区块链应用的论文5000字,区块链应用的论文有哪些

今天，我们要讨论的话题是区块链应用的论文，其中拓展的三个关键词分别是：区块链技术、智能合约、区块链安全。

首先，让我们来谈谈区块链技术。区块链技术是一种分布式数据存储技术，它能够记录和存储数据，并且可以在网络中共享。区块链技术的最大特点是，所有的数据都是可信的，而且不可篡改，可以被多个用户共同使用，从而极大地提高了数据的安全性和可靠性。区块链技术的应用非常广泛，可以用于金融、物流、医疗、政府等行业，以及许多其他行业，可以大大提高效率，改善服务水平。

其次，我们再来谈谈智能合约。智能合约是一种在区块链上运行的自动执行程序，它可以根据给定的条件自动执行，从而实现自动的合约执行。智能合约的优势在于，它可以自动执行，没有任何人的干预，可以极大地提高效率，减少合约执行的时间，且不易受到恶意干扰，可以大大提高合约的安全性。智能合约的应用也非常广泛，可以用于金融、物流、智能制造等行业，以及许多其他行业，可以大大提高效率，改善服务水平。

最后，我们来谈谈区块链安全。区块链安全是指在区块链网络中，保护数据安全的技术手段。区块链安全的核心是密码学，它可以保证数据的安全性，并且可以防止数据的篡改。此外，区块链安全还可以应用于分布式认证、智能合约安全等方面，以保护网络数据的安全性。因此，区块链安全对网络安全具有重要意义，可以大大提高网络安全水平，更好地保护网络数据。

以上就是今天我们要讨论的关于区块链应用的论文的三个关键词：区块链技术、智能合约、区块链安全。这三个关键词都可以用于提高网络数据的安全性和可靠性，从而改善服务水平，提高效率。

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㈠ A paper analyzing the prospects of blockchain in the financial field

A paper analyzing the prospects of blockchain in the financial field

Blockchain technology was born in In 2008, the first application was Bitcoin. Blockchain technology uses a decentralized consensus mechanism to maintain a complete, distributed, and non-tamperable ledger database, allowing participants in the blockchain to implement a unified ledger system without establishing a trust relationship. . In 2015, many mainstream financial institutions in Europe and the United States recognized the application prospects of this technology and explored the application of blockchain technology in the financial field. The International Monetary Fund pointed out in a report that "it has the potential to change finance." Some people believe that blockchain technology will change human society as profoundly as double-entry accounting and shareholding.

Blockchain will make it possible for all individuals to become important nodes in the allocation of financial resources. It will also promote the improvement of the existing financial system and financial rules, and build a shared and win-win situation. type of financial development ecosystem. The emergence of blockchain technology is a revolution in human credit creation. It allows both parties to the transaction to carry out economic activities without the need for third-party credit intermediaries, thereby achieving low-cost value transfer. It can be said that blockchain technology is a more efficient value exchange technology in the Internet era. The Internet has evolved from an information Internet that transmits information to a value Internet that transfers value. This is conducive to traditional financial institutions taking advantage of the opportunity to transform and transform endogenous businesses. Processes and application scenarios are Internetized.

1. Characteristics and shortcomings of blockchain

(1) Main characteristics of blockchain

(1) Decentralization. In the blockchain, there is no centralized hardware or management organization. The distributed structure system and open source protocol allow all participants to participate in the recording and verification of data, which is then sent to various nodes through distributed propagation. Each participant The nodes are all "self-centered", and the rights and obligations are equal. Blockchain is not simply decentralized, but multi-centered or weakly centered. When the Internet of Things makes it possible for all individuals to become central nodes, the central status of traditional financial intermediaries changes, transforming from a monopoly-type, resource-advantaged center and strong intermediary to an open platform, becoming a service-oriented multi-center. Center of differentiation.

(2) To trust. From a trust perspective, blockchain uses a set of open and transparent mathematical algorithms based on consensus specifications and protocols to enable all nodes to automatically and securely exchange data in a trustless environment. Blockchain essentially solves the problem of trust through mathematical methods. All rules are expressed in the form of algorithmic programs. Participants do not need to know the credit level of the counterparty, and do not need transaction endorsement or guarantee verification from a third-party institution. They only need trust. A common algorithm creates credit, generates trust, and reaches consensus for participants through the algorithm.

(3) Timestamp. A block is data over a period of time andGenerated by code packaging, the header of the next block contains the index information of the previous block, and a chain is formed by connecting the end to the end. The blocks that record the complete history and the chain that can be completely verified form a timestamp that can trace the complete history. It can provide retrieval and search functions for each piece of data, and can use the blockchain structure to trace the source, one by one. verify. Therefore, the blockchain is timestamped when generated, forming a database that cannot be tampered with or forged. Modifications to the database on a single node are invalid unless more than 51% of the nodes in the system can be controlled at the same time, so the data reliability of the blockchain is very high.

(4) Asymmetric encryption. Blockchain uses an asymmetric encryption algorithm, that is, a "key pair" is used in the encryption and decryption process. The two keys in the "key pair" have asymmetric characteristics. In the application scenario of blockchain, on the one hand, the key is the public key visible to all participants. Participants can use the public key to encrypt a piece of authenticity information, and only the owner of the information can use the private key to decrypt it. On the other hand, the private key is used to sign the information, and the signature is verified by the corresponding public key to ensure that the information was sent by the real holder. Asymmetric encryption minimizes friction boundaries in value exchange, enables transparent data anonymity, and protects personal privacy.

