Re: [saag] Ubiquitous Encryption: content filtering

[Nico Williams <[e-mail]>]

On Mon, Jun 22, 2015 at 04:25:28PM -0400, Stephen Kent wrote:
> On purely technical grounds, an argument for filtering in the "middle"
> is reasonable. It's much easier for a mobile operator, [...]
> 
> So, from an engineering perspective, the argument about the conflict
> between end-to-end encryption and operator (including enterprise IT
> staff) access to traffic is a valid consideration, irrespective of the
> telecom-regulator argument.

But it isn't just a matter of engineering the protocol.  There are
security problems involved in making this happen (like: how do you
express to the user that there is one (or more!) middle box filtering
and/or modifying their traffic?  how do users get to opt out?  how is
scope limited?  (e.g., how do you prevent the device/operator from
MITMing the user when the user is NOT using the operator's network?)).

And anyways, operators already get to do this by simply forcing users to
use devices from the operators (modified to have MITM CA trust anchors).
What new technology is being requested here, regardless of whether
we'd publish it (though the current position as to that is clear: no;
but the IETF consensus can always change)?

Nico
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