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Annual Workshop February 5th, 2014. A Formal Approach to Analyze Privacy in Electronic Services. MSEC Koen Decroix. Outline. Introducing Privacy in Loyalty Services Conceptual model of inShopnito Framework for Formal Reasoning on Privacy Privacy Analysis of inShopnito Conclusions.
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Annual Workshop February 5th, 2014
A Formal Approach to Analyze Privacy in Electronic Services MSEC Koen Decroix [Koen Decroix – MSEC - KU Leuven]
Outline • Introducing Privacy in Loyalty Services • Conceptual model of inShopnito • Framework for Formal Reasoning on Privacy • Privacy Analysis of inShopnito • Conclusions
… Max Schrems, an Austrian student, did! Now he sues Facebook for their data practices on the personal data they collected about him.
Once, there were small local family-run stores binding customers with …
… with the years, they were replaced by big chains also binding customers …
For the convenience of their customers, loyalty services evolved to electronic services integrated with other online (third-party) services. Is this the full story? Share your shopping activities with friends on Facebook Authenticate
Not transparent to users When registering to such services, you agreed with their terms and policies and gave them your consentfor collecting, processing, and forwarding your personal data.
Your past online activities leave non-erasable, possibly harmful, traces behind and might get spread around.
Citizens must be protected for these data practices. This is where the European data protection legislation comes into play.
… designers have to consider multiple types of requirements Complex
Need for formal modeling, as a support during design of composite services.
Privacy analysis is based on user profiles built from the formal models. Its feedback must be useful for system designers and users as well.
… but looking into more detail … From specifications of service providers’ data practices (= service policies), we can derive that …
System Independent Model Vocabulary (Concepts) Theory Behavior Inference Rules User Model System Model Trust Perception Organizations Services Logic Component Conclusions Initial State Service Policies Input Model Credentials Profiles Storage Access Control Identifiability Model Distribution Output Pseudonyms Identities
Privacy Analysis - Feedback Linkabilities Collaborations Attributes & Violations
inShopnito modeled for two user types Advertisers are not trusted • Trusts • Grocery Store • Loyalty Program Provider • inShopnito No trust in organizations Loyalty credential: Idemix what if X509 is used?
Detect Violations in inShopnito Advertisers not allowed to have the customer’s his: Name Address eMail address Violations of rules 1, 2, 3 are found only in case a X509 certificate is used in case of the user model
It is a formal approach to analyze privacy power to prove properties • Approach is useful during service design • privacy by design is one of the principles in EU reform of data protection legislation. • analyzing linkabilities, collaborations, attributes in user profiles. • verify compliance with legislative and corporate level rules (detecting violations). • Approach is useful for education of people • EU reform of data protection authorities get the task to educate people. E.g., model a user that participates to a survey about Facebook. Afterwards, perform a privacy analysis based on his assumptions and present him the difference between what he thinks and what can happen.