Re: [Rats] Android attestations: Re: draft-richardson-rats-usecases-00 comments

[Michael Richardson <[e-mail]>]

Anders Rundgren <[e-mail]> wrote:
    > I don't have much data on StrongBox so maybe I was out of line there,
    > but the idea I had was that keys would not be stored in secure silicon,
    > but rather encrypted in the TEE or RE environment.  In that case
    > StrongBox would be a crypto processor with embedded keys which also
    > would be used for provisioning/attestation:
    > https://github.com/ietf-teep/architecture/issues/52#issuecomment-486929941

So I think you are saying that you want software running outside of
TEE/RE environment to be able to ask for a key to decrypt an private
(assymetric) key (also stored outside of the TEE).  This software would do
something with the key, and then destroy the key.

Is this a use case where the software needs to make some kind of claim
to the TEE (which is the relying party now), in order to get this access?

I can easily see a situation where there are three trusted modules that
the software interacts with:

1) an attestation service that measures and attests to the integrity of the
   software running... produces a claim (A)

2) the StrongBox that releases the private key-key based upon claim (A) to
   produce some signature X.

3) a trusted module that counter-signs signature X, to say that the
   end-user authorized the transaction via hardware FOO.

--
Michael Richardson <[e-mail]>, Sandelman Software Works
 -= IPv6 IoT consulting =-