ECON 425/563 // CPSC 455/555
NOVEMBER 6, 2008
Online Online PrivacyPrivacy
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OutlineOutline
Large amounts of sensitive information flow around the web.
Privacy-enhancing technology has been developed and deployed (example: P3P).
Economic approaches to the management of private information
(Acknowledgements: L. Cranor, C. Lu, and H. Varian)
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Online privacy in the Online privacy in the comics!comics!
Cathy February 25, 2000
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Why is Cathy concerned?Why is Cathy concerned?
Cathy March 1, 2000
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How did Irving find this out? How did Irving find this out? He snooped her email
He looked at the files on her computer
He observed the “chatter” sent by her browser
He set cookies through banner ads and “web bugs” that allowed him to track her activities across web sites
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What do browsers chatter What do browsers chatter about?about?
Browsers chatter aboutIP address, domain
name, organization, Referring pagePlatform: O/S,
browser What information is
requestedURLs and search
terms
Cookies
To anyone who might be listeningEnd serversSystem
administratorsInternet Service
ProvidersOther third parties
Advertising networks
Anyone who might subpoena log files later
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A typical HTTP requestA typical HTTP request
GET /retail/searchresults.asp?qu=beer HTTP/1.0Referer: http://www.us.buy.com/default.aspUser-Agent: Mozilla/4.75 [en] (X11; U; NetBSD
1.5_ALPHA i386)Host: www.us.buy.comAccept: image/gif, image/jpeg, image/pjpeg, */*Accept-Language: enCookie: buycountry=us; dcLocName=Basket;
dcCatID=6773; dcLocID=6773; dcAd=buybasket; loc=; parentLocName=Basket; parentLoc=6773; ShopperManager%2F=ShopperManager%2F=66FUQULL0QBT8MMTVSC5MMNKBJFWDVH7; Store=107; Category=0
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What about cookies?What about cookies? Cookies can be
useful used like a staple to
attach multiple parts of a form together
used to identify you when you return to a web site so you don’t have to remember a password
used to help web sites understand how people use them
Cookies can do unexpected things used to profile users and
track their activities, especially across web sites
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How do cookies work?How do cookies work? A cookie stores a small string of characters
A web site asks your browser to “set” a cookie
Whenever you return to that site your browser sends the cookie back automatically
Cookies are only sent back to the site that set them
browsersite
Please store cookie xyzzy
First visit to site
browsersite
Here is cookie xyzzy
Later visits
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YOU
Searchengine
Ad
Search formedical
information
BookStore
Ad
Buy book
Ad companycan get yourname and
address frombook order and
link them to your search
Readcookie
Setcookie
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Web bugsWeb bugs Invisible “images” embedded in web
pages that cause cookies to be transferred
Work just like banner ads from ad networks, but you can’t see them unless you look at the code behind a web page
Also embedded in HTML formatted email messages
For more info on web bugs see:
http://www.privacyfoundation.org/education/webbug.html
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Referer log problemsReferer log problemsGET methods result in values in
URL
These URLs are sent in the referer header to next host
Example:
http://www.merchant.com/cgi_bin/order?name=Tom+Jones&address=here+there&credit+card=234876923234&PIN=1234& -> index.html
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A Technological ApproachA Technological Approach
The Platform for Privacy Preferences (P3P) is a standard, computer-readable format for privacy policies and a protocol allowing web browsers and other tools to read and process privacy policies automatically.
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Who created P3P?Who created P3P?
World Wide Web Consortium (W3C) – a nonprofit, industry-supported consortium including researchers and engineers from over 420 institutions.
Participants in the development of P3P came from around the world, including representatives from industry, government, nonprofit organizations, and academia.
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Why was P3P created?Why was P3P created? To increase consumer trust.
“If the ability to spend is the fuel that propels the economic engine, then consumers’ trust and confidence in that engine is the lubricant.”
To protect privacy by allowing informed choice.
Privacy is the ability of individuals to exercise control over the disclosure and subsequent uses of their personal information. Hence notice is fundamental to the individual’s ability to protect his or her privacy.
To make choice easy.Privacy policies are difficult and time-consuming to locate, to read, and to understand; and they change frequently without notice.
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How does P3P work? (1)How does P3P work? (1)1. User sets
personal privacy preferences on a tool such as a browser.
