## 1 Introduction
In SSI systems, individuals have complete control of their data and of the devices associated with them and choose in a completely autonomous way how, when, where, and with whom to share it, also choosing which specific data to share. These systems allow us to carry out more smoothly management and verification processes which in traditional systems are typically slow, expensive, and not entirely reliable. In addition to exploiting VCs, these systems allow us to develop scalable and reliable solutions that guarantee data privacy while managing the complexity and overhead of IoT medical device administration. The proposal is conceived as a decentralized application that includes two subsystems: one on chain and another off chain. On the blockchain side, the proposal includes two smart contracts. One implements the so-called verifiable registry to make the entities operating as issuers publicly known, to guarantee the integrity of the VCs' claims, and to make the credential status publicly accessible. The other implements the DID register and allows for the building of the DDO associated with each DID. On the off-chain side, the proposal exploits Veramo, a Javascript framework, for identity management and data sharing as VCs and the InterPlanetary File System (IPFS) for storing VCs' schemas. A prototype of the model proposal for the use case related to the creation and exchange of medication prescriptions and a schema for prescriptions are described in Section 4.5. The novelty of the model proposal lies in exploiting information technologies that promote communication and integration among different systems, facilitating the exchange of information and resources to amplify operational efficiency, reduce information silos within individual structures, and, as a result, to promote collaboration among the various stakeholders in the sector that can be both public and private. All this is thanks to the creation and the exchange of all medical records as VCs, which represents the element of differentiation from other works present in the literature as detailed in Section 2. The model proposal is based on open standards and common protocols to encourage innovation, allowing the entire healthcare system to adapt to changes by integrating new tools and services more easily without having to completely redesign their IT infrastructures. In this regard, as detailed in the following sections, the model proposal relies on the Veramo platform, on protocols such as DIDcomm, on peer DID connections, and on data sharing platforms such as the IPFS. It is necessary to highlight that the implementation of a healthcare system that fully embraces the potential of the model proposal requires collaboration between institutions, technology providers, healthcare professionals, and patients. It is also essential to address issues related to governance, regulation, and user education to ensure an effective and safe transition to this new paradigm. Data privacy laws and regulations, such as the GDPR in Europe, place stringent requirements on the management of clinical data, but as already highlighted, the SSI paradigm is compliant with this regulation by definition. Today, many organizations such as Trinsic ref. [9], Connect ref. [10], Dock ref. [11], Esatus ref. [12], Talao ref. [13], Veramo [14; 15; 16], and the ESSIF refs. [1; 3; 17] are working on solutions for storing and managing credentials, hence for managing an SSI (see works by [18; 19; 20]), but governance models that define principles, terminology, standards, and responsibilities and trust frameworks that define specifications and rules need further investigation to allow individuals to operate through their SSI in several specific sectors [4; 21; 22].