(5) Smart contract: Since the blockchain can realize point-to-point value transfer, corresponding programming scripts can be embedded during transfer. This smart contract method is used to handle some unforeseen transaction patterns and ensure Blockchain can continue to be effective. This kind of programmable script is essentially a list of many instructions to achieve pertinence and conditionality in value exchange and to achieve specific uses of value. Therefore, any value exchange activity based on the blockchain can achieve hard control over its use, direction and various restrictions through intelligent programming, eliminating the cost of soft constraints by law or contract.

(2) Main problems of blockchain

(1) High energy consumption problem. There is an impossible triangle in the traditional currency and banking system, that is, it is impossible to achieve decentralization, low energy consumption and high security at the same time. The impossible triangle also exists in the construction of blockchain. For example, in the actual application of Bitcoin, its development has brought about the rapid expansion of computer hardware, and the main costs in the "mining" process have shifted to hardware costs and electricity costs. Therefore, after applying blockchain technology to achieve equity cost benefits, maximizing its technical efficacy has become an urgent problem to be solved.

(2) Storage space problem. Since the blockchain records every transaction information from the initial information in the system, and each node has to download, store and update data blocks in real time, if the data of each node is completely synchronized, the network pressure will be great, and each node will The storage space capacity requirements of each node may become a key issue restricting its development.

(3) The problem of stress resistance. The system built based on blockchain follows the barrel theory and must take into account the worst processing speed and network environment among all network nodes. Therefore, if blockchain technology is promoted toIn a large-scale trading environment, its overall ability to withstand pressure has yet to be verified. If the transaction volume generated per second exceeds the design capacity of the system (the weakest node), transactions will automatically enter the queue and be queued, resulting in a poor user experience.

2. Application of blockchain in the financial field

(1) Financial infrastructure

Blockchain may be used as the infrastructure of the Internet in many fields. All show broad application prospects. In the financial industry, blockchain technology will first affect financial infrastructure such as payment systems, securities settlement systems, and transaction databases. Later, the technology will also expand to general financial services, such as credit systems, "anti-money laundering," etc. This is because, based on the characteristics of blockchain technology, it will first enter the infrastructure field with high trust requirements and high cost of traditional trust mechanisms. In the past, infrastructure was a public product, but new technologies and new systems of blockchain have made it more It is possible for multiple people to participate in the provision of public goods. The future of Internet finance will use Internet technologies such as blockchain to transform the core production systems of traditional financial institutions and build financial enterprises on the Internet.

The current information Internet can be collectively referred to as the TCP/IP model, and HTTP is the most important application protocol in the application layer. In the Internet of Value, blockchain is a point-to-point transmission protocol in the application layer. Its value is the same as that of the HTTP protocol in the information Internet. The huge potential and prospect of blockchain is that it can reconstruct the infrastructure and core production systems of the traditional financial industry, not just at the application level such as APPs. This is because, at the network level, the blockchain is based on the IP communication protocol and the distributed network; at the data level, the blockchain database system is brand new and is significantly better than the existing one. There is a database of the financial system; at the application level, registration and settlement, clearing systems, smart contracts, and the Internet of Things based on the blockchain can greatly improve efficiency. Financial activities on the blockchain are programmable finance. .

(2) Digital Currency

From the perspectives of security and cost, it is a general trend that banknotes will be replaced by new technologies and new products. The establishment of digital currency issuance and circulation systems is very necessary for financial infrastructure construction and economic development. Following the integration of traditional currency and digital currency, the issuance, circulation and trading of digital currency should be led by the central bank, reflecting convenience and security, and achieving a balance between protecting privacy, maintaining social order, and combating illegal and criminal activities. It is conducive to the effective operation and transmission of monetary policy. It is necessary to retain the control of monetary sovereignty. Digital currency is freely convertible and controllable.

The success of blockchain technology on Bitcoin proves the feasibility of programmable digital currency. Research from the Bank of England suggests that central banks could consider issuing blockchain-based digital currencies, which could increase financial stability. The technical routes of digital currency can be divided into two types: account-based and non-account-based. They can also be used in layers to try to coexist. districtThe characteristic of blockchain technology is distributed bookkeeping, which is not account-based and cannot be tampered with. If the digital currency focuses on protecting personal privacy, this technology can be used. However, the current blockchain occupies too many computing resources and storage resources and cannot cope with the current scale of transactions. This problem needs to be solved before it can be promoted and applied.

(3) Self-finance

From the perspective of services and non-monetary creation, modern finance is realized through intermediaries. In the Internet era, it is possible to achieve direct finance in the true sense of disintermediation. However, this possibility is not complete. The main reason is that the current Internet finance is based on the original finance and cannot be jumped out. Blockchain technology provides a possibility. Blockchain can be divided into public blockchain and private blockchain. Public blockchains are like Bitcoin. Once the protocol is approved, it becomes an integral part of the blockchain. Private blockchains still need to be permissioned, and blockchain technology in banking systems requires auditing of each participant. Private blockchain is very similar to a form of self-finance, and public blockchain is more similar to the support and guarantee for the bottom layer of private blockchain. When blockchain technology is widely used and third-party financial management technology is generally available, self-financing based on blockchain technology will become completely possible.

3. Blockchain Application and Financial Supervision

Blockchain technology is currently the only tool that can be used to record and prove transaction consistency and company financial accuracy without the need for a third party. Therefore, it can meet the requirements of potential regulators and the public for audit effectiveness, accuracy and timeliness, and has broad application prospects in the financial field. However, its development is still restricted by the current system. On the one hand, blockchain has had an impact on the current system because its decentralized and autonomous characteristics dilute concepts such as the state and supervision. For example, digital currencies represented by Bitcoin challenge the country's right to issue currency and regulate monetary policy, causing monetary authorities to take a conservative attitude towards the development of digital currencies. On the other hand, regulatory authorities also lack full understanding and expectations of this new technology, and the establishment of laws and systems will be seriously delayed, resulting in the lack of necessary institutional norms and legal protection for blockchain applications, increasing the risks for market entities.

