Polygon’s technical lead explains what to expect from zkEVM

The Ethereum ecosystem is set to witness one of the hottest blockchain trends this year, with numerous companies eager to exploit Polygon’s upcoming zkEVM rollup.

What are zero-knowledge proofs?

Zero-knowledge (ZK) technology is a cryptographic solution reshaping the blockchain industry. They execute languages and low-level bytecode at a programmable level, backed by the same rules as the Ethereum mainnet.

It is a virtual machine that utilizes zero-knowledge proofs to verify data without revealing any information about the data’s content or properties. It is a censorship-resistant protocol replicating the transaction execution environment of the Ethereum mainnet.

Vitalik Buterin, the founder of Ethereum, categorized zkEVMs into four main types and a fifth. Here is his breakdown of these types.T

1. Type-1 zkEVMs: fully equivalent to Ethereum
2. Type-2 zkEVMs: EVM (not Ethereum) equivalence
3. Type-3 zkEVMs: departing from EVM
4. Type-4 zkEVMs: close cousins to the EVM

“The project is a full engineering project,” said Jordi Baylina, who leads the technical team building the Polygon zkEVM. “The idea is that with these electronics, we somehow built a processor. On top of that, a program can be written that processes transactions. It’s a full stack of components with different teams working in each of these layers in these stacks.”

In a YouTube video released Mar. 2, Baylina explained the technical components behind the rollout, “the system that we are building is censorship resistant. It’s not a perfect solution, but up to a certain point because the system is not universal.”

“We created the assembly itself. It’s a new processor, new assembly, new way of writing hardware. So it’s like you are creating a technology, but at the same time you need to learn to use the technology you are creating, which is, from the generic perspective is fascinating, but it’s also very challenging.”

Technical details

With the zkEVM rollup, an ERC-20 transfer will define unique data infrastructures such as ProgramCounter, GlobalCounter, EVMWord, GasInfo, and GasCost, which include and contain elements such as stack, memory, and opcodes. The pc and gc are encapsulated to usize, whereas EVMWord encapsulates a u8 array with a length of 32.

While StackAddress is represented as a usize, Stack is a dynamic array consisting of EVMWord. MemoryAddress is also a usize, with values between 0 and 1023, while Memory is an array of u8. To simplify memory-related operations, developers cleverly utilize Rust macros to extract critical memory information such as index and range traits and implement them standardized. On the other hand, Storage is represented by a HashMap, and its key values are all EVMWord.

The race for zkEVM supremacy

The race is on to hit the market with a working product.

Several projects are in a race to launch the first fully functional and EVM-equivalent zkEVM, with some of the top contenders being Polygon zkEVM, zkSync, StarkNET, and Scroll.

Polygon zkEVM’s is open-source and aims to cut transaction costs by up to 90%, while zkSync 2.0 is live on the Ethereum Testnet, allowing developers to write Solidity smart contracts. StarkNET uses ZK-STARKs, which are more secure but have limitations, and Scroll is building a high composability solution that prioritizes security and transparency.

Polygon’s $250M bet on zkEVM

Polygon purchased the Hermez Network for $250 million in 2021 and later launched its Ethereum Layer-2 ZK-rollup solution, Polygon Hermez, in mid-2022. In July 2022, Polygon announced the rebranding of Polygon Hermez to Polygon zkEVM, which adopted the Type-2 zkEVM approach to be EVM-equivalent but not Ethereum-equivalent.

Developers will need to adapt code and EVM tools to the ZK-rollup. Polygon aims to reach 2000 transactions per second and cut transaction costs by up to ninety percent, making it less expensive than the Ethereum Mainnet. Polygon launched its zkEVM Public Testnet on October 10.

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