Bitcoin lock script and unlock script

1. Introction to seven core technologies of blockchain operation on January 15, 2018
1. Blockchain links
as the name suggests, blockchain is a chain composed of blocks. Each block is divided into block head and block body (including transaction data). The block head includes the prevhash value (also known as hash value) of the previous block used to realize the block link and the random number (nonce) used to calculate the mining difficulty. The hash value of the previous block is actually the hash value of the head of the previous block, and the random number calculation rule determines which miner can obtain the right to record the block
2. Consensus mechanism
blockchain is accompanied by the birth of bitcoin, which is the basic technology architecture of bitcoin. Blockchain can be understood as an Internet-based decentralized accounting system. A decentralized digital currency system like bitcoin requires the consistency of accounting of honest nodes without a central node, which needs blockchain to complete. Therefore, the core of blockchain technology is a consensus mechanism to reach a consensus on the legitimacy of transactions between indivials without mutual trust without central control
there are four main types of consensus mechanisms in blockchain: pow, POS, dpos and distributed consistency algorithm
3. Unlocking script
script is an important technology to realize automatic verification and contract execution on blockchain. Every output of every transaction does not point to an address in the strict sense, but to a script. A script is like a set of rules that constrain how the receiver can spend the asset locked on the output
the validation of transactions also depends on scripts. At present, it depends on two kinds of scripts: Lock script and unlock script. Locking script is a condition added to the output transaction, which is realized by a script language and located in the output of the transaction. The unlocking script corresponds to the locking script. Only when the conditions required by the locking script are met can the assets corresponding to the script be spent, which is located in the input of the transaction. Many flexible conditions can be expressed by script language. Interpretation script is similar to the "virtual machine" in our programming field, which runs in every node of the blockchain network in a distributed way
4. Transaction rules
blockchain transaction is not only the basic unit of a block, but also the actual effective content recorded by the blockchain. A blockchain transaction can be a transfer, or the deployment of smart contracts and other transactions
as far as bitcoin is concerned, a transaction refers to a single payment transfer. The transaction rules are as follows:
1) the input and output of the transaction cannot be empty
2) for each input of a transaction, if its corresponding utxo output can be found in the current transaction pool, the transaction will be rejected. Because the current transaction pool is the transaction not recorded in the blockchain, and each input of the transaction should come from the confirmed utxo. If it is found in the current trading pool, it is Shuanghua trading
3) for each input in a transaction, the corresponding output must be utxo
4) each input unlocking script must verify the compliance of the transaction together with the corresponding output locking script
5. Transaction priority
the priority of blockchain transaction is determined by the blockchain protocol rules. For bitcoin, the priority of a transaction to be included in a block is determined by the time when the transaction is broadcast to the network and the amount of the transaction. With the increase of transaction broadcast time on the network and the increase of transaction chain age, the priority of transaction will be improved and eventually be included by the block. For Ethereum, the priority of the transaction is also related to the transaction fee that the publisher is willing to pay. The higher the transaction fee that the publisher is willing to pay, the higher the priority that the transaction is included in the block
6. Merkle proof
the original application of Merkle proof is bitcoin, which was described and created by Satoshi Nakamoto in 2009. Bitcoin blockchain uses Merkle proof to store transactions in each block. So that the transaction can not be tampered with, but also easy to verify whether the transaction is included in a specific block
7. RLP
RLP (recursive length prefix) is one of the main encoding methods of object serialization in Ethereum. Its purpose is to encode the sequence of arbitrary nested binary data.

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3.

in 2019, the expenditure scale of China's blockchain market will be close to US $300 million

according to the statistical data of in depth analysis report on business model innovation and investment opportunities of China's blockchain instry , released by foresight Instry Research Institute, as of 2017, the expenditure scale of China's blockchain market is only US $83 million. In 2018, the expenditure scale of China's blockchain market will reach US $160 million. It is predicted that the expenditure scale of China's blockchain market will be close to US $300 million in 2019. At this stage, the overall market scale of blockchain is small, because most blockchain projects in the market are in the trial stage, with little investment. On the other hand, many enterprises have realized the potential of blockchain and plan to increase the budget in the future. Affected by this, China's blockchain market will usher in rapid growth. It is estimated that the market expenditure will reach US $1.95 billion by 2023, and the average annual compound growth rate will be 60.51% from 2019 to 2023

statistics and forecast of China's blockchain market expenditure scale from 2017 to 2023

data source: Analysis on adverse factors of China's blockchain development sorted out by the prospective instry research institute

1. Immature technology. At present, blockchain technology is not mature in system stability, application security, business model, etc., which can not meet the requirements of "high efficiency and low energy", "decentralization" and "security" at the same time. First, performance. The transaction throughput that can be carried out on the blockchain is not high, and the current block capacity is very small, which leads to network congestion, and it is difficult to meet the needs of high-frequency business. Many projects are also starting to optimize, but there is still a certain distance from the transaction throughput of real scenes such as banks and stock exchanges. Second, consensus mechanism. In terms of energy consumption, consensus algorithms such as workload proof consume a lot of energy and cost, which makes blockchain waste a lot of network computing power and pairing power; In terms of types, there are too few types of blockchain consensus mechanisms at present. In the future diversified business scenarios, more abundant consensus mechanisms are necessary to adapt. Third, security. Privacy protection, harmful information on the chain, smart contract vulnerability, consensus mechanism and private key protection, computing power attack, cryptography algorithm security and other issues make the blockchain face a severe situation of platform security and application security. Fourth, the database problem. Different from traditional databases, blockchain applications require a lot of write operations, hash calculation and verification operations. The database system for blockchain is still a difficult point to break through