Once blockchain financial technology is widely deployed in the financial industry, the de-financial nature of supervision will occur, and supervisory functions, supervisory methods and supervisory means will be redefined. For example, if securities lending, repurchases, and margin trading can be traded through the blockchain, regulatory authorities can consider using the information from this public ledger to monitor systemic risks in the market, which is not only efficient but also reliable. From a macro-financial perspective, after the emergence of the financial era, the currency creation and transmission mechanism and the credit creation pattern will change. From a micro-finance perspective, with the further development of blockchain technology, finance and business have become difficult to distinguish, and will transcend the meaning of separate and mixed industry supervision. The reform of the financial supervision system needs to be discussed from this perspective.

Blockchain technologyThe "decentralization" brought about still requires centralized departments to provide regulatory and guarantee support. Regulators can proactively embrace new technologies in Internet finance. U.S. Securities and Exchange Commission member Kara Stein believes that regulators need to be in a leading position, taking advantage of the advantages of blockchain technology and quickly responding to its potential weaknesses. For example, blockchain technology hopes to break privileges and human manipulation and allow computer algorithms to achieve "free credit notarization." But in practice, due to the lack of supervision, digital currency transactions such as Bitcoin face high risks of speculation and money laundering. Therefore, the application of blockchain technology requires regulatory authorities to formulate relevant standards and specifications to ensure that financial innovative products are used appropriately. At the same time, it is necessary to improve the protection of consumer rights and interests, strengthen education on the protection of financial consumer rights and interests, and improve consumers' awareness of risk prevention.

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㈡ Blockchain Graduation Project Proposal

Background of the project research:

With the development of modern technology and information industry, at this stage, the The Fourth Industrial Revolution has begun to take shape, and the world is about to enter a technological era centered on new technologies such as the Internet and artificial intelligence. At the same time, blockchain technology has emerged as the times require and has become a hot topic of concern for many international governments and industries. Blockchain technology has been regarded as the core technology with the greatest potential to trigger the fifth round of disruptive revolution after steam engines, electricity, information and Internet technology. In the past 10 years, with the strong support of the government and policies, the development situation of my country's philanthropy has been relatively optimistic. However, as the scale of charity continues to develop and expand, my country's public welfare undertakings have gradually revealed some shortcomings. The biggest problems existing in traditional public welfare undertakings are insufficient credibility, imperfect internal management of charitable organizations, and high costs. However, many Internet public welfare service companies are currently actively using the new technology of blockchain to solve this problem. Blockchain technology has the characteristics of decentralization, information traceability and non-tampering, openness and transparency, and smart contracts. It can make up for the shortcomings of traditional public welfare undertakings such as opaque information and low management efficiency. Blockchain technology will enter public welfare undertakings and will Bring new development opportunities to the charity industry.

The main content of the research: This topic mainly includes the following three aspects:

[if !supportLists] 1. [endif] Combination of blockchain technology and public welfare Problems that arise and solved.

[if !supportLists] 2. [endif] Make a public welfare query webpage based on blockchain technology

[if !supportLists] 3. [endif] The query system Application issues and explanations

Purpose of the research:

As the scale of my country’s public welfare continues to develop and expand, our shortcomings have also been exposed, including lack of credibility, and charitable organizations Lack of management and use ofBlockchain technology can solve this problem. This technology will track and store data and behaviors throughout the donation process, realize the complete disclosure of the public welfare chain, enable donors to effectively supervise, avoid shortcomings such as low efficiency and clear fund flows, control risks for public welfare projects, and improve Credibility and transparency of public welfare projects promote the development and progress of public welfare projects and enhance trust between people. According to the attributes and characteristics of the blockchain system, public welfare enterprises can implement full-cycle tracking, evidence storage and auditing of data and behaviors in the public welfare process, so that all parties involved in public welfare projects can conduct full-process tracking and effective supervision of the project, avoiding Due to the shortcomings of artificially reducing efficiency in public welfare, it provides a rational method for public welfare projects to control risks and judge effects, improve the transparency of public welfare undertakings, and promote the development of public welfare.

Significance of the project research: This project intends to develop an open and transparent system for tracking public welfare donations based on blockchain technology and combined with the actual development of public welfare undertakings in my country. Through in-depth analysis of blockchain technology and charity business, we found that blockchain technology has natural advantages in solving the problem of public welfare transparency. Blockchain technology can be understood as a distributed accounting method that can record all transaction information and ensure that it cannot be tampered with. This determines that wherever justice, fairness, and integrity are required, blockchain has great technology. Room to play. At the same time, the addition of smart contracts directly solves the business problem of earmarked funds.

