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MeerToken Series- UTXO Asset Issuance
Asset issuance depends on smart contracts, because even the simplest transfer transaction will involve certain transaction processing logic in the specific implementation process, and the assets of the UTXO model are no exception. I believe many friends know that the account model supports smart contracts, but some friends may not be very clear about how to implement UTXO smart contracts. Let's first look at the definition of smart contracts in the blockchain field. It refers to the technology that uses blockchain technology to ensure that transactions can be automatically executed in a trustless manner. So the key lies in whether blockchain technology can be used to ensure the automatic execution of contracts. The essence of a blockchain system is a state machine, that is, a machine that can change its internal state by inputting external variables. Here, the external variable is the transaction, and the internal state is the balance of the ledger and other data. Therefore, smart contracts need to accept transactions and then trigger the state change of the blockchain. The blockchain of the UTXO model represented by Bitcoin basically adopts a stack-based scripting language. Friends who have a certain programming foundation know that the last-in-first-out feature of the stack allows multiple subroutines to be executed in order. Simply understand that the stack-based scripting language actually has the expressive power of a high-level language, so it can implement relatively complex smart contracts. However, the blockchain is a decentralized value exchange system. Overly complex smart contracts may not only easily cause vulnerabilities and instability, but also drag down the entire blockchain. Therefore, Bitcoin not only limits the number of instructions, but also removes loop statements. Therefore, Bitcoin's scripting language is Turing incomplete. Simply understand that although the expressive power of UTXO-based smart contracts is limited, it can still support common applications of value circulation. Typical examples are cross-chain atomic swaps or multi-party signatures. With the development of smart contracts, higher requirements are placed on the functionality of the UTXO script language, so many solutions to enhance UTXO have emerged. The most intuitive solution is the colored coin solution, which uses OP_RETURN to terminate the execution of the script in advance, and then frees up 83 bytes of data space for free definition. Therefore, an application can write consensus data into this space, and then expand the data rules of the standard client for the application to parse the data. Obviously, the advantage of this solution is flexibility, and there is no need to change the consensus of the blockchain, and the deployment cost is low; the disadvantage is also obvious, that is, the data cannot be guaranteed to be secure through the blockchain consensus. A more ideal solution is to add a dedicated asset release instruction, which is the solution adopted in Qitmeer's testing phase. Qitmeer has added an Op_Token asset release instruction, which can convert the Qitmeer test network's native asset PMeer into the same number of minimum units (Qit, $1Pmeer=10^8Qit$) of assets. For example, if you want to issue an asset called TestToken, the smallest unit of TestToken is TestBit, $1TestToken=10*10^8TestBit$, then you need to spend 10 PMeer. It can be seen that the assets issued by Qitmeer have costs, which to a certain extent avoids the generation of junk assets. More importantly, compared with the colored coin solution, the issued assets need to be agreed upon by the entire network like the native assets, so you can get the same security and high-quality value circulation services as the native assets.
In the Qitmeer mainnet stage, Op_Token was further upgraded to the MeerToken asset issuance scheme. From the previous analysis, it can be seen that although the assets issued by the Op_Token instruction can enjoy the same security and value support as the native assets, there are still differences in the issuance mechanism, so it is necessary to handle the native assets and the issued assets differently in the asset-related processing flow. In computer professional terms, the abstraction level is not high. Therefore, the maintenance cost is high, there is a potential risk of instability, and the scalability is also limited. To address this issue, in the Qitmeer mainnet stage, the issued assets and the native assets are completely unified at the data structure level, and all operating mechanisms are exactly the same. Each asset has an asset number, and the special feature of the native asset is that it is the first asset that has been issued by default with the launch of the mainnet. Finally, let me summarize. With the continuous development of blockchain applications, the UTXO model is also in the process of continuous upgrading. From the most primitive transaction model of static data structure to the smart contract model of stack scripting language with certain flexibility. The demand for asset issuance has also led to the emergence of a transition plan for colored coins in the blockchain community. Qitmeer's OpToken asset issuance plan in the testnet stage solved the problem that the colored coin scheme transactions had no value support and the transactions could not be secured through consensus. In the mainnet stage, it more innovatively unified the native assets and issued assets, further improving the stability and scalability of Qitmeer. |
