Consumers Anonymous?
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Consumers Anonymous? The Privacy Risks of De-Identified and Aggregated Consumer Data 6 October 2011 Public Interest Advocacy Centre http://www.piac.ca Acknowledgements PIAC gratefully acknowledges the financial support of the Office of the Privacy Commissioner of Canada Contributions Program for this study. We are also grateful for time and knowledge of various stakeholders consulted during the research of this project. In particular, PIAC would like to acknowledge the assistance and cooperation of the Canadian Bankers Association, the Canadian Life and Health Insurance Association and Insurance Bureau of Canada and their members for answering our questions and providing insights into their members’ practices. Janet Lo, John Lawford, and Roxane Gunning drafted the report. Janet Lo and John Lawford conducted the research for this study. Eden Maher, Diane Tsang, Amy Zhao, and Roxane Gunning provided research assistance. 2 Copyright 2011 PIAC Contents may not be commercially reproduced. Any other reproduction with acknowledgment is encouraged. The Public Interest Advocacy Centre (PIAC) Suite 1204 ONE Nicholas Street Ottawa, Ontario K1N 7B7 Canadian Cataloguing and Publication Data Consumers Anonymous? The Privacy Risks of De-Identified and Aggregated Consumer Data ISBN 1895060-99-0 3 TABLE OF CONTENTS 1. INTRODUCTION ................................................................................................................ 7 2. METHODOLOGY ................................................................................................................ 8 3. DE-IDENTIFICATION DEFINED ......................................................................................... 8 4. THE CONSUMER INTEREST IN DE-IDENTIFICATION ....................................................11 4.1. The data brokerage industry .......................................................................................11 4.2. Consumer tracking online ...........................................................................................12 4.3. The health industry .....................................................................................................12 4.3.1. American cases: IMS Health v. Ayotte and IMS Health v. Sorrell .........................13 4.3.2. Canada and IMS ..................................................................................................15 5. DE-IDENTIFICATION TECHNIQUES DESCRIBED ...........................................................16 5.1. Removal of personal information .................................................................................18 5.2. Generalization .............................................................................................................18 5.3. Suppression ................................................................................................................19 5.4. Assignment of unique identifiers .................................................................................20 5.5. Aggregation ................................................................................................................20 5.6. Irreversible coding .......................................................................................................21 5.7. Reversible coding .......................................................................................................21 5.8. Swapping ....................................................................................................................23 5.9. Randomization or Substitution ....................................................................................23 5.10. Heuristics ................................................................................................................24 5.11. k-anonymity .............................................................................................................24 6. CANADIAN INDUSTRY DE-IDENTIFICATION POLICIES AND PRACTICES ...................25 6.1. General review of industry privacy policies..................................................................25 6.1.1. Search engines ....................................................................................................44 6.1.2. Telecommunications service providers ................................................................50 6.1.3. Social networking websites ..................................................................................50 6.1.4. Data compilers and aggregators ..........................................................................52 6.1.4.1. American complaint against real time bidding of targeted profiles of individual users 54 6.2. Consultation with industry associations .......................................................................59 6.2.1. Canadian Bankers Association ............................................................................59 6.2.2. Canadian Life and Health Insurance Association .................................................62 6.2.3. Insurance Bureau of Canada ...............................................................................63 7. RE-IDENTIFICATION OF INDIVIDUALS FROM DE-IDENTIFIED DATA ...........................65 7.1. Defining re-identification ..............................................................................................65 7.2. Re-identification techniques ........................................................................................65 7.3. Evaluating the risk of re-identification for consumers ..................................................66 7.4. Case study: AOL’s release of user data and identifiability through one’s IP address ...69 7.5. Case study: the Netflix study .......................................................................................70 7.6. Unique identification through zip code, gender, birth date: Latanya Sweeney .............71 7.7. Linking individual profiles through usernames .............................................................72 7.8. De-anonymizing social networks .................................................................................72 4 7.9. Financial lending on the internet .................................................................................73 7.10. Location-based information .....................................................................................74 7.11. Uses and re-identification of individuals from aggregate consumer data .................74 8. PERSPECTIVES OF DE-IDENTIFICATION AND RE-IDENTIFICATION ...........................75 8.1. The value of de-identified and aggregated data ..........................................................75 8.2. Paul Ohm and failure of the anonymization .................................................................78 8.3. Dr. Khaled El-Emam and best practices for the de-identification of personal health information ............................................................................................................................79 8.4. Robert Gellman’s proposed legislative-based contractual solution for the sharing of de- identified data ........................................................................................................................81 9. POSSIBLE HARMS FLOWING FROM USE OF DE-IDENTIFIED DATA AND RE- IDENTIFICATION OF CONSUMERS ........................................................................................83 9.1. Oscar H. Gandy, Jr. on rational discrimination and cumulative disadvantage ..............83 9.1.1. Group-based harm ...............................................................................................84 9.2. Online tracking and targeting ......................................................................................85 9.2.1. Consumer groups complaint to the Federal Trade Commission regarding selling profiles of individual users to the highest bidder in real time ...............................................87 9.2.2. Predictive data mining algorithms ........................................................................88 9.3. Loss of consumer and social autonomy ......................................................................89 9.3.1. Lack of consumer awareness and informed consent ............................................89 9.3.2. Issues with transparency and accuracy................................................................90 9.3.3. Unanticipated secondary uses and disclosures without the consumer’s knowledge and consent .......................................................................................................................91 9.3.4. The decline of consumer anonymity .....................................................................92 9.4. Potential for abuse ......................................................................................................93 9.4.1. Redlining or its new form: “weblining” .......................................................................93 9.4.2. Price discrimination ..............................................................................................94 9.4.3. Consumer ranking ...............................................................................................94 9.4.4. Unfair economic opportunity and increased barriers to fair exchange ..................95 9.4.5. Privacy, once breached, is easily re-breached .....................................................95 9.5. Loss of democracy and the expansion of laws, policies and procedures mandating consumers to provide personal information