The adversary may also be interested in history disclosure: the ability to query a user's history to see if they have issued certain censored search queries, or visited censored sites.
The adversary may also be interested in history disclosure: the ability to query a user's history to see if they have issued certain censored search queries, or visited censored sites.
4.**Correlate activity across multiple sites**
4.**Correlate activity across multiple websites or services**
The primary goal of the advertising networks is to know that the user who visited `siteX.com` is the same user that visited `siteY.com` to serve them targeted ads.
The adversary may want to correlate user identities or sessions across multiple remote services.
The advertising networks become our adversary insofar as they attempt to perform this correlation without the user's explicit consent.
For instance, advertising networks may wish to know that a user who visited `site-x.com` is the same user that visited `site-y.com` to serve them targeted ads while law-enforcement may wish to associate anonymous activity on `site-b.com` with a known identity on `size-a.com` to build a criminal case.
