4 ms·

Unfortunately, that is only correct for the example cited in the article I linked to. The RFC being drafted contains attestation possibilities for both clients

by c0l0 3y ago

Unfortunately, that is only correct for the example cited in the article I linked to. The RFC being drafted contains attestation possibilities for both clients and servers, as per sections 4.1. (TLS Client as Attester) and 4.2. (TLS Server as Attester). Nothing in this prevents servers from discrimincating against clients that fail to produce TPM-backed attestation that they run exclusively the exact software builds, cryptographically signed by a central arbiter of trust, that the server expects/requires them to.

zb3 3y ago
That's why I mentioned intel deprecating SGX, because newer desktop CPU's don't support that, so it'd be impractical for websites to discriminate based on that. Also note that servers running in the cloud can naturally be clients. It's only bad if this is meant to restrict the power of the consumer over their own (non-rented) devices.
- c0l0 3y ago
  I'm sorry to say that I am not convinced. In recent years, Microsoft has introduced [Virtualisation-based Security](https://learn.microsoft.com/en-us/windows-hardware/design/device-experiences/oem-vbs https://learn.microsoft.com/en-us/windows-hardware/design/de...) - funnily enough while recycling one of actual security experts' most-loathed acronym, "VBS" - for OS components that are deemed critical, such as Windows Defender Credential Guard. If your OS, that is now also a hypervisor, shards off some "critical" computation, such as computing RA-TLS nonces - into a privileged domain that your regular user domain may not access, and that privileged, TMP-attested domain is protected by all the secure/measured boot shenanigans that are going on with Windows 11 and its mandatory TPM, it's as game over as it was with SGX directly in your CPU (barring some grave implementation bugs that will make everything vulnerable to state-level actors regardless). Also, Arm silicon, for example, has TrustZone, which afaiui serves a similar purpose as SGX did.

by c0l0 3y ago

zb3 3y ago

That's why I mentioned intel deprecating SGX, because newer desktop CPU's don't support that, so it'd be impractical for websites to discriminate based on that. Also note that servers running in the cloud can naturally be clients. It's only bad if this is meant to restrict the power of the consumer over their own (non-rented) devices.

c0l0 3y ago
I'm sorry to say that I am not convinced. In recent years, Microsoft has introduced [Virtualisation-based Security](https://learn.microsoft.com/en-us/windows-hardware/design/device-experiences/oem-vbs https://learn.microsoft.com/en-us/windows-hardware/design/de...) - funnily enough while recycling one of actual security experts' most-loathed acronym, "VBS" - for OS components that are deemed critical, such as Windows Defender Credential Guard. If your OS, that is now also a hypervisor, shards off some "critical" computation, such as computing RA-TLS nonces - into a privileged domain that your regular user domain may not access, and that privileged, TMP-attested domain is protected by all the secure/measured boot shenanigans that are going on with Windows 11 and its mandatory TPM, it's as game over as it was with SGX directly in your CPU (barring some grave implementation bugs that will make everything vulnerable to state-level actors regardless). Also, Arm silicon, for example, has TrustZone, which afaiui serves a similar purpose as SGX did.