Subject: Re: [Rats] No root of trust requirement in RATS/EAT

From: Michael Richardson <[email-masked]>
Date: Mon, 07 Oct 2019 14:27:34 +0200

Laurence Lundblade <[email-masked]> wrote:
    > An Android phone often looks like this:
    > - Linux / Android apps
    > - Linux kernel
    > - TA’s (Trusted Apps — apps running the TEE)
    > - TEE kernel

    > It must be allowed for any one of these to generate RATS/EAT
    > attestations. It might be that only the Android app generates RATS/EAT
    > attestations. This phone is just one example. Other devices, like cars,
    > may be similar.

I just wanted to +1 your comments (10 weeks later).
Not every use of RATS protocol mechanism will be a typical TCG
secure-boot/trusted-boot use case. 

    > If there is a normative or descriptive text saying a root of trust is
    > required to generate an attestation, then we have to redefine root of
    > trust to so that Android apps are roots of trust. This is very counter
    > to the normal definition of root of trust. By common definition the
    > root of trust of the above phone would be the TEE. Such a redefinition
    > for RATS would be very confusing. So I don’t think normative text
    > should require a root of trust.

...

    > I know that large parts of the TCG and TEE worlds have the root of
    > trust as a fundamental part of their architectures. It makes sense
    > there. However, these groups fundamentally work on the security
    > internals of end points. The IETF does not. It focuses on on-the-wire
    > security. Thus, it makes sense that orientations around end-point
    > internal security implementation is different.  Some of what goes in
    > the TCG and TEE worlds doesn’t carry over to the IETF.

I have an image of a network map (with a cloud of course), and at the
boundary into the device, inside the box,
         it says, "Here be (roots of) Dragon (trust)"

    > I know reorienting the RATS architecture draft to not hinge on roots of
    > trust is a big upheaval, but I think it is necessary.

I don't recall your comments getting any on this thread.

-- 
]               Never tell me the odds!                 | ipv6 mesh networks [ 
]   Michael Richardson, Sandelman Software Works        | network architect  [ 
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