Ethereum L2 expansion plan and zero-knowledge proof
Introduction
- A brief overview of existing solutions at the Ethereum L2 layer
- A brief overview of the future expansion direction of Ethereum L2
- A brief overview of the basic concept of zero-knowledge proof and the application of zero-knowledge proof in Ethereum
- A brief overview of the two products of stark ware, but not recommended for existing use and research
- Brief overview of polygon zkEVM, recommended use and research
zk-SNARK and zk-STARK
zk-SNARK and zk-STARK are the underlying technologies of zero-knowledge proof. Both are non-interactive proofs.
zk-SNARK, full spell Zero-Knowledge Succinct Non-Interactive Argument of Knowledge, that is, Zero-Knowledge Succinct Non-Interactive Argument of Knowledge.
zk-STARK, full spell Zero-Knowledge Scalable Transparent Argument of Knowledge, that is, Zero-Knowledge Scalable Transparent Argument of Knowledge.
The intuitive difference between the two is that zk-SNARK requires trusted settings, but zk-STARK does not.
Ethereum L2 expansion plan
There are two parameters that can be used to classify L2 scaling solutions. One is based on the encryption proof used, and the other is whether their Data Availability (DA) is stored on-chain or off-chain.
There are two main types of proofs:
- Validity Proofs - This is a mathematical proof that uses zero-knowledge (ZK, zero-knowledge) cryptography to ensure transaction validity
- Fraud Proofs - This kind of proof introduces a so-called Dispute Time Delay (DTD), once the proof is submitted to L2, the verifier has a certain amount of time to mark the invalid proof; invalid proof May contain incorrect state transitions, thus imposing penalties on the validators involved; the state is then rolled back to the most recent valid snapshot state
Data availability stored on-chain or off-chain:
- On-chain: State data is put together with all executed calldata (smart contract function calls, native token transfers, signatures) of all transactions into a cryptographic proof of transaction bundle/rollup, which makes all data accessible and verifiable on-chain.
- Off-chain: Executed calldata and state are processed by L2 and stored off-chain. This makes the scheme less secure and decentralized. However, the off-chain storage data scheme is easier to pack more transactions into a rollup, and therefore much faster than the on-chain calling data proof scheme.
Rollup
Rollup is currently the preferred layer-2 network solution for Ethereum expansion. By using Rollup, users can reduce gas bills by up to 100 times compared to a layer-1 network .
Rollups bundle ("bundle") hundreds of transactions into a single transaction on a layer-1 network. This will spread the cost of a layer network to everyone in the Rollup, making it cheaper for each user. Rollup transactions are executed outside the layer 1 network, but transaction data will be published to the layer 1 network. Rollup inherits the security of Ethereum by publishing transaction data to the layer-1 network. There are two different ways to implement Rollup: optimistic Rollup based on fraudulent proofs, and zk Rollup based on zero-knowledge proofs. Their main difference is how to publish this transaction data to the layer network.
Layer 2 based on optimistic rollup is Optimism and Arbitrum. Its advantages are: it is not difficult to be compatible with EVM, and you can directly use solidity to deploy smart contracts and directly develop Dapps; the disadvantages are: long waiting time for withdrawals, security, TPS and transaction costs It is not as good as zk-Rollup.
Layer 2 based on zk-Rollup is StarkNet and zkSync, its advantages are: higher security, more time-sensitive transaction confirmation, TPS and transaction cost are significantly better than optimistic rollup; but its disadvantage is that it is not easy to be compatible with EVM.
Currently the industry is developing zkEVM solutions, and now the polygon team has launched the first open source zkEVM solution, polygon zkEVM.
strong goods
StarkWare is currently the industry-leading zk-Rollup expansion solution development company. The core members of its team are the proposers and improvers of the two algorithms, and develop two product lines based on zk Stark technology: the expansion service engine StarkEx, Layer 2 expansion network StarkNet.
For the StarkWare team, its two "product lines" can be understood from two aspects.
On the one hand, from a technical point of view, both are solutions based on zk Stark technology. At the same time, the difference between the two is that StarkEx provides a series of basic components to provide programs for Ethereum chain applications (DApps). Serve. With the characteristics of customization, it can meet the needs of high scalability of special applications. In June 2020, the product was officially deployed on the Ethereum mainnet; while StarkNet's positioning is the opposite, it uses a general-purpose layer-2 expansion solution to meet users' needs for blockchain transaction efficiency and transaction cost optimization. Meet the compatibility and composability requirements of different applications, but the scalability (TPS, Gas fee optimization) is not as good as the customized StarkEx engine.
On the other hand, from the perspective of business model, StarkEx is oriented to B-end cooperative project parties, earning service fees or project sharing; while StarkNet is oriented to the vast number of C-end users, developers, sequencers, provers and other ecological participants. Profit by expanding the L2 ecosystem through tokenomics and technical support. Therefore, both technically and commercially, the two "product lines" complement each other.
Special attention: starkNet smart contracts are not compatible with EVM, but use the self-developed Cairo language
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starkware official website: Homepage - Starkware
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starknet contract code: https://etherscan.io/address/0xE267213B0749Bb94c575F6170812c887330d9cE3#code
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Stark ware introduction and starkEx architecture: research on StarkEx and StarkNet based on customized engine and layer2 expansion scheme of zero-knowledge proof system
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starkEx Github: starkware-libs/starkex-core (github.com)
polygon zkEVM
Polygon zkEVM is the first source code available for zk-Rollup, a zero-knowledge proof Ethereum Virtual Machine, and the first L2 scalability solution of its kind. Provides full EVM opcode equivalence for a smooth user experience and the security of Ethereum. The original project was named Hermez, and it was renamed Polygon zkEVM after Hermez was acquired by Polygon in August 2021. In V God's EVM compatibility level classification, the current Polygon zkEVM is tied for the third level with Scroll, surpassing other ZK Rollups, and is at the forefront of the current ZK Rollup in terms of EVM compatibility.
strong and trustless
- zk-SNARKs guarantee Ethereum-level security
- High throughput of 2000 TPS
- unmanaged architecture
- Full ownership and control of assets (censorship resistant)
- Data Availability on Ethereum Mainnet
The only decentralized zk-rollup
- Fully open source and community driven
- Seamless integration with Hermez REST API
- Permissionless Coordinator Network
- Decentralized Auction Model with Validation Reward Tokens
- Governance Minimization Strategy
Simplify Token Transfers
- Simple web and mobile app wallet
- Low cost token transfer
- Atomic swaps
- Fees paid in a single currency
- Fast and efficient withdrawals (withdrawals) within minutes
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polygon zkEVM official website: Polygon | Ethereum's Internet of Blockchains - Polygon
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official documentation of polygon zkEVM: Polygon zkEVM Documentation | Polygon Wiki
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polygon zkEVM GitHub：Polygon zkEVM (github.com)