# An SSI-Based Solution to Support Lawful Interception
## 1 Introduction
In contrast, verifiable credentials are used in SSI that can be interoperable across different organizations and jurisdictions (even if this introduces trust problems in cross-border authentication that should be suitably addressed in each specific application context). Overall, the numerous advantages of SSI make it the preferred solution for the future of digital identity [17]. For these reasons, we propose a solution relying on the state-of-the-art SSI Sovrin framework [18]. A core element of our proposal is the access control mechanism built on top of the SSI substrate. This aspect is very relevant, especially in the case of the LEA relying on an external agency to collect such data. In this case, proper authorizations should be provided to prevent unauthorized access. Although some guidelines are provided in this direction (such as the adoption of RBAC [19] or VACM [20]), no concrete proposal is currently available. Another relevant aspect of our contribution is that the proposed solution applies to real-life contexts. Indeed, it is compliant with the Sovrin SSI stack [21,22] and its evolution, the ToIP stack [23]. The above framework represents the state of the art in the SSI environment [24]. Starting from this framework, we built a proof of concept of the solution (publicly available on GitHub) using standard and well-consolidated technologies. We used this proof of concept to verify that the designed solution is technically possible. However, the used code has been developed quickly and lacks scalability, security, and integration with existing infrastructure, thus making it unsuitable for real-world experimentation. The proposed solution provides three key benefits related to automation, security, and interoperability in lawful interception procedures, which are discussed below. Unlike traditional lawful interception, which is usually handled by manual operations, our solution enables machine-readable authorizations, allowing access control, credential issuance, and verification to be fully automated. In this way, the absence of human intervention minimizes errors and improves efficiency. The use of verifiable credentials enhances security by eliminating the need for centralized identity providers, which can be hacked or manipulated, reducing single points of failure. Moreover, selective disclosure is supported, allowing users to share only necessary information and thus reducing privacy concerns. The lack of standardized interaction protocols between LEA and LEMF has led to fragmented implementations across different countries. Our solution addresses this problem using decentralized identifiers, Verifiable Credentials that follow the W3C format, and the DIDComm protocol, which ensures that different entities involved in the LI procedure, even across various jurisdictions and countries, can seamlessly interact. This paper is structured as follows. In the next section, we provide background notions about the LI procedure and the SSI paradigm. In Section 3, we discuss the faced problem and highlight the contribution of the proposed solution. The proposed approach is described in Section 4. In Section 5, we design the SSI stack underlying our approach and, in Section 6, we provide a proof of concept. The related literature is contextualized in Section 7. Finally, in Section 8, we draw our conclusion.