[dix] Re: [Ietf-http-auth] More requirements

On 7/14/06, EKR <ekr@networkresonance.com> wrote:
> "Ben Laurie" <benl@google.com> writes:
>
> > On the plane to IETF I realised that there were several more potential
> > requirements to add to ekr's list:
> >
> > 12. Single Site Unlinkability (SSU)
> > The user should be able to visit the same site multiple times without
> > the site being able to tell that it is the same user, even if the user
> > is, for example, asserting the same external claims each time. This
> > protects the user's privacy. Obviously if data provided by the user is
> > unique to that user (for example, age and address combined are often
> > sufficient to uniquely identify a person) then no amount of cleverness
> > can provide SSU, but SSU should be available to the extent permitted
> > by the uniqueness of the data provided.
>
> This is an interesting requirement and obviously of value, but
> it's worth noting that there are contexts in which linkability
> (CI) is precisely what's desired--blog comments, for example.
>
> So, you wouldn't want to design a system that always provided
> SSU. :)

Totally agreed.

> > 15. Claim Minimality (CM)
> > The ability to show only exactly what is needed, (for example, the
> > user is over 21 rather than the user's exact age, or if there are
> > mutlple claims the ability to show a subset). This improves privacy
> > and reduces linkability.
>
> Note that this ties in with IAC.

Right - the distinction is that rather than merely separating claims
you want to be able to prove properties of claims instead of revealing
their actual content.

>
> -Ekr
>
>
>

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