P RIVACY, T RUST, AND R EPUTATION Jose Miguel Such July 27th, 2011

Privacy Concerns The era of global connectivity: –More than 2 billion world-wide users with connection to the Internet (2011). 90% of users are concerned or very concerned about their privacy. 95% of users admitted they have declined to provide personal information to web sites when asked.

Solution?? becoming hermits (not using online social networks, e-commerce sites, etc.) We aim at enhancing privacy in agent- based e-commerce applications and online social networks. becoming hermits (not using online social networks, e-commerce sites, etc.)

Privacy in E-Commerce B2C scenarios Secondary use of data Profiling (Buyer profiling) Price discrimination (Amazon, 2000) Poor judgment (customer segmentation) Direct Marketing Spam (junk mail)

Privacy in E-commerce (II) Strategies for preserving customer’s privacy in e-commerce: –Pseudonymity –Pseudonym Change –Multiple Pseudonyms –Pseudonym Sharing –Injecting fake preferences

Privacy in E-commerce (III) What if privacy loss comes with a benefit? Westin, 2003: –56% Pragmatists –34% Fundamentalists –10% Unconcerned Disclosure Decision Making based on the Privacy-Utility Tradeoff

Privacy in Social Networks Friendships do not always have an associated benefit in terms of a utility. How to decide if a particular disclosure is appropriate or not?

Privacy in Social Networks (II) Disclosure decision making model based on information theory measures of privacy and intimacy. Based on the disclosure reciprocity phenomenon: –one person’s disclosure encourages the disclosure of the other person in the interaction, which in turn, encourages more disclosures from the first person

Privacy in social networks (III) Intimacy –to what extent agents know each other Privacy loss –the privacy lost by disclosing an attribute What and when to disclose? –What: Privacy-intimacy tradeoff –When: Balance (like a trust model)

Trust and Reputation In an open electronic market how to: - choose an interaction partner? - decide when to honour a previous commitment? - punish misbehaving agents?

Trust and Reputation Trust: –The subjective probability by which an individual, A, expects that another individual, B, performs a given action on which its welfare depends. (Gambetta) Reputation: –a social evaluation of a target entity attitude towards socially desirable behavior which circulates in the society (and can be agreed on or not by each one of the entities in the society) (Sabater et. Al.)

Trust and Reputation (Vulnerabilities) Privacy techniques Exacerbate Vulnerabilities of Trust and Reputation Models –Whitewashing –Sybil Attack Accountability and Law Enforcement –It could be needed the identity of the user behind the agent

Trust and Reputation (Vulnerabilities) Solution based on: –Regular pseudonyms –Permanent pseudonyms

Interests The final decision on disclosing or not may be affected by biases: –Individual –Social –Cognitive –Emotional We are interested in behavioral economics and experimental economics to model these biases

P RIVACY, T RUST, AND R EPUTATION Jose Miguel Such July 27th, 2011