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How does P3P work? (2)How does P3P work? (2)
2. Browser requests privacy policy from a (P3P-compliant) Web site.
3. Browser compares the privacy policy with the user’s privacy preferences and acts accordingly. (Symbols, pop-up prompts, etc.)
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P3P Policy Elements P3P Policy Elements Include:Include:
Who is collecting these data?
What information is being collected?
For what purpose?
Which information is being shared with others?
Who are these data recipients?
Can users access their identified data?
Can users make changes in how their data is used?
What is the policy for retaining data?
How are disputes resolved?
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Purpose Specifications:Purpose Specifications: Completion and support of activity for which data was
provided
Web site and system administration
Research and development
One-time tailoring
Pseudonymous decision or analysis
Individual decision or analysis
Contacting visitors for marketing of services or products
Historical preservation
Contacting visitors for marketing of services or products via telephone
Other purpose
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What P3P AccomplishesWhat P3P Accomplishes
Makes privacy notices easy to locate and easy to understand.
Allows users to specify their privacy preferences once so that they can be automatically compared to a web site’s privacy policy.
Assists users in making decisions about when to disclose personal information, how much, and to whom.
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What P3P Does NOT What P3P Does NOT Accomplish Accomplish
Does NOT replace privacy regulations.
Can NOT protect the privacy of users in jurisdictions with insufficient data privacy laws.
Can NOT ensure the companies or organizations follow their stated privacy policies.
“P3P does not protect privacy, in and of itself. It does, however, help create a framework for informed choice on the part of consumers. Any efficacy that P3P has is dependent upon the substantive privacy rules established through other processes – be they a result of regulatory, self-regulatory, or public pressure.”
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Controversy over P3P Controversy over P3P
“In the context of proper legislation, P3P is the most promising solution to cyberspace privacy. It will make it easy for companies to explain their practices in a form that computers can read, and make it easy for consumers to express their preferences in a way that computers will automatically respect.”
– Professor Lawrence Lessig, Stanford Law School.
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Controversy over P3PControversy over P3P
P3P is:
a) Pretty Poor Privacy,
b) a Pretext for Privacy Procrastination, and
c) “a tacit acceptance of the great increase in the tracking and monitoring of our minor activities that take place over the Web.”
– Karen Coyle, Information Technology Specialist,
University of California
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Support for P3PSupport for P3P
Provides notice and consent
Promotes transparency and accountability
Intuitive
Flexible and global
Worthwhile process
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Criticism of P3PCriticism of P3P Lack of enforcement
Used as a procrastination tool
Unclear legal consequences
Importance of default settings
Unable to maintain current experience
Expensive to implement and maintain
Overly broad and vague purpose specifications
Ultimatum-style communication
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More Criticism of P3PMore Criticism of P3P
Consumer and business confusion
Rejected by the European Union
Lack of actual choice
Assumes the need to gather information
Does not address third-party data collection
Lack of control over an irreversible choice
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Basic ConflictBasic Conflict
What is the real problem?
Lack of knowledge about how information will be used?
OR
The gathering of the data itself?
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Universal AgreementUniversal Agreement
Enforcement mechanisms are needed.
“A technical platform for privacy protection…must be applied within the context of a framework of enforceable data protection rules, which provide a minimum and non-negotiable level of privacy protection for all individuals. Use of P3P in the absence of such a framework risks shifting the onus primarily onto the individual user to protect himself” – European Commission, 1998.
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Economic View of PrivacyEconomic View of Privacy
Non-adoption of P3P and other privacy-enhancing technologies is not due to technological flaws. It is due to economic incentives.
Rational consumers want some of their personal information available to producers. They will experience more privacy (e.g., less intrusive marketing) and reduced search costs if their true preferences are known.
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Complication: Secondary UseComplication: Secondary Use Customers can benefit from
collection and analysis of personal information by merchants with whom they transact directly.
If that information is sold to a third party that does not know the customers, that third party will use it more clumsily and reimpose cost on the customers.
The seller of this information has externalized these costs.
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Privacy as a Property RightPrivacy as a Property Right
Data collectors can externalize the costs of secondary use because current law gives them property rights in the databases they construct.
Alternative: Vest the property rights in the data subjects, and compensate them for use of their data.
Varian gives examples of how to structure information markets and set prices: http://people.ischool.berkeley.edu/~hal/Papers/privacy
Opponents of this approach would rather ban sale of personal information altogether and establish a true “right to privacy.” Relying on property rights to control the dissemination and use of personal information ensures that only the rich will have privacy.