Blockchains have redefined financial and digital infrastructures by enabling decentralized applications (dApps) and self-custodial assets. Yet they remain isolated due to insecure, inefficient interoperability protocols. Existing cross-chain bridges rely on extra trust assumptions, while cross-layer solutions struggle to enhance execution without compromising security, limiting scalability, expressiveness, and privacy.

CROSS aims to develop a trust-minimized interoperability framework to unify blockchain ecosystems. We address three key challenges: (RQ1) designing secure, trust-minimized cross-chain protocols for diverse consensus mechanisms; (RQ2) enhancing execution layers with expressiveness, privacy, and scalability while preserving security; and (RQ3) establishing a formal security framework for interoperability.

Building on prior work, we will extend interoperability to PoS, BFT, and DAG-based systems and introduce the first universal trust-minimizing cross-chain protocol. Leveraging our work on the celebrated BitVM, we will conduct the first systematic approach to bridging blockchain consensus with carefully crafted execution layers to inherit the union of their properties. Finally, we will develop a rigorous security proof methodology for securely composing interoperability protocols.

CROSS will enable decentralized applications to seamlessly interact across blockchains while maintaining security and efficiency, laying the foundation for a unified blockchain ecosystem.