Nowadays, the concept of Immutable Decentralized/Centralized Distributed Ledger Technology, otherwise called Blockchain, is rising in many fields of the society. It is easy to hear about it in fields as energy, automotive, economy, voting, law, insurance, cloud computing, supply chain management, etc. However, many problems are present. In particular, from a technological point of view, the problem of scalability-intended as the capability to maintain the network, composed by a very huge number of nodes, up, with a reasonable operational velocity- should be solved in order to be really suitable in production; as well as the question of maintaining a high level of security in terms of data exchanged and identity of members, is an important issue, and has taken central stage thanks to legislation like the European Union's General Data Protection Regulation (GDPR).