Building a Cross-Chain Identity: A Self-Sovereign Identity-Based Framework

There is a lack of effort in standardizing how users can connect their identities belonging to different blockchains and how to transfer on-chain data associated with each identity between ledgers. The absence of a general solution for managing a cross-chain identity can cause fragmentation, leading to the possibility of realizing applications that are more prone to security bugs. In this paper, we propose a framework to build a cross-chain identity based on the principles and standards of a new identity management paradigm, i.e., Self-Sovereign Identity (SSI). Promoting the standardization of applications running on the blockchain enhances their security and encourages the adoption of this technology in an increasing number of application contexts. According to the SSI paradigm, users create and update their identities in a blockchain without intermediaries. Following this principle, our framework does not require intermediaries to transfer identity-associated data from a source blockchain to a target blockchain. We realize that using a blockchain relay, an interoperability solution for storing and validating the headers of the source blockchain on the target blockchain. In our paper, we provide a new relay, the StateRelay, reducing the final usage costs for users willing to realize a cross-chain identity. We will show this by comparing its costs, in terms of transaction fees, with the other relay solutions in the literature.