Re: Documenting the proposal for TPM 2.0 security in the face of bus interposer attacks

From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: linux-integrity@vger.kernel.org,
	linux-security-module@vger.kernel.org, monty.wiseman@ge.com,
	Monty Wiseman <montywiseman32@gmail.com>,
	Matthew Garrett <mjg59@google.com>
Subject: Re: Documenting the proposal for TPM 2.0 security in the face of bus interposer attacks
Date: Wed, 21 Nov 2018 01:12:22 +0200	[thread overview]
Message-ID: <20181120231222.GH8391@linux.intel.com> (raw)
In-Reply-To: <1542734581.2814.28.camel@HansenPartnership.com>

On Tue, Nov 20, 2018 at 09:23:01AM -0800, James Bottomley wrote:
> On Tue, 2018-11-20 at 13:10 +0200, Jarkko Sakkinen wrote:
> [...]
> > This is basically rewrite of TPM genie paper with extras. just
> > shorten it to include the proposed architecture and point to the TPM
> > Genie paper (which is not in the references at all ATM).
> 
> I really don't think so.  The paper only gives details of bound
> authorization sessions for TPM 2.0 which suffer from no to weak entropy
> problems.  The reason for using salted ones in the document, which
> aren't mentioned at all in the genie paper, is so we have a high
> entropy cryptographically unguessable HMAC and encryption key.

Point taken.

I will re-read the paper with care as soon as I have time and give
better feedback.

> Only if you have some type of security seal, which most laptops don't
> have.

Agreed went over the top on this one.

/Jarkko