Vitalik advocates for the revival of Plasma combined with ZK-SNARKs, effectively enhancing development experience and security.

Recently, Ethereum co-founder Vitalik Buterin published a new article titled "Exit games for EVM validiums: the return of Plasma," discussing the progress of blockchain scalability solutions, with a focus on the Plasma solution before the rise of Rollup, and contemplating the potential of reintegrating it into modern blockchain frameworks.

Research Director Pan Zhixiong: Plasma and Rollup are core Ethereum layer-2 scaling solutions ZK,Optimistic.

Before reading Vitalik's article: his implicit suggestions

The author believes that every time Vitalik publishes articles on technology trends, he often implies his "point of view" on the development roadmap of technology. He tries to infer solutions for different approaches, and discuss their pros and cons, subtly revealing his views on the technology development. In his previous article "Different Directions of Ethereum L2," he distinguished various second-layer solutions from the perspectives of application requirements and security, while also defining which technologies are not suitable to be called L2.

Introduction to Vitalik｜What are the trade-offs and advantages of different approaches to Ethereum L2

The author believes that this perspective on the revival of Plasma technology is also based on its integration with ZK-EVM, optimizing the long-term development of Ethereum L2. It reiterates that although Rollup is the current gold standard, it is still considered a transitional solution in the long run.

Understanding "Exit games" first

Referring to the article "Plasma and Rollup are the core of Ethereum's layer 2 expansion" by Pan Zhixiong: Exit refers to the process of submitting transaction data on the Plasma chain to Ethereum regularly.

"When interacting between the Plasma blockchain and the Ethereum chain, not all transaction data of the Plasma chain is included, meaning it does not contain the data for every state change of the Plasma chain. This could make Ethereum unable to recover every piece of data if it is disconnected from the Plasma circle, so it heavily relies on Plasma for protection.

The exit period of the Plasma blockchain is relatively long because each node regularly submits the relevant data to the Ethereum chain. However, due to the mechanism of fraud proofs, users can enter the Ethereum chain very quickly, but it may take at least a week to exit the Plasma blockchain to ensure higher security. Otherwise, someone could exploit it in a short period, posing risks to the funds."

Exit games for EVM validiums: the return of Plasma

The evolution of Plasma: Technical flaws that led to its exit

Vitalik wrote that Plasma is a blockchain scaling solution invented in 2017 that allows most data and computations to be done off-chain, except for specific elements such as deposits, withdrawals, and Merkle roots.

This method aims to significantly improve scalability without being restricted by the availability of on-chain data.

Over the years, Plasma has evolved through various iterations such as Minimal Viable Plasma, Plasma Cash, etc. However, due to high client-side data storage costs and challenges in extending beyond payment applications, it has largely been overshadowed by rollup technology.

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Revisiting Plasma with Validity Proofs

Vitalik stated that the introduction of validity proofs like ZK-SNARKs has reignited interest in Plasma technology.

Validity proofs can address the primary challenge of client-side data storage in payment applications for Plasma and promote the possibility of creating a Plasma-like chain supporting the Ethereum Virtual Machine (EVM). While Plasma's security mechanisms may not cover all use cases, especially complex applications, they can still protect most assets in practice.

Plasma Cash and Homogenized Tokens

Vitalik introduced the Plasma Cash project and explained its limitations.

Plasma Cash is a simpler version of Plasma that treats each token as a unique non-fungible token (NFT) and can trace its history.

Plasma chain operators are responsible for block creation and issuance. However, applying this model to homogeneous tokens like ETH and USDC poses challenges. One approach is to consider small denominations of coins as individual NFTs, but this may result in high network costs. Alternatively, adjacent tokens can be treated as a unit for transfer or exit, leading to fragmentation and complexity in managing multiple small denominations.

Expanding Plasma to EVM

Expanding Plasma to support EVM would increase complexity as many EVM state objects do not have clear owners, and EVM does not restrict dependency relationships.

This makes it challenging to coordinate incentives to prove state validity and makes the creation of exit games more complex. However, introducing validity proofs can simplify the design of the Plasma chain by verifying every block on the chain, reducing the risk of operator misconduct and the amount of data users need to download.

Parallel UTXO graphs and total state exits

Vitalik believes that implementing parallel UTXO graphs for ETH and ERC20 tokens using SNARKs proofs can simplify EVM compatibility by avoiding the complexity associated with account-based systems. Additionally, a simpler "Plasma EVM" solution is proposed, requiring operators to include transactions or provide specific state branches upon request, with block rollbacks for non-compliance.

Plasma has been underestimated: limitations and future potential

While these solutions are powerful, they cannot provide complete security guarantees in all cases, especially when state objects lack clear economic owners.

Despite these limitations, Plasma offers an opportunity to bypass data availability issues and reduce transaction costs. In 2023, the emergence of ZK-EVM provides new opportunities for exploring Plasma in enhancing security and simplifying blockchain technology for developers.