Original author: cookies, venture capital analyst Original translation: Felix, PANews When Ethereum faced network congestion, sky-high fees made the Ethereum network too expensive for some users to afford, causing many users to leave the Ethereum ecosystem. Given Ethereum's rollup-centric roadmap and Vitalik's position that ZK rollups will beat Optimistic rollups in the future. Polygon, an Ethereum sidechain designed to solve scalability problems, sees the potential of ZK in bringing the next billion users into the blockchain field and has invested $1 billion to build ZK solutions. Regarding Polygon's layout on ZK, venture capital analyst cookies interprets Polygon's four major ZK solutions. Polygon Hermez | zkEVMHermez is the first decentralized ZK Rollup on the Ethereum mainnet and began providing payment services as early as March 2021. Polygon Hermez is based on the ZK-SNARK architecture and aims to solve the scalability problem of the Ethereum blockchain by using zero-knowledge proofs to enable faster and cheaper transactions on the Ethereum network. Since the EVM was not created to generate ZK proofs (ZKP), Polygon Hermez mainly builds zkEVM by recreating all the EVM operation codes. Why zkEVM?By building zkEVM, the EVM operation codes simulated by Polygon Hermez can bring the following advantages:1. Inheriting the strong security of Ethereum2. Easy to adopt, because the Ethereum developer community can easily migrate their EVM work to zkEVM and use existing tools (good development experience). Performance The ZK-SNARK-based architecture is able to provide up to 2000 TPS and keep the cost below 300,000 Gas. Polygon Zero | SNARK + STARKPolygon Zero was formerly known as Mir Protocol. When Polygon Zero first developed Plonky 2, it took 2 minutes to generate a recursive proof. Now Plonky 2 can generate a recursive proof on a laptop in just 170 milliseconds. Polygon Zero will eventually build the most scalable zkEVM powered by Plonky 2. Plonky 2 is a recursive SNARK that is 100x faster than any other ZK scaling solution on Ethereum.This is achieved by combining the advantages of STARKs (fast proofs and no trusted setup) and the advantages of SNARKs (recursion, low verification cost). EVM Compatibility Plonky 2 is compatible with native Ethereum, supports Solidity code, and converts it to ZK bytecode. This allows Polygon Zero to leverage the existing Ethereum dApp ecosystem. Polygon Miden | STARK STARK-based rollups have the following features: Transparent and scalable: no trusted setup/preprocessing required Lean cryptography: future quantum computer attacks are impossible High performance: leading proof generation and verification times Polygon Miden is centered around the Miden VM (Virtual Machine) and supports arbitrary programs. It is more developer-friendly by hiding all the cryptographic complexity of ZKPs and following architectural patterns familiar to developers (stack machines, read-write memory, etc.). Security One of the main features of Polygon Miden is security. The protocol removes some unsafe features (available on the EVM), which makes it easier to perform static analysis of smart contracts and prevent certain bugs at the Virtual Machine (VM) level. EVM compatibility Miden is compatible with Ethereum at the Solidity level. Developers can deploy most Solidity smart contracts on Miden without modification. Another novelty is the compatibility with other languages ​​such as Move and Sway. At the performance release, TPS will be between 1000 and 2000. Once the shards are deployed on Ethereum, TPS will reach about 20,000 TPS. Polygon Nightfall | Optimistic + ZK In contrast to the above ZK solutions, Nightfall focuses on private transfers and payments, supporting ERC 20, ERC 721 and ERC 1155 tokens. Any data that does not need to be stored on the smart contract is stored off-chain, optimizing the smart contract. The team is working on an instant withdrawal mechanism so that users can bypass the 1-week deadline for submitting fraud proofs. The protocol is significantly slower, reaching a maximum of 105 TPS. But it is estimated that the gas fee for transfers can be reduced by up to 86%, stabilizing at about 9000 gas. Comparison The figure below is the author's summary of the four solutions: Conclusion Obviously, Polygon is investing a lot of time and money to take the lead in developing the ZK expansion solution.Let’s wait and see the performance of the mainnet and how it works together with other ZK protocols.