Oskar Sandberg (born 13 January 1980 in Falun, Sweden), is a key contributor to the Freenet Project, and a graduate student at the Chalmers Technical University in Gothenburg, Sweden. Oskar collaborated with Ian Clarke to design the new "darknet" model employed in Freenet 0.7, work which was presented at the DEF CON security conference in July 2005. Oskar is also working on a Ph.D. about the mathematics of complex networks, especially with regard to the small world phenomenon. Besides this he has an active interest in distributed computer networks and network security, and has been an active contributor to the Freenet Project since 1999.