Overview
Scroll (SCR) is a Layer 2 scaling solution built on Ethereum, leveraging zero-knowledge rollups (zk-rollups) to enhance scalability while maintaining Ethereum’s decentralization and security. By offloading computation from the mainnet, Scroll reduces transaction fees, increases throughput, and ensures compatibility with existing Ethereum tools. With the introduction of the SCR token, Scroll is moving towards full decentralization through a community-driven governance model.
Scroll’s key metrics at the time of mainnet launch | Source: Scroll blog
Core Features
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Zero-Knowledge Rollups (zk-Rollups): Scroll batches off-chain transactions and submits proofs to Ethereum, ensuring high throughput with low fees.
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Ethereum Compatibility: Scroll zkEVM maintains compatibility with Ethereum’s Virtual Machine (EVM), allowing developers to migrate dApps seamlessly.
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Three-Layer Architecture:
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Settlement Layer: Uses Ethereum for final data availability and transaction verification.
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Sequencing Layer: Executes and batches transactions into L2 blocks.
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Proving Layer: Generates zk proofs for state transitions and ensures correctness.
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Transaction Cost Reduction: Transaction fees on Scroll are significantly lower than those on the Ethereum mainnet, enabling affordable microtransactions.
Technical Overview
Transaction Lifecycle
Sequencing transactions in Scroll | Source: Scroll whitepaper
In Scroll, every transaction follows three key steps before it’s fully completed and secure. By following this three-step process—Confirmed → Committed → Finalized—Scroll ensures fast and secure transactions, backed by the power of Ethereum. This combination of speed and security makes Scroll a powerful Layer 2 solution for anyone interacting with the blockchain.
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Confirmed:
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This is the first step. When a user submits a transaction (like transferring tokens or interacting with a dApp), Scroll’s network processes and executes the transaction on its Layer 2 system.
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The transaction is added to a new block on the Scroll Layer 2 (L2) network, similar to how blocks are created on the Ethereum blockchain. At this point, the transaction is visible on the network, but it hasn’t been fully secured on Ethereum yet.
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Committed:
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Once several transactions have been confirmed, Scroll groups them into batches. Think of this step like bundling several receipts together into one envelope for safekeeping.
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This batch of transactions is then submitted to the Ethereum blockchain. This ensures the data is safely recorded on Ethereum, which acts as the main layer for security and availability. Even if Scroll’s network experiences downtime, the data is still available on Ethereum, providing a backup.
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Finalized:
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In the final step, a zero-knowledge (zk) proof is created to verify that all the transactions in the batch were processed correctly. This is like a digital certificate proving everything inside the batch is accurate and trustworthy.
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Once Ethereum confirms the zk proof, the batch of transactions becomes finalized. At this point, the transactions are set in stone, meaning no one can change or reverse them.
Sequencing and Proving Model
Source: Scroll whitepaper
Scroll’s network has three important parts that work together to make transactions fast, secure, and compatible with Ethereum.
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Sequencer: It collects transactions happening on Scroll's Layer 2 (L2) network (like token transfers or smart contract operations). Instead of sending every single transaction to Ethereum individually (which would be slow and costly), the sequencer batches them into groups. This way, many transactions are combined into one package. Once the transactions are grouped, the sequencer posts the batch data to Ethereum, ensuring it’s safely recorded on the main blockchain. This process keeps things efficient and ensures the data is available even if Scroll experiences technical issues.
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Proving Layer: After the sequencer has batched transactions, it’s time for the Proving Layer to get to work. This layer uses GPU-accelerated provers (super-powerful computers) to create zero-knowledge (zk) proofs. A zk proof acts like a mathematical guarantee that all the transactions in the batch were processed correctly—without anyone needing to recheck each individual transaction. By using these advanced proofs, Scroll ensures that transactions are finalized quickly and securely on Ethereum.
