What is the Rollups technology and how it helps to scale Ethereum?

What is the Rollups technology and how it helps to scale Ethereum?

How evidence works with zero confirmation?

The method of evidence with zero disclosure (Zero-Knowledge Proof, ZKP) was formulated by scientists of Shafi Goldvasser and Silvio Mikali in 1985 in the article “The complexity of knowledge of interactive evidence systems”. They proposed a way to prove the reliability of the message without disclosing its details.

Transaction project in the ZK-Rollup protocol

Rollaps also include user balance in L2 networks, presented in the form of a measure of Mercla. Its root is stored in the contract, which allows you to track the change in the state of the network. The values ​​of the first level also transmitted values ​​confirming each transaction. The data include the root of the merchase, which is calculated in several stages. Intermediate values ​​are recorded in the blockchain and confirm each translation in the package.

What are the advantages of ZK-Rollups technology?

Initially, evidence with zero disclosure was used in the projects of anonymous cryptocurrencies, but in recent years they have found wide application as solutions for scaling Ethereum.

ZK-Rollups allows you to process user data without disclosing private information about them. In https://gagarin.news/ particular, the algorithm can check the availability of funds without showing the user balance. These properties are important for companies that need to protect the personal data of customers.

Also, the use of solutions based on ZK-Rollups significantly reduces transaction commissions. Many translations are combined into one package in which all data is compressed – for example, instead of the address, an index is used. This allows you to save a smaller amount of information in the first -level blockchain. Costs are distributed between all senders, so each of the users pays less.

ZK-Rollups provide low delays when withdrawing funds to the main network, since the smart contract checks the reliability of the data before the package is included in the blockchain.

What are the varieties of ZK evacuation?

There are many implementations of ZK-rollaps, of which the most popular: ZK-Snarks (and its variety Plonky2), ZK-Starks, ZKSYNC and others. Each of the technologies differs in size “evidence” and the computational costs that are required to verify.


ZK-Snark creates confirmation, which has a small size and is easily verified. To obtain evidence using elliptical curves. The calculation of their values ​​requires less costs than the hash, so the algorithm is characterized by a lower cost. The method requires the destruction of evidence immediately after sending it. To work the algorithm, the node generates open and closed and key, after which the latter is destroyed. A public key is used to create another pair of keys. Further, the private key is used to generate confirmation, and public to check it.


ZK-STARKS forms evidence that does not involve interaction between the inspector and the verifier. Data validation takes less time, so the technology is easier to scale. The algorithm uses drifting, which makes it resistant to an attack of a quantum computer.


ZKSYNC is an L2 protocol based on the same name algorithm of rolls. The platform allows you to translate assets and supports smart contracts. A feature of the algorithm are a low gas limit on a transaction that does not exceed 500 gwei. The main advantage of ZKSYNC 2.0 is compatibility with Ethereum Virtual Machine.

What projects are used by ZK-Rollups and Optimistic Rollups?

Today, the Ethereum ecosystem has several popular solutions using ZKP:

  • Starknet platform. On the basis of its private version called Starkex, large Defi Protokols Rhino, Immutable X, Dydx and Sorare work. -This is a light blockchain using ZK-Snark technology to create blocks of 22 KB blocks. The platform allows you to perform smart contracts and run decentralized applications. – decentralized trade protocol, which uses the book of orders. Implemented on the Ethereum network, ZK canceles are used to work. -“Rollp” based on ZK-STARKS, working using a special virtual machine MIDEN VM.

In addition to ZKP -based rolls, you can also distinguish a solution group called Optimistic Rollups. The difference between them lies in the method of checking transactions: in Optimistic, transactions packages are considered valid, and transactions are checked only if anyone disputed it.

Evidence with zero disclosure retain data on the main network after the validation of each translation. Thanks to this, the technology ensures the maintenance of the current state of the network. At the same time, unlike ZK-Rollups, when withdrawing funds from the protocol based on Optimistic Rollups, a fraud check is required, which can take up to two weeks. The specified period determines the time of withdrawal of funds to the blockchain of the first level. However, the need to verify data in ZK-Rollups increases resource consumption and financial costs.

On the basis of Optimistic Rollups, two popular Ethereum L2-protocols-Arbitrum and Optimism work.

Name The technology used The volume of locked liquidity (Tvl)
Polygon Polygon Mineden (ZK-Stark), Polygon Nightfall (Optimistic Rollups), Polygon Zero (Plonky2), Polygon Hermez (ZK-Snark) $ 1.3 billion
Arbitrum One Optimistic Rollups $ 1.06 billion
Optimism Optimistic Rollups $ 993 million
Loopring ZK-Snark $ 128 million
ZKSYNC ZKSYNC $ 63.76 million
Dydx ZK-Stark (Starkex) $ 372 million
Aztec Plonk (ZK-Snark) $ 11.9 million
Starknet ZK-Stark $ 2.86 million (not counting projects on Starkex)

Comparison of TVL protocols based on “ROLLAPS”. TVL – Defi Llama and L2Beat as of October 31, 2022.

What is a validium?

There are comprehensive solutions – validiums. This is a compromise that combines evidence stored at different levels. Confirmation is sent to the main blockchain, and the data is stored outside of it. The decision reduces the commission, but implies dependence on the external storage. In case of violation of the latter, users will not lose funds, but will not be able to make transactions.

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