Re: SVSM Attestation and vTPM specification additions - v0.60

[James Bottomley <James.Bottomley@HansenPartnership.com>]

On Wed, 2023-01-11 at 08:49 -0600, Tom Lendacky wrote:
> On 1/10/23 17:09, James Bottomley wrote:
> > On Tue, 2023-01-10 at 17:00 -0600, Tom Lendacky wrote:
> > > A GUID still works, though, to describe that the TPMT_PUBLIC
> > > supplied is for the EK - unless you want to go with the known
> > > handles, e.g. 0x81010001 for the EK RSA handle or 0x81010002 for
> > > the EK EC handle, etc.
> > 
> > You should probably use the hierarchy handle for that case:
> > 0x40000001 for the Owner (storage) seed and 0x40000006 for the
> > endorsement seed.
> 
> Looking at the spec, do you mean 0x4000000B for the endorsement seed?
> 
> Table 28 of the TPM 2.0 Structures document has TPM_RH_EK
> (0x40000006) as "not used", but TPM_RH_ENDORSEMENT (0x4000000B) as
> "references the Endorsement Primary Seed (EPS), endorsementAuth, and
> endorsementPolicy"

Yes, probably ... I don't really ever use it except as input the the
command line tsscreateprimary -hi e or create_tpm2_key --parent
endorsement.

But I still say don't bother: the endorsement key is all that needs to
be attested because there are well known processes to use it to attest
every other TPM key.  If you're using the SVSM vTPM because you care
about measurements, you need the endorsement key not the storage key
(you only need the latter if you're inserting other keys).

James