t3rn's Trustless Eth2 Light Client

Monthly Update on t3rn's Multichain Protocol Development

Author

Maciej Baj
May 11, 2023

Dear t3rn community,

Welcome to the second edition of Multichain Matters, our monthly newsletter where we share updates on our latest advancements and offer insights into the behind-the-scenes of the t3rn protocol.

Here's what we'll be covering:

  • Marketing Highlights

  • Community Engagement

  • t3rn Protocol Updates

  • Fork Resolution and Security Levels

  • Smart Contract Integration & ABI Recoding

  • Polkassembly Proposal

In addition to our engineering efforts, we've been making strides on the marketing front to help spread the word about t3rn and our mission. Here are some highlights from our latest marketing and communication endeavors:

In the first blog Part 1: What are t3rn Executors?, we introduced the role of the Executors, and explained how to become one and start generating yield by executing multichain transactions. In the second blog Part 2: Execution Lifecycle, we covered the three stages of an XTX (cross-chain & fail-safe transactions) life cycle, we dived deeper into generating yield as an executor of t3rn’s cross-chain traffic in a trustless & open-market manner and we covered the world of Executor incentives, which are a critical component of t3rn tokenomics.

 

In this blog post, we talk about concepts such as liquidity (having more funds available for transactions), execution value, and execution speed, going through an example of a transaction presenting three different scenarios. If you are interested in becoming an Executor on the t3rn network, please reach out to us via this contact form and join our Discord community for updates and support.

Missed the session? Don't worry! The recorded AMA is now available for you to catch up on all the topics discussed, from t3rn's unique features to recent partnerships and collaborations. Don't miss this chance to learn more about t3rn and our roadmap.

The completion of t3rn's second grant from the Web3 Foundation set the stage for the development of XBI standard. XBI offers a high-level interface that simplifies integration for developers. With XBI, you can easily communicate and execute transactions across different blockchain networks within Dotsama, unlocking new possibilities for decentralized applications.

XBI also recognizes and interacts with popular smart contract formats like EVM and WASM, making it a versatile tool for developers seeking flexible interaction with the Polkadot ecosystem. Stay tuned for more on XBI's development in our new section on our website!

I'm excited to share with you our latest progress on the trustless Eth2 light client, which is now in its prototype stage as an on-chain Substrate pallet. This component will be integrated into the t0rn test Parachain on Rococo. Let's take a closer look at some of the most interesting components of the light client:

Fork Resolution and Security Levels

We've implemented the next sync committee via a trustless inclusion proof, as well as finality and fork choice mechanisms. Our fork-choice implementation follows Ethereum's native checkpoint finality logic, where the finality of a slot/block is determined by its epoch. There are two levels of finality for epochs: justified and finalized.

  • Justified represents a completed epoch with the next one already running and is not deterministically final. In theory, this epoch could still end up on the wrong fork, but this would result in ⅓ of all staked Ether being burned.

  • Finalized, on the other hand, is positioned behind the justified epoch and considered final, with the only way to revert it being through a user-activated hard fork.

Our light client adheres to this concept for fork resolution, and users and smart contract developers can choose their preferred security level. The time variance between the justified and finalized methods is significant, with justified proofs taking around 6.5 minutes and finalized proofs taking 13 minutes. More insights on speed modes are available at this dedicated Github Pull Request: https://github.com/t3rn/t3rn/pull/865

Smart Contract Integration and ABI Recoding

The inclusion proofs verification is exposed to smart contracts via a uniformed interface, coined internally as “Portal Precompiles”. This allows smart contract developers to access light client primitives and build security-oriented applications such as bridges with full traffic transparency and verified transaction content. We also have a pretty cool ABI re-coder (https://github.com/t3rn/t3rn/pull/667), which supports encoding and decoding between RLP (Ethereum smart contracts' encoding standard) and SCALE (Polkadot and Parachains' encoding). This means that native services to the Polkadot ecosystem and Ethereum smart contracts can exchange data and interact via the interface available to t3rn smart contracts.

The Header Relayer Client development is underway and will feed the light client with new headers. For now, header submissions are batched in epochs. Additionally, Executor's (t3rn Executors, Part 1: What are t3rn Executors?) integration is ongoing, and when finished, it will execute Ethereum transactions and generate the required inclusion proofs. We expect the Eth2 light client engineering to wrap up by the end of June, followed by the QA phase. We have an ongoing Polkassembly proposal for treasury support for security audits, QA efforts, and future maintenance of the light client, future-proofing for the next Eth2 network upgrades: https://polkadot.polkassembly.io/treasury/261. You can find a rundown of interesting implementation details and plans in the proposal and thread. There is also a lively discussion happening on the Polkadot Forum about security concerns for bridging assets to Polkadot.

It's important to note that the sync committee is not part of the Casper FFG signing. We stick to this finality concept because it aligns with the native understanding of finality. We believe our stance on this matter is clear in our response here. The sync committee's role in the native consensus has sparked considerable discussion—an excellent topic for a future newsletter, perhaps?"

I’m always around if you’ve got any cool ideas or feedback to share. You can reach out to me on Twitter @Maciej_Baj. Follow me to stay in the loop and join the conversation!

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Stay tuned for more updates and insights in the upcoming "Multichain Matters" newsletter issues!

Maciej Baj, Founder and CTO of t3rn