W3C home > Mailing lists > Public > www-p3p-public-comments@w3.org > November 2001

Re: Can P3P work in the real world?

From: Lorrie Cranor <lorrie@research.att.com>
Date: Mon, 12 Nov 2001 09:30:27 -0500
Message-ID: <011101c16b86$cac0b0a0$3e06cf87@research.att.com>
To: "David Wall" <dwall@Yozons.com>, <www-p3p-public-comments@w3.org>
Dear David,

Thank you for your comments about P3P. We
are sorry that you have had difficulties implementing P3P
on your web site. We are in the process of developing
better documentation, which we think will make the P3P
implementation process much easier. In addition,
a number of software tools are under development which
make this process much easier.

http://www.w3.org/P3P/implementations has
the latest information on implementations. The IBM P3P
Policy Editor is a good tool for generating P3P policies.
The P3P Compact Policy Translator can help you understand
what your compact policy really says.

Let me also try to address some of your comments and

> 1) It's too complex, allowing policies to vary page by page.

This is an option -- but most web sites seem to be
declaring one policy for the whole site. Sites do not have
to take advantage of this complexity.

> 2) It requires changes to all existing web sites/pages.

Deploying P3P requires each web site to add one or
two files to the site. It does not require changes to every
page, nor the installation of any new web site software.

> 3) Generating an accurate policy.xml file is quite complex compared to
describing the situation in the human readable privacy policy.

If you use a P3P policy generator tool the problem should
not be that complex. Furthermore, we hope it will become
easier as better documentation becomes available over
the next few months.

> 4) Who enforces that the policy.xml or compact policy are accurate for a
site?  What's the fallback if the site says they do X to allow a user agent
such as IE 6 to believe they don't track you, etc., but then do Y instead?

This is the same problem we have enforcing human-readable
privacy policies. How do you know that they are accurate?
Depending on what country or jurisdiction a web site is in,
there is probably a government agency that would investigate
accusations of false claims in privacy policies. We expect that
such agencies would also be interested in false claims in
P3P policies.

> 5) It's rather hard for a web site to be compliant, generating accurate
policies, keeping them up-to-date, etc.

The same thing holds true for huaman-readable privacy policies.
Sites should be very careful any time they change their practices in
ways that impact their privacy policies.

> 6) It's rather hard for a user agent to make sense of such policies.

Actually, since user agents are computer programs, they can
be developed to do all sorts of interesting things with P3P policies,
including functioning exactly as you describe in your next point.

> 7) It's rather hard for an end user to make sense of such policies.
> It seems that a simpler standard would have been more powerful, including
the ability for the user agent to determine:
> a) Allow/disallow persistent cookies.
> b) Allow/disallow session cookies.
> c) Allow/disallow third-party cookies.
> d) Warn if a site shares my information with third parties for marketing
> e) Warn if a site doesn't have a customer service mechanism to correct
incorrect data about me.
> f) Warn if a site doesn't allow me access to view and update the data they
keep about me.
> g) Provide a link to their posted privacy policy page.
> Personally, these questions are much easier for me to handle as a web site
operate and as a web surfer, and I have the basic control I need.  In
practice, privacy policies change over time, and unless users keep a copy of
each policy as they visit and the time they visited it, it would be hard to
claim that a web site violated their privacy policy if the most current
policy would not be in violation.  And what remedies does the average Joe
have if the web site does violate the policy, and how would that Joe even
know it?

These are all things that a user agent could do. It is now up to
software implementers to decide whether a user agent with this
sort of functionality is worth building. Right now we're seeing fairly
simple user agents that essential put an overlay on top of the
complicated choices so that end users see something
much simpler.

> Is this standard just something to make people feel good, but the
implementation will be so complex that it's ignored by the masses?

No. We realize it will take some time for implementers to
figure out what the best ways are to present these complicated
concepts to users in a useful way, but we do believe that over
time P3P will become something truely useful. If your company
focusses on the privacy of the individual, then I think you
should be able to appreciate this. There are a lot of different
opinons about what are the important privacy issues, and
these vary from country to country as well as from person to person.
We developed P3P to be very flexible, but we expect that user
agent tools will be developed that will simplify this complexity
for users.

> Our company focuses on the privacy of the individual.  We use cookies to
track the login/use of our web app while logged on.  We encrypt all client
data.  We don't share with third parties and don't do any advertising.  Yet
I've found getting a P3P privacy policy in place rather complex (I'm not
entirely sure it's accurate in comparison to the human readable one which
is), less sure about the compact policy since I don't really even know what
it says (because of the cryptic codes!), and yet IE 6 still won't work with
my site when using HIGH level security -- though it will at medium-high.  Oh

You may find
useful for better understanding IE6. You may also be interested
in joining the www-p3p-policy mailing list
to discuss your questions with other folks working on
implementing P3P


Lorrie Cranor
P3P Specification Working Group Chair

> David
> ---------------------------------------------
> David A. E. Wall
> Chief Software Architect
> Yozons, Inc.
> 724 17th Avenue
> Kirkland, WA 98033 USA
> Tel 425.822.4465    dwall@yozons.com
> Fax 425.827.9415    www.yozons.com
Received on Monday, 12 November 2001 09:32:35 UTC

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