Eventually, trust between citizens will be enhanced, donation channels will be accelerated, and the development of social donations will be promoted

2. Literature review (current status and development of relevant research at home and abroad Trend)

[if !supportLists] (1) [endif] Current status of foreign blockchain-related industries

China and Europe are gradually occupying the world in blockchain industry policies, and the EU is The European Blockchain Observation Forum has been established in February 2018. Its main responsibilities include: policy determination, industry-university-research linkage, cross-border BaaS

(Blockchain as a Service) service construction, standard open source formulation, etc. Investing 5 million euros in Horizon2020 as a blockchain research and development fund (before December 19, 2018), it is expected that investment in blockchain will reach 340 million euros within three years (2018-2020). In the United States, due to different policies among states, although blockchain is still a craze among American start-ups, the promotion of industrial policy has been slow. The Middle East, led by Di Pai, is leading the trend of blockchain. The government is taking the lead and enterprises are cooperating to explore new technology applications of blockchain. Japan and South Korea are also relatively active in the Asia-Pacific region. Japan mainly uses NTT, and the government provides support behind the scenes.With support, South Korea uses finance as an entry point to explore blockchain applications. Isism is also a constant threat to all areas of Chinese society. A comprehensive review of the development status of new media culture in major foreign developed countries, summarizing experiences, and drawing lessons have certain implications for the development of new media culture in China.

[if !supportLists] (2) [endif] Current status of domestic new media research

The State Council of China issued the "Thirteenth Five-Year Plan for National Informatization", Blockchain New technologies such as big data, artificial intelligence, and machine deep learning have become the focus of the country’s layout. The People's Bank of China issued the "Thirteenth Five-Year Plan for the Development of Information Technology in China's Financial Industry", which clearly proposed to actively promote research on the application of new technologies such as blockchain and artificial intelligence, and organize pilot projects for national digital currencies. In October 2017, the Ministry of Industry and Information Technology released the "White Paper on China's Blockchain Technology and Application Development", which is the first official guidance document for blockchain.

Governments across the country, especially in coastal areas, have established blockchain experimental sites and research institutes. At present, the governments of Shenzhen, Hangzhou, Guangzhou, Guiyang and other places are actively establishing blockchain development zones and providing special support policies. China Guangzhou officially released 10 Guangzhou blockchain strategies in December 2017 to create a blockchain enterprise technology innovation zone in Huangpu District and Development Zone. In March 2018, the Shenzhen Municipal Economic, Trade and Information Commission issued the "Notice of the Municipal Economic, Trade and Information Commission on Organizing and Implementing the Second Batch of Support Plan for the New Generation Information Technology and Information Security Transformation of Shenzhen's Strategic Emerging Industries in 2018". The district Blockchain is on the list of support directions. This is the fifth local government in China to introduce support policies for blockchain after Guangzhou, Guiyang, and Gehangzhou.

(3) Current status of blockchain in the open source field

Hyperledger (Hyperledger)

Hyperledger (Hyperledger) is developed by the Linux Foundation The open source project to promote blockchain digital technology and transaction verification, launched in 2015, has attracted the participation of many companies including IBM, Intel, Fujitsu, UPS, Cisco, Huawei, Redhat, Oracle, Samsung, Tencent Cloud, Internet Finance, etc. Currently, There are already more than 200 member units, and Bran Behlendorf, founder of the Aache Foundation, serves as the executive director of the ledger project.

The goal of the Hyperledger project is to allow members to work together to build an open platform to meet user cases from many different industries and simplify business processes. Process Ledger has multiple blockchain platform projects, including the Fabric project contributed by BIM, IntThe Sawtooth project contributed by el, as well as Iroha, Burrow, Indy, etc.

The development status of blockchain in the field of standards

ITU-T

ITU-T (International Telecommunication Union Standardization Organization) from 2016 to 2017 At the beginning of the year, SG16 (Study Group), SG17 and SG20 respectively launched research on the overall needs and security of distributed ledgers to attract application in the Internet of Things. Established three focus groups (Focus Group on Distributed Ledger (FG DLT), Focus Group on Data Processing and Management (FG DPM), and Focus Group on Fiat Digital Currency (FG DFC)), focusing on blockchain and distributed ledger respectively. Technology application and service research, establishing a trustworthy Internet of Things and smart city data management framework based on blockchain, and carrying out standardization work on blockchain applications based on digital currency. Huawei serves as the chairman of the Architecture Group of the Focus Group on Distributed Ledgers (FG DLT) and the Blockchain Group of the Focus Group on Data Processing and Management (FGDPM).

Two committees of CCSA (China Communications Standards Association) have established subgroups and projects respectively:

CCSA TC10 (Internet of Things Technical Working Committee) Established in October 2017, the Internet of Things Blockchain Subgroup: Responsible for the application research and standardization of blockchain technology in the Internet of Things and its covered areas such as smart cities, Internet of Vehicles, edge computing, Internet of Things big data, Internet of Things industry applications, logistics and intelligent manufacturing, and is led by China China Unicom technical experts serve as team leaders, and Huawei technical experts serve as deputy team leaders.

The Blockchain and Big Data Working Group under CCSA TC1 (Internet and Application Technology Working Committee) completed two blockchain industry standards: "Blockchain: Part 1 Overall Technical Requirements for Blockchain ” and “Blockchain: Part 2 Evaluation Indicators and Evaluation Methods”, in which Huawei actively participated.

JPEG

During the 78th JPEG Conference in February 2018, the JPEG Committee organized a special session on blockchain and distributed ledger technology and their impact on the JPEG standard. Meeting. Taking into account the potential impact of technologies such as blockchain and distributed ledgers on future multimedia, the committee decided to establish an ad hoc group to explore use cases and standardization needs related to blockchain technology in a multimedia environment, with a focus on imaging and multimedia applications. standardization work.

IETF

The "Decentralized Internet Infrastructure Proposal" was established at the ETF99 meeting in June 2017edRG

(Research Group), plans to study the blockchain architecture and corresponding standards. In 2018, IETF will likely pay more attention to the implementation of blockchain interconnection standards on the blockchain. develop.



