Bridges & Interoperability | Kuneco April 2021


In this tutorial, we will explore the transcript from the Kuneco April 2021 event, focusing on bridges and interoperability. The discussion features David Ansernino, VP of Engineering at ChainSafe Systems, and James Westwick, a representative from a company called Vin Presbyter. They provide insights into the ChainBridge project and its integration with Celo, as well as their vision for the future of bridges and trust models.

Overview of ChainBridge

ChainBridge is a developer toolkit designed to build bridges between different blockchains. It offers several key properties:

  1. Extensibility: ChainBridge supports integrations for various chains, allowing for the development of bridges that follow a basic protocol or include additional features.
  2. Modularity: The supported chains can be combined in different ways to construct bridges between each other.
  3. Customizability: The data passed across the bridges can be arbitrary, and the on-chain components are not limited to specific interactions like token transfers.

The architecture of ChainBridge consists of three chains (A, B, and C) with a bridger layer in the middle. The bridger layer contains modules responsible for reading and submitting transactions to the respective chains. These modules communicate with each other to facilitate transfers.

Trust Mechanisms: Merkel Inclusion Proofs and BLS Aggregate Signature Verification

To address trust assumptions in relayers, ChainBridge combines two proof mechanisms: Merkel inclusion proofs and BLS aggregate signature verification.

  • Merkel inclusion proofs: These proofs demonstrate that a transaction is included in a block by reconstructing the root hash using a series of hashes. They are easy to verify and have low space complexity.
  • BLS aggregate signature verification: In the Celo network, validators individually sign new blocks, and their signatures are combined to create an aggregate signature associated with the block. Similarly, the public keys of validators are combined to produce an aggregate public key. By verifying these aggregate signatures, the system can ensure the production of a specific block.

By combining these proof mechanisms, ChainBridge reduces trust assumptions in relayers and provides verifiability for transaction inclusion in valid blocks.

Future Developments and Improvements

ChainSafe Systems is focused on improving the developer experience and expanding ChainBridge’s capabilities. Their plans include:

  • Refactoring the overall architecture to reduce friction when building custom bridges.
  • Creating more documentation and tutorials to lower the barrier of entry.
  • Adding support for additional chains beyond Celo, such as EVM-based chains and Substrate-based chains.
  • Exploring the potential of Layer 2 solutions and their impact on bridge functionalities.
  • Investigating alternative trust models to further decentralize bridge operations.

Optics: Trust-Minimized Bridge Solution

James Westwick introduces Optics, a trust-minimized bridge solution that aims to create a cohesive and cost-effective ecosystem for cross-chain messaging. Optics optimizes ease of integration and minimizes trust in off-chain actors.

The solution involves an updater, an off-chain actor that attests to message commitments. Fraudulent commitments are publicly verifiable, allowing for slashing and revoking the bond of the updater. Optics serves as an accountability system for oracles, ensuring publicly verifiable information.

Panel Discussion: Interoperability and Bridging

The panel discussion touches upon various topics related to interoperability and bridging. Participants discuss the need for standardization of bridge roles, the integration of oracles, and the challenges faced in bridging Bitcoin. They also express the importance of reducing gas costs and exploring Layer 2 solutions for more efficient bridging.


In conclusion, bridges and interoperability are critical components for the growth and connectivity of blockchain ecosystems. Projects like ChainBridge and Optics are actively working on improving trust models, expanding support for different chains, and exploring Layer 2 solutions. By addressing technical challenges and enhancing developer experience, these projects aim to create more efficient and decentralized bridge solutions that unlock the full potential of cross-chain interactions.

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