In-depth Analysis of Sui Native Cross-chain Bridge Technology Architecture

The native cross-chain bridges of Sui provide a trust-minimized solution for the cross-chain transfer of Sui assets. Recently, significant progress has been made in the development of native bridges in the Sui ecosystem, which not only enhances the accessibility of Sui but also improves interoperability with other blockchains.

As a key component of the Sui ecosystem, the Sui native bridge facilitates the secure and efficient transfer of assets and data between Sui and other blockchain networks. This functionality not only broadens the impact of Sui applications but also provides a pathway for deeper integration into a broader blockchain environment. The enhancement of interoperability drives the growth and adoption of Sui, allowing assets from other networks ( such as Ethereum ) to migrate securely and conveniently to Sui.

Background of Sui Native Bridge

In the blockchain ecosystem, cross-chain bridges are protocols that allow interaction and communication between independent blockchain networks. Cross-chain bridges facilitate the transfer of cross-chain data, allowing users to transfer assets from one chain to another, and even perform more complex operations such as cross-chain messaging.

The Sui native bridge uses a locking and minting mechanism, which is one of the most widely used cross-chain bridge solutions. The bridge holds Ethereum native assets in Ethereum smart contracts, while in the direction of bridge interactions, Sui assets will be minted or burned.

As the native bridge of Sui, the Sui native bridge does not require additional trust. Its security is guaranteed by the nodes of the Sui network, and the code has been embedded into the Sui framework.

Currently, the Sui native bridge is available on the testnet, supporting bridging tokens such as ETH, WETH, WBTC, and USDT between the Ethereum Sepolia and Sui testnets. After the mainnet launch, more assets will be prioritized for support. Future versions will add new features such as custom cross-chain messaging and integration with other blockchains.

Advanced Architecture

The Sui native bridge consists of four key components: the Sui Bridge Committee or node network, the Sui Bridge smart contract, full nodes running on Ethereum and Sui, and the bridging client.

The client is the interface between the user and the Sui Bridge infrastructure, coordinating bridging operations by submitting correctly formatted transactions and collecting node signatures. The client submits transactions on both sides of the bridge using full nodes. Sui Bridge nodes also run Ethereum and Sui full nodes to listen for and respond to bridging operations. Although the bridging client is permissionless, many nodes will open the client to ensure network activity.

When bridging from Ethereum to Sui, users deposit assets into a smart contract on Ethereum. The client observes the transaction and coordinates the bridging process. After the committee verifies the legitimacy of the request, it mints the bridging assets for the user through a package on Sui. Due to lower costs, Sui validating nodes currently subsidize the associated gas fees, creating a seamless bridging experience.

The process is similar when bridging from Sui to Ethereum, but users must manually submit a claim transaction on Ethereum. This transaction includes node signature data, allowing for the redemption of locked assets.

All bridge records and approvals are stored on-chain objects. The Sui Bridge contract also handles governance operations controlled by the committee.

Bridging Message

To ensure low gas fees, the Sui native bridge constructs messages that are lightweight and easy for the receiving chain to decode. It uses a universal message format to ensure efficient decoding, verification of messages, and signatures.

These bridging messages are designed to be simple and efficient, with an extremely minimal structure that only includes basic fields such as message type, version, sequence number, source chain identifier, and payload. The simplified design reduces complexity and computational overhead, ensuring low gas fees while facilitating fast and reliable cross-chain communication.

Bridge Security

Determining the trust model of the bridge is one of the most important design decisions when developing cross-chain bridges to support a thriving ecosystem and large-scale liquidity. Cross-chain bridges should be both secure and decentralized, and developing native bridges provides the opportunity to leverage Sui's security.

Like the operators of validating nodes who ensure the security of Sui, they also manage and maintain the infrastructure for the operation of the Sui native bridge. The Sui native bridge inherits a decentralized network of node operators, who have the ability to run and protect the Sui infrastructure.

Most bridging operations are conducted on Sui, treating Sui as the control panel for the bridge. This is thanks to the security inherited from the software developed using Move.

Bridge Committee

The Sui native bridge is protected by the same set of validating nodes that ensure the security of Sui. During the testnet phase, the committee is composed of a portion of the testnet validating nodes. After the mainnet goes live, most of the (, if not all, active Sui validating nodes will become part of the committee. A dynamic management committee will be implemented to allow new validating nodes to join. Only Sui validating nodes are allowed to become part of the committee, ensuring the inheritance of its security assumptions, attributes, and social consensus.

To maintain high security and compatibility with other blockchain networks, the Sui native bridge uses the Elliptic Curve Digital Signature Algorithm ) ECDSA ( for committee signing. By utilizing ECDSA, it ensures seamless interoperability and secure transaction validation, enhancing the integrity and credibility of the system.

) Signature Verification

The Sui native bridge uses recoverable ECDSA signatures, allowing the public key to be recovered directly from the signature. This feature simplifies the verification process, enabling us to retrieve the public key and confirm the authenticity and integrity of the signature without prior knowledge of the public key.

A message is considered valid only when the total weight of the signatures reaches or exceeds a predetermined threshold. This threshold mechanism ensures that a sufficient number of authentic signatures are required to verify the message, thereby enhancing the security and reliability of the system. By implementing this approach, fraudulent activities can be prevented, ensuring that only legitimate transactions are processed.

Building Interoperability

The Sui native bridge not only provides a secure and efficient means of transferring assets between blockchain networks but also lays the foundation for more advanced cross-chain interactions. By leveraging its robust trust model, integrating ECDSA for secure and verifiable transactions, and adopting a committee-based signature verification process, the Sui native bridge ensures high security and reliability while maintaining flexibility.

The scalability and flexibility of this bridge architecture allow for future expansions and integration with other blockchain networks. As the ecosystem develops, the bridge will support a wider range of assets and functionalities, such as customized cross-chain messaging, enabling unique cross-chain interactions.

The Sui native bridge represents a significant advancement in the field of Sui interoperability, providing a seamless and highly secure cross-chain asset transfer solution. With its launch on the mainnet, users can expect an increasingly powerful and versatile cross-chain bridge that meets current needs while also anticipating future demands.