5 min read

Overview

In this guide, we will learn about the Polygon zkEVM protocol, which combines cryptographic zero-knowledge proofs and the Ethereum Virtual Machine (EVM) to provide a Layer-2 Rollup solution.

What is Polygon?

Polygon, previously known as Matic, is a blockchain platform offering diverse blockchain solutions. Their most popular offering is Polygon PoS, a Layer 2 proof-of-stake blockchain providing low-cost transactions, full EVM compatibility, and web3 community support.

Other offerings from Polygon include Polygon Supernets, Polygon Miden, Polygon ID, and last but not least, Polygon zkEVM, which we will cover in the next section.

Not only does Polygon support a full fledge of blockchain solutions, but they have also partnered with some of the biggest companies in the world, such as Starbucks, Disney, Reddit, and Meta to offer decentralized products such as NFTs, the Metaverse and an accelerator program to further web3 innovation.

What is Polygon zkEVM?

Polygon zkEVM is an exciting new development in the world of Ethereum-compatible blockchains. It combines two powerful technologies, zero-knowledge proofs (aka zk-proofs) and Ethereum Virtual Machine (EVM), to create a highly scalable and secure blockchain solution.

So what does that mean exactly? Well, let's break it down. First, let's talk about zero-knowledge proofs. These are cryptographic proofs that allow a party to prove the authenticity of a piece of data without revealing any additional information. For example, let's say you have a friend who doesn't believe you have a superpower. You claim that you can unlock any door without a key. To prove your claim, you could use a zero-knowledge proof by asking your friend to choose any door and not show you the key. Then, you can approach the door and unlock it without a key. Your friend can see that the door is unlocked, but they still don't know how you did it or what your secret method is. This is a zero-knowledge proof because you proved your claim without revealing any information about your method.

By using zero-knowledge proofs, it's possible to prove that a transaction is valid without revealing any sensitive information about the transaction itself. This makes it possible to build more secure and private blockchains, which is a huge benefit in today's digital world. To learn more about zero-knowledge proofs, check out this QuickNode Guide - Intro to Zero-Knowledge Proofs.

Next, let's talk about the Ethereum Virtual Machine (EVM). This is the software that runs on the Ethereum blockchain and allows developers to write smart contracts. Smart contracts are self-executing contracts that are stored on the blockchain and can be programmed to execute when certain conditions are met automatically.

What does this all mean for users transacting on the chain? The Polygon zkEVM Mainnet Beta will be at least one order of magnitude cheaper than Ethereum. Users can expect to pay around ~$0.000084 for a single transaction, which should have a finality of ~2-3 seconds.

Now, let's briefly dive deeper into the architecture of the zkEVM protocol.

At the heart of the Polygon zkEVM is three components, the Trusted Sequencer, Trusted Aggregator, and Consensus Contract.

• The Trusted Sequencer generates and publishes proofs of valid state transitions and is supported by a network of Trusted Aggregators, which help to process and validate transactions in a scalable and efficient manner.
• The Trusted Aggregator retrieves L2 batches from the Trusted Sequencer and generates zk-proofs attesting to the validity of the batches' integrity. These ZK proofs are generated using a special off-chain EVM interpreter.
• The Consensus Contract serves as the final arbiter of truth, ensuring that all state transitions are valid and that the system remains secure and trustworthy. This Consensus Contract resides on Ethereum L1 and plays a big role in ensuring that Polygon zkEVM uses Ethereum L1 security.

zkEVM vs. EVM

zkEVMs offer other compelling benefits compared to the Ethereum Virtual Machine (EVM).

For one, it boasts a low cost compared to other layer-2 rollups. Unlike optimistic rollups, which must post all transaction data on-chain, zkEVMs only need to publish final state changes, thanks to zero-knowledge proofs. This cost-saving feature is passed on to the applications and end-users of the zkEVM, making it an attractive option for those who are mindful of their budget.

Additionally, zkEVM provides fast finality due to its validity being finalized once it is published on Ethereum L1. Lastly, zkEVM provides scalability as it follows different consensus rules compared to Ethereum but still verifies its proofs on Ethereum L1.

Additionally, use cases of the Polygon zkEVM include:

• DeFi: Lending Protocols, DEXs, and Yield protocols all have a secure place on Polygon zkEVM due to its fast finality times and Ethereum L1 security.
• NFTs: Interoperability, low costs, and fast transaction finality on the Polygon zkEVM allows NFTs and Gaming to thrive.
• Payments: Polygon zkEVM provides a low-fee environment for users interested in transacting in real time. Transactions can be completed near-instantaneously.

To learn more about the differences between the Ethereum Virtual Machine (EVM) and Polygon zkEVM, take a look at the following resource.

zkEVM Bridge

Interoperability is the ability to exchange data with other blockchains and is a crucial feature of any blockchain. Luckily, the Polygon zkEVM has a bridge that users can use to communicate or transfer assets to and from. The bridge currently supports communication and transfer to the Ethereum mainnet and other L2s built on top of Ethereum.

The bridge architecture in a nutshell, follows a process of locking a token on the origin blockchain and minting a wrapped version of the token on the destination blockchain.

To participate in the Polygon zkEVM ecosystem, check out the Polygon zkEVM Bridge here.

Connecting to zkEVM

In order to interact with Polygon zkEVM, you'll need an API endpoint. You can do this by running your own local node (see instructions here), or you can leave the heavy lifting to us and get up to 8x faster response times by creating an endpoint on QuickNode. Sign up for a free account here).

QuickNode supports both HTTP and WebSocket requests to the Polygon zkEVM network. QuickNode currently supports the Polygon zkEVM Testnet network. Once your endpoint is created, you can use this API endpoint on a web3 wallet or dApp to make fast and efficient calls to the Polygon zkEVM chain!

Additional Resources

If you want to dive deeper into the Polygon zkEVM protocol, take a look at the following resources:

• QuickNode Polygon zkEVM API Documentation
• Intro to Zero-Knowledge Proofs
• Run a local zkNode
• Run a Production zkNode
• Zero-Knowledge Research

Final Thoughts

That's it! I hope this guide has given you a good overview of Polygon zkEVM and the power of zero-knowledge proofs. If you're having trouble, have questions, or want to talk about what you can build on zkEVM, drop us a message on Discord or Twitter!

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