[svsm-devel] vTPM service attestation format update

[Dionna Amalie Glaze]

On Fri, Mar 7, 2025 at 6:24 AM James Bottomley
<James.Bottomley at hansenpartnership.com> wrote:
>
> On Fri, 2025-03-07 at 11:48 +0000, Geoffrey Ndu wrote:
> > Since the single_service_manifest call for the vTPM effectively
> > certifies EKs, why don’t the “selector” be the handle values for EK
> > certificates, as specified by the TCG in 2.2.2.5.1 of “TCG EK
> > Credential Profile For TPM Family 2.0; Level 0”? This approach would
> > simplify the user experience, as every SVSM would function
> > identically, and  SVSM vTPMs would exhibit analogous behaviour to
> > physical TPMs.
>
> Because to make life easier we might want to short circuit the EK/AK
> makecredential/activatecredential round trip and simply construct a
> signing EK to use in place of an arbitrary AK.  Then to make the
> signing EK easily useful, we might want it not to have a policy
> statement tying it to the endorsement hierarchy password (particularly
> as we know that will be empty).  To allow this type of thing we need to
> allow flexibility in the EK creation which isn't listed in the TCG
> profile EK templates.
>

I have local changes to tpm-rs that I haven't pushed to make this
commit work on its own, but this is what I'm prototyping.

https://github.com/coconut-svsm/svsm/commit/db1ad6018b04b995e0278455eb2f9a66569cbcc9

> Regards,
>
> James
>


-- 
-Dionna Glaze, PhD, CISSP, CCSP (she/her)