3. The proposed research methods (plans, technical routes, etc.) and feasibility demonstration

This topic mainly studies blockchain technology Research methods used in combination with charitable donations:

1. Collect relevant theories using literature methods, collect literature materials and related theories using information retrieval, screening and other methods, and come to the blockchain The current state of technology and mastering blockchain decentralization technology.

2. Combine the technology with public welfare by combining theory and practice. Complete improvements to the system.

3. Use the method of comparative analysis to discuss the current development status of new media operations from both domestic and foreign aspects, as well as existing problems in the development of my country's new media operation models, and look forward to the development prospects of this technology field.

Feasibility demonstration:

1. Technical feasibility. The research goals involved in this topic already have considerable theoretical foundations at home and abroad. Through literature survey, we can learn about actual, reliable and useful information data, and the actual requirements are not difficult.

2. Economic feasibility. The research on this topic can be done by accessing literature and materials through the Internet and libraries. It is convenient and feasible and does not require a lot of economic consumption. Therefore, from an economic point of view, it is completely feasible.

3. Operational feasibility. This topic requires the combination of blockchain technology and public welfare, especially the tracing of applications in these aspects. A comprehensive analysis of the graduation project system on this topic can be achieved through the analysis of both Study literature and existing documents, use the data you collected to organize and analyze, apply what you have learned, and complete this project completely. From an operability point of view, it is completely feasible.

4. Expected results (or expected results)

1. Through research on the data, clarify the relevant concepts of blockchain technology, skillfully use dapp, and create a web page.

2. Through distributed applications, creating a system that allows the public to quickly browse and understand the public welfare process will increase convenience for the further development of my country's public welfare undertakings.

3. I hope that I can continue to learn and make progress from the process of writing this paper. Being able to master the relevant knowledge of blockchain will be helpful to your future career.

ㅢ Re-understanding the blockchain: Enlightenments brought by more than 1,550 application cases

Author: Ran Wei

(This article is excerpted from the "2021 Global Blockchain Application Market Report")

When we talk about blockchain, as long as the blockchain Anyone who knows something about the chain can express some of his or her own opinions on related topics to a greater or lesser extent. For example: from the perspective of technical system, blockchain is a new application of computer technology such as distributed data storage, point-to-point transmission, consensus mechanism, encryption algorithm; from the perspective of functional attributes, blockchain is decentralized, non-tamperable, and full-process. Features such as leaving traces, traceability, collective maintenance, openness and transparency.

Looking back at the history of blockchain, there is no way around Bitcoin. On January 3, 2009, the Bitcoin genesis block with serial number 0 was born. A few days later, on January 9, 2009, Bitcoin block number 1 was born. When two blocks are connected, the blockchain is "born."

The inventor of Bitcoin, whose pseudonym is "Satoshi Nakamoto", may find it difficult to imagine: In the past 12 years, with Bitcoin as the center, a huge "cryptocurrency family" has spread all over the world. The financial market set off a "big wave" that continues to this day. During this period, innovation and risks related to cryptocurrency are intertwined, progress and bubbles coexist, and pursuit and criticism coexist, and it drives government departments of various countries to continuously improve the monetary and financial systems, social governance and supervision systems.

At the same time, the blockchain that accompanies Bitcoin is also evolving rapidly, and has long gone beyond the scope of "Bitcoin's underlying technology" and has been applied to every corner of social and economic development.

So, what mechanism does blockchain work through? What are its advantages compared to traditional technologies and models? What is its application effect? In the "2021 Global Blockchain Application Market Report" jointly released by Capital Lab and Yuanwang Think Tank, we tried to provide a certain basis for the above issues through research on more than 1,550 application cases around the world in 2020 and the first quarter of 2021. Empirical answer. At the same time, based on the study of these cases, we can establish a new understanding of blockchain: blockchain is trust, blockchain is sharing, blockchain is transaction, blockchain is substitution, and blockchain is efficiency.

In the Bitcoin creation paper "Bitcoin: A Peer-to-Peer Electronic Currency System", "Satoshi Nakamoto" repeatedly emphasized that Bitcoin has the characteristics of not relying on a "trusted third party". That is the characteristic of “decentralization”.

On the other hand, the underlying technology of Bitcoin, the blockchain, is precisely designed for "trust." In other words, reshaping "trust" in the digital age is the most basic function of the blockchain, but this trust has been transformed from trust between people and legal entities to trust between machines and machines. Trust between blocks and between nodes. Interestingly, subsequent birthsThe new “smart contract” function further strengthens this trust through integration with the blockchain.

Identity coding and authentication are the first steps to achieve the above-mentioned trust mechanism, and the distributed identity (Decentralized Identity, DID) system is the core of it. With DID applications, everyone from individuals to organizations to IoT devices, from physical items to virtual products, can be given digital "identities" and achieve trusted interactions. It is precisely because of this that blockchain-based certificate storage, empowerment, verification, circulation, and transactions can be realized, and only then can blockchain be implemented in various industries.

Application cases from around the world show that new trust mechanisms provide new rules and motivation for social and economic operations:

l China is comprehensively promoting blockchain electronic certificates Applications such as "one fish, one code", "one fruit, one code", "one tea, one code" and other applications are driving the global Anti-counterfeiting traceability of agricultural products and upgrading of food safety systems;

l Through the combination of blockchain, big data, and artificial intelligence, the credit "portrait" of an enterprise is more accurate and can be obtained faster and more accurately. Lower-cost financing services;

l Public welfare organizations have put charity funds "on the chain" to form a more transparent and standardized public welfare tracking and management system;

l Relevant cities in China have launched a blockchain-based gas cylinder product traceability management system, and the credibility of the source of gas cylinder file information and the level of gas cylinder safety management have been greatly improved;

l Germany is developing its distributed energy resources Assets establishes a digital registration system based on identity authentication to promote the development and trading of renewable energy and cope with the arrival of the digital energy era...

