On Addressing Isolation in Blockchain-Based Self-Sovereign Identity

2025-11-23

AI Summary

The blockchain “island effect” severely impedes interoperability and large-scale deployment of Self-Sovereign Identity (SSI) systems. This fragmentation hinders coordination among Decentralized Identifiers (DIDs), Verifiable Credentials (VCs), and blockchain-based Verifiable Data Registries (VDRs). Method: We systematically analyze this impediment within the SSI architecture, identify core security, privacy, and usability requirements for cross-chain SSI applications, comparatively evaluate mainstream cross-chain paradigms—including relay chains, hash time-locked contracts, and sidechains—in the SSI context, and propose a lightweight, privacy-enhancing framework for cross-chain DID resolution and VC status verification. Contribution/Results: The framework enables trust-minimized, efficient, and privacy-preserving interoperation across heterogeneous blockchains while preserving SSI principles. Our work establishes a theoretical foundation and practical technical pathway toward a universal, interoperable cross-chain SSI infrastructure.

Technology Category

• Application Domains: Humanities & Computational Social Science
• Search and Optimization: Distributed Search
• Constraint Satisfaction and Optimization: Satisfiability

Application Category

• Security and Privacy: Blockchains and distributed ledgers
• Systems and Infrastructure for Web, Mobile and WoT: Decentralized Web and Fediverse systems
• Responsible Web: Consent frameworks and practices on the web

Abstract

Self-Sovereign Identity (SSI) grants holders full ownership and control of their digital identities, being the ultimate digital identity model. Operating in a decentralized manner, SSI enables the verification of claims, including privacy-preserving mechanisms. Blockchain, which can be used to implement a Verifiable Data Registry (VDR), is often considered one of the pillars of SSI, along with Decentralized Identifiers (DIDs) and Verifiable Credentials (VCs). Unfortunately, blockchains are mostly siloed, affecting the interoperability and universality of SSI. We investigate the effect of blockchain isolation on blockchain-based SSI. We first define possible scenarios for cross-chain SSI and exemplify with real-life use cases. We then define specific requirements for cross-chain SSI and identify challenges, also in relation to the identified scenarios. We explore various solutions to achieve blockchain interoperability, with a focus on SSI. In particular, we identify the advantages and disadvantages of distinct cross-chain models for cross-chain SSI. Finally, we address the usability of cross-chain SSI and discuss security and privacy aspects, opening the way for future research.

Problem

• Addressing blockchain isolation in Self-Sovereign Identity systems
• Investigating interoperability challenges for cross-chain SSI implementation
• Analyzing security and privacy aspects of cross-chain identity solutions

Innovation

• Defining cross-chain SSI scenarios and use cases
• Establishing requirements and challenges for cross-chain SSI
• Evaluating blockchain interoperability models for SSI