RE: de-identification text for Wednesday's call

Dan - my apologies - I used those terms to represent one end of a spectrum.  Let's step away from those particular terms to represent the most conservative side of the spectrum and instead speak to the range of possible points of application of consumer protection with respect to de-identification.

On one side of the spectrum we have a possible solution that is completely based on administrative and operational controls (as you pointed out earlier) and on the other side of the spectrum is a possible solution that completely relies on technology alone ("and provides for leeway as anonymization technology improves").  In the middle is a solution that is a mix and allows organizations the latitude to devise a solution that matches their ability to mitigate risk and maintain some value in data - while not being overly prescriptive on the specific technology employed.  All points on the spectrum focus on the desired outcome - that de-identified data not later be re-identified.

While we both agree on the outcome (I believe), we disagree on the best route to get there.  I would suggest we move away from prescriptive elements in the text and provide organizations the flexibility to innovate and build solutions they believe meets the goal.  As long as a company is stating they will meet the goal, you have all of the necessary commitment to hold them accountable to that outcome.

Evidence:  I believe the perceived harm is that de-identified data can later be re-identified, fair?  If yes, then any solution in the spectrum serves that purposes but forces companies most likely to the middle or more conservative side of the spectrum to mitigate their risks without being overly prescriptive.

Industry implementation of a standard that is too weak will be worse for users than having no standard at all, since it will provide only the guise of protection:  Compared to today's world, even this "in the middle" solution to de-identification GREATLY moves the needle in the correct direction - I hope you agree.  Will there be bad actors or companies that overstate their ability to maintain a de-identified state and fail?  Absolutely.  This approach ensures they will be appropriately held accountable and at the same time allow good actors an attractive (voluntary) option to enhance consumer privacy.

Your concerns:  I do not mean to dismiss your concerns and hopefully have done a better job this time of fairly representing a shared goal and spectrum of options to achieve that goal.  I believe our best path forward is to agree on the goal and avoid prescriptive requirements on exactly how to achieve it.  While we each have our own views into what the rest of the Working Group holds out as priorities (which can only be proven through a vote which the W3C likes to avoid), I hope this compromise position both represents a meaningful advance for consumer protection for consumer advocates and provides enough flexibility for voluntary adoption by industry.

- Shane

From: Dan Auerbach [mailto:dan@eff.org]
Sent: Tuesday, April 02, 2013 1:39 PM
To: public-tracking@w3.org
Subject: Re: de-identification text for Wednesday's call

Shane,

Labeling my view as "totalitarian" or "absolutist" is inaccurate and not appreciated. My approach allows lots of leeway as anonymization technology improves, and takes into account that perfect anonymization is impossible. It seems to me that you plan to label anything "totalitarian" that suggests that keeping raw logs is not a viable approach in general. To be clear, I don't even want to suggest that keeping raw logs is *always* prohibited, just that it should be in the normal case where records have relatively high entropy. I'm also happy to discuss examples in great detail, but in my experience you have been unwilling to engage in discussing the nitty gritty details of what anonymization should entail.

On 04/02/2013 01:09 PM, Shane Wiley wrote:
Dan,

As with HIPPA, I believe differentiated treatment of internal and external datasets is appropriate as this changes the risk profile of re-identification - again, the root of the conversation being a "risk-based" approach versus a totalitarian approach as you suggest.  My solution meets the perceived consumer harm in this case
Do you have evidence for this claim?



- yours of course does as well but goes far too far over the top of what is actually needed.  If your goal is to create a compromise end-point that will likely be implemented by industry then my recommended approach gets us there.
Any compromise must provide meaningful protection to users. Industry implementation of a standard that is too weak will be worse for users than having no standard at all, since it will provide only the guise of protection.


  If you'd like to instead stand by absolutist approaches, that is of course your prerogative and we'll have those removed through the standard W3C process.  I'm simply trying to save everyone some time and get to a meaningful outcome quickly.
Glibly dismissing my concerns is not a way to gain allies, or move the W3C process forward. I don't think your view is as universally shared as you seem to think that it is.




- Shane

From: Dan Auerbach [mailto:dan@eff.org]
Sent: Tuesday, April 02, 2013 12:21 PM
To: public-tracking@w3.org<mailto:public-tracking@w3.org>
Subject: Re: de-identification text for Wednesday's call

Shane,

Why hash at all in this case? If you are relying on operational and administrative controls, you might as well just pledge not to look up the cookie when you receive it. If you are rotating (and discarding) salts frequently, then it will have a positive effect, but otherwise I don't think hashing provides any benefit here.

But this is an aside to our main disagreement about the larger issue about the role that operational and administrative controls should play. I agree that they should play a role, but only after de-identification of data has been achieved. If the result of a DNT:1 request is business as usual, with minor scrubbing and the caveat that only 4000 engineers at a large corporation get default access to a specially marked database instead of 10000, then that will not be a successful standard. (Of course I welcome more detailed information about operational and administrative controls.)

One last point I wanted to make is that of course the data sets I mentioned refer to public data. We don't have access to internal corporate data sets. There are laws in place to protect the pilfering of that data, so of course no-one is going to steal data then publish an academic paper about it, effectively painting a big target on themselves for federal prosecutors and corporate legal teams. In light of this, the right empirical question to ask is: of large publicly available data sets that contain user data and are somewhat akin to log data, how often are there successful re-identification or attribute disclosure attacks? Can you point to any public data sets where such an attack has not been found?

If your argument is instead that public data should be treated differently from non-public data, then I'd suggest that this is out of scope for the DNT conversation. DNT is about giving users the choice to opt out of tracking by companies, which must entail meaningfully curbing data collection and retention by that company, not merely a request that a company not make public its collected data. (Indeed, in addition to being an excessively weak demand by the user, this would in some cases be a vacuous request, since making that information public is already prohibited by law.) The de-identification question exists within the scope of what the companies themselves can do with the data -- is the data de-identified with respect to the entity that collected the data?

Best,
Dan

On 04/02/2013 11:03 AM, Shane Wiley wrote:
Dan,

Once the one-way hash is applied (and other elements of record appropriately cleansed) the data is moved to a system that is not allowed to be accessed externally.  Its these operational and administrative controls that are essential to ensure de-identified data is not re-identified at some later time.  I believe you're looking only at the technical merits which is only seeing a small portion of the overall solution.

- Shane

From: Dan Auerbach [mailto:dan@eff.org]
Sent: Tuesday, April 02, 2013 10:59 AM
To: public-tracking@w3.org<mailto:public-tracking@w3.org>
Subject: Re: de-identification text for Wednesday's call

On 04/02/2013 08:50 AM, Shane Wiley wrote:
once the one-way hash function has been applied the data is never again able to be accessed in real-time to modify the user's experience.
I think I'm confused, can you explain this more? How is this possible? If you are just hashing a cookie string, your web server receives a request that includes a cookie string, you hash that cookie string (which is in incredibly fast operation), match the hashed cookie against the stored data, and return personalized results.

Or are you salting the hash differently for every request, or combining the cookie with an ephemeral piece of data (the timestamp) before hashing and then throwing away the timestamp?

Thanks for clarifying, apologies if I'm just being dense.

Dan





--

Dan Auerbach

Staff Technologist

Electronic Frontier Foundation

dan@eff.org<mailto:dan@eff.org>

415 436 9333 x134





--

Dan Auerbach

Staff Technologist

Electronic Frontier Foundation

dan@eff.org<mailto:dan@eff.org>

415 436 9333 x134




--

Dan Auerbach

Staff Technologist

Electronic Frontier Foundation

dan@eff.org<mailto:dan@eff.org>

415 436 9333 x134