jats:p This paper explores, through empirical research, how values, engineering practices, and technological design decisions shape one another in the development of privacy technologies. We propose the concept of “privacy worlds” to explore the values and design practices of the engineers of one of the world’s most notable (and contentious) privacy technologies: the Tor network. By following Tor’s design and development we show a privacy world emerging—one centered on a construction of privacy understood through the topology of structural power in the Internet backbone. This central “cipher” discourse renders privacy as a problem that can be “solved” through engineering, allowing the translation and representation of different groups of imagined users, adversaries, and technical aspects of the Internet in the language of the system. It also stabilizes a “flattened,” neutralized conception of privacy, risking stripping it of its political and cultural depth. We argue for an enriched empirical focus on design practices in privacy technologies, both as sites where values and material power are shaped, and as a place where the various worlds that will go on to cluster around them—of users, maintainers, and others—are imagined and reconciled. </jats:p>