January 20, 2019

Archives for October 2009

PrivAds: Behavioral Advertising without Tracking

There’s an interesting new paper out of Stanford and NYU, about a system called “PrivAds” that tries to provide behavioral advertising on web sites, without having a central server gather detailed information about user behavior. If the paper’s approach turns out to work, it could have an important impact on the debate about online advertising and privacy.

Advertisers have obvious reasons to show you ads that match your interests. You can benefit too, if you see ads that are relevant to your needs, rather than ones you don’t care about. The problem, as I argued in my Congressional testimony, comes when sites track your activities, and build up detailed files on you, in order to do the targeting.

PrivAds tries to solve this problem by providing behavioral advertising without having any server track you. The idea is that your own browser will track you, and analyze your online activities to build a model of your interests, but your browser won’t reveal this information to anyone else. When a site wants to show you an interest-based ad, your browser will choose the ad from a portfolio of ads offered by the ad service.

The tricky part is how your browser can do all of this without incidentally leaking your activities to the server. For example, the ad agency needs to know how many times each ad was shown. How can you report this to the ad service without revealing which ads you saw? PrivAds offers a solution based on fancy cryptography, so that the ad agency can aggregate reports from many users, without being able to see the users’ individual reports. Similarly, every interaction between your browser and the outside must be engineered carefully so that behavioral advertising can occur but the browser doesn’t telegraph your actions.

It’s not clear at this point whether the PrivAds approach will work, in the sense of protecting privacy without reducing the effectiveness of ad targeting. It’s clear, though, that PrivAds is asking an important question.

If the PrivAds approach succeeds, demonstrating that behavioral advertising does not require tracking, this doesn’t mean that companies will stop wanting to track you — but it does mean that they won’t be able to use advertising as an excuse to track you.

Chilling and Warming Effects

For several years, the Chilling Effects Clearinghouse has cataloging the effects of legal threats on online expression and helping people to understand their rights. Amid all the chilling we continue to see, it’s welcome to see rays of sunshine when bloggers stand up to threats, helping to stop the cycle of threat-and-takedown.

The BoingBoing team did this the other day when they got a legal threat from Ralph Lauren’s lawyers over an advertisement they mocked on the BoingBoing blog for featuring a stick-thin model. The lawyers claimed copyright infringement, saying “PRL owns all right, title, and interest in the original images that appear in the Advertisements.” Other hosts pull content “expeditiously” when they receive these notices (as Google did when notified of the post on Photoshop Disasters), and most bloggers and posters don’t counter-notify, even though Chilling Effects offers a handy counter-notification form.

Not BoingBoing, they posted the letter (and the image again) along with copious mockery, including an offer to feed the obviously starved models, and other sources picked up on the fun. The image has now been seen by many more people than would have discovered it in BoingBoing’s archives, in a pattern the press has nicknamed the “Streisand Effect.”

We use the term “chilling effects” to describe indirect legal restraints, or self-censorship, because most cease-and-desist letters don’t go through the courts. The lawyers (and non-lawyers) sending them rely on the in terrorem effects of threatened legal action, and often succeed in silencing speech for the cost of an e-postage stamp.

Actions like BoingBoing’s use the court of public opinion to counter this squelching. They fight legalese with public outrage (in support of legal analysis), and at the same time, help other readers to understand they have similar rights. Further, they increase the “cost” of sending cease-and-desists, as they make potential claimants consider the publicity risks being made to look foolish, bullying, or worse.

For those curious about the underlying legalities here, the Copyright Act makes clear that fair use, including for the purposes of commentary, criticism, and news reporting, is not an infringement of copyright. See Chilling Effects’ fair use FAQ. Yet the DMCA notice-and-takedown procedure encourages ISPs to respond to complaints with takedown, not investigation and legal balancing. Providers like BoingBoing’s Priority Colo should also get credit for their willingness to back their users’ responses.

