Celo Tech Talks Part 15 - Cross Chain Interoperability


Judy Piper, an engineering leader at C Labs, welcomes the audience to the Celo Tech Talk series. The Tech Talk series aims to share knowledge about Celo technology with the growing Celo community. Judy gives a brief overview of previous Tech Talks, which covered various topics such as Celo’s architecture, consensus mechanism, stability protocol, and more. She mentions that all the Tech Talk sessions are available on the Celo YouTube channel.

Guest Introduction

Judy introduces James Preswitch, a protocol engineer at C Labs, who will be discussing cross-chain communication with sharding, roll-ups, and new chains. James shares his background, including his previous work in the blockchain space, co-founding a company called Summa, and working on cross-chain solutions for various prominent chains. He explains how Summa was acquired by C Labs, and he now focuses on consensus systems, hard fork changes, and cross-chain interoperability at C Labs.

Understanding Cross-Chain Communication

James starts by explaining the concept of bridges in the context of blockchain interoperability. He states that the goal of bridges is to enable the use of assets from one blockchain (e.g., Bitcoin) in decentralized applications (dApps) on another blockchain (e.g., Ethereum). He emphasizes that communication between different blockchains is challenging due to the differences in nodes, software, and chains themselves.

Trusted Communication Channels and Relays

James discusses two approaches for achieving cross-chain communication: trusted communication channels and relays. Trusted communication channels involve a trusted party forwarding messages between blockchains. Relays, on the other hand, run the sender’s consensus process on the destination chain, allowing for a more decentralized approach. He explains the complexities and trade-offs associated with each approach, such as the overhead and additional complexity of proof-of-stake relays.

Challenges and Considerations

James highlights that chains are passive and can only respond to transactions within their own network. He explains that cross-chain communication requires active communication channels, which can be challenging to implement due to the lack of direct connectivity between different blockchains. He emphasizes the need for programmatic criteria and trusted setups to ensure the authenticity of messages being sent across chains.

Sharding and Atomic Swaps

James briefly mentions sharding and its relation to cross-chain communication. He explains that sharding involves following along with the consensus process of another chain, and its success or failure impacts the communication between the chains. He also mentions atomic swaps, stating that they are still a work in progress and not directly relevant to the current discussion.

Conclusion and Q&A

Judy announces that this Tech Talk concludes the series for the year and provides an overview of the upcoming topics for the next year’s Tech Talks. James concludes his presentation, highlighting the challenges and trade-offs involved in cross-chain communication. He addresses a few questions from the audience, discussing topics such as gas costs, trust in the relay, and incentivizing different actors in the trustless bridge.