[tboot-devel] Reading embedded EK's certs from a TPM?

[Joanna R. <jo...@in...>]

Hello,

I would like to be able to (generically) read an embedded Endorsement
Keys certificate from a TPM's NV memory.

Apparently some TPM vendors do embedded such certificates (in addition
to the actual EK key) on the TPM, see e.g. this datasheet:

http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATA_BRIEF/DM00037936.pdf

... where we can read:

"Provisioned with Endorsement key and Endorsement Key certificate"

"NV storage allocated space: 4 Kbytes (1.2 Kbytes used by EK certificate)"

Additionally the actual CA and intermediate certificates are published:

http://www.st.com/internet/mcu/product/252378.jsp

and the Infineon seems to be doing the same:

http://www.infineon.com/cms/en/product/chip-card-and-security-ics/embedded-security/trusted-computing/trusted-platform-module-tpm1.2-pc/channel.html?channel=ff80808112ab681d0112ab6921ae011f

Unfortunately, the datasheet, nor any other document I was able to find,
tells how one could retrieve such a certificate out of the TPM's NV
memory. And ideally that this worked for all the TPMs from all sorts of
vendors...

Of course, without being able to authenticate the EK key, all the Remote
Attestation schemes are pretty useless in practice, so I thought this
might be a good list to ask this question, as one of the primary
applications of tboot is remote attestation actually. Plus, tboot has
quite a few tools to talk to the TPM.

Thanks,
joanna.