A Proof Calculus for Attack Trees in Isabelle -- Confidentiality of Interactions in Concurrent Object-Oriented Systems -- Using Oblivious RAM in Genomic Studies -- Towards Efficient and Secure Encrypted Databases: Extending -- Message-Locked Encryption in Three-Party Model -- Searchable Encrypted Relational Databases: Risks and Countermeasures -- Private verification of access on medical data: an initial study -- Default Privacy Setting Prediction by Grouping User's Attributes and Settings Preferences -- Bounding Privacy Leaks in Privacy Preserving Data Mining -- Threshold Single Password Authentication -- Towards A Toolkit for Utility and Privacy-Preserving Transformation of Semi-structured Data Using Data Pseudonymization -- Enforcement of External Anonymization -- DLoc: Distributed Auditing for Data Location Compliance in Cloud -- Inonymous: Anonymous Invitation-Based System -- Order-Preserving Encryption Using Approximate Integer Common Divisors -- Privacy-Preserving Deterministic Automata Evaluation with Encrypted Data Blocks -- Securing Proof-of-Stake Blockchain Protocols -- Merged Mining: Curse or Cure? -- Atomically Trading with Roger: Gambling on the success of a hardfork -- Smart Contracts and Blockchain Identity -- In Code We Trust? Measuring the Control Flow Immutability of All -- Smart Contracts Deployed on Ethereum -- Who Am I? Secure Identity Registration on Distributed Ledgers -- User-centric System for Verified Identities on the Bitcoin Blockchain -- Towards a Concurrent and Distributed Route Selection for Payment Channel Networks -- Graphene: A New Protocol for Block Propagation Using Set Reconciliation -- Revisiting Difficulty Control for Blockchain Systems -- Secure Event Tickets on a Blockchain.

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.