Department of Computer, Control and Management Engineering

Proving that an endpoint (e.g. URL, telephone number, ecc.) is controlled by a subject is crucial in many applications. In the web, this is witnessed by the widespread adoption of HTTPS. In centralized architectures, this task is usually carried out by trusted certification authorities (CAs). In decentralized applications, for example based on blockchains, or for self-sovereign identity management (SSI), it would be desirable to perform these checks in a decentralized way, relying on the collective behavior of a society of individuals rather than on a single trusted entity. In any case, the result should be a widely usable certificate, as in the centralized CA case. In this paper, we show two blockchain-based methods to prove the association between a subject and an endpoint in a decentralized manner. Our methods are compatible with a wide variety of endpoints and contribute to fill the gap of the current SSI approaches with respect to decentralization. We analyze the security of our proposal and provide a proof-of-concept implementation. We also evaluate performances, costs, and compatibility with current standardization efforts about SSI.