Collaborative Search Engine - Privacy-aware Collaborative Search Engines

Privacy-aware Collaborative Search Engines

Search terms and links clicked that are shared among users reveal their interests, habits, social relations and intentions. In other words, CSEs put the privacy of the users at risk. Studies have shown that CSEs increase efficiency . Unfortunatelly, by the lack of privacy enhancing technologies, a privacy aware user who wants to benefit from a CSE has to disclose his entire search log. (Note, even when explicitly sharing queries and links clicked, the whole (former) log is disclosed to any user that joins a search session). Thus, sophisticated mechanisms that allow on a more fine grained level which information is disclosed to whom are desirable.

As CSEs are a new technology just entering the market, identifying user privacy preferences and integrating Privacy enhancing technologies (PETs) into collaborative search are in conflict. On one hand, PETs have to meet user preferences, on the other hand one cannot identify these preferences without using a CSE, i.e., implementing PETs into CSEs. Today, the only work addressing this problem comes from Burghardt et al. They implemented a CSE with experts from the information system domain and derived the scope of possible privacy preferences in a user study with these experts. Results show that users define preferences referring to (i) their current context (e.g., being at work), (ii) the query content (e.g., users exclude topics from sharing), (iii) time constraints (e.g., do not publish the query X hours after the query has been issued, do not store longer than X days, do not share between working time), and that users intensively use the option to (iv) distinguish between different social groups when sharing information. Further, users require (v) anonymization and (vi) define reciprocal constraints, i.e., they refer to the behavior of other users, e.g., if a user would have shared the same query in turn.