Privacy Technologies and Policy 6th Annual Privacy Forum, APF 2018, Barcelona, Spain, June 13-14, 2018, Revised Selected Papers - Medina, Manel; Medina, Manel; Mitrakas, Andreas; Mitrakas, Andreas; Rannenberg, Kai; Rannenberg, Kai; Schweighofer, Erich; Schweighofer, Erich; Tsouroulas, Nikolaos; Tsouroulas, Nikolaos (Springer International Publishing : Imprint: Springer, 2018)