As a result of the attention, Ralph Lauren apologized for the image: “After further investigation, we have learned that we are responsible for the poor imaging and retouching that resulted in a very distorted image of a woman’s body. We have addressed the problem and going forward will take every precaution to ensure that the caliber of our artwork represents our brand appropriately.”

May the warming (and proper attention to the health of fashion models) continue!

[cross-posted at Chilling Effects]

Privacy as a Social Problem, Not a Technology Problem

Bob Blakley had an interesting post Monday, arguing that technologists tend to frame the privacy issue poorly. (I would add that many non-technologists use the same framing.) Here’s a sample:

That’s how privacy works; it’s not about secrecy, and it’s not about control: it’s about sociability. Privacy is a social good which we give to one another, not a social order in which we control one another.

Technologists hate this; social phenomena aren’t deterministic and programmers can’t write code to make them come out right. When technologists are faced with a social problem, they often respond by redefining the problem as a technical problem they think they can solve.

The privacy framing that’s going on in the technology industry today is this:

Social Frame: Privacy is a social problem; the solution is to ensure that people use sensitive personal information only in ways that are beneficial to the subject of the information.

BUT as technologists we can’t … control peoples’ behavior, so we can’t solve this problem. So instead let’s work on a problem that sounds similar:

Technology Frame: Privacy is a technology problem; since we can’t make people use sensitive personal information sociably, the solution is to ensure that people never see others’ sensitive personal information.

We technologists have tried to solve the privacy problem in this technology frame for about a decade now, and, not surprisingly (information wants to be free!) we have failed.

The technology frame isn’t the problem. Privacy is the problem. Society can and routinely does solve the privacy problem in the social frame, by getting the vast majority of people to behave sociably.

This is an excellent point, and one that technologists and policymakers would be wise to consider. Privacy depends, ultimately, on people and institutions showing a reasonable regard for the privacy interests of others.

Bob goes on to argue that technologies should be designed to help these social mechanisms work.

A sociable space is one in which people’s social and antisocial actions are exposed to scrutiny so that normal human social processes can work.

A space in which tagging a photograph publicizes not only the identities of the people in the photograph but also the identities of the person who took the photograph and the person who tagged the photograph is more sociable than a space in which the only identity revealed is that of the person in the photograph – because when the picture of Jimmy holding a martini washes up on the HR department’s desk, Jimmy will know that Johnny took it (at a private party) and Julie tagged him – and the conversations humans have developed over tens of thousands of years to handle these situations will take place.

Again, this is an excellent and underappreciated point. But we need to be careful how far we take it. If we go beyond Bob’s argument, and we say that good design of the kind he advocates can completely solve the online privacy problem, then we have gone too far.

Technology doesn’t just move old privacy problems online. It also creates new problems and exacerbates old ones. In the old days, Johnny and Julie might have taken a photo of Jimmy drinking at the office party, and snail-mailed the photo to HR. That would have been a pretty hostile act. Now, the same harm can arise from a small misunderstanding: Johnny and Julie might assume that HR is more tolerant, or that HR doesn’t watch Facebook; or they might not realize that a site allows HR to search for photos of Jimmy. A photo might be taken by Johnny and tagged by Julie, even though Johnny and Julie don’t know each other. All in all, the photo scenario is more likely to happen today than in the pre-Net age.

This is just one example of what James Grimmelmann calls Accidental Privacy Spills. Grimmelmann tells the story of a private email message that was forwarded and re-forwarded to thousands of people, not by malice but because many people made the seemingly harmless decision to forward it to a few friends. This would never have happened with a personal letter. (Personal letters are sometimes publicized against the wishes of the author, but that’s very rare and wouldn’t have happened in the case Grimmelmann describes.) As the cost of capturing, transmitting, storing, and searching photos and other digital information falls to near-zero, it’s only natural that more capturing, transmitting, storing, and searching of information will occur.

Good design is not the whole solution to our privacy problem. But design has the huge advantage that we can get started on it right away, without needing to reach some sweeping societal agreement about what the rules should be. If you’re designing a product, or deciding which product to use, you can support good privacy design today.