This book constitutes the refereed conference proceedings of the 12th International Workshop on Data Privacy Management, DPM 2017, on conjunction with the 22nd European Symposium on Research in computer Security, ESORICS 2017 and the First International Workshop on Cryprocurrencies and Blockchain Technology (CBT 2017) held in Oslo, Norway, in September 2017. The DPM Workshop received 51 submissions from which 16 full papers were selected for presentation. The papers focus on challenging problems such as translation of high-level buiness goals into system level privacy policies, administration of sensitive identifiers, data integration and privacy engineering. From the CBT Workshop six full papers and four short papers out of 27 submissions are included. The selected papers cover aspects of identity management, smart contracts, soft- and hardforks, proof-of-works and proof of stake as well as on network layer aspects and the application of blockchain technology for secure connect event ticketing.