How zkEVM works — types of zkEVMs and Polygon zkEVM vs zkSync

Ethereum has revolutionized the world of decentralized applications and smart contracts. As blockchain technology evolves, Ethereum has been seeking innovative ways to improve its scalability and privacy. One such solution is zkEVM, an advanced approach that relies on zero-knowledge proofs to enhance the Ethereum Virtual Machine (EVM). 

With the introduction of zkEVM (Zero-Knowledge Ethereum Virtual Machine), privacy and scalability have become focal points in the Ethereum ecosystem. In this blog post, we'll delve into the inner workings of zkEVM, explore its types, and compare two popular Layer 2 solutions: Polygon zkEVM and zkSync. We'll explore how it benefits developers and users.

To understand how zkEVM works, we need first to understand a few concepts:

What is Ethereum?

Ethereum is a decentralized, open-source blockchain platform that enables developers to create and deploy smart contracts. Without intermediaries, these self-executing agreements can facilitate various transactions, ranging from financial operations to supply chain management.

What is Ethereum Virtual Machine (EVM)?

The Ethereum Virtual Machine (EVM) is the runtime environment for executing smart contracts on the Ethereum blockchain. As a Turing-complete, stack-based virtual machine, EVM processes opcodes and performs arbitrary computations, making it an essential component of the Ethereum ecosystem.

What are Zero-Knowledge Proofs (ZKP)?

Zero-Knowledge Proofs (ZKP) are cryptographic techniques that allow one party (the prover) to demonstrate the validity of a statement to another party (the verifier) without revealing any information about the statement itself. By constructing mathematical proof, ZKP ensures the statement's authenticity.

zkEVM: Combining EVM with Zero-Knowledge Proofs

The Goal of zkEVM

The primary objective of zkEVM is to enhance privacy and scalability in the Ethereum ecosystem. By integrating zero-knowledge proofs with the Ethereum Virtual Machine, zkEVM enables private and scalable smart contracts while maintaining compatibility with existing contracts and developer tools.

Key Features of zkEVM

zkEVM's main features include its layered architecture, use of zkProofs, and the ability to generate and verify proofs for smart contract execution. These features contribute to the privacy and scalability of the Ethereum network.

How zkEVM Works: A Step-by-Step Guide

Step 1: Layered Architecture

zkEVM utilizes a layered architecture, which separates the EVM computation into distinct layers, such as control flow, arithmetic operations, and memory and storage manipulation. This approach simplifies the construction of the zero-knowledge proof.

Step 2: Execution Trace Generation

When a smart contract is executed on zkEVM, an execution trace is produced. This trace is a series of steps detailing the contract's execution and includes information about the program counter, stack, memory, and storage.

Step 3: Circuit Construction

The execution trace is then converted into a mathematical representation called a circuit. The circuit is a set of equations representing the constraints necessary for the execution trace to be valid. It is used to generate a zkSNARK proof that verifies the correctness of the execution without disclosing the trace itself.

Step 4: Proof Generation and Verification

The prover generates a zkSNARK proof, attesting to the accurate execution of the smart contract. The verifier then checks the proof. If it is valid, the verifier accepts the computation's result and updates the blockchain state accordingly.

Types of zkEVM

zkSNARK-based zkEVM

zkSNARKs, or Zero-Knowledge Succinct Non-Interactive Arguments of Knowledge, are cryptographic proof enabling efficient computational integrity verification. zkSNARK-based zkEVM leverages this technology to ensure privacy and scalability in the Ethereum network. The advantages of zkSNARKs include their small proof size and fast verification times. However, one limitation of this approach is the need for a trusted setup, which can be a potential security vulnerability if not executed correctly.

zk-STARK-based zkEVM

Another type of zkEVM is the zkSTARK-based zkEVM, which employs Zero-Knowledge Scalable Transparent Arguments of Knowledge. zkSTARKs are an alternative cryptographic proof system that eliminates the need for a trusted setup. They offer enhanced security and scalability but may have larger proof sizes and longer verification times than zkSNARKs. The choice between zkSNARK-based and zkSTARK-based zkEVM will largely depend on the specific use case and the desired balance between security, privacy, and performance.

Polygon zkEVM vs zkSync

Polygon zkEVM

Polygon zkEVM is a Layer 2 scaling solution that combines the power of zkEVM with the robust Polygon ecosystem. It aims to provide developers with a seamless, high-performance environment for building and deploying smart contracts on Ethereum. Some key features of Polygon zkEVM include fast transaction times, reduced gas fees, and enhanced security through zero-knowledge proofs. Additionally, Polygon zkEVM benefits from the broader Polygon ecosystem, which offers a range of developer tools and resources for building decentralized applications.

You can read more about Polygon zkEVM here: www.auroblocks.com/blog/what-is-polygon-zkevm-how-it-enhances-ethereum-and-layer-2-scaling-solutions

zkSync

zkSync is another Layer 2 scaling solution that leverages zero-knowledge proofs for efficient transaction processing on Ethereum. Like Polygon zkEVM, zkSync aims to provide Ethereum users and developers with a high-performance environment. However, there are some differences in their implementation and use cases. zkSync focuses on delivering a seamless user experience with features like instant transaction confirmations and low gas fees. While zkSync has support for smart contracts, its primary focus is on improving transaction throughput and reducing costs for simple transfers.

You can read more about zkSync here: www.auroblocks.com/blog/zkrollups-and-development-on-zksync-2-0

Comparison

When comparing Polygon zkEVM and zkSync, it is essential to consider their respective performance, security, privacy, ecosystem integration, and developer experience. Both Layer-2 scaling solutions offer improvements in transaction throughput and reduced gas fees.

However, Polygon zkEVM may have an edge in smart contract execution and compatibility with the Ethereum ecosystem, making it a more attractive option for developers building complex decentralized applications. On the other hand, zkSync may be better suited for users looking for a solution focused on simple transfers and ease of use.

Refer to the table below for a detailed comparison: 

Use Cases and Benefits of zkEVM:

Privacy-Preserving Smart Contracts

zkEVM allows developers to create privacy-preserving smart contracts, ensuring that sensitive information remains confidential while still enabling the execution and verification of transactions.

Scalability

By employing zkSNARKs, zkEVM reduces the computational load on the Ethereum network, which can lead to improved transaction throughput and reduced congestion.

In conclusion, zkEVM represents a significant advancement in the Ethereum ecosystem by incorporating zero-knowledge proofs to enhance privacy and scalability. This innovative technology allows for the execution of smart contracts while safeguarding sensitive data and improving overall blockchain performance. By examining the different types of zkEVM and comparing Polygon zkEVM and zkSync, we explored the potential benefits and trade-offs associated with each solution. As the blockchain ecosystem continues to evolve, it is essential to stay informed about these innovations and their implications for the future of decentralized technology.

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