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zkEVM: The zkEVM is the brains of Scroll’s network. It’s an upgraded version of Ethereum’s smart contract engine (called the Ethereum Virtual Machine, or EVM) that integrates zero-knowledge proof technology. This means that all smart contracts running on Ethereum can also run smoothly on Scroll without needing to be rewritten. Developers can deploy their existing dApps on Scroll, enjoying lower fees and faster speeds, while still benefiting from Ethereum’s security. The zkEVM also ensures that every transaction follows strict security rules, giving users peace of mind that their assets and data are safe.
Together, the Sequencer, Proving Layer, and zkEVM form the core of Scroll’s infrastructure. They ensure transactions are processed quickly, securely, and at a lower cost, while staying fully compatible with Ethereum’s tools and ecosystem. This makes Scroll an ideal platform for anyone looking to use dApps without the high fees and delays of the Ethereum mainnet.
SCR Token and Tokenomics
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Token Name: Scroll (SCR)
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Total Supply: 1,000,000,000 SCR
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Airdrop Snapshot Date: October 19, 2024
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Launch and Airdrop Round One Claim Date: October 22, 2024
Token Utility
The SCR token is integral to decentralizing Scroll’s governance, proving, and sequencing mechanisms:
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Governance: SCR powers the Scroll DAO, giving holders voting rights on protocol upgrades and operational decisions.
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Proving Incentives: Provers are rewarded in SCR for generating zk proofs (ZKPs).
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Sequencing Role: SCR is critical for maintaining high-performance sequencing operations and ensuring real-time transaction finality.
Token Distribution
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Airdrops (15%):
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7% allocated to the first airdrop for early contributors and active users.
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8% reserved for future airdrops over the next 12-18 months.
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Ecosystem & Growth (35%):
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25% allocation for ecosystem and growth
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10% allocated to the Scroll DAO Treasury.
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Scroll Foundation Treasury (10%): 20 million SCR unlocked at launch, with the rest released gradually over four years.
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Core Contributors (23%): Tokens allocated to the core team and advisors, with a four-year vesting schedule.
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Investors (17%): Tokens unlock after one year, fully vested by the fourth year.
Token Release Schedule
Key Developments and Roadmap (as of October 2024)
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Launch of Scroll Mainnet: Scroll officially launched its mainnet on Ethereum, delivering a Layer 2 solution powered by zk-rollups to enhance scalability and reduce transaction costs. This step ensured the platform's compatibility with Ethereum-based dApps and tools, promoting wider adoption.
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Curie and Bernoulli Upgrades:
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Curie Upgrade (July 2024): Introduced gas fee reductions of about 1.5x, compressed transaction data using the Zstd algorithm, and adopted a modified EIP-1559 fee model. Additionally, new EVM opcodes were integrated, enabling better dApp performance.
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Bernoulli Upgrade (April 2024): Added support for EIP-4844 data blobs and implemented SHA2-256 precompile, improving security and transaction efficiency on the Scroll network.
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Testnet Operations and Feedback Collection: Before the mainnet launch, Scroll operated on the Sepolia testnet, allowing developers and users to interact with dApps, perform transactions, and provide feedback. This testing phase was essential in refining network functions before moving to production.
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Introduction of zkEVM Circuit Updates: Throughout 2024, Scroll enhanced its zkEVM by increasing the number of layers in its proving system and optimizing the recursion mechanism for SNARK aggregation, resulting in faster transaction finality.
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Progressive Decentralization Roadmap: The roadmap includes plans to decentralize network components like governance, sequencing, and proving through a community-driven DAO and ecosystem partnerships. This approach ensures resilience against centralization risks as the network matures.
Conclusion
Scroll’s zk-rollup technology offers an efficient, scalable solution for Ethereum users, maintaining security while reducing costs. The introduction of SCR accelerates the shift toward a decentralized infrastructure, empowering the community through governance and staking opportunities. With partnerships across mobile, energy, and financial sectors, Scroll is positioned to become a key player in the future of Layer 2 scaling solutions.
