- Polygon zkEVM is on the brink of an upgrade to become the first Type 2 zkEVM.
- Polygon Labs contends that the upgrade would provide the “optimal” balance between EVM equivalence and performance.
- This article explains the shift and how it affects users and developers.
Positive developments continue to come in hard and fast for Polygon zkEVM. As the Polygon-powered Ethereum Layer 2 bolsters DeFi activity in its mainnet beta stage 2, the network looks set to take a critical technological leap forward.
On Saturday, January 27, developers kicked off the ten-day timelock for the Etrog update, which promises to make Polygon zkEVM the first Type 2 zkEVM in a move that could see it attract more developers and optimize user experience.
In this article, DailyCoin explains what this means for developers and end users and how it compares with other zkEVM models, starting with why there are different models in the first place.
Why Are There Different Types of zkEVMs?
zkEVM’s are often hailed as the gold standard of scaling solutions because they can scale the Ethereum network without sacrificing security and decentralization. But these solutions have their challenges.
As Polygon Labs Developer Relations Engineer Jarrod Watts has previously highlighted, Ethereum was not initially designed with ZK applications in mind. Due to this design, some EVM operational codes can be difficult to prove, meaning that the closer a ZK virtual machine is to the EVM in operational code equivalence, the more difficult it is to generate ZK proofs.
The challenge of building an EVM-compatible ZK rollup is that Ethereum was not originally designed around ZK-friendliness.
This means that there are many parts of the Ethereum protocol that take a large amount of computation to ZK-prove.
— Jarrod Watts (@jarrodWattsDev) July 17, 2023
Faced with this challenge when designing zkEVMs, developers often have to perform a balancing act between compatibility and efficiency. The varying approaches to strike this balance have led to the different zkEVM types.
The ZK-EVM Types
In an August 2022 blog post, Ethereum co-founder Vitalik Buterin classified zkEVMs into four and a half categories based on EVM compatibility and performance. These classes are:
- Type 1: These are zkEVMs that are fully Ethereum equivalent and do not change any part of the Ethereum system. However, these take the longest time to generate proofs. An example of a Type 1 zkEVM is Taiko.
- Type 2: Like type 1, these zkEVMs are also fully Ethereum equivalent. Unlike Type 1, however, they make minor changes to the system to improve the proof generation times. While there are currently no Type 2 zkEVMs, Polygon, Linea, and Scroll have been working toward it, with Polygon looking set to take pole position.
- Type 2.5: These zkEVMs are EVM equivalent like the other two classes. However, they change gas costs to allow for faster proof generation. On the downside, these changes create DApp incompatibilities. Like Type 2, there are currently no Type 2.5 zkEVMs, though Kakarot has announced it is working on one.
- Type 3: These are almost EVM equivalent zkEVMs. They make changes to allow for even faster proof generation and easier development. Type 3 zkEVMs include Polygon zkEVM, Linea, and Scroll.
- Type 4: These zkEVMs are only high-level language equivalent. They do not support some DApps but are the easiest to build and the fastest in proof generation. zkSync Era is a type 4 zkEVM.
So what does becoming a Type 2 mean for Polygon zkEVM?
An Optimized Experience?
In the blog post announcing the beginning of the Etrog update ten-day timelock, Polygon Labs developers contend that Type 2 zkEVMs strike the “optimal” balance between EVM equivalence and performance.
The Etrog update means that developers could copy and paste their Ethereum code on the zkEVM with no required changes, thanks to the network’s complete EVM equivalence. The team would hope that this new level of compatibility will attract even more Ethereum developers to build for the rollup.
On the other hand, users may have to face slower withdrawal to Ethereum due to slower proof generation than Type 3. Nonetheless, Polygon Labs maintains that the Polygon zkEVM would remain relatively fast and cheap. To improve the user experience and bolster network efficiency, Etrog modifies the network to allow blocks to hold multiple transactions and batches to hold multiple blocks.
Etrog will go live on the Polygon zkEVM on February 6.
On the Flipside
- Type 2 compromises on proof generation speeds for full EVM equivalence.
- L2Beat data at the time of writing ranks Polygon zkEVM as the thirteenth largest Ethereum Layer 2 chain by TVL with $116 million.
Why This Matters
With Polygon zkEVM set to revamp its zkEVM model, you must understand what it entails and how it affects you.
Read this for more on Polygon zkEVM:
Polygon zkEVM Turns to Grants to Lure Builders in DeFi Push
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