I first thank my thesis advisors Thiemo Voigt and Adam Dunkels for being my excellent advisors, and also for being the great colleagues you still are. Thiemo and Adam have complemented each other superbly, giving me feedback, perspectives, insights, and having made every single new venture truly fun. My deepest thanks also go to my professor Per Gunningberg, Uppsala University. Per has in a seemingly easy way spotted erroneous assumptions, has valued my research contributions, and has connected my own work with another broader world of research. I want to thank all colleagues in the Networked Embedded Systems group:

in partial ful2llment of the requirements for the degree of

EinepolicybasierteZugriffskontrollarchitektur fürdasMultiServiceInternet vomFachbereich18 derTechnischenUniversitätDarmstadt genehmigteDissertation zurErlangungdesGradeseines Doktor-Ingenieur(Dr.-Ing.) von DiplomWirtschaftsinformatikerChristophRensing geborenam4.7.1967inDüsseldorf