ECDSA Support on Windows

[spilikin]

Hi,

do you have any plans to support ECDSA EK/AK on Windows?

Currently the windows implementation seem to ignore the KeyConfig altogether:

https://github.com/google/go-attestation/blob/master/attest/tpm_windows.go#L289-L314

P.S. RSA works like a Charm

[hslatman]

@spilikin I believe AKs can only be RSA on Windows. There's some changes to the implementation logic you linked above in the PR here #343 that mention it in a comment. It builds on changes from #274.

[spilikin]

@hslatman thanks for reply. I will give this branch a try, it seems to implement the App-Keys (TPM.NewKey) on Windows as well.

[hslatman]

@spilikin yes, it does 🙂

Note that there's more Windows things in #317. #343 was created to upstream the changes in smaller batches for easier review.

If you want to have all of the Windows support we've worked on, you could try checking out the surrogate branch from https://github.com/smallstep/go-attestation/tree/surrogate. That's the fork with renamed Go module that we're currently using. It's not fully up-to-date with changes from this repo, though.

[skepth]

@spilikin

I believe the following commits added support for ECDSA AK's:

• 1b202b1
• c7aee80

Can we go ahead and close this issue?

[hslatman]

I believe the following commits added support for ECDSA AK's:

* [1b202b1](https://github.com/google/go-attestation/commit/1b202b12e80969eb8c5933a9197c16f5f7529d37)

* [c7aee80](https://github.com/google/go-attestation/commit/c7aee80c5d760a084adf51055b748d04a3187818)

Can we go ahead and close this issue?

I believe that only enables EC AK support on Linux; not Windows. IIRC EC AKs are not supported on Windows, but it's been a long time since I tried it.

Besides that I did some work on EC application keys on Windows that's in open PRs (see earlier comment). It might be time to have a(nother) look at that, and get it all properly upstreamed, considering there seems to be some more activity on this repo again.