Retargeting Without Tracking
This addresses privacy concerns for internet users by offering a less intrusive alternative to existing retargeting systems, though it appears incremental as it builds on known cryptographic techniques.
The paper tackles the problem of intrusive and suboptimal retargeting ads by proposing the first privacy-preserving system that eliminates systematic tracking, using homomorphic encryption to distribute the algorithm between users and advertisers, which trivially solves issues like frequency capping and ads freshness.
Retargeting ads are increasingly prevalent on the Internet as their effectiveness has been shown to outperform conventional targeted ads. Retargeting ads are not only based on users' interests, but also on their intents, i.e. commercial products users have shown interest in. Existing retargeting systems heavily rely on tracking, as retargeting companies need to know not only the websites a user has visited but also the exact products on these sites. They are therefore very intrusive, and privacy threatening. Furthermore, these schemes are still sub-optimal since tracking is partial, and they often deliver ads that are obsolete (because, for example, the targeted user has already bought the advertised product). This paper presents the first privacy-preserving retargeting ads system. In the proposed scheme, the retargeting algorithm is distributed between the user and the advertiser such that no systematic tracking is necessary, more control and transparency is provided to users, but still a lot of targeting flexibility is provided to advertisers. We show that our scheme, that relies on homomorphic encryption, can be efficiently implemented and trivially solves many problems of existing schemes, such as frequency capping and ads freshness.