In the Layer 2 ecosystem headed by Rollup-like expansion solutions, at least 6 teams are already trying to solve the problem of cross-network transfer performance.
Written by: Pan Zhixiong
Layer 2 expansion technology can help Ethereum achieve a leap in performance. In the long run, there is no problem with at least two orders of magnitude increase in throughput. However, in addition to the uncertain factor of security, the user experience during the exit period and the separation of liquidity between different Layer 2 networks may become the most noteworthy topic at present.
Of course, users can use Ethereum Layer 1 to conduct cross-Layer 2 transactions. For example, users can withdraw Optimism assets to Layer 1, and then recharge to zkSync. However, this is very unfriendly to most users (Gas is very high), and the settlement speed may also be affected.
One of the most painful is the time window problem of Layer 2 assets withdrawing to Layer 1. Especially for the early Optimism network, the withdrawal period was designed for 7 days to ensure the security of the network. This means that if the user’s second-tier assets need to be withdrawn to the first-tier, they need to wait 7 days, during which the funds are frozen and cannot be used.
Fortunately, some teams have been aware of this problem for a long time, and provide a solution that can solve the slow exit period or help assets transfer quickly between different Layer 2 networks, which will greatly enhance the user experience and the popularity of Layer 2 .
In the Layer 2 ecosystem led by Rollup- type expansion solutions, at least 6 teams are already trying to solve this problem. In the future, they may also get involved in expansion solutions such as Plasma or side chains to provide a more comprehensive and comprehensive asset transfer tool. The main ones are:
CBridge Connext use state and Celer channel technology, high speed payment channel is opened in a different network, a similar principle lightning credits bit network;
Maker will open a special asset bridge for the USD stablecoin DAI issued by the agreement. When Maker’s oracle can read the data on Layer 2, it can safely and quickly provide an instant transfer channel from L2 to L1;
Hop Protocol sets up bridges for different assets in different L2 networks, introduces special verification nodes and AMM components, and finally realizes asset transfer among multiple networks;
The main direction of StarkWare is to realize the interoperability of assets between different networks through the “Conditional Txs” technology;
DeGate will initially provide cross-network transactions through a centralized asset custody method, and then it will turn to decentralized solutions.
MakerDAO (dedicated asset bridge)
As one of the oldest DeFi applications in the Ethereum ecosystem, Maker, the issuer of the USD stable currency DAI, will initially design a dedicated DAI asset fast transfer channel for the Optimism network . Users can quickly transfer DAI on Layer 1 to Optimism through the Maker solution. In the network, DAI in the Optimism Layer 2 network can also be quickly withdrawn to the Layer 1 network.
The program can be achieved mainly because the program will Optimism release of all transaction data to Layer 1, there Optimism network design called monotonically increasing list of transactions “recognized the transaction chain” Canonical Transaction Chain (CTC), publishing in The transactions in this list can then be considered as certain and unchangeable (unless the Layer 1 block is also reorganized).
Therefore, the core of Maker’s plan is to design a new set of ” oracles ” and relay components to read the data in the CTC, and use this as a basis to release Layer 1 liquidity for Layer 2 users in advance.
The user first submits the withdrawal request from Layer 2 to Layer 1. After the oracle reads the CTC transaction, it can cast a liquidity certificate named fDAI on Layer 1 for the user 7 days in advance. Then users can use “fDAI Treasury” to mortgage fDAI and exchange out DAI.
In addition, although the withdrawal cycle is 7 days, any withdrawal transaction is 7 days, so a withdrawal 7 days ago has just returned to Layer 1. This continuous DAI withdrawal capital flow can be used as The source of funds for DAI in the vault.
But for this ” oracle ” component, whether it may bring some centralization risks, the plan has not been explained in detail. They “do not need to trust” for the program (Trustless) advantage is so explained: “In addition to Oracle, this system does not require the introduction of trust assumptions.”
At present, Maker has not mentioned the plans of other Layer 2 networks, so at present it only focuses on Optimism, focusing on launching the official Layer 2 DAI solution for the network as soon as possible.
Detailed program introduction:
” Announcing the Optimism Dai Bridge with Fast Withdrawals “
Celer cBridge (status channel)
The second-layer expansion project Celer launched the cross-chain payment network Celer cBridge , through which users can transfer value within or between any Ethereum Layer 2 network, Ethereum main chain, and other Layer 1 or Layer 2.
cBridge is implemented by extending the Celer state channel, enhancing the existing protocol so that it can run on multiple chains at the same time. The Celer state channel network has added the function of state channel cross-chain payment . To test this function, you need to deploy the CelerPay contract on each EVM test chain , or deploy the corresponding contract or plug-in on a non-EVM compatible chain ( Such as the Celer Substrate module on Polkadot).
In simple terms, state channels are a special type of two-layer network expansion solution. Bitcoin Lightning Network technology can also be summarized as state channel technology, which can usually be used to solve small payment scenarios and move high-frequency transactions to the chain. Under the treatment, reduce the pressure on the chain.
