According to data from L2Beat, the total amount of encrypted assets (TVL) locked in the zkSync network has exceeded 140 million US dollars, an increase of 38% in 7 days. zkSync is an Ethereum Layer 2 network based on the ZK Rollup expansion scheme. At present, its TVL growth ranks first among many Layer 2 networks, which shows that more and more funds and users are experiencing the zkSync network and its applications.
Before the Ethereum mainnet is officially upgraded to 2.0, one of the ways to solve the congestion on the chain is to build a layer 2 network (Layer2) that can perform most of the activities outside the chain, in order to ease the calculation and storage pressure on the mainnet and increase the amount of ether Scalability of the Square.
Among the various technologies that make up the Layer2 network, Rollup is gradually considered to be the optimal solution, because it can complete the actual calculation and storage of smart contracts off-chain, and submit transaction data in batches through a series of compression techniques and save them in ether. On the mainnet of Fangfang, there is no need to verify one-by-one data. In this way, the security of the layer2 network can not only be guaranteed by the Ethereum main network without destroying the decentralization of the network, but also increase the scalability and efficiency of the network. More importantly, Rollup allows applications on the Ethereum mainnet to easily migrate to Layer 2.
The Layer 2 network is constructed using the Rollup technology, and various paths are formed due to different cryptographic verification algorithms. Optimistic Rollup, ZK Rollup, and Arbitrum Rollup have become mainstream solutions. At present, Layer 2 networks using various schemes have made achievements, and each school is developing in R&D and practice.
Among them, ZK Rollup uses the "zero-knowledge proof" verification method to implement Rollup's expansion plan, which is regarded as the ultimate choice for Layer 2 by Vitalik Buterin, the founder of Ethereum.
The recent surge of TVL on the zkSync network has further verified the feasibility of ZK Rollup, especially since zkSync launched the 2.0 version of the public test network in February this year, the ZK Rollup expansion technology solution that supports it has also attracted more and more attention from the blockchain technology community .
So, what exactly is the ZK Rollup expansion plan? How is it different from Optimistic Rollup and Arbitrum Rollup? Besides zkSync2.0, which other networks use ZK Rollup technology? This issue of DeFi Cellular will answer them one by one.
Overview of ZK Rollup scheme
Introduction
ZK Rollup is a layer2 solution that implements Rollup technology based on the "Zero Knowledge Proof" verification method. "ZK" is the abbreviation of "Zero Knowledge". Technical researcher Barry Whitehat proposed.
Retaining the principle of Rollup technology, ZK Rollup can complete complex calculations off-chain, generate proofs, transmit them back to the main network for proof verification, and store some data to ensure data availability, and share the security of the main network.
The characteristic of ZK Rollup is the "ZK" part, the "zero-knowledge proof" algorithm allows the prover to convince the verifier that a certain result is correct without providing any useful information to the verifier.
For example, A wants to prove to B that he has the key to a room, assuming that the room can only be unlocked with the key, and cannot be opened by any other method. At this time, there are two ways: either, A shows the key to B, and B uses the key to unlock the room, thereby proving that A has the correct key for the room; or B determines that there is an object in the room, and A uses his own The possessed key opens the door, then takes out the object and presents it to B, thus proving that he does possess the key to the room.
The latter method is similar to zero-knowledge proofs. Its advantage is that in the whole process of proof, B cannot see the appearance of the key, thus avoiding the leakage of the key.
"Zero-knowledge proof" is an important technical means for the blockchain that emphasizes privacy, and the Bitcoin network is one of the applications. In addition to privacy, technical researchers have also begun to apply it to improve the performance of blockchains. ZK Rollup is one of them. It advocates that if a block requires a large amount of data verification to complete the packaging and open the next block, you may as well Only one person verifies and generates the proof, and others can verify that the proof is correct, thus avoiding the need for everyone to spend a long time to verify a proof, thereby improving the efficiency of data verification.
