Re: [Uta] Opportunistic encryption and authentication agility

On Tue, Mar 25, 2014 at 4:47 PM, Trevor Perrin <trevp@trevp.net> wrote:
> On Tue, Mar 25, 2014 at 1:24 PM, William Chan (陈智昌)
> <willchan@chromium.org> wrote:
>> On Tue, Mar 25, 2014 at 1:09 PM, Trevor Perrin <trevp@trevp.net> wrote:
>>>
>>> On Mon, Mar 24, 2014 at 9:51 AM, Daniel Kahn Gillmor
>>> <dkg@fifthhorseman.net> wrote:
>>> > On 03/24/2014 12:36 PM, Keith Moore wrote:
>>> >
>>> >> So, what's the incentive for either clients or servers to support OE if
>>> >> clients just silently accept it without any indication to the user?
>>> >> Just for the good of mankind?
>>> >
>>> > I'd say "to increase the cost of pervasive monitoring" and "to resist
>>> > surveillance by passive attackers"
>>>
>>> I'd go further - OE for HTTP could have strong auth added to it in the
>>> future, such as pinning or DANE, which *could* be indicated to the
>>> user.
>>
>>
>> Please be cautious about suggesting user indications. UI is complicated and
>> all that. More specifically in the browser case, even if you could strongly
>> authenticate a connection over which you request a http:// page, I wouldn't
>> want to give that page the https lock treatment. Note that https:// has
>> different semantics (referer semantics, mixed content, etc).
>
> Good points, thanks.  Maybe adding other auth methods to HTTP-over-TLS
> would be best done silently, with no UI unless a security failure
> occurs?

Sadly this doesn't work. If I can imitate the website because of a
WebPKI failure, I can pretend to not support whatever additional auth
is done. It's the reason OCSP stapling doesn't work.

Furthermore, taking an economic perspective, authentication has a
winner-take-all aspect to it. A new client has to support the
authentication everyone already uses. But a site only has to support
the authentication the client accepts. Any new authentication
mechanism will only be adopted in domains where the existing one
doesn't work.

Sincerely,
Watson Ladd
>
> I think I like that, as I think catching "badness" is more useful than
> indicating "goodness".  But these are hard Qs, I'm just trying point
> out some possibilities at this point.
>
>
> Trevor
>
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