Among the three types of blockchains (public chain, alliance chain, private chain), alliance chain has been the most widely used. In addition to considerations of technical performance, operational efficiency, operability, expected results, etc., this is mainly because all parties in the alliance already have a certain foundation of trust. This also shows from another perspective that in blockchain applications beyond cryptocurrencies such as Bitcoin, "multi-centralization" rather than complete "decentralization" is a more realistic option.

In addition, it is undeniable that unlike the proof-of-work mechanism that Bitcoin “mining” relies on, the blockchain cannot completely ensure the integrity of the on-chain data from the source in the actual application process. Authenticity. In other words, a certain alliance member or node may provide false data intentionally or unintentionally. However, with the help of blockchain's non-tampering, traceability, multi-party consensus and other characteristics, the alliance can identify counterfeiting behavior and impose corresponding punishments, such as "kicking" the counterfeiting members from the nodes. Therefore, in a sense, the basicTrust in the blockchain largely builds alliance members’ awe for the authenticity of data and their deterrence against data fraud.

If "trust" is the foundation of blockchain applications, data sharing is the core of blockchain applications. Without data sharing, there will be no cooperation, and the practical application of blockchain will be impossible.

l The State Administration of Foreign Exchange's "Cross-border Financial Blockchain Service Platform" pilot has been fully launched, promoting foreign trade exports through information exchange between foreign exchange bureaus, taxation, banks and enterprise-related market entities. Business development;

l The "Insurance/Claims Alliance Chain" jointly established by 11 insurance companies in Taiwan has been put into operation, and each company has achieved "single application and common documents" on this platform;

l Blockchain platforms such as Contour and TradeLens are reshaping the global supply chain and providing impetus for the digital transformation of international trade through data collaboration among enterprises, financial institutions, shipping companies, terminals, customs and other institutions... .

l In China, through data collaboration, various government departments have realized "one data, one source, one source for multiple uses, one network, and full network operation";

l Through The "Judicial Chain" platform enables all types of electronic evidence to be seamlessly connected with judicial institutions such as notarization, arbitration, judicial appraisal, and courts, which improves the efficiency of the judicial system while reducing costs;

l Targeting grassroots nationwide The court's "cross-domain collaboration mechanism for trial auxiliary matters" can realize "cross-domain service and cross-domain evidence collection" between courts in different regions, effectively improving the efficiency of trial auxiliary matters and trial quality and efficiency, and reducing judicial operation costs... ….

l China's "Guangdong-Hong Kong-Macao Greater Bay Area Combination Port" project was officially launched, which can support the interconnection and interoperability of trade parties among the five major customs jurisdictions of the Greater Bay Area and become the first connected port in the Greater Bay Area , customs, logistics, enterprise, finance and other trade processes, interconnected and shared blockchain network;

l Japan's KDDI Telecom, Hitachi, Kansai Electric Power, Sekisui Construction and other large enterprises have established blocks Chain Alliance NEXCHAIN ​​to form a cross-industry real estate information sharing and management model and promote cross-industry innovation;

l The French Renault Group completed the test of its blockchain project "XCEED" for zero Sharing compliance information between component suppliers and automakers and simplifying compliance certification….

Although the above application cases in finance, government affairs and various industries are only a few typical cases, they are enough to illustrate that: on the one hand, data sharing is an inherent requirement of blockchain applications. In terms of specific implementation, everything must start from breaking "data islands" and "information asymmetry"; on the other hand, the application practice of blockchain has in turn promoted cross-layerLevel, cross-department, cross-industry, cross-region, cross-border data sharing and unprecedented cooperation.

It can also be seen from the above cases that based on the transparency, security, trustworthiness and other characteristics of the blockchain, data sharing allows cooperation that originally seemed impossible to be achieved, and more Open innovation results; data sharing can effectively improve the operating efficiency of business systems, financial systems and social governance systems; various organizations promote their own organizational changes and process changes while sharing and cooperating with external institutions.

Based on trust and sharing, "transaction" is the most intuitive and deepest manifestation of the value of blockchain applications. Currently, blockchain is opening a new chapter in the transformation of transaction models in various industries around the world.

From a functional architecture point of view, blockchain-based transactions are by no means just a change in the transaction process, but integrate the unique functions of the blockchain, which are the key to anti-counterfeiting traceability, supply and demand docking, and warehousing. Integrated integration of blockchain applications such as logistics, payment/settlement, supply chain financing, insurance, and network security.

In terms of application form, blockchain-based transactions transcend the traditional concept of product or service transactions and represent the realization of the value of a wider range of data in circulation.

From the perspective of application scenarios, transactions based on blockchain involve the upgrading of the physical industry, the digital advancement of the financial industry, and the innovative application of the "token economy".

In the physical industry, take the application of agricultural blockchain as an example: on the one hand, supply chain traceability based on blockchain has become an important barrier to food safety; but on the other hand, for growers or For farmers, the supply chain traceability function is far from enough. How to help them expand the sales of agricultural products and obtain more income as much as possible is the "hard truth" for blockchain technology to continue to promote agricultural development. In other industries, the same applies.

