Original author: Day, vernacular blockchain
Previous article, we introduced Bitcoin in Bitcoin Layer 2side chainandUTXO+ client validation, today we will introduce the remaining 2,RoullpandTaproot Consensus。
01 Roullp
Roullp was originally a Layer 2 scalability solution on Ethereum, used to improve the performance and throughput of the blockchain network. Roullp migrates most of the transaction data and calculations off-chain, and only records the summary or transaction of the transaction on the chain. Aggregate information, thereby reducing the burden on the main chain and improving overall performance.The core idea of Roullp is to combine on-chain security with off-chain efficiency.
There are some challenges and limitations in implementing the Roullp scheme on Bitcoin.Bitcoin itself does not support smart contract verification, so introducing the Roullp scheme on Bitcoin requires other methods for verification.For example, introduce client verification or build a self-built DA layer. This results in the security of Bitcoin Layer 2 projects being highly dependent on client verification or self-built DA layers, rather than the security of Bitcoin itself.
Picture source network, intrusion and deletion
Furthermore, the native nature of Bitcoin does not match the nature of Roullp’s scheme，Because the Roullp solution mainly comes from the second-layer solution of Ethereum and is designed based on the characteristics of Ethereum. Bitcoin only acts as a certificate depositor and does not participate in the verification process, so it is somewhat different from the Roullp scheme in terms of nativeness.
In addition, the Roullp solution also has challenges in terms of the degree of decentralization of Bitcoin Layer 2.This involves the decentralization of asset management and second-layer ledgers. Currently, most of Ethereums sequencer nodes are centralized and run by the Layer 2 project itself, which also causes the Bitcoin Layer 2 project to face some problems in terms of decentralization.
Although it is technically feasible to implement the Roullp scheme on Bitcoin, it faces challenges in terms of Bitcoins nativeness, decentralization, and security.BTC Layer 2 projects currently on the market also have varying degrees of flaws and limitations, so the development and widespread adoption of such projects still requires further development and verification.Let’s talk about some of the representative projects:
Merlin Chain
Merlin Chain is a Bitcoin Layer 2 solution that integrates the ZK Rollup network, decentralized oracles and on-chain BTC fraud prevention modules.The goal of Merlin Chain is to improve the efficiency and scalability of Bitcoin transactions and make the Bitcoin ecosystem more active. Merlin Chain uses ZK-Rollup technology to compress a large number of transaction proofs to improve transaction efficiency and scalability.
On Merlin Chain, the sequencer node is responsible for collecting and batching transactions, and generating compressed transaction data, ZK state root and zkEVM proof. The compressed transaction data and ZK proof are then uploaded to Taproot on Bitcoin’s Layer 1 through the decentralized Oracle network.Taproot is available as a public resource across the web to ensure transparency and security.
Although Merlin Chain has been criticized by everyone for its weak technology, Merlin chain is the most popular BTC Layer 2 in terms of ecological and community activity and implementation level, and the current amount of locked funds is more than 3.5 billion US dollars.
B² Network
B² Network utilizes zero-knowledge proof and ZK Rollup technologies to improve the performance and scalability of the Bitcoin network and is compatible with Ethereums smart contract functions.This solution records transaction data and verification proofs on the Bitcoin mainnet, and ensures the correctness of the data through a challenge-response mechanism.
The architecture of B² Network consists of two main parts: Rollup layer and DA layer.In the Rollup layer, the users transactions and related verification certificates are processed and recorded, and the users status is also stored in this layer. These transaction and verification proofs are then transferred to the DA layer for storage and verification.
The DA layer includes decentralized storage, B² nodes and the Bitcoin network.At this layer, a copy of the Rollup data is stored permanently and verification proofs are verified. However, since the Bitcoin mainnet itself cannot directly verify the data of the DA layer,B² Network adopts a special method, which writes the digest of the verification proof (Commitment) into the Bitcoin main network and sets a time-locked challenge, similar to the OPs fraud proof.
A major problem of B² Network is that the Bitcoin main network cannot directly verify the data of the DA layer, so a challenge-response mechanism is needed to solve this problem, which may affect the decentralized nature and security of the system.
B² Network recently strategically launched B² Hub, which will provide services for other ZK Rollups and provide data availability layer (DA) functions.In addition, it has entered into strategic cooperation with Babylon to realize the Restaking and LSD functions of BTC Layer 2.
Bison
Bison is a native ZK Rollup solution based on Bitcoin, designed to increase transaction speed and enable advanced features on the Bitcoin network.Developers can use ZK Rollup to build innovative DeFi solutions, such as DEX/CEX, borrowing services, and automated market makers. Unlike the Ethereum Virtual Machine (EVM) used by other Layer 2 solutions,Bison uses Cario VM (the same as StarkNet) and is mainly built ecologically around inscriptions.
In terms of technical solutions, Bison is still essentially a sovereign rollup, which is verified through its own nodes.The DA (Dispute Assistant) only saves and publishes the verification results in the form of inscriptions to the Bitcoin main network, and cannot fully inherit the value of Bitcoin.
Whether Bison can develop in the future is closely related to whether the inscription ecology can rise again.
02 Taproot Consensus
Taproot Consensus is a Layer 2 solution based on Bitcoin native technology. It consists of three core components: Schnorr Signature, MAST Contract and SPV Node Network.
Schnorr Signature is an efficient Bitcoin signature algorithm with better privacy protection.Schnorr Signature can expand the number of Bitcoin multi-signature addresses to 1,000, realizing the decentralization of multi-signature addresses.
MAST Contract provides coding for multi-signature management. It does not rely on people to sign, but relies on code-driven.
The SPV Node Network consists of Bitcoin light nodes, allowing users to conveniently and securely verify Bitcoin payments without saving full blockchain data.
Taproot Consensus relies on the consensus of the Bitcoin light node network to drive multi-signature, achieving decentralized Bitcoin cross-chain and management.
After looking through the information, Taproot Consensus should be considered a new second-tier track created by the BEVM project team, so they are the only representative project.
Representative project: BEVM
BEVM is a Bitcoin Layer 2 that uses BTC as Gas and is compatible with EVM. The goal is to improve the scalability of Bitcoin, reduce transaction fees, and cultivate a more secure and decentralized financial ecosystem.
The core design of BEVM is based on BTCs Taproot upgrade in 2021, using the Musig 2 aggregate signature algorithm to achieve decentralized BTC cross-chain. The Musig 2 aggregate signature algorithm is brought about by the Taproot upgrade and can allow 1,000 Bitcoin light node addresses Form a decentralized asset network and process the transfer of BTC assets through this network to ensure the security of assets on BTC Layer 2;BEVM is fully compatible with EVM. DeFi, GameFi and other applications that can run in the EVM ecosystem can be seamlessly migrated to Bitcoin Layer 2. Users can directly use BEVM ecological applications in mainstream encryption wallets (such as Metamask, OK Wallet, etc.).
At the end of last month, BEVM completed tens of millions of US dollars in financing, with a post-investment valuation of 200 million. Recently, BEVM cooperated with BN Wallet to launch cooperation activities.
03 Summary
The above is the current mainstream project progress of Bitcoin Layer 2. Looking at it as a whole, we can actually find thatIt is very similar to the development of Ethereum Layer 2, both are solving the same problem, introducing smart contracts on the basis of Bitcoin’s nativeness (security is linked to Bitcoin) and decentralization.In order to achieve the goal, certain compromises will be made in some aspects.
There is another problem, that is, the projects supported by domestic and foreign institutions are also different. The two sides do not buy each others support, and they are in a state where they are playing their own games. Relatively speaking, they are relatively fragmented.
