An article to understand Scroll: the low-key challenger of the zkEVM competition
Compilation of the original text: Deep Tide TechFlow
Compilation of the original text: Deep Tide TechFlow
Given the popularity of the EVM among developers, there has been a desire to combine the scalability of zk Rollup technology with the developer experience of the EVM. This has led to an arms race of zkEVM systems, in which the main players are Scroll, zkSync, and Polygon, with Scroll keeping a low profile relative to the other two.
Due to the limitations of the EVM, zkEVM faces a necessary trade-off between compatibility/equivalence and performance. Vitalik Buterin listed a scale from 1 to 4 in an effort to clarify the difference between the various zkEVM design choices:
Scroll is in the middle of this tradeoff: they are building a 2.5 zkEVM.
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What Makes Scroll Different
By maintaining EVM equivalence, builders are able to directly migrate their applications from Ethereum L1 to Scroll without any modifications to their code. They are also fully open source, allowing anyone to use and verify their code.
Scroll also uses a fork of Geth for their sequencer, allowing it to inherit the battle-tested system for optimal compatibility with Ethereum.
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The structure of Scroll
Scroll's architecture has three main components: Scroll nodes, Roller network, and verification bridge.
The purpose of Scroll nodes is to build blocks from users' transactions and submit them to L1, as well as receive messages from L1.
The three main components of Scroll Node are Sequencer, Coordinator and Repeater.
The orderer receives a batch of transactions from the L2 mempool and executes them to generate a new L2 block.
The block's execution trace is then sent to the coordinator, who passes it to a randomly selected Roller to generate a proof.
The relayer monitors the state of the L2 blocks, their data availability and proof of validity from the rolling contract, and deposit and withdrawal events from the bridge contract to ensure everything can be verified.
The Roller network is responsible for generating proofs of validity. The Roller network will receive execution traces from the coordinator, send them to seven different proof circuits, aggregate them into one final circuit, and send the final block proof back to the coordinator.
The verification bridge consists of two contracts: Rollup contract and cross-chain bridge contract.
The cross-chain bridge contract handles messages sent between L1 and L2, including bridge transactions of ERC-20 Token.
The Rollup contract receives and stores state root and block data as Ethereum state and calldata. Once a block proof has been verified by the Rollup contract, the block is considered finalized.
route map
route map
Scroll has been in Pre-Alpha testing for the past 3 months, including permissioned smart contract deployment and whitelisted user access.
The next stage will be the Alpha testnet, where they will allow permissionless deployment of smart contracts, available to anyone.
Scroll’s mainnet will have a two-stage launch.
Phase 1 will run with a centralized orderer alongside a decentralized prover;
The main goal of the second phase is to decentralize the sorter.
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