2. Unclear application scenarios

currently, the blockchain project is still in the exploration stage, and no specific landing scenarios can be found. At present, the more promising fields are finance, sharing economy, Internet of things, public services, etc., but from the perspective of the existing blockchain technology maturity, there are still many problems in the application of blockchain, and there is still a gap from the actual use. First, the immaturity of blockchain technology restricts the implementation of commercial applications. At present, although there are many kinds of blockchain core technologies such as privacy protection algorithm and consensus mechanism, they generally do not have commercial availability. Second, the application mode of blockchain is still in exploration, and the "irreplaceable" advantage of blockchain has not been reflected. Blockchain itself represents a consensus system, so we should build a consensus system in line with the corresponding business scenarios from a higher level, rather than just "business + blockchain". There are many users in China, and the business scenario is complex. Moreover, any commercial proct will involve a very large flow and population. The current blockchain technology can not meet the demand

3, lack of professional talents

blockchain technology is a multi-disciplinary and interdisciplinary technology, which mainly involves operating system, network communication, cryptography, mathematics, finance, proction and so on. However, at present, there are still deficiencies in interdisciplinary and fields in China, and the supply of talents in related fields is seriously insufficient. On the one hand, there is a large gap of R & D technical talents. Blockchain technology research and development mainly focuses on go, JavaScript, C and C + programming languages, and new smart contracts use Haskell, Ocaml, rhoang and other new functional programming languages. In China's talent market, there is a big gap for technical talents with senior R & D experience in relevant languages. On the other hand, there is a lack of bottom design talents. Different from R & D technical talents, blockchain bottom system architecture designers need to master a number of interdisciplinary professional skills, not only to deeply understand the block chain bottom design principle, but also to have the system architecture design experience, but also to master the business logic of specific application scenarios. Although some colleges and universities have launched interdisciplinary ecation and blockchain special skills discipline setting, professional talents are still very scarce

analysis of favorable factors for China's blockchain development. In January 2017, the Ministry of instry and information technology issued the development plan of software and information technology service instry (2016-2020), which proposed that the innovation in blockchain and other fields should reach the international advanced level. In August 2017, the State Council issued the guidance on further expanding and upgrading information consumption and continuously releasing the potential of domestic demand, proposing to carry out the pilot application of new technologies such as blockchain and artificial intelligence. In October 2017, the State Council issued the guidance on actively promoting the innovation and application of supply chain, which proposed to study the use of blockchain, artificial intelligence and other emerging technologies to establish a credit evaluation mechanism based on supply chain

in March 2018, the Ministry of instry and information technology (MIIT) issued the key points for standardization of informatization and software service instry in 2018, proposing to promote the establishment of the national informatization and instrialization Integration Management Standardization Technical Committee, and the national blockchain and Distributed Accounting Technology Standardization Committee. In June 2018, the Ministry of instry and information technology issued the instrial Internet development action plan (2018-2020) to encourage the application and research of emerging cutting-edge technologies such as edge computing, deep learning and blockchain in the instrial Internet

since the blockchain was listed in the 13th five year plan for national informatization for the first time in 2016, the national government has paid more and more attention to the blockchain. 24 provinces and cities or regions, including Beijing, Shanghai, Guangdong, Hebei, Jiangsu, Shandong, Guizhou, Gansu and Hainan, have launched dividend policies to carry out the layout of the blockchain instry chain, Actively explore instry applications based on blockchain

At present, China's blockchain technology continues to innovate, and the blockchain instry graally takes shape, and has begun to be applied in supply chain finance, credit reference, proct traceability, right trading, digital identity, electronic evidence and other fields, which is expected to promote China's economic system to achieve technological change, organizational change and efficiency change, To make important contributions to the construction of a modern economic system. With the continuous influx of entrepreneurs and capital, the number of enterprises is increasing rapidly. The application of blockchain will accelerate the landing, boost the high-quality development of traditional instries, accelerate the instrial transformation and upgrading, use blockchain technology to "rece costs" and "improve efficiency" for the real economy, and boost the standardized development of traditional instries. In addition, blockchain technology is becoming a new business form and a new driving force for economic development. Blockchain technology is promoting a new round of business model reform and becoming an important support for building a social system of integrity

In the past, the circulation of physical banknotes was difficult to trace, but with the application of blockchain technology, the flow of all digital assets will have a "chain" to check. For example, in the financial field, blockchain is expected to solve the pain points and difficulties in the payment field, rece the complexity of transactions, improve the end-to-end speed of transactions, rece the communication cost in the transaction process, and improve the transparency and non tamperability of transaction records. The cost of reconciliation, clearing and settlement among financial institutions, especially cross-border financial institutions, has always been very high, and there are complex manual processes. The application of blockchain technology can help rece the cost of reconciliation and dispute resolution among financial institutions, and significantly improve the processing speed and efficiency of payment business, It also makes small cross-border payments possible. In addition, the application of blockchain will also extend to many fields, such as health care, ecation, charity, social management and so on. The market prospect is very broad