The Layer-2 world is quite colorful; currently, according to L2BEAT data, there are actively over 40 blockchains. All these Layer-2 projects are adopting different approaches while trying to scale Ethereum. I wonder how this competition will evolve in a few years? Who will be the main players then? Let's get to know one of these projects, Scroll, more closely today.
Table of Contents
What is Scroll?
Scroll’s Founding Team
What is zkEVM?
How does Scroll work?
Scroll’s zkRollup Workflow
Scroll Ecosystem
What is Scroll?
Scroll is a zkEVM layer-2 solution to the Ethereum blockchain. Like many other L2s they aim to scale blockchains so that they can be accessible to billions of users. This requires making them both scalable and cheap enough to be accessible for all as well as being secure and easy-to-use for the ordinary user.
Scroll's Founding Team
Scroll, founded in 2021, started with the initiative of Ye, a mathematician, who, after the DeFi boom in 2020 and subsequent congestions on Ethereum, wondered, "How can we use zero-knowledge proofs here in a practical way?" Moving forward, Scroll began its journey with a three-person team comprising founding partners Ye Zhang, Sandy Peng, and Haichen Shen.
What is zkEVM?
A zero-knowledge Ethereum Virtual Machine (zkEVM) is a virtual machine that executes smart contract transactions in a way that’s compatible with both zero-knowledge-proof computations and existing Ethereum infrastructure. This enables them to be part of zero-knowledge rollups, layer-2 scaling solutions that increase transaction throughput while lowering costs.
A layer 2 is EVM compatible if it can run programs created for Ethereum environments without modifying the underlying smart contract logic. This makes layer 2s compatible with existing Ethereum smart contract patterns, token standards, and tooling. Being EVM compatible is important for the widespread adoption of these layer 2s, as it enables developers familiar with Ethereum’s Solidity programming language to build highly scalable applications using the same battle-tested tools they’re used to.
How does Scroll work?
First of all, it is useful to understand the architecture of Scroll in this regard. The scroll consists of 3 main components:
Scroll Node: Facilitates user and application interactions with Scroll by constructing L2 blocks, committing these to Ethereum's base layer, and managing L1 and L2 message exchanges. It comprises:
Sequencer: Accepts L2 transactions via a JSON-RPC interface, compiles transactions into L2 blocks, and generates new state roots based on the Ethereum node implementation (Geth).
Coordinator: Receives block execution traces from the Sequencer and assigns a Roller for proof generation.
Relayer: Monitors contracts on both Ethereum and Scroll for block status and message relay between L1 and L2.
Roller Network: Consists of provers (Rollers) that generate zkEVM validity proofs, ensuring transactions are executed correctly. They utilize hardware accelerators to improve proof generation efficiency. The process involves converting execution traces to circuit witnesses, generating zkEVM circuit proofs, and aggregating these proofs for block validation.
Rollup and Bridge Contracts: Connect Scroll to Ethereum, ensuring data availability for L2 transactions and facilitating asset and message transfers between L1 and L2. Rollup contracts store state roots and block data, while Bridge contracts enable cross-layer communication and asset bridging.
Scroll’s zkRollup Workflow
Block Generation and Commitment: The Sequencer compiles transactions into blocks, submitting transaction data to the Rollup contract for data availability and state roots for validation.
Proof Generation: The Coordinator selects a Roller to generate a validity proof for each block trace, with the possibility of parallel processing for efficiency. Every certain number of blocks, proofs are aggregated into a single proof.
Finalization: The aggregated proof is submitted to the Rollup contract, verifying the block's validity against its state roots and transaction data commitments, thus finalizing the blocks on Scroll.
For further details https://scroll.io/blog/architectureÂ
Scroll Ecosystem
Currently, there are over $150M worth of assets on Scroll. Moreover, you can find more than 100 apps & tools that operate on or are integrated with Scroll. An important point on the side of Scroll is that it provides EVM compatibility at the bytecode level, which allows applications like Aave to deploy their applications here first, despite other competing zk rollups (e.g., zkSync, Starknet) going to mainnet earlier than Scroll. This is why, for now, they are in a more advantageous position compared to other zk rollups in terms of having a more diverse ecosystem and integrating things from Ethereum faster.
Wrapping Up
When we look at Ethereum's rollup-centric roadmap, we can see how important rollups are. However, having many L2s makes things more competitive with each passing day. At this point, focusing on zk technology seems to provide the necessary infrastructure for the "next billion users" idea that is always brought up. Scroll stands out by focusing on this and being a grassroots, native team. Also, bytecode compatibility allows developers working on it to use their familiarity with Ethereum as quickly as possible. We will see together which rollups will emerge in the future; let's see how Scroll will position itself at that point.
If you want to follow Scroll more closely, you can take a look at our dashboard.