Under the ZK Rollup scheme, after multiple transaction data on the Layer 2 network are packaged, an off-chain "zero-knowledge proof" result is created, and the mainnet (Layer 1) verifier can quickly check whether the proof is correct. Moreover, because the transaction data from Layer 2 to Layer 1 can be verified in real time, it can also realize instant settlement when assets from Layer 2 are transferred to Layer 1.
The difference between ZK Rollup and other Rollup schemes
ZK Rollup is an implementation of using Rollup technology to build the Ethereum Layer2 network, and the other is mainly Optimistic Rollup. The difference between the two is mainly in the verification algorithms used.
Optimistic Rollup uses the "fraud proof" verification algorithm. Its premise is that the verifier must pledge a certain amount of ETH "deposit" on the Layer2 network as an endorsement of "not lying". Under this premise, it assumes that all transactions on the Layer2 network are valid. , the data submitted to layer1 (Ethereum main network) is correct. If someone objects to any transaction, at this time, the data needs to be verified one by one on the Ethereum main network. Whichever verifier submits a problem with the data will be If it is judged as fraudulent by the network, then the validator's deposit will be confiscated.
Under the principle of such a verification algorithm, when each batch of transactions aggregated on Layer 2 is submitted to Layer 1, there will be a 7-day objection submission period. This also adds a 7-day waiting period when users withdraw or withdraw crypto assets from the network under the Optimistic Rollup scheme.
This not only makes the experience of Optimistic Rollup related networks unfriendly, but more troublesome is that once objection data occurs, all transaction data must be re-verified on the mainnet, which increases the burden on the mainnet.
Therefore, in response to this pain point, Arbitrum Rollup has improved on Optimistic Rollup. It advocates dividing the objection part into blocks to find the most controversial part. The Ethereum main network only verifies the disputed part, so as to alleviate the problem of the main network. Validation burden.
In addition, the progress of Arbitrum Rollup lies in the realization of compatibility with EVM, which enables the layer2 network using this technology to carry applications on the Ethereum mainnet seamlessly. Therefore, many DeFi applications choose to deploy the "Arbitrum version" . In contrast, the Optimistic Rollup expansion solution is not 100% compatible with EVM.
It can be seen that the Arbitrum Rollup solution is an "improved version" of Optimistic Rollup. Still, there is a waiting period when funds are withdrawn from the Arbitrum Rollup-related network, a pain point that needs to be improved.
In terms of compatibility with EVM, ZK Rollup has been difficult to make breakthroughs before. Ethereum founder Vitalik Buterin (flower name Buterin) once said in a public speech that due to the complex underlying technology of ZK Rollup, it may take several years to be fully compatible with the Ethereum virtual machine. In the short term, Optimistic Rollup is the It is a feasible choice for the expansion plan of the square, but in the long run, it will be more inclined to ZK Rollup.
With such a comment by Buterin, ZK Rollup is considered to be the "holy grail" of Ethereum's expansion plan.
Surprisingly, ZK Rollup-compatible EVM development progressed much faster than expected. In February this year, the zkSync 2.0 public beta network using the ZK Rollup solution was launched, which is compatible with EVM. This means that in the near future, the ZK Rollup solution will no longer be shelved, and the network based on it will usher in the migration of applications.
At present, the main players in the Layer 2 implementation of the ZK Rollup scheme are StarkWare and zkSync.
zkSync is continuously upgraded to complete EVM compatibility
In 2019, the MatterLabs team began to develop the zkSync network using the ZK Rollup expansion solution. In June 2020, the zkSync 1.0 version was launched, mainly focusing on payment. As the Layer 2 expansion layer, the transfer fee on the zkSync1.0 chain is extremely low, processing transactions quickly, and the fee is not limited to ETH. Other Ethereum standard assets transferred using this network can also be used as transaction fees. Assets enter and exit the Ethereum main network. Usually from a few minutes to a few hours.
zkSync official website
At present, users can activate the zkSync network account by authorizing the Ethereum wallet. Assets such as ETH and USDT under the ERC-20 standard can freely enter and exit the network, and assets can be transferred with other zkSync accounts.
