## 1 Introduction  
The digital transformation triggered by the pandemic in all the countries of the European Union, and in all sectors, has created a new information technology (IT) scenario in which the Blockchain technology, the Self-Sovereign Identity paradigm, Internet of Things (IoT), and, in general, the new technologies that will emerge, will lead to an improvement in the economy and society in general. During the pandemic, entrepreneurs, workers, schools, and society as a whole in general have developed new digital habits to survive the crisis by trying in every way to carry on their usual activities. In this new scenario, digital innovation will impact e-Government, business models, and society as a whole. Everyone will feel the impact. Therefore, it is necessary to spread greater awareness of these technologies, of the change taking place, and of the systems already in use or under development that aim at a more equitable and sustainable society by focusing on digital transformation. The EU has launched a series of regulations that aim to create a more sustainable economy based on technology at the service of the community, such as the European Blockchain Service Infrastructure (EBSI) and European Self Sovereign Identity Framework (ESSIF) initiatives. The former aims at the creation of an institutional blockchain infrastructure, shared by all Member States and at the service of citizens. The latter aims at the creation and use of SSI models in order to facilitate cross-border interaction (refs. [1; 2; 3]). In the short to medium term, the Self-Sovereign Identity paradigm will overturn all the IT processes with which users have interfaced in recent years in the most diverse fields,from the financial world to that of healthcare. The principles on which an SSI is based are aligned with those of the General Data Protection Regulation (GDPR) and aim to protect and limit the use and processing of citizens' personal data. For example, the GDPR gives EU citizens the right to delete personal data and the right to request the correction of incorrect data, rights that can be implemented with an SSI system but which lead to inevitable incompatibilities if one considers the blockchain technology alone. In fact, the data present in a blockchain are mostly immutable; they can be kept without time limits, thus entering into conflict with the so-called right to be forgotten of the interested party, but also with the principle of minimization with regard to their use, given that the personal data entered in a blockchain are public and can be consulted by all participants even without the user having given consent [4]. The SSI-blockchain union can play a fundamental role in this context. In fact, if on the one hand, the SSI paradigm gives individuals control of their data, on the other hand, the blockchain guarantees their integrity, thus allowing for the creation of a single system capable of guaranteeing security and privacy, while enabling online identity management. Nowadays, companies and organizations, including hospitals, and clinics, find themselves having to manage an ever-increasing amount of data that have to be both processed and archived using centralized systems that typically present problems related to security, privacy, data ownership, and data isolation. In the digital age, data represent us and constitute our only personal identity. Therefore cyber security, oriented towards the protection of personal data, is necessary to ensure that our data are not misrepresented, distorted, or used without our consent [5; 6; 7; 8]. The SSI paradigm solves these problems and allows for the creation of a system in which digital identities can operate thanks to their corresponding Decentralized Identifier (DID), DID document (DDO), and wallet. Sensitive data are managed by Mobile Wallets, and therefore by applications installed on the user's own devices, and no longer outsourced to third-party information systems.