Against the above background, new trading platforms in the global physical industry continue to emerge:

l The Indian government uses blockchain platforms to help farmers in remote areas sell agricultural products to reduce the While eliminating intermediate fees, obtain higher income;

l The Swiss company Cerealia builds a blockchain-based agricultural product trading and financing platform to promote the export of agricultural products in emerging market countries around the world;

l The world's largest independent refined sugar producer, Al Khaleej Sugar Company of the United Arab Emirates, launched DigitalSugar.io, a blockchain-based sugar product trading platform, to realize spot-based international raw sugar trading;

l Ganzhou, Jiangxi Province has launched an international timber electronic trading platform based on blockchain, which will manage the entire timber transaction process on-chain and will provide supervision for the timber market across all industries including cloud warehouses, logistics, finance, and insurance.Chain services;

l Shandong Province has launched the Shandong Internet Traditional Chinese Medicine Trading Platform, which will realize online integrated services of quality control, trading, payment, settlement and supervision through blockchain and other technologies;

l Weitang Town, Xiangcheng District, Suzhou has released a blockchain-based pearl online trading platform, which will store core pearl parameters and test reports on the chain and add supply chain management, trade finance, smart contracts, and payment settlement. , incentive mechanism and other functions;

l Honeywell launched GoDirect Trade, an online trading platform for new and second-hand aircraft parts, to provide guidance for large manufacturers on how to apply blockchain to parts trading and Circulation provides a valuable reference….

In the financial industry, blockchain is promoting the digital advancement of financial transaction business in aspects such as securities trading, asset securitization, trade financing, and cross-border settlement:

l The Australian National Stock Exchange has launched ClearPay, a digital securities trading platform based on distributed ledger technology, which can provide multi-currency, real-time DVP settlement on the same day and will replace the original exchange settlement system;

l Switzerland The company Finka has launched a related securitization token investment platform based on livestock from organic pastures in Bolivia to promote the development of the local livestock industry;

l The American company Securitize has established a Japanese real estate investment platform based on digital securities , aiming to revitalize idle real estate in rural Japan and enhance the vitality of the rural economy;

l China Postal Savings Bank and China Construction Bank completed the first cross-blockchain platform forfaiting transaction, Hua Xia Bank Kunming Branch’s first Realize forfaiting resale business in the secondary market;

l Nanjing Iron and Steel completed blockchain-based iron ore transactions with Rio Tinto of Australia and Vale of Brazil respectively;
< br /> l Baosteel Co., Ltd. and Australia's Rio Tinto completed the first blockchain-based RMB cross-border settlement transaction...

Of course, while blockchain promotes the advancement of financial transaction business, dark sides such as hype, scams, money laundering, and cyber attacks related to blockchain and cryptocurrency continue to follow. How to continue to promote financial innovation while also carrying out efficient risk prevention and control and effectively cracking down on illegal crimes is an important issue that requires long-term response. From a global perspective, China has responded with clear attitudes, strict measures, and effective measures in this regard.

The transaction changes realized by the blockchain in the real industry and financial industry are only the initial stage of the blockchain changing the traditional transaction method. The "Token Economy" is the blockchain "transaction" A higher level of functionality.

In "TongUnder the framework of "Certificate Economy", from electronic certificates to skill certificates, from credit records to public welfare activity participation records, from social media traces to carbon emission reduction actions, when various data become encrypted digital rights certificates, and can be circulated and When exchanged, it is given the "token" function.

Regardless of the investment/speculation craze of "Non-Fungible Token (NFT)", we can already see To many early applications of "token economy" around the world:

l The HotCity project supported by the Austrian government uses a crowdsourcing model combined with blockchain and gamification tokens to encourage residents to submit heating bills waste heat hotspots to more efficiently meet urban heating needs;

l Ford establishes "Green Miles" for commercial and municipal fleets with hybrid vehicles to help improve urban air quality;

l Weibin District, Xinxiang City, Henan Province issued tokens based on the merchant and enterprise points system in its blockchain industrial park project to establish a new commercial service platform;

l Released by Chengdu City Based on the blockchain-based community governance product "Liandong Community", residents can obtain "time bank" points from the platform through volunteer services and other activities, and redeem them for benefits and discounts provided by community merchants;

l The Electric Vehicle Charging Network Working Group (EVGI) of the global non-profit organization "Mobile Open Blockchain Initiative" launched a global standard system for decentralized vehicle charging technology, covering the Tokenized Carbon Credit (TCC) scenario;

l The blockchain reward platform MiL.k cooperates with Korean retailers to provide blockchain-based points management services for its members. Members can convert existing points into local MLK passes through the MiL.k platform Certificates can also be exchanged for other third-party points...

From the above cases and more cases, it can be seen that the "token economy" has several distinctive features:

"Token economy" gives asset attributes and tradable attributes to a wider range of data, and can improve the operating efficiency of the entire social and economic system through cross-domain and cross-platform mutual trust and circulation;

"Token economy" is a new process of value creation and realization, which does not necessarily use currency directly as the medium of transaction, but is more embodied in the exchange, mutual benefit and reconfiguration of various elements and resources;

"Token economy" is often combined with incentive mechanisms. Through incentives for "good people and good deeds", "good companies" and "good institutions", it will effectively reshape the social value system and social credit system.

In general, the "token economy" will give birth to new production factors, reshape production relations, and greatly solve the problem ofRelease social productivity; "Token Economy" represents the evolution of "Information Internet" to "Value Internet", indicating the most exciting future of the digital economy; "Token Economy" based on blockchain has begun to take shape, and Begin to bring about lasting and visible changes in economic operations, social governance, and everyone's lifestyle. All types of institutions and individuals should be mentally and physically prepared for this change.

