This book constitutes the revised selected post conference proceedings of the 15th International Workshop on Data Privacy Management, DPM 2020, and the 4^th International Workshop on Cryptocurrencies and Blockchain Technology, CBT 2020, held in conjunction with the 25th European Symposium on Research in Computer Security, ESORICS 2020, held in Guildford, UK in September 2020. For the CBT Workshop 8 full and 4 short papers were accepted out of 24 submissions. The selected papers are organized in the following topical headings: Transactions, Mining, Second Layer
and Inter-bank Payments. The DPM Workshop received 38 submissions from which 12 full and 5 short papers were selected for presentation. The papers focus on Second Layer, Signature Schemes, Formal Methods, Privacy, SNARKs and Anonymity.