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Optimistic vs. ZK rollups: Who will win Ethereum's Layer 2?


Introduction


Rollups move computation (and state storage) off-chain, but keep some data per transaction on-chain. To improve efficiency, they use a whole host of fancy compression tricks to replace data with computation wherever possible. The result is a system where scalability is still limited by the data bandwidth of the underlying blockchain, but at a very favorable ratio: whereas an Ethereum base-layer ERC20 token transfer costs ~45000 gas, an ERC20 token transfer in a rollup takes up 16 bytes of on-chain space and costs under 300 gas. 


Optimistic rollups are layer 2 (L2) protocols designed to extend the throughput of Ethereum's base layer. They reduce computation on the main Ethereum chain by processing transactions off-chain, offering significant improvements in processing speeds. Unlike other scaling solutions, such as sidechains, optimistic rollups derive security from Mainnet by publishing transaction results on-chain, or plasma chains, which also verify transactions on Ethereum with fraud proofs, but store transaction data elsewhere.


As computation is the slow, expensive part of using Ethereum, optimistic rollups can offer up to 10-100x improvements in scalability. Optimistic rollups also write transactions to Ethereum as call data, reducing gas costs for users.


Optimistic vs. ZK rollups


According to Vitalik Buterin, “optimistic rollups are likely to win out for general-purpose EVM computation and ZK rollups are likely to win out for simple payments, exchange, and other application-specific use cases.” Does the market reflect this prediction or is the marketplace showing something different?


Rollups with ZKLoopring: 

An L2 protocol that allows for non-custodial gas-free decentralized trade.

ZKSync: Popular L2 scaling and privacy engine based on zero-knowledge proofing.

Immutable X: Highly scalable, non-custodial L2 protocol for NFTs.


Rollups that are optimistic

Optimism: Cheap, scalable, EVM-equivalent architecture-based L2 extension of the existing Ethereum software.

Boba Network: Hybrid computational platform and L2 .scaling solution that utilizes Optimistic Rollups

Arbitrum Bridge: Ethereum L2 scaling chain.


The case for Optimistic or ZK rollups


Ready for DeFi

Recently improvised documents about Arbitrum ensure the simplicity of the process for migrating applications. Therefore you are less likely to confront issues, notably achieving the set of functionalities of alternative EVM-supported scaling solutions in the specific optimistic rollups.


Whereas compatibility is a significant and critical issue for the protocols of ZK rollups. The basic need for validity proofs for every type of transaction in the segment of ZK rollups issues complexities for developing the roll-up technology. It serves promising results in the field of use cases across discrete tasks like direct transfer and trading.


Validity proof

The most noticeable point of difference in ZK rollups versus optimistic rollups comparison brings attention to the validity proof. As a significant fact, it is the first point of difference between the two layers of scaling approaches introduced in this discussion. In the specific case of ZK rollups, you mainly have validity proofs about ZK proof techniques to ensure transaction validity effectively.


On the contrary, optimistic rollups do not come with inheritance validity proofs. You, as a user, would have to challenge a specific transaction bundle in optimistic rollups for the significant computation of fraud proofs to determine the validity of transactions.


Ease of Programming

You can speculate that data compression flexibility and EVM compatibility are vital highlights of the optimistic rollups for ensuring ease of programming. The specific data compression advantages in optimistic roll-ups help effectively publish complete transaction data to Ethereum’s necessary and leading network as detailed call data.


In contrast, ZK rollups do not need significant publishing transaction data on Ethereum. The particular ZK-STARKs and the ZK-SNARKs are held responsible for efficiently verifying the accuracy of the rollup state. Nevertheless, you still struggle with programming the significant ZK rollups, which require clear cryptographic proof.


Transaction Costs

Optimistic rollups represent a knowledgeable, optimistic view on the segment of cost as you invest only in the particular areas that matter of scalability. The roll-up prices are considerably lower as the optimistic rollups significantly depend on publishing minimal amounts of data on Ethereum. Without needing to provide proof for a transaction unless it is challenged in an impressive number of cases. Moreover, the support of EIP 4844 protocols can help make optimistic rollups cheaper for you.


On the other hand, ZK rollups accompany massive amounts of cost as a reason for computational proof. The excessive amount of overhead accounts for the cost associated with the verification creation of the evidence for the different numbers of transaction blocks.TrustThe significant element of trust also issues one of the critical determinants in the Ethereum layer 2 comparisons based on different factors. You do not need a trusted set-up in the case of optimistic rollups. However, ZK rollups depend on a specific trusted setup for acquiring desired functionality.


Live Monitoring

In the scenario of ZK rollups, you do not have to think about monitoring the layer 2 chain in real time for the detection of fraud. Contrarily, the verifiers must maintain track of the fundamental role of the state along with the one referred to in the state route to enable fraud detection for optimistic rollups effectively.


Security

The aspect of security in optimistic rollups effectively depends on crypto-economic incentives for users like you to ensure roll-up safety. At the same time, ZK rollups depend on the cryptographic security proof with ZK proofs. Therefore both these roll-up types are placed toe to toe with each other in a competition on a security basis.


Who will be the winner?


The intense competition to “win Ethereum” boils down to one question: Will developers and users flock to the most advanced technology, or will they just go with what works?


Steven Goldfeder, CEO of Offchain Labs, which created Arbitrum, said ZK rollups are “orders of magnitude” more expensive than optimistic ones because of the intensive calculations required.ZK supporters say optimistic rollups take too long to be fully completed since they can be challenged up to seven days after they are executed, which could mean a delay in withdrawing tokens. Some services will pay users instantly, minus a small fee, and take on the risk of being challenged. Challenges are rare, though, because of the penalties for posting a faulty rollup or challenging an authentic one.


Leading Projects on Optimistic Rollups


Curve is a decentralized finance (DeFi) platform built on the Ethereum blockchain. It is designed to provide users with a fast, efficient, and secure way to trade and exchange cryptocurrencies. Curve offers a variety of features, including low-cost trading, liquidity pools, and support for a wide range of cryptocurrencies. It is a popular platform among DeFi users and is known for its user-friendly interface and advanced trading features.


Perpetual is designed to provide users with a decentralized, trustless, and secure way to trade and exchange cryptocurrency assets. Perpetual Protocol uses a unique liquidity pool model to facilitate trading and offers a variety of features, including low fees, high liquidity, and support for a wide range of cryptocurrencies.


Uniswap is a decentralized exchange (DEX) that allows users to trade and exchange Ethereum-based tokens without the need for a central authority. Uniswap uses a unique liquidity pool model to facilitate trading and offers a variety of features, including low fees, high liquidity, and support for a wide range of tokens.


About Goshen


Goshen is a fully Ethereum-equivalent L2 blockchain that makes it easier and inherently more secure to scale. We are currently live on the Goerli Testnet.


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