Post-Quantum Secure Cross-Chain Interoperability Protocols for Next-Generation Blockchain Systems

Abstract

Blockchain systems are fundamentally dependent on classical cryptographic primitives, which are increasingly threatened by the rapid advancement of quantum computing. In cross-chain communication and interoperability protocols, where safe asset transfer and validation across heterogeneous networks are crucial, this danger is especially serious. Ensuring quantum-resilient interoperability is crucial for preserving security, trust, and long-term sustainability as next-generation blockchain ecosystems move toward multi-chain architectures. Relays, bridges, and atomic swaps are examples of existing interoperability methods that mostly rely on public-key cryptography, which is susceptible to quantum assaults like Shor's algorithm. In the post-quantum era, this vulnerability puts digital assets and cross-chain transactions at risk of compromise. This paper suggests a quantum-resilient cross-chain interoperability protocol framework to overcome this difficulty and allow safe and effective communication between various blockchain platforms. The suggested design incorporates post-quantum cryptographic techniques, such as hash-based and lattice-based signature algorithms, with consensus bridging and cross-chain transaction validation procedures. Additionally, a hybrid cryptographic transition model is presented to provide a progressive transition towards quantum-safe primitives while guaranteeing backward compatibility with current classical systems. The proposed structure greatly increases resilience against quantum attackers while maintaining interoperability efficiency, according to experimental evaluation. Robustness against replay attacks, signature forging, and key compromise under quantum threat models is confirmed by security analysis. The suggested protocol ensures strong and quantum-resilient interoperability in next-generation blockchain infrastructures by offering a scalable and future-ready foundation for safe multi-chain ecosystems.