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100%! As a _user_ I personally would love if I could store all my session authentication info in my device's TPM/SEP for my own safety. I do this with my SSH ke

100%! As a _user_ I personally would love if I could store all my session authentication info in my device's TPM/SEP for my own safety. I do this with my SSH keys for specifically the reason you suggest—I like that my private keys are non-exportable and so installing a public key on a server is a solid authentication for one device and one device only. This, however, only establishes trust on _my_ end. My SSH servers cannot know or trust that my keys are well guarded because, for all they know, I have a crumby TPM and/or store them unencrypted in my .ssh folder. You cannot make a trust decision based on TPM storage because you have no idea what the TPM actually did (or if aforesaid TPM even _exists_ at all) unless you require remote attestation, which is both non-portable, non-free, and requires you support only users who have a specific variety of CPU.

mjg59 5y ago
https://github.com/google/go-attestation https://github.com/google/go-attestation is a free implementation of remote attestation that's not associated with any CPU type and will work on anything that has a TPM. But what we want here isn't really remote attestation (which implies attesting to the overall state of the device), it's key attestation (where you verify that the key was generated on a legitimate TPM). But there's still a legitimate privacy concern, in that the attestation is still rooted in an immutable key that would allow anyone who performed key attestation with you to associate your identity with a specific computer.
- nybble41 5y ago
  > key attestation (where you verify that the key was generated on a legitimate TPM) This is the same problem, just one level further down. The scheme depends on hardware acting against the desires of its owner—whether we're talking about the entire system or just the TPM portion. The privacy concerns are real but not the full extent of the problem.

mjg59 5y ago

https://github.com/google/go-attestation https://github.com/google/go-attestation is a free implementation of remote attestation that's not associated with any CPU type and will work on anything that has a TPM. But what we want here isn't really remote attestation (which implies attesting to the overall state of the device), it's key attestation (where you verify that the key was generated on a legitimate TPM). But there's still a legitimate privacy concern, in that the attestation is still rooted in an immutable key that would allow anyone who performed key attestation with you to associate your identity with a specific computer.

nybble41 5y ago
> key attestation (where you verify that the key was generated on a legitimate TPM) This is the same problem, just one level further down. The scheme depends on hardware acting against the desires of its owner—whether we're talking about the entire system or just the TPM portion. The privacy concerns are real but not the full extent of the problem.