Sui Lutris: An efficient blockchain protocol that combines DAG with a no-consensus solution

Blockchain technology has made significant progress since the birth of Bitcoin. With the emergence of new applications such as games and NFTs, the industry continues to explore ways to improve technological efficiency, particularly in handling high loads and providing real-time latency. L1 Blockchains face two major challenges: first, achieving high throughput while maintaining low latency, and second, ensuring the long-term stability of the consensus protocol. When addressing these challenges, it is also essential to maintain decentralization through the dynamic participation and reconfiguration of validating nodes.

One way to achieve high throughput is to use a DAG-based consensus protocol. Such protocols enable the blockchain to process a large number of transactions simultaneously, making them very suitable for application scenarios like gaming and NFT. However, DAG-based protocols can lead to a few seconds of latency, which can be a high time cost for regular transfers or gaming operations.

On the other hand, non-consensus protocols show great potential in reducing latency and scalability. These protocols can quickly process transactions without consensus and do not require a total ordering of independent transactions for parallel processing. However, they are limited to a class of restricted simple Blockchain operations, which constrains the expressiveness of smart contracts, and dynamically reconfiguring the validator set can be challenging.

Although these methods have potential, they have not yet been applied to production-level blockchain and have only been published at academic conferences. Sui Lutris is a protocol that supports Sui, combining DAG-based consensus with non-consensus methods to achieve sub-second latency and sustained throughput of thousands of transactions per second. It also maintains the capability to express complex contracts on shared objects, generate checkpoints, and reconfigure the validator set across periods.

Sui Lutris adopts a unique approach that combines the two methods mentioned above. When operating on assets owned by a single owner, the system uses a consistent broadcasting protocol among validators to achieve latency below consensus. Consensus is only relied upon when processing complex smart contracts on shared objects. Sui Lutris also supports network maintenance operations, such as defining checkpoints and reconfiguring validators. This strategy provides a method that balances efficiency and security when handling transactions in a replicated Byzantine environment.

The transaction lifecycle of Sui Lutris is as follows: Users create and sign a transaction, which is sent to the validating nodes. The validating nodes perform validity checks, sign, and return. The client collects responses from the majority of validating nodes to form a transaction certificate, at which point the transaction reaches finality. The certificate is sent back to all validating nodes for confirmation. If exclusive objects are involved, they can be processed immediately. All certificates are forwarded to the DAG-based Consensus protocol. The consensus outputs the total order of certificates, and the validating nodes execute transactions containing shared objects. Clients collect responses from validating nodes to assemble effect certificates as proof of transaction settlement. Each consensus submission forms a checkpoint for driving the reconfiguration protocol.

Sui Lutris also provides additional features that support production-grade Blockchain:

1. Implement the checkpoint protocol to generate a causal history of all transactions for auditing and synchronization.

2. Support reconfiguration at the end of each period, updating the validator set and voting rights.

3. Securely "unlock" incorrectly locked assets at the end of the period, minimizing the damage from the vulnerability.

Sui Lutris supports the Sui blockchain, which manages a large amount of value. It combines high efficiency and security, providing new ideas for the development of blockchain technology.