Sui Public Chain Core Distributed System Protocol Analysis

Mysten Labs updated the Sui Lutris white paper on August 18, confirming the following key results after months of testing:

1. With the use of PTBs and 5K TPS, Sui can handle 140k to 150k operations per second, which far exceeds the benchmark performance during the mainnet peak (around 700 TPS).

2. Even in the case where some validator nodes stop running, Sui's final confirmation delay can still be kept below 0.5 seconds.

The white paper also details how external testers can reproduce this data in their own validation tests, providing security proofs and a detailed description of the Sui operational mechanism.

After the launch of the Sui mainnet, we have seen some exciting applications go on-chain, such as games and NFTs. Recently, Mysten Labs released a technical report on Sui Lutris, a distributed system that supports Sui. Sui Lutris enables Sui to maintain low latency under conditions of high throughput and long-term stability.

Blockchain technology has developed for more than a decade since the birth of Bitcoin, during which new application scenarios such as games and NFTs have emerged. The blockchain community has been exploring ways to improve efficiency, especially in handling high loads and providing real-time responses.

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 overcome through the dynamic participation and configuration of validation nodes.

An effective way to achieve high throughput is to use DAG-based consensus protocols, such as Narwhal/Bullshark used by Sui. These types of protocols allow blockchains to execute a large number of transactions simultaneously, making them very suitable for applications like games and NFTs. However, DAG-based protocols may lead to delays of several seconds, which can significantly impact common transfers or game operations.

On the other hand, consensus-free protocols have shown great potential in reducing latency and scalability, as demonstrated by the early research prototype FastPay. These protocols achieve rapid transaction processing by eliminating the consensus step, allowing independent transactions to be processed in parallel without additional handling. However, this approach is only applicable to a limited range of simple blockchain operations, which restricts the expressive power of smart contracts, and poses challenges in reconfiguring a dynamically changing set of validating nodes.

Although both protocols have potential, they are currently not widely used in product-level blockchains and mainly remain at the academic discussion stage. Sui Lutris, as the core protocol supporting the Sui network, cleverly combines DAG-based consensus and non-consensus methods, achieving the advantages of both: sub-second latency (less than 1 second) and sustained throughput of thousands of transactions per second. At the same time, Sui 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 hybrid approach. For operations involving assets owned by a single owner (unique objects), the system uses a consistent broadcasting protocol among verification nodes to achieve consensus-lower latency. For complex smart contracts involving shared objects, Sui Lutris relies on a consensus mechanism. Additionally, 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 includes the following steps:

1. Users create and sign transactions to modify their owned objects or the combination of exclusive and shared objects.

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

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

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

5. Consensus output certificate number, verifying that the node executes transactions containing shared objects.

6. The client can collect responses from most validation nodes and assemble them into 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 process, Sui Lutris also provides a range of features that support product-level blockchain:

• Implement checkpoint protocol to generate a history of all transactions in the system for auditing and synchronization.
• Supports reconfiguration at the end of each cycle, allowing changes to the set of validating nodes and their voting rights.
• Safely "unlock" mistakenly locked assets at the end of the cycle, minimizing erroneous losses.

As a blockchain managing a large number of user assets, the security of the underlying Sui Lutris is crucial. The complete technical report provides detailed information about the security and activity protocols, as well as the security proofs of partial synchrony with Byzantine participants in the standard distributed system model.