Want cheaper and safer interoperability? Drop traditional bridges

We should be building cross-chain solutions as if consensus mechanisms are unnecessary — because they are. ​​Blockchain technology has been celebrated for its potential to revolutionize various industries through decentralization, security and transparency. However, as the ecosystem expands, the complexities and costs associated with interoperability between different blockchains have become increasingly apparent. 

Consensus algorithms are essential for individual blockchain networks, ensuring that all participants agree on the state of the ledger to maintain integrity and security. Yet, when these mechanisms are applied to interoperability solutions like cross-chain bridges, they introduce significant inefficiencies and risks.

Implementing consensus in interoperability often leads to extreme over-collateralization — sometimes more than 100 times the value of the assets being transferred. Funds get locked up in validator nodes to secure the network, tying up enormous amounts of capital. For example, a common bridge is paying each validator around $30,000 per month, totalling a staggering $3 million per month for their 100 validators. The additional costs of incentivizing and maintaining a community of validators only add to this financial burden.

Read more from our opinion section: Don’t let Web3 repeat Web2’s interoperability mistakes

This over-collateralization isn’t just expensive; it’s economically inefficient. The total value locked (TVL) metric is frequently highlighted in the DeFi space. But, when it comes to bridges, these numbers often mask these underlying inefficiencies by presenting them as indicators of success rather than sunk costs. While consensus aims to provide security, it doesn’t guarantee consistency in interoperability solutions. 

Bridges introduce non-deterministic data, meaning the same input doesn’t always produce the same output across different chains. Without consistency, the stability of the entire system decreases with each additional blockchain connected. This instability increases the risk of tokens or transactions being duplicated, stuck or disappearing altogether. It is estimated that billions of dollars have been stolen from bridges , including $650 million from Ronin, $326 million from Wormhole and $566 million from Binance’s BNB Chain bridge.

The lack of consistency also hampers DeFi abstractions and composability. Bridges often rely on hardcoded primitives that require hard forks to modify, complicating innovation and slowing down the evolution of dapps. Many interoperability solutions struggle to scale effectively. Since these bridges can be considered blockchains, with their own consensus mechanisms, they introduce additional layers of complexity and potential bottlenecks. This not only slows down transaction times, but also adds more points of failure to the system.

Read more from our opinion section: Blockchains still aren’t great at communication

The crux of the matter is simple: Consensus mechanisms are unnecessary for interoperability, and may in fact be counterproductive. By eliminating the need for consensus in cross-chain solutions, we can significantly reduce costs and complexity. Instead of relying on validators to maintain a consensus, we can use deterministic proofs and verification methods that are inherently secure and efficient. 

The key to enable consensus-less interoperability is to move proof and verification mechanisms out of layer-1 smart contracts. This approach mitigates major bottlenecks like limited cross-chain data availability. By decoupling from individual layer-1 constraints, dapps are enabled to process data more freely and create additional value without being hindered by consensus-related limitations — benefiting not only blockchains, but most importantly, users.

Read more from our opinion section: Interoperability isn’t just a buzzword

By focusing on deterministic computations, interoperability solutions can ensure that transactions are predictable and verifiable without the overhead of consensus mechanisms. Techniques like refereed delegation of computation (RDoC) and cryptographic validation provide the necessary security assurances. This approach reduces the risk of inconsistencies and errors, enhancing the overall stability of cross-chain interactions.

Removing consensus from interoperability is not just a cost-saving measure; it’s a strategic evolution in building blockchain networks. This paradigm shift allows for greater levels of abstraction, improved efficiency and more room for innovation. Developers can create more complex and composable dapps without being hindered by the limitations imposed by consensus-driven bridges.

The current reliance on consensus mechanisms for interoperability is both costly and inefficient. By rethinking our approach and eliminating unnecessary consensus layers in cross-chain solutions, we can build a more robust, scalable and efficient blockchain ecosystem. This strategic move not only reduces operational costs but also fosters innovation, allowing blockchain technology to reach its full transformative potential.

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