Detailed introduction:
Connext (Status Channel)
Connect’s Vector is also the state channel technology used , and a very early version is currently available on the mainnet.
Recently they released a new version to achieve interoperability between Polygon (Matic) and the sidechain xDai, and launched the xDai-Polygon Bridge beta, allowing users to use the state channel to transfer xDai to Dai on Polygon, as well as on Polygon. Go to xDai for Dai.
The Connext team actually launched the state channel technology on the Ethereum mainnet very early, and launched version 2.0 in September 2019, but as for the adoption rate, there are actually few reports. According to the ecological illustration book compiled by the official before, it is mainly based on wallets, and the supported applications have not been able to enter the field of vision of most people.
Later, Connext began to get involved in a new product direction in 2020. Although they still use the state channel technology they are most familiar with, the entry point has changed. In August last year, Connext participated in the expansion challenge initiated by Reddit and launched the Spacefold solution to try to solve the high-frequency needs of social networking scenarios, which also laid the foundation for the follow-up Vector.
At present, Vector launched the Ethereum mainnet in January this year, but the version number is 0.1.0, so it can be considered that it is still in the early stage, and more complete versions will be launched in phases in the first and second quarters.
reference:
StarkWare (conditional transfer)
The zero-knowledge proof research and development organization StarkWare officially launched the expansion network StarkNet based on the ZK Rollup concept in January this year, but this is not the subject of this article, but they provide a complete solution for the interoperability of Layer 2, based on ” conditional transfer ” (Conditional Transactions) or “condition of payment” (Conditional payment) implementation.
Conditional transfer is a cryptographic- based component that can be used to achieve permissionless interoperability in the blockchain. In simple terms, conditional transfer is a transaction that takes the occurrence of certain “events” (such as payment, status change) as a condition. After a conditional transaction is defined in a certain network, once its conditions are met in another network, The conditional transaction will take effect.
This series of functions will be implemented in stages,
The first stage: Layer 2 exchange based on StarkEx can realize quick withdrawal to Layer 1
The second stage: Two Layer 2 networks based on StarkEx can quickly transfer money to each other
The third stage: any two Layer 2 networks to achieve fast transfer
Regarding whether the solution is ” trustless “, the team stated that ordinary users do not need to trust at all, but for liquidity providers (LP), it may be necessary to trust nodes to package and publish their conditional transactions (because they can choose not to Packaging), but this layer of trust can also be removed in some ways, such as bypassing these nodes through smart contracts on the chain.
reference:
Hop (Universal Asset Bridge)
Hop Protocol is a scheme somewhat similar to Maker. In their scheme, a universal asset bridge is designed, and through the introduction of ” Automatic Market Maker” (AMM) components and the role of ” Connector ” (Bonder), the layer 2 network is finally realized. Fast migration of assets between.
When using Hop’s solution, assets need to be transferred to the Layer 2 network through Hop. For example, the ETH that enters the second layer through Hop’s asset bridge is called Hop ETH (or hETH). hETH and ETH are completely equivalent, at least it can be exchanged through Hop.
However, there is also an “official” version of ETH in the Layer 2 network, which is the ETH version commonly used by more people. The official version of ETH and hETH should also be completely equivalent in theory, but due to liquidity reasons, there may be Some spreads.
So Hop Protocol introduced AMM components and ” connectors “. AMM is designed to solve the short-term fluctuations in the price difference between the official version of ETH and hETH, and the ” connector ” (Bonder) role can be used in advance. The user who releases the liquidity provides liquidity and can also obtain part of the income (because it saves the user a 7-day withdrawal cycle).
Bonder can advance the official version of ETH for the network in advance by observing the transaction data between different Layer 2 networks, and arbitrageurs between different Layer 2 networks will continue to rebalance (to gain revenue) to maintain the price of AMM at a comparison Within a reasonable range.
There are still many details of the plan, as well as the parts that need to be improved, such as the decentralized mechanism of multiple Bonders, etc., for others, please refer to the project white paper .
DeGate (hosted)
DeGate, the second-tier transaction protocol initiated by the Bihu and MYKEY team, adopts a more pragmatic approach, that is, they act as intermediaries to provide fast cross-chain services for assets, but this introduces centralization risks, and users who use this still need Trust DeGate and the team behind it, and wait until the facilities are complete before turning to a decentralized solution.
In the early days of DeGate, a fast channel for cross-layer asset transfer was realized directly through centralized custody of assets. The first phase will realize a fast exchange channel between L1 and L2, and then consider opening a fast exchange channel between different L2s depending on the situation. At different L2 online times, after all, this solution can be more flexibly connected to different networks.
DeGate stated in the white paper that the security of the assets under custody is guaranteed by the net assets held by Home DAO itself. When a mature oracle service appears on L2 on Ethereum, DeGate Bridge will turn to implement assets in a decentralized manner. Bridge.
For more details, please refer to DeGate’s white paper
