XIR: A Framework for Interoperability across Cross-Chain Protocols Based on a Verifiable Intermediate Representation

XIR is a framework for cross-chain interoperability that uses a verifiable intermediate representation to compose existing protocol connections, preserving message identity and verification history across protocol boundaries. By binding an application message to an ordered record of authenticated deliveries, XIR enables XIR Gateways and Adapters to create multi-hop paths without requiring direct point-to-point configurations for every pair.

Analysis of 25 million transaction events across six protocols (Axelar, CCIP, Hyperlane, LayerZero, Relay, Wormhole) covering 286 blockchains reveals that while direct connectivity reaches only 14.64% of ordered pairs, XIR increases reachability to 96.86%. This improvement avoids 67,018 additional point-to-point configurations, reducing the deployment complexity from quadratic to linear relative to the number of blockchains.

The open-source prototype, integrating Hyperlane and LayerZero, demonstrates that XIR maintains source authorization, ordered evidence integrity, per-hop policy enforcement, and at-most-once delivery. The system achieves this by having source gateways authenticate applications, intermediate gateways verify and extend the delivery record, and destination gateways validate the complete history before execution.

The paper addresses a core scalability and composability problem in cross-chain messaging: when interoperability is implemented as a set of point-to-point connections between blockchains, each source–destination pair requires its own bridge, validator set, message format, or trust configuration. This makes the network graph sparse and hard to extend, because adding a new chain or protocol does not automatically make it reachable from all existing chains. The authors frame this as a reachability and configuration-cost problem, arguing that direct pairwise coupling becomes increasingly impractical as the number of participating chains and cross-chain applications grows.

The proposed contribution is XIR, a framework built around a verifiable intermediate representation for cross-chain messages. Rather than requiring every protocol to understand every other protocol’s native message format and verification rules, XIR abstracts cross-chain communication into a canonical, verifiable form that can be translated into and out of chain- or protocol-specific representations. The emphasis on verifiability suggests that the intermediate representation is not merely a data schema, but a semantic layer that preserves the necessary security properties—such as message authenticity, ordering, finality assumptions, or proof requirements—so that interoperability does not silently weaken trust assumptions.

This matters because cross-chain ecosystems are increasingly composed of heterogeneous chains, bridges, relayers, and application-specific interoperability layers, yet much of their integration remains bespoke and pairwise. A well-designed intermediate representation could reduce integration overhead, improve composability, and make cross-chain trust assumptions more explicit and auditable. In practical terms, XIR is relevant to anyone building cross-chain applications, bridge infrastructure, or interoperability standards, because it targets the transition from ad hoc point-to-point connectivity toward a more systematic, verifiable, and scalable model of cross-chain communication.