What is Scroll?

Introduction to the Scroll Project

Scroll is a Layer 2 solution based on zkRollup on Ethereum, aiming to improve its performance and usability, thus addressing Ethereum’s congestion issues. Scroll was founded in 2021 by Ye Zhang, Sandy Peng, and Haichen Shen, with the vision of creating an EVM-equivalent zkEVM for better compatibility.

Main Mechanisms of Scroll

Zero-Knowledge Proof

A brief introduction to zkRollup as a scaling solution:
To ensure the security of Rollup, it must prove that its off-chain computations (transaction processing) have been executed correctly. There are two main mechanisms for proving the validity of off-chain computation: zero-knowledge proofs (zkRollup) and fraud proofs (optimistic Rollup). When zkRollup executes transaction computation and publishes the resulting state to L1, it also publishes a validity proof. This mathematical proof can demonstrate that the resulting state is indeed the one generated after correctly executing a batch of transactions.
Unlike previous solutions, Scroll’s zero-knowledge proof system consists of two independent layers, each adopting a different zero-knowledge proof system. This can be understood as DApp proof aggregation and inter-layer recursion.
The first layer directly generates proofs for different DApps. Scroll uses a universal and transparent zero-knowledge proof system in the first layer, meeting three attributes:

• (1) Fast proving with short (or none) proving keys;
• (2) Infinite scalability with low space complexity;
• (3) Setup for all DApps.

The first requirement allows users to efficiently generate proofs, even by themselves. This enables future privacy-preserving smart contracts with minimal proving efforts on the user’s side. Users can also outsource proof generation to miners, who can efficiently generate proofs without storing large proving keys for various DApps. The second and third requirements ensure that all smart contract logic is supported without requiring trusted setups or computation-heavy operations.
The second layer aggregates the proofs generated by the first layer and produces a succinct proof for them. This is a wrapping layer that can be seen as a direct bridge between Scroll and Ethereum, meeting two attributes:

• (1) Short proofs;
• (2) EVM-friendly verification algorithm.

These two requirements make on-chain verification more efficient. The purpose of this wrapping layer is to provide a universal on-chain verifier. With this wrapping, the on-chain verification smart contract can be generalized for various DApps. Miners will use universal proving keys to generate proofs for this layer.

Rollup Process

Let’s take a look at the Scroll zk-rollup network structure. The Scroll Network consists of three main components: Scroll Node, Roller Network, and Rollup Contract.

1. Scroll Node collects user transactions, constructs Rollup network blocks, and submits the created blocks to Ethereum. It also facilitates message passing between Ethereum and Rollup.
2. Roller Network is a network of Rollers, which act as provers that generate zero-knowledge proofs. Rollers are responsible for creating block proofs that represent the validity of a block.
3. Rollup Contract verifies the proofs received from Rollers, accepts the state roots summarizing the Scroll network’s state, and stores the state roots and block data in Ethereum’s state.

Rollup Process:

The Sequencer in Scroll Node continuously generates blocks and provides the execution trace T to the coordinator while submitting block data D to the Rollup contract on the Ethereum network. The coordinator selects a random Roller from the Roller Network and transmits T. The selected Roller generates P, which is a zero-knowledge proof of T. The generated P is sent back to the coordinator, who periodically collects P and sends it to another Roller to create A, a summary of these zero-knowledge proofs. Finally, the coordinator receives A and submits it to the Rollup contract on Ethereum, where the Rollup contract verifies it and grants finality to the corresponding block.

Block Finality:
When a block is created, its finality is determined through several stages. The block’s status changes depending on the process it is in:

• Pre-submitted: The block is proposed by the Sequencer, and T is passed to the Roller’s state. The block has not yet been submitted to Ethereum, but if the Sequencer is trustworthy, the block can be used in the pre-submitted state.
• Submitted: The block data has been submitted to the state of the existing Rollup contract on Ethereum. This means that the block data is available on the Ethereum network, but since verification is not yet confirmed, the validity of the operations cannot be guaranteed.
• Finalized: The entire process described above has been completed and verified to the aggregated ZKP state on Ethereum. Since the validity of the operations has been proven on the Ethereum network, it is a state that anyone can trust securely.

Scroll’s Position in Layer 2

Before the project’s TGE, Scroll’s TVL exceeded $960 million. The chain hosts an active copy of Aave V3, with over $330 million in locked value. Scroll has become one of the most prominent EVM-compatible chains.
The chain has achieved $367 million in bridge deposits, with the remainder being native assets. Scroll has two native DEXs and a suite of yield farming and DeFi lending protocols. The chain reports weekly active addresses at 255.52K.
Scroll is also a profitable chain, retaining revenue for its validators. At its peak, daily revenue reached $100,000.

Scroll’s Funding Background and Partners

• April 1, 2022: Scroll completed a $30 million Series A round, led by Polychain Capital, Bain Capital Crypto, and others.
• March 6, 2023: Scroll completed a $50 million funding round (undisclosed stage), co-led by Polychain Capital and Sequoia Capital.

Total Funding: $80 million
Latest Funding Valuation: $1.8 billion
Scroll’s ecosystem is thriving, with most mainstream DApps already extended to its mainnet, such as Lido, Ether.Fi, Chainlink, and AAVE. Uniswap and other established DApps have also recently announced participation in the ecosystem, building applications on the mainnet.

Scroll Tokenomics

$SCR: Governance Token

$SCR will be the main governance mechanism of the protocol, and as Scroll decentralizes, it will evolve into a protocol utility token:

1. Governance Right: Scroll will first decentralize governance through the Scroll DAO. Voting weight will be determined based on $SCR holdings within the community.
2. Proving Right: For long-term sustainability, the protocol will incentivize external parties to run provers and optimize their performance. $SCR will be involved in aligning the miner community and creating a robust prover network.
3. Sequencing Right: The Sequencer is responsible for ordering transactions and generating Layer 2 blocks, requiring high guarantees of liveness and real-time censorship resistance. $SCR will also serve as a bidding mechanism and incentive for sequencing rights.

Token Distribution

$SCR is expected to start transfers and sales on October 22, with an initial total supply of 1 billion tokens:

• Airdrop Rewards: 15%
• Foundation: 10%
• Ecosystem Development: 35%
• Early Contributors: 23%
• Investors: 17%
  15% of SCR tokens will be used for airdrops. The eligibility snapshot will be taken on October 19, with the first airdrop beginning on October 22. The airdrop will be split into two parts, with 7% of the tokens for the first airdrop and the remaining 8% reserved for future airdrops.
  Visit https://scroll.io/ to claim $SCR.

Gate.io Pre-market Trading for $SCR

To celebrate the upcoming launch of $SCR, Gate.io has introduced the pre-market trading for $SCR, allowing investors to get early access to this highly anticipated token.
Here are the steps to participate:

1. Visit the Pre-Market page, stake USDT, and mint $SCR tokens.
2. Trade $SCR PreToken on the $SCR PreMint trading page.
3. After the settlement date, complete the $SCR token delivery.![]

For more details on Gate.io $SCR PreMint benefits: https://www.gate.io/announcements/article/39754