W3C home > Mailing lists > Public > public-webid@w3.org > October 2012

Re: [saag] Liking Linkability

From: Robin Wilton <wilton@isoc.org>
Date: Wed, 24 Oct 2012 12:26:58 +0100
Cc: Ben Laurie <ben@links.org>, Halpin Harry <H.halplin@ed.ac.uk>, public-identity@w3.org, saag@ietf.org, "public-privacy@w3.org list" <public-privacy@w3.org>, public-webid@w3.org
Message-Id: <E8AC244A-1D90-49F2-BD8A-2CF13E11D4B7@isoc.org>
To: Ben Laurie <benl@google.com>

Robin Wilton
Technical Outreach Director - Identity and Privacy
Internet Society

email: wilton@isoc.org
Phone: +44 705 005 2931
Twitter: @futureidentity

On 24 Oct 2012, at 10:30, Ben Laurie wrote:

> On 23 October 2012 10:58, Robin Wilton <wilton@isoc.org> wrote:
>> On 23 Oct 2012, at 09:44, Ben Laurie wrote:
>> <snip>
>> Not disagreeing with any of the above, but observing that:
>> a) There's no particular reason you could not have an email per site
>> as well as a key per site.
>> b) Linkability it not, as you say, inherently bad. The problem occurs
>> when you have (effectively) no choice about linkability.
>> But it's very hard to use either of those mechanisms (separation through
>> emails or keys) without giving some third party the ability to achieve total
>> linkability. (In other words, both options remove effective choice).
> I agree that emails are a problem, but not at all sure why keys are?
> In the case of appropriate selective disclosure mechanisms, even if
> there were a third party involved, they would not be able to link uses
> of the keys. Also, if you insist on using linkable keys, then per-site
> keys do not involve third parties.

It may just be that I'm not getting a clear mental picture of your architecture. But here was my thinking: 

- If you use symmetric keys, you get a system which can't scale unless you opt for Schneier's idea of a key serverů but then the key server becomes a point of potential panopticality.

- If you use PKI, *and* you want your communicating parties to be able to validate the certs they're relying on, then you have to design a CRL- or OCSP-like mechanism into the architecture, and again you end up with a component which is potentially panoptical. (Plus, you have to address the 20-year-old problem of how to make PKI usable by human beings, when recent history suggests that PKI only takes off where human beings are kept well away from it).


> On email, this is a soluble problem, but not without using a
> completely different delivery mechanism.

>> Yrs.,
>> Robin
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Received on Wednesday, 24 October 2012 11:28:39 UTC

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