TL;DR

• Interoperability remains key to blockchain evolution despite implementation difficulties

• Bridges prevail, but must adapt to scaling trends like rollups and modularity

• Standards, shared systems, and add-ons facilitate cross-network communication

• New interoperability models emerged in the restaking era, see examples

Interoperability has long been a significant challenge in the crypto space. It involves enabling different distributed systems to communicate seamlessly without relying on a single chain or orchestration layer. Traditionally, this has meant exchanging data and assets across networks to improve connectivity and user experience.

However, achieving compatibility and performance in externally verified interoperability systems has often compromised security. Recent losses of $3 billion in blockchain bridges highlight these vulnerabilities.

Restaking offers a new approach by sourcing cryptoeconomic security and node decentralization from Ethereum. As a result, new interoperability models have emerged, promising to deliver both safety and efficiency.

Interoperability is a key driver of blockchain technology evolution because it provides scalability of the networks and unlocks new functionality, anchored in the ability to verify and relay the state across them. That’s why researchers and practitioners have tried to overcome the differences in language, interface, and execution platforms since the beginning of the crypto era.

Various services now facilitate interoperability through messaging and transfer protocols, from atomic swaps to decentralized oracles, from multi-chain standards to cross-chain bridges. While bridges remain prominent, they must adapt to scaling trends like rollups and specialized modular layers.

A modular approach divides blockchains into interconnected components. This makes it easier to launch chains, but they remain isolated from existing ones. Common standards, shared systems, or built-in elements facilitate seamless cross-network communication.

For example, a common consensus and data availability (DA) layer for rollups eliminates the need for third-party bridges and uses native inter-rollup connectivity instead. They can use the same validator set to establish the order and validity of transactions and make all the data available for everyone to verify transactions and reconstruct the state.

A shared sequencer can make cross-rollup interoperability faster and cheaper. It can guarantee that rollups have transactions included in the same block, reducing the reliance on bridges to order and execute transactions across rollups.

ZK rollups can form ecosystems with out-of-the-box interoperability using a novel bridging technique based on validity proof aggregation. Storage proofs, light-client-based state verification through ZKPs, and other developments can help facilitate composability.

Below are some examples of how restaking enhances interoperability in the modular future.

Interoperability solutions historically struggled to prioritize security without sacrificing statefulness, capital efficiency, speed, or connectivity. Restaking removes the need to consider the level of trust and risk users can tolerate by deriving them from the same source as rollups: Ethereum itself. With more than $100 billion securing the network, this security budget is an order of magnitude larger than any other Proof of Stake (PoS) network.

Provided sufficient security is in place, external interoperability verification between Ethereum rollups is the only one that can simultaneously provide excellent performance and global compatibility, compared to native, local, or optimistic methods.

In this scenario, a set of third-party security providers validates data communication between rollups. Restaking makes this model game-theoretically secure because the staked value of their verifier set always is greater than the value that the verifier set can transfer in a single state transition period.

Example: Omni

Developers can include third-party modules to enable interoperability with other deployments when building chains, regardless of their roll-up framework or execution environment.

This often comes with the ability to configure security settings according to the application’s needs. If the application’s functionality relies on validator signatures, the economic trust derived from restaking can ensure that they will not attempt to falsify or censor cross-chain messages.

When validators’ stakes and the state they attest to are on the same chain, the slashing mechanism can verify whether the validator’s signature matches the latest root or if the checkpoint they signed was fraudulent. The slashing condition is communicated via the native rollup bridge, which allows validators to repurpose their original stake across many different rollups.

In summary, Ethereum validators can add economic security to outbound cross-chain communication.

Example: Hyperlane

In the broader blockchain landscape, trust-minimized interoperability between heterogeneous networks can be enhanced by increasing the security and reliability of cross-chain transactions through restaking. This approach is particularly practical when using Bitcoin as a secondary staking asset, leveraging its stability, market size, and associated trust.

A key component of this approach is the modular dual-staking system. It requires native and ETH-backed operators to meet their respective quorums for successful individual validation. The response will not be considered valid if either quorum is not reached. This dual validation process enhances security and consensus by involving agreement from two distinct and diverse sets of validators.

Example: zkBridge

Security is the most critical aspect of cross-chain messaging protocols and their reliable verification models. Established bridge solutions can replace their internal implementation of critical security features, such as authenticating messages in the attestation layer, and integrate them into restaking to benefit from independent validation.

To illustrate, a popular safety mechanism to ensure reconciliation involves tracking the total circulating supply of all the assets across all chains and preventing bridging assets that don’t have enough available balance on the source chain. Using an independent set of validators to maintain the integrity of token transfers also means separating the responsibilities of moving and securing messages, thus improving system modularity and maintainability.

Example: Wormhole

Leveraging Ethereum as a source of trust, restaking offers trustless, extensible, and generalized interoperability solutions. If you have an idea for such a solution, Nektar can bootstrap your network.

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