Due to the incompatibility of zkSync1.0 with EVM, the availability of the network is limited, and the application scenarios it can support are very limited. However, due to the low transfer fee and instant account arrival, the main application direction of zkSync1.0 is payment.
In February of this year, the public test network of zkSync 2.0 was launched, achieving EVM compatibility, and thus became the first blockchain network that utilizes the ZK Rollup solution and is compatible with EVM.
zkSync2.0 supports developers to deploy decentralized applications on the network using Solidity, the native programming language of Ethereum. Existing DeFi applications on the Ethereum mainnet can also be integrated into the zkSync2.0 network. Both developers and users have low fees and high cost. Use this Layer2 network efficiently.
Application Representative
Decentralized Exchange Application (DEX) ZigZag
ZigZag does not adopt the automatic market maker (AMM) mechanism commonly used in DEX, but adopts a decentralized order book model, which is the convenience brought by the natural "aggregation" of the underlying ZK Rollup technology, which allows traders to use the smallest Slippage and highly liquid orders for spot trading, trying to be an on-chain alternative to centralized exchanges (CEX).
Layer2 cross-chain bridge Orbiter Finance
Orbiter Finance is a cross-chain bridge built for the Layer2 network. It supports the cross-chain transfer of assets between Layer2 networks such as zkSync, Arbitrum, and Optimism, and also supports the mutual transfer of assets between Layer2 and Layer1.
StarkWare systematically creates Layer2
zkSync2.0 is compatible with EVM and breaks the technical bottleneck of ZK Rollup.
StarkWare can be regarded as a company. It was founded in 2018 and has a complete set of Layer2 system solutions. The scalability of the network was further enhanced, and the algorithm was commercialized, forming two landing modules, StarkNet (Layer2 expansion network) and StarkEx (expansion technology).
StarkWare official website
StarkNet
It is a Layer 2 network built on Ethereum. The test network has been launched in November 2021, supporting developers to deploy applications. Users can send transactions to the network. All transactions will be processed in batches on a regular basis to generate STARK proofs, and then Verify these proofs on the Ethereum mainnet. Since the computational content required for verification is very small, the processing efficiency on the chain is improved.
Since StarkNet is not yet compatible with EVM, it has not been migrated to Ethereum's top DeFi applications. At present, the main applications on this Layer 2 are the decentralized trading application (DEX) Myswap and the one-stop trading application JediSwap
StarkEx
It is a set of scalable engine technology that provides scaling solutions and program services for Ethereum applications. It has been used in many well-known decentralized applications, including decentralized perpetual contract trading application dYdX, decentralized trading application DeversiFi, NFT Ecosystem Immutable X.
As a futures trading platform, dYdX (DYDX) needs high-speed settlement, and StarkEx helps it greatly improve the settlement speed and enhance the user experience.
DeversiFi is the first DEX to use the StarkEx scaling engine. It uses the order book model, which is realized by processing transactions off-chain and completing settlement on-chain. In the past, the on-chain settlement method had high requirements on the performance of the chain, which was restricted by the Layer 1 network. Now, the StarkEx engine solves this, providing instant settlement, high liquidity, low slippage and more for non-custodial transactions. In addition, DeversiFi uses the privacy layer of the zkSTARK algorithm, which well guarantees the user's transaction privacy.
Immutable X is Ethereum's Layer 2 expansion solution for NFT assets. It is built on the StarkEx engine. The assets and transaction data on the network are guaranteed by Ethereum, and users do not need to worry about security issues. What's more, StarkEx supports the withdrawal of assets to the Ethereum chain, which is instantly credited without a 7-day interval. At present, the card game Gods Unchained (GODS) and the combat role-playing game Illuvium (ILV) have chosen to integrate with Immutable X to provide users with a fast, 0 gas transaction experience.