Collaborative Search and User Privacy:How Can They Be Reconciled?

Collaborative search engines (CSE) let users pool their resources and share their experiences when seeking information on the web. However, when shared, search terms and links clicked reveal user interests, habits, social relations and intentions. In other words, CSE put privacy of users at risk. This seriously limits the proliferation and acceptance of CSE. To address the problem, we have carried out a qualitative study that identifies the privacy concerns of CSE users. In particular, our study reveals the range and type of concerns when sharing query terms and search results with different social groups, e.g., family members or colleagues. To control the information shared, the participants of our study have called for anonymity and reciprocity in combination with time- and/or context-dependent conditions. To facilitate the specification of privacy preferences, we define a general policy structure to express privacy needs in the context of CSE. We also give an approach to address the reciprocity condition identified in the study, and we discuss options to anonymize sharing of query terms.