Sui Public Chain Core Distributed System Protocol: Sui Lutris Report Analysis

After several months of rigorous testing, the core technology team of the Sui public chain released an updated version of the Sui Lutris white paper on August 18. The white paper confirms two key performance indicators:

1. Under the conditions of using PTBs and 5K TPS, Sui can process 140k to 150k operations per second. This data far exceeds the benchmark results during the peak of the mainnet (approximately 700 TPS).

2. Even in the case where some validation nodes stop operating, Sui's final confirmation delay can still be maintained at under 0.5 seconds.

The white paper also details how external testers can reproduce these performance data in their own validation tests, providing security proofs and an in-depth description of the Sui operation mechanism.

After the launch of the Sui mainnet, applications such as games and NFTs have emerged rapidly, showcasing an exciting development momentum. Recently, the technical team of Sui released a technical report on the distributed system supporting Sui's operation—Sui Lutris. The design goal of Sui Lutris is to achieve low latency while ensuring high throughput and long-term stability.

In the decade since the birth of Bitcoin, blockchain technology has made significant progress, especially in emerging application areas such as gaming and NFTs. The blockchain community has been working to enhance the efficiency of blockchain technology, with a particular focus on high-load processing and real-time latency optimization.

Currently, L1 blockchains face two main challenges: achieving high throughput while maintaining low latency, and ensuring the long-term stability of the consensus protocol. These challenges can be addressed through the dynamic participation and configuration adjustment of validation nodes.

An effective way to achieve high throughput is to adopt a DAG-based consensus protocol, such as Narwhal/Bullshark used by Sui. These protocols allow blockchains to process a large number of transactions simultaneously, making them very suitable for application scenarios like games and NFTs. However, DAG-based protocols typically result in delays of a few seconds, which can significantly impact common transactions or gaming operations.

On the other hand, non-consensus protocols show great potential in reducing latency and improving scalability, as demonstrated by the early research on the FastPay prototype. These protocols enable fast transaction processing by eliminating the consensus step, avoiding additional handling of independent transactions in parallel processing. However, this approach is only suitable for a limited category of simple blockchain operations, which restricts the expressiveness of smart contracts, and it faces challenges when dynamically adjusting the set of validating nodes.

Although both protocols have development potential, they have not yet been widely adopted in production-level blockchains. They mainly remain in the discussion phase of academic conferences and have not been widely adopted by the blockchain community. Sui Lutris, as the core protocol supporting the Sui network, innovatively combines DAG-based consensus with non-consensus methods to achieve the advantages of both: sub-second latency (less than 1 second) and sustained throughput of thousands of transactions per second. Sui not only achieves these two goals but also maintains the ability to execute complex contracts on shared objects, generate checkpoints, and reconfigure the validator set across cycles.

Consensus and Non-consensus Methods

Sui Lutris adopts a unique approach that integrates the two aforementioned technological routes. To ensure the security of operations involving single-owner assets (unique objects), the system employs a consistency broadcasting protocol among verification nodes, achieving latency below consensus. For complex smart contracts running on shared objects, Sui Lutris relies solely on the consensus mechanism for processing. In addition, Sui Lutris supports network maintenance operations, such as defining checkpoints and reconfiguring verification nodes. This innovative strategy provides a solution that balances efficiency and security when handling transactions in a replicated Byzantine environment.

The transaction lifecycle of Sui Lutris is as follows:

1. Users create and sign transactions to change the objects they own or mix objects.

2. Transactions are sent from the full node to each Sui Lutris validator node, where the validator nodes perform validity and security checks, sign, and return to the client.

3. The client collects responses from most validation nodes to form a transaction certificate, at which point the transaction reaches a final confirmation status.

4. After the certificate integration is completed, it is sent back to all verification nodes, which check its validity and confirm receipt. Transactions involving unique objects can be processed and executed immediately, without waiting for the consensus engine. All certificates will be forwarded to the DAG-based consensus protocol.

5. The number of the consensus final output certificate, verification nodes check and execute transactions that contain shared objects.

6. The client can collect responses from most verification nodes, assemble them into a valid certificate, and use it as proof of transaction settlement.

7. Subsequently, checkpoints are formed for each consensus submission, and these checkpoints can also be used to drive the reconfiguration protocol.

In addition to the main trading process, Sui Lutris also offers a range of features that support production-grade blockchains:

• Implement the checkpoint protocol to generate a historical record of all transactions in the system for complete auditing and efficient synchronization.
• Supports reconfiguration at the end of each cycle, adjusting the set of validating nodes and their voting rights.
• Safely "unlock" assets that have been mistakenly locked at the end of the cycle, minimizing losses caused by errors.

Sui, as a blockchain that manages a large amount of value for users, is fundamentally supported by Sui Lutris. The complete technical report provides detailed information on the operation of security and liveness protocols, as well as security proofs that are partially synchronized with Byzantine participants in a standard distributed system model.