This paper presents a privacy-enhancing protocol for digital advertising that uses temporary pseudonyms to safeguard users' behavioral profiles from pervasive online tracking. By integrating well-established anonymity techniques such as Tor and blind signature, the protocol generates robust, verifiable online identities that enhance security against ad fraud while ensuring personal data remains unlinkable to individuals. For behavioral targeting, the ad ecosystem is limited to ephemeral profile data. A key advantage of this privacy-friendly approach is its seamless integration with the existing advertising pipeline, fulfilling industry needs for retargeting and ad attribution, while maintaining low computational complexity on the user side.