Subject: [homenet] DNCP "Distrust" operation

From: David Lamparter <[email-masked]>
Date: Tue, 24 Mar 2015 16:08:29 +0100

Hi Steven & Markus,
Hi homenet list,

the DNCP draft contains 4 variants of bootstrap ceremonies, but the only
thing I can find about distrust is that "Configured Distrust" exists as
a state.  Can you detail how that works?  (And possibly add that detail
to the draft? - If/when someone else implements this, I can see them
skipping this entirely by just failing to notice its existence.)

Thanks,

-David

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From: Markus Stenberg <[email-masked]>
Date: Tue, 24 Mar 2015 10:11:27 -0500

> On 24.3.2015, at 10.08, David Lamparter <[email-masked]> wrote:

As you can see, there is a priority list of states that a trust verdict can have.

The ‘configured distrust’ essentially has highest priority; if someone publishes that for another node, it will not be trusted, period.

Improvements on how it is described are welcomed as always :)

Cheers,

-Markus

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From: David Lamparter <[email-masked]>
Date: Tue, 24 Mar 2015 17:55:43 +0100

On Tue, Mar 24, 2015 at 10:11:27AM -0500, Markus Stenberg wrote:
> The ‘configured distrust’ essentially has highest priority; if someone
> publishes that for another node, it will not be trusted, period.

There are sections on user interface for creating "Configured Trust"
state, yet nothing on creating "Configured Distrust" state.  Why is that
different?

> Improvements on how it is described are welcomed as always :)

I don't have the solution - just seeing a (security) issue...

At the very least I guess we need something along like:
"Installation of 'Configured Distrust' state does not suffer from the
bootstrap problem since trusted devices are known.  However, devices
implementing certificate-based trust MUST implement an user interface
add Configured Distrust;  devices relying on button or first-use models
MAY instead have an interface to clear all configured trust state."

(I guess for some ROM-based 64kB device it's easier to have a "clear
all" button, while for standard wifi routers I'd expect a web interface
with a distrust button.)

-David