[nasr] Re: [saag] Re: NASR BOF Follow-Up

[Eric Rescorla <[e-mail]>]

On Fri, Apr 11, 2025 at 9:45 AM Henk Birkholz <[e-mail]>
wrote:

> On 11.04.25 15:38, Eric Rescorla wrote:
> >
> >
> > On Fri, Apr 11, 2025 at 2:01 AM Henk Birkholz
> > <[e-mail]> wrote:
> >
> >     On 10.04.25 21:01, Eric Rescorla wrote:
> >      >
> >      >
> >      > On Thu, Apr 10, 2025 at 11:40 AM Henk Birkholz
> >      > <[e-mail]> wrote:
> >      >
> >      >     On 03.04.25 21:11, Eric Rescorla wrote:
> >      >
> >      >      > [0] Of course you could hash the individual configuration
> >     values,
> >      >      > but this is much the same as publishing the configuration.
> >      >
> >      >     Is it? I am curious why.
> >      >
> >      >
> >      > Because the values themselves are generally low entropy, so if you
> >      > publish their hashes, then it's generally easy to determine the
> >     preimage.
> >      >
> >      > -Ekr
> >
> >     Would some salt help here (like the salted hashes in sd-cwt)?
> >
> >
> > Probably not very much. What salt does is make it more difficult to
> > amortize computation
> > across multiple hashed values. However, if the total number of possible
> > values
> > is low (e.g., you have some configuration setting with 3 values) then
> > you can
> > just exhaustively search at query time.
>
> That makes a lot of sense - and might be another good reason not to put
> these types of Claims into Evidence. I still think it is better to
> include software components that provide the conveyance mechanism (e.g.,
> a YANG server with YANG Push capability) in a TCB and then use
> successfully appraised software components for trusted telemetry to
> convey such values for evaluation.


That may be better from some angles but I think brings us back to
Richard's question about whether operators are in fact willing to
allow counterparties to access their devices to get this configuration data.

It also doesn't affect--one way or the other--the need to understand
which configuration directives are relevant and what acceptable
values are.

-Ekr