In the world of blockchains, bridges are like the highways of the digital realm. Just as a traditional bridge connects two separate pieces of land, blockchain bridges link different blockchains, allowing the transfer of assets and information. Scroll, like many modern blockchains, utilizes bridges to interact with the wider crypto landscape, especially Ethereum.

What is a bridge in Scroll?

Scroll's bridge is a specialized system that allows users to move assets (like ETH, ERC-20 tokens, even NFTs) between the Scroll network and the Ethereum main network (and potentially other blockchains in the future). This bridge provides access to a wider range of assets and applications that may not be directly compatible with Scroll. Think of it as the gateway that expands Scroll's horizons.

Why do we need a bridge in Scroll?

• Expanded Opportunities: Bridges open the gates for tokens and assets on other blockchains to enter the Scroll ecosystem, significantly expanding what users can access and do.
• Increased Liquidity: Allowing assets to flow between Scroll and other networks increases liquidity in the Scroll ecosystem, which can improve asset prices and reduce risks.
• Cross-Chain Applications: Bridges lay the foundation for innovative applications and services that tap into the benefits of both Scroll and other blockchains.

How does the Scroll bridge work?

The details can get a bit technical, but conceptually here's the gist:

• Deposit: When you want to move an asset from Ethereum to Scroll, you initiate a transaction on the Ethereum network. This transaction essentially "locks" your asset in a secure smart contract on Ethereum. The smart contract holds your asset until an equivalent amount is minted on the Scroll network.
• Confirmation: The Ethereum network verifies the validity of your transaction and broadcasts it to the wider network. Once confirmed, the Scroll network receives a notification of the locked asset.
• Minting: Upon receiving the confirmation, the Scroll network mints a corresponding "wrapped" version of the asset. This wrapped token represents your original asset on the Scroll network and functions identically, allowing you to interact with it within Scroll's ecosystem.
• Reversal: When you want to move your asset back to Ethereum, you initiate a burn transaction on the Scroll network. This transaction "burns" (destroys) the wrapped token you hold on Scroll.
• Release: The Scroll network recognizes the burn transaction and communicates with the Ethereum smart contract that holds your original asset. Once verified, the smart contract unlocks and releases your original asset back to you on the Ethereum network.

Multichain Bridges

Scroll is also integrating several additional bridges to support multichain onboarding, providing more flexibility and access to diverse ecosystems. Here’s an overview of where some of these bridges are and their general structure:

Orbiter Finance

Orbiter Finance is a decentralized cross-rollup bridge designed to facilitate asset transfers between Ethereum and various Layer 2 solutions and sidechains. It uses a combination of smart contracts and off-chain relayers to securely transfer assets across different networks.

Its structure:

• Off-Chain Relayers: Relay information and validate transactions between different blockchains.
• Smart Contracts: Lock, mint, and burn assets to reflect their state across the bridged chains.

Bungee Exchange

Bungee is a bridge aggregator that enables users to transfer assets between multiple blockchains through a single interface. It intelligently routes transactions through the most efficient bridges available.

Its structure:

• Bridge Aggregation: Integrates multiple bridges to provide the best routing options.
• Smart Routing: Dynamically selects optimal paths for asset transfers based on factors like cost and speed.

Owlto Finance

Owlto Finance offers a cross-chain liquidity aggregation protocol that facilitates seamless asset transfers between various blockchains. It focuses on providing deep liquidity pools and efficient transaction processing.

Its structure:

• Liquidity Pools: Maintain pools of assets on different chains to facilitate instant swaps.
• Aggregation Protocol: Combines liquidity from multiple sources to ensure optimal execution.

Phesant Bridge

Phesant Bridge is designed to facilitate fast and secure cross-chain transfers of assets. It leverages a hybrid approach combining on-chain smart contracts with off-chain components to enhance efficiency and reliability in bridging operations.

Its Structure:

• On-Chain Smart Contracts: Handle the locking and unlocking of assets, as well as minting and burning of wrapped tokens, ensuring the integrity of cross-chain transfers.
• Off-Chain Validators: Provide a decentralized network of validators that confirm transactions and facilitate communication between different blockchains, enhancing security and reducing the risk of fraudulent transfers.

Wormhole

Wormhole is a generic message-passing protocol that allows arbitrary data to be transferred between blockchains, making it suitable for transferring assets, NFTs, and other cross-chain interactions.

Its Structure:

• Guardians: Decentralized set of validators that oversee cross-chain transactions.
• Generic Messaging: Supports various types of data and asset transfers between chains.

Stargate Finance

Stargate is a composable cross-chain bridge that provides native asset transfers between blockchains.

Its Structure:

• Unified Liquidity: Centralized liquidity pools accessible across multiple chains.
• Composable Bridges: Integrates with other protocols to enhance cross-chain capabilities.

Bridges are integral to Scroll's vision of expanding the potential of Ethereum and blockchain technology as a whole. By facilitating seamless interactions with other networks, Scroll's bridge unlocks access to a wider universe of assets, applications, and communities. It cements Scroll's role not as an isolated system, but a vibrant and connected player within the ever-evolving blockchain landscape.