Consensus Mechanisms in Distributed Ledgers for the Protection of Confidential Data: A Multivocal Literature Review

Distributed Ledger Technologies (DLT) open new opportunities for data protection since they bring decentralization and sovereignty over the ownership of data. On the practical side, implementations of this technology are limited. Due to its novelty, the fundamentals for their design and development are still emerging. An essential feature of DLT is the consensus mechanism, which is used so that the members of the DLT network validate and append data to the ledger. The design decision of which mechanism to use will significantly impact the functionality of the system. Therefore, it is a decision that cannot be taken lightly. Software engineers, developers, and other practitioners in the field can use the knowledge and understanding of the implementations that already exist to help with these decisions. This paper presents the results of a multivocal literature review carried out to identify the consensus mechanisms used in DLT for the protection of confidential data. Twenty-seven studies were selected; in those studies, twenty-one different consensus mechanisms were identified. The review showcases the mechanisms that have been identified and their contexts, alongside a discussion of their relevance and characteristics.