Sui Public Chain Core Distributed System Protocol: Sui Lutris Analysis

Mysten Labs released an updated version of the Sui Lutris whitepaper on August 18 after several months of testing. The whitepaper confirms two key performance indicators:

1. Using PTBs technology, Sui can handle 140,000 to 150,000 operations per second, with peak TPS reaching 5000. This far exceeds the current benchmark level of about 700 TPS on the mainnet.

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 elaborates on the operational mechanism of Sui, providing security proofs and guidance for external testers to reproduce relevant performance data.

After the Sui mainnet went live, applications such as games and NFTs quickly emerged. The Sui Lutris technical report recently released by Mysten Labs introduces the core distributed system protocol that supports the Sui network. Sui Lutris enables Sui to maintain low latency while ensuring high throughput and long-term stability.

Since the birth of Bitcoin, blockchain technology has made significant progress, with emerging applications such as games and NFTs continuously appearing. The industry is also continuously exploring methods to enhance blockchain efficiency, especially in handling high loads and achieving real-time responses.

Currently, L1 blockchains face two major 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 of validator nodes.

An effective way to achieve high throughput is to adopt a DAG-based consensus protocol, such as Narwhal/Bullshark used by Sui. Such protocols allow blockchains to execute a large number of transactions simultaneously, making them very suitable for application scenarios like games and NFTs. However, DAG-based protocols typically introduce a delay of a few seconds, which significantly affects ordinary transfers 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 of the FastPay prototype. These protocols achieve rapid transaction processing by eliminating the consensus step, allowing for independent transactions to be processed in parallel without synchronization. However, their application is limited to simple blockchain operations, which restricts the expressiveness of smart contracts, and there are challenges in dynamically adjusting the set of validating nodes.

Although both protocols have potential, they have not yet been widely adopted in production-grade blockchains. Most of them have only been proposed at academic conferences and have not been widely adopted by the blockchain community. Sui Lutris, as the protocol supporting the Sui network, innovatively combines DAG-based consensus with non-consensus methods to achieve the advantages of both: sub-second latency and sustained throughput of thousands of transactions per second. At the same time, Sui retains the ability to execute complex contracts on shared objects, generate checkpoints, and reconfigure the set of validating nodes across cycles.

Combining Consensus and Non-Consensus Methods

Sui Lutris adopts a unique hybrid approach. For operations on exclusively owned asset ( and exclusive object ), the system employs a consistency broadcast protocol among validating nodes to achieve sub-consensus latency. Sui Lutris relies on consensus only when processing complex smart contracts on shared objects, which are objects that any user can modify. Additionally, Sui Lutris supports network maintenance operations such as defining checkpoints and reconfiguring validating nodes. This novel strategy provides a solution that balances both advantages when handling transactions in a replicated Byzantine environment.

The transaction lifecycle of Sui Lutris includes the following steps:

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

2. The transaction is sent to the Sui Lutris validation node through full nodes for validity and security checks, and it is returned to the client after signing.

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

4. The complete certificate is sent back to all validating nodes for verification. Transactions involving exclusive objects can be processed immediately without waiting for the consensus engine. All certificates are forwarded to the DAG-based consensus protocol.

5. Consensus output certificate number, verification nodes check and execute transactions containing shared objects.

6. The client can collect responses from most validation nodes and assemble a valid certificate as proof of transaction settlement.

7. Create checkpoints for each consensus submission to drive the reconfiguration protocol.

In addition to the main trading processes, Sui Lutris also provides multiple features that support production-level blockchains:

• Implement the checkpoint protocol after reaching final confirmation, generating a history of all transactions in the system for auditing and synchronization.

• Support reconfiguration at the end of each cycle to adjust the set of validating nodes and their voting rights.

• Safely "unlock" assets that were erroneously locked due to client double-spending attacks at the end of the cycle, minimizing losses.

As the infrastructure of Sui, the security of Sui Lutris is crucial. The complete technical report provides a detailed explanation of the operation of the security and activity protocol, as well as the security proof of partial synchronization with Byzantine participants in a standard distributed system model.