Author: Haotian, encryption researcher Source: X, @tmel0211
When the Fomo wave is sweeping, I have contacted some "real" Bitcoin developers and found that they are not hot-headed and say that Bitcoin layer 2 will subvert Ethereum and the like. if.
On the contrary, everyone has a consensus:The Bitcoin ecosystem will have opportunities, but it will definitely be different from the DeFi Lego combination paradigm of Ethereum. Next, based on technical logic discussion, how should the Bitcoin ecosystem be implemented?
Indeed, the new asset issuance method of inscriptions has brought many people back to the ICO moment in 2017, and their enthusiasm was completely ignited. This wave of inscription craze has brought new users, new application scenarios, and new incremental funds. To some extent, it is not an exaggeration to call this bull market a Bitcoin bull.
As a result, side chains, Lightning Network, Taproot Assets, RGB, BitVM and other directions are crowded with Bitcoin orthodox layer2 "coveters", and they often talk about it The Bitcoin ecology has made a high-profile statement that it will replicate everything in Ethereum, which really makes people feel excited.
Just like the unsustainability of the ICO asset issuance craze, the inscription market is also eager to take on a new Bitcoin layer 2 craze at the end of the Fomo craze.
It is true to have such ambitions and demands, but if you want to copy the ecological and diverse gameplay of Ethereum to Bitcoin, it is really not feasible. The Bitcoin ecosystem It is necessary to explore a landing route that matches its native characteristics.
The core logic is that the native features of the Bitcoin chain have "limited" computing and verification capabilities, even the storage capabilities in the Taproot address Segwit exist Dust attack 'controversy'.
Limited computing determines that more complex transaction logic must be implemented outside the chain. For example, bitVM boldly imagined a method that uses the chain The combination of external circuit + on-chain logic gates (0, 1), Turing-complete calculation based on the optimistic Rollup concept, has a lot of imagination and reasonable technical logic, but the engineering volume is comparable to the Qin Dynasty's human computer in the Three-Body Problem , impractical;
Limited verification makes Bitcoin more suitable for asset settlement rather than global state verification. For example, the current Schnorr of Bitcoin nodes The signature and MAST data structure characteristics bring certain verification capabilities, but Schnorr only aggregates multiple signatures and is limited to multi-signature scenarios. MAST allows the creation of more complex scripts, but it relies on the UTXO model and can only do asset settlement, and Global status verification cannot be implemented. Building a complex light node matrix can only enhance the interoperability between the side chain and the main chain, and improve the security and response speed of asset settlement;
There is no doubt about the storage controversy. Bitcoin has developed to the present in a minimalist style. This is the consensus that emerged from the end of the last round of large and small block wars. Therefore, the idea of trying to make a big fuss based on Taproot's script space will definitely not work. Although it may not necessarily reach the level of fork that Segwit is castrated, upgrade protocols such as Atomics, RUNE, and PIPE all tend to compromise in the direction of small blocks, such as discarding large Json data packets and returning to the optimization and application of OP_Return space.
These limitations determine that Bitcoin’s layer2 expansion plan is very different from Ethereum:
1) Bitcoin Data Availability lacks data availability capability. Ethereum’s DA is the calculation + verification capability of the main network Validators on the data submitted by the second layer of layer 2. Obviously, although Bitcoin can accept certain data, the main network does not Possess feasible and efficient calculation and verification capabilities.
Therefore, Bitcoin DA is more like a "bulletin board" in nature. The original RAW Data is stored in the Bitcoin block and can only be used by off-chain indexers. To carry out accounting and confirm rights. This will inevitably test the accounting and verification capabilities of the indexer. If there are multiple indexers, the challenge will be further increased, and there will be problems with confusion and errors in the accounting logic.
2) The interoperability of Bitcoin is limited. The second layer of Ethereum submits the status to the main network. The main network has contracts that can cooperate with the second layer to expand similarly. The 7-day challenge time window and security mechanisms such as layer 2 escape cabins ensure that the main network can protect the assets of second layer users if the second layer Sequener does evil. Obviously, Bitcoin without smart contract capabilities does not have this layer of security. Users can only trust that Bitcoin layer 2 will not do evil.
3) The Bitcoin UTXO security model is limited to the "payment" scenario. Similar to the second-layer solution of Ethereum Plasma, if the second-layer keeps the Nonce Hash corresponding to each transaction in the form of UTXO and the main network, it can find an absolute security model based on UTXO.
But just as Plasma can only be limited to payment scenarios, Bitcoin layer 2 built based on the UTXO model also has this limitation. Generally speaking, mechanisms such as EVM with complex smart contracts and multiple states cannot rely solely on this security mechanism unless other Bitcoin off-chain consensus is added.
Based on this technical logic and understanding, the narrative space of Bitcoin layer 2 is also extremely clear:
1) Use Bitcoin as the settlement layer, and build an independent consensus on the second layer to provide a complete set of DA, Interoperability, VM virtual machines and other ecological carrying capabilities that are in line with Ethereum. However, such a comprehensively powerful chain is tantamount to recreating an Ethereum execution chain. Many people don’t know that Ethereum actually also has a Beacon settlement chain. The Ethereum 2.0 main chain we see can also be regarded as a Beacon. layer2 of the chain.
The reason why everyone has a weak perception of the settlement chain is because the core of the main network is the interactive verification capability. If you only do the settlement chain, it will process a lot of calculations and Only the chain that verifies the operation will become the real "main chain".
The question is, if we use Bitcoin as the settlement chain, do other chains dare to call themselves the main chain? Does the Bitcoin ecosystem allow such a "consensus" to exist?
2) Use Bitcoin for payment solutions, including Lightning network, Taproot assets and client-side verification RGB, which are essentially based on Bitcoin main The UTXO model of the Internet provides security guarantees, which actually limits the best application scenario for these directions to be payment.
The circulation experience of small satoshis on the Lightning Network is already very smooth. Taproot assets and RGB are actually similar, and are relatively more suitable for the payment channel of stable coins.
If you want to superimpose some DeFi and EVM states on the state channel and client verification, it is equivalent to adding more complex ones to the original UTXO model. Verification logic, naturally some states that cannot be verified by the main network will be submitted to the main network, which essentially relies on off-chain consensus. This type of solution may work, but compared to the transaction scenario controlled by the pure UTXO model, the security level will also be reduced accordingly.
Above. How does the Bitcoin ecosystem come to fruition?
If the Bitcoin ecosystem empowered by pure Bitcoin security consensus points to subsequent stablecoin application consumption scenarios such as Lightning network and Taproot assets;
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If in addition to the Bitcoin mainnet consensus, some off-chain consensus is allowed, point to the RGB client to verify complex application scenarios that can implement complex layer 2 smart contracts;
If the Bitcoin mainnet only does the settlement chain and relies on independent consensus outside the chain, then all kinds of side chains, alliance chains, index chains, etc. can automatically It seems that any solution that builds consensus and strictly implements transparent settlement of assets is acceptable.
If a Bitcoin Turing computing verification solution such as BitVM is really implemented, it will not change the consensus of the Bitcoin main network and the cost will be lower than that of Ethereum Smart In terms of contract structure, the above conclusion must be overturned.
In short,the impossible triangle conflict of security + decentralization + scalability is even more intense on the Bitcoin mainnet. The so-called Bitcoin orthodox layer 2 may be a false proposition. In my opinion, if you choose the orthodox consensus, you have to accept the expansion of "limitations". If you want to break through the limitations, don't use the banner of the invincible consensus.
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