Many people believe that blockchain can transform industries ranging from finance to supply chains to healthcare and more. But despite being around for more than a decade, challenges continue to hinder blockchain adoption, with one of the most pressing issues being the problem of how to scale to support millions of transactions.
To overcome this challenge once and for all, ZK-Rollups, or Zero-Knowledge Rollups, are an extremely promising concept that aims to dramatically increase the throughput of blockchains. ZK-Rollups are Layer-2 scaling solutions that take advantage of Zero-Knowledge Proofs to enable benefits beyond just increasing throughput, also giving users complete privacy.
ZK-Rollups: the basic concept explained
Zk-Rollups use a Layer-2 network that sits above the main blockchain, where transactions can be offloaded and bundled before being processed as one large transaction back into the main chain. They use ZK proofs to obscure transaction details and verify their accuracy using a ‘validity proof’ submitted to the main chain. In this way, they reduce the overall load on the main chain, allowing it to process many more transactions. Another advantage is significantly lower gas costs, because these costs are spread over all bundled transactions.
The secret sauce of ZK-Rollups is the zk-SNARK, or Zero-Knowledge Succinct Non-Interactive Argument of Knowledge, a cryptographic technique that allows one party to prove to the other that a transaction is accurate, without any reveal information. details of that transaction.
In a nutshell, ZK-Rollups work as follows:
- The users submit their transaction to the ZK-Rollup contract
- The operator processes these transactions off-chain before merging them into batches
- Then it generates a validity proof for the entire batch using zk-SNARKS
- This proof, together with the final status of the update package after all transactions have been processed, is sent to the main net
- The mainnet verifies the validity and updates all wallets involved in that batch of transactions.
- Finally, users can then withdraw their funds from the smart contract
The benefits of ZK rollups
ZK-Rollups offer significant advantages over older scaling techniques such as sidechains and ‘Optimistic Rollups’ that currently lead the way on Ethereum.
Like ZK-Rollups, Optimistic Rollups also process transactions off-chain and bundle them into batches to submit to the relay chain. But instead of using ZK receipts, they use a tamper-proof mechanism where transactions are assumed to be valid unless someone disputes them. This requires the use of a ‘window’ or period during which anyone is free to check and verify the transactions, and issue a challenge if he or she discovers someone is cheating. Should the challenge be successful, the fraudulent transaction will be reversed and the challenger will earn a reward.
Side chains are an alternative. They are independent blockchain networks that run parallel to the mainnet and use their own consensus mechanisms that allow them to process transactions themselves. They are connected to the main grid via a ‘two-way link’, which allows the transfer of assets between the two chains.
ZK-Rollups offer compelling advantages over optimistic rollups and sidechains:
- Increased transaction finality compared to Optimistic Rollups, as the use of ZK proofs means they can be verified immediately after submission to the mainnet. The challenge period with Optimistic Rollup means that transactions are always deferred.
- Greater security compared to Sidechains because they inherit the security of the underlying mainnet through the use of validity proofs. Sidechains rely on their own security models, which are much weaker than established blockchains like Ethereum.
- Lower gas costs are another advantage of ZK-Rollups compared to Sidechains. Because many transactions are merged into one transaction, which is then processed on the main chain, the gas fee paid to Ethereum can be shared across all transactions in the bundle. Side chains cannot do this. They still process each transaction independently, causing the user to pay the full transaction fee.
What is the state of ZK rollups?
Several projects bring ZK-Rollups to the mainstream. One of the most promising is the modular zkEVM Layer-2 network, Prom ZkEVM, which has created a solution that supports Ethereum, EVM-compatible blockchains, and non-EVM blockchains.
This extensive support is essential for Prom ZkEVM as it is on a mission to provide interoperability between all major blockchains. Its architecture allows it to submit proofs of validity to two blockchains simultaneously.
Prom ZkEVM’s use of recursive STARK technology has proven to be both extremely scalable and highly economical, while its high degree of interoperability makes life simple for Web3 developers. Additionally, it also supports ‘account abstraction’ features enabled by the ERC-4337 standard, allowing dApps to implement easy-to-use features such as traditional email-based account recovery methods.
zkSync is another big name in the ZK-Rollup space. As one of the first ZK-Rollup implementations, it has a significant first mover advantage that has contributed to its adoption, winning over hundreds of dApp developers with the promise of 2,000 transactions per second.
These impressive speeds are backed by strong security, which zkSync inherits from Ethereum, and low transaction fees. Additionally, many developers find zkSync’s mature rollups easier to implement, meaning dApps can support frictionless asset transfers between EVM chains, without any latency.
More specialized ZK-Rollups like Immutable X are aimed at niche use cases within Ethereum, such as Web3 games. It is aimed at blockchain games that use NFTs as in-game characters, weapons and accessories. In many games these assets are extremely cheap, so it is necessary to keep transaction costs to a minimum. This is why Immutable It allows players to instantly buy and sell cheap assets at negligible costs.
Furthermore, players of blockchain games must be able to make transactions immediately. They want to be able to purchase a new weapon or item and immediately use it in their next game. Immutable X does this and has an incredible speed of 9,000 transactions per second. As an added benefit, Immutable
Blockchain scalability achieved
The progress of projects like Prom ZkEVM, zkSync and Immutable ZK-Rollups offer more than just promises: they actively transform blockchains, helping them achieve scale while improving the security and privacy of every user.
Leveraging the advanced capabilities of ZK-proofs, ZK-Rollups dApps provide a powerful, versatile, secure, and privacy-preserving way to scale on any blockchain.
