Suggested entry into the TCPA spec

[AARG!Anonymous]

Here is a suggestion for how to appraoch the TCPA spec based on the parts
I have found to be relatively good explanations.  The spec is available
from http://www.trustedcomputing.org/docs/main%20v1_1b.pdf.

First read the first few pages up to page 7.  This provides an overview
and a block diagram, although at this point not all the terms will be
familiar.  One hint: the "root of trust for measurement" is the set of
hardware which has to be working for the boot measurement process to work:
the CPU, the TPM, the part of the BIOS that deals with measurements, the
motherboard, the secure connections of the chips to the motherboard.
If all this stuff is OK then the measurements will be accurate.
(Measurements basically are hashes of code and of machine configuration
status.)  The "root of trust for reporting" is the endorsement key, or
more fundamentally the cert on the endorsement key.  The cert is issued by
the manufacturer, AKA the "TPM Entity" or TPME.  That's what makes other
people believe your attestations.  And the "root of trust for storage"
is the storage root key, described in the section on protected storage.

There are a few more pages of introduction which aren't too clear,
then a long section of data structures which should be skipped until
you need to reference them.

This brings you to page 97, authorization and ownership.  I haven't
really studied this part.  Probably just read this one page to get
an idea of what is involved.  I still need to learn more about this.

I'd skip on to pages 136-137, on the measurement process and the
PCRs which hold the results of the measurement.

Then I'd read pages 145-150 on protected storage.  This part is pretty
well written.  It is a reasonably self contained part of the TPM
functionality.  You just need to know a little bit about the PCRs from
the earlier section to understand how data is locked to the specific
program which is running.

Then I'd read page 261 on the endorsement key, and then 267-269 on
how it is used to create a pseudonymous identity.  This is the part
about communicating with the Privacy CA.  BTW an expert told me he has
concerns about possible security loopholes in this protocol, but he is
communicating with TCPA about them.

I think if you just read these selections, about 15 pages, you will have
a much better idea of how the spec works.  Then you can read some of
the specific API descriptions to see more details about the functionality.

There is also a glossary at the end which can be helpful for some (but
not all) of the terminology.

There is another spec,
http://www.trustedcomputing.org/docs/TCPA_PCSpecificSpecification_v100.pdf
that describes the specific register and trap binding for implementing
the TCPA API on Intel PCs.  It is much shorter but it is pretty
incomprehensible until you have at least read the basics of the main
spec.

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