A Survey of Query Log Privacy-Enhancing Techniques from a Policy Perspective

As popular search engines face the sometimes conflicting interests of protecting privacy while retaining query logs for a variety of uses, numerous technical measures have been suggested to both enhance privacy and preserve at least a portion of the utility of query logs. This article seeks to assess seven of these techniques against three sets of criteria: (1) how well the technique protects privacy, (2) how well the technique preserves the utility of the query logs, and (3) how well the technique might be implemented as a user control. A user control is defined as a mechanism that allows individual Internet users to choose to have the technique applied to their own query logs.