Play Integrity. An increasing number of apps are officially supporting GrapheneOS thr…

> No freedom lost, just security gained

As far as I can tell, it flags unlocked bootloaders? So this is already huge freedom lost.

Re: Remote Attestation

#93

Post by marginalia_nu »

I don't understand how this stuff prevents me from MITM:ing the attestation and routing requests to another device that is clean and attested? I.e. how do you know that the remote TPM belongs to the device you're talking to?

Re: Remote Attestation

#94

Post by Dibby053 »

whiatp wrote: post #61

Something worth calling out is that, as far as I've seen, most server TPM implementations are not great against physical access attacks. If servers might be physically compromised (eg. you are leaving a server unsupervised in a colo) shenanigans are still possible. The TPMs are on separate chips from the main processor. If something were to man-in-the-middle the communications with the TPM, the hash digests can be "c…

Have the CPU and the security chip derive their private keys from physical unclonable functions (to prevent extraction), let them exchange public keys once during manufacture, and from that point onward encrypt the SPI bus.

This is what some smartphones seem to do. I don't know if server motherboards do it but it would help a lot against this kind of attack.

Re: Remote Attestation

#95

Post by matheusmoreira »

egorfine wrote: post #85

This is an incredibly nice technology that absolutely will be used to prevent you from using your computer as you wish.

It's all about who owns the keys to the machine. Attestation with our own keys is good for us. It becomes a problem when it's the manufacturer's key, the digital fiefdom owner's key or the government's key.

Remote attestation reveals the fact the computer belongs to corporations and governments. The user's attempts to claim ownership are "tampering".

Re: Remote Attestation

#96

Post by rcxdude »

matejdro wrote: post #91
Cider9986 wrote: post #64

GrapheneOS has an implementation of this with their Auditor app. You can use their service or you can use another Android. No freedom lost, just security gained. https://attestation.app/about There's also Android's hardware attestation API which apps can use to verify integrity in a more secure and privacy-respecting way than Google Play Integrity. An increasing number of apps are officially supporting GrapheneOS thr…

> No freedom lost, just security gained As far as I can tell, it flags unlocked bootloaders? So this is already huge freedom lost.

With grapheneOS you can lock the bootloader with your own keys. Huge difference. (That said, I don't know if the apps which demand the attestation trust anything but the official grapheneOS keys)

Re: Remote Attestation

#97

Post by spacebanana7 »

matheusmoreira wrote: post #95
egorfine wrote: post #85

This is an incredibly nice technology that absolutely will be used to prevent you from using your computer as you wish.

It's all about who owns the keys to the machine. Attestation with our own keys is good for us. It becomes a problem when it's the manufacturer's key, the digital fiefdom owner's key or the government's key. Remote attestation reveals the fact the computer belongs to corporations and governments. The user's attempts to claim ownership are "tampering".

Not your keys, not your computer

Re: Remote Attestation

#98

Post by mindslight »

marginalia_nu wrote: post #93

I don't understand how this stuff prevents me from MITM:ing the attestation and routing requests to another device that is clean and attested? I.e. how do you know that the remote TPM belongs to the device you're talking to?

The TPM is tamper proof hardware that includes privileged crypto keys that are installed (generated) by the device manufacturer with their identity retained / cataloged. The asymmetry of these privileged keys are where the private/control concerns end up coming from. If these top-level keys were instead unknown to everybody except the device owner (including an enterprise), then there would be no way for a random third party attacker to know whether it was talking to a hardware RPM or a software emulation of one.

Re: Remote Attestation

#99

Post by getcrunk »

marginalia_nu wrote: post #93

I don't understand how this stuff prevents me from MITM:ing the attestation and routing requests to another device that is clean and attested? I.e. how do you know that the remote TPM belongs to the device you're talking to?

Same way drm works, it’s going to be in layer of hw/sw that you don’t have control over. We don’t have commonly have control on the cpu, chipset, uefi. And on the top side things like widevine on the application layer
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