Like other new technologies, in the process of application and popularization, blockchain continues to produce substitution effects in terms of platforms, media, models, methods, etc.: physical documents are replaced by electronic documents, and credit records are replaced by electronic documents. Tokens are replaced, manual review is replaced by data verification, and the city management platform is replaced by the "city brain"...

Such substitutions have become the norm:

l Argentina’s central bank has begun a proof-of-concept for a new blockchain clearing system, which may replace the existing clearing system;< br />
l Korea Minting and Security Printing Corporation (KOMSCO) expanded its blockchain digital gift certificate business to replace paper gift certificates and achieved record revenue despite a sharp decline in the issuance of banknotes and coins. Improvement;

l Courts across China have begun to use blockchain electronic seals to replace traditional paper seals in the enforcement of real estate seizures;

l The Shanghai court system is using artificial intelligence , the adoption of new technologies such as blockchain, and explore the use of digital court trial records to replace manual court trial transcripts;

l The Japanese company SUSMED launched a "Clinical Data Monitoring System Demonstration Using Blockchain Technology" pilot, indicating that the drug Or the necessary monitoring process in clinical trials of medical equipment can be replaced by a blockchain system;

l Alipay and Wukong Car Rental have cooperated to launch a "face-swiping" car rental service, which uses blockchain technology and credit-free security mode, tourists can rent a car by simply "swiping their face" and return the vehicle through mobile operations;

l Under the new crown epidemic, local governments in China have intensively launched "non-face-to-face" vehicles that combine blockchain technology ", no contact, zero errands" government service has replaced the traditional offline service method, providing a strong guarantee for the smooth progress of remote bidding, "cloud" customs clearance, financial support, resumption of work and production, etc. during the epidemic... .

In addition, we can also see that through the use of blockchain technology, various enterprise-level services are also realizing substitution and evolution: from paper contracts to electronic contracts, to program-based, Blockchain contracts that can automatically execute smart contracts. Blockchain is pushing contract signing into the era of "chain signing"; from offline human resources companies to online human resources platforms to the blockchain-based human resources market , global human resources services have experienced from the 1.0 era to the 2.0 era, and thenContinuous changes to the 3.0 era.

Generally speaking, when the blockchain "invades" various industries, it will "mercilessly" delete all unnecessary links and processes, all unnecessary manual operations, and accelerate the The era of paperless, unmanned and automated is coming.

In the process of our analysis of more than 1,550 blockchain application cases around the world, words like "improve", "accelerate", "shorten", "lower", "reduce", "save", " Words such as "save" appear frequently in front of our eyes. These words show that the improvement of efficiency is the common pursuit of all parties involved in blockchain applications and is also the most direct result of the substitution effect of blockchain.

Numerous application practices are contributing to this:

l Kenyan company Shamba Records provides blockchain traceability, transaction and financing services to farmers in the country, currently covering more than 6,000 Small farmers and helped them increase their income by at least 40%;

l TradeWaltz, a blockchain trading platform invested by NTT DATA, Mitsubishi and other companies, completed a trial run, and the results showed that the platform can reduce traditional 50% of the workload of the trade process;

l Walmart Canada has significantly reduced invoice disputes with carriers by 97% through the application of the DL Freight blockchain platform;

l The State Grid Corporation of China’s power transaction certificate traceability inquiry platform has been put into operation, automating the entire authenticity review process for registered users and saving 99% of trusted manual review time;

l COSCO Shipping Lines and Shandong Port Group Qingdao Port have cooperated to launch a blockchain paperless import and delivery model, which can save customers nearly 24 hours on average per container;

l Taizhou, Zhejiang uses "materials" The "Internet + Blockchain" recycling system solves the problem of marine pollution control. Compared with traditional processing methods, this recycling system can save 94% of labor costs and 84% of operating costs...

In summary, through the joint action of trust mechanism, sharing mechanism and transaction mechanism, blockchain has formed an obvious substitution effect, improved the operational efficiency of finance, government affairs and various industries, and will Continue to create systemic change. This change is reshaping the relationship between people and machines, people and society, and people and the environment, and clearly points to three ultimate goals: efficiency, well-being, and environmental protection.

㈣ "Blockchain Core Technology and Applications" pdf download to read the full text online, please ask for Baidu Netdisk cloud resources

"Blockchain Core Technology and Applications" (Zou Jun) Electronics Book network disk download for free online reading

Link: https://pan..com/s/1UOvg6VlKPGiK6PVL8Ji_Sw extraction code: r1fw

Book title: Blockchain core technology and application

Author: Zou Jun

Douban score: 8.6

Publisher: Machinery Industry Press

Publication year: 2018-8-1

Number of pages: 388

Content introduction:

Recommended by well-known experts and written by powerful experts, its authoritativeness, comprehensiveness and thoroughness are beyond doubt. In-depth explanation of blockchain core technology, platform and application development, covering architecture, consensus, encryption, P2P, Bitcoin, Ethereum, Hyperledger, EOS, potential framework, issues and evaluation, etc. This book is divided into three parts, and the contents are explained as follows.

Basics (Chapter 1~6), focusing on blockchain technology ideas, general architecture and core technologies. When writing this part, we pay attention to being easy to understand and taking into account the overall situation. It is the cornerstone and blueprint of learning, covering blockchain ideas and values, general architecture models, basic concepts and core technologies (encryption, consensus, P2P network, etc.).

Practical chapter (Chapter 7~9), explains the core mechanisms and technical details of the mainstream blockchain development platforms Bitcoin, Ethereum, and Hyperledger Fabric, and provides point-to-point electronic cash systems, smart Three cases include contract development, complete Fabric network construction and application development.

The advanced chapter (Chapter 10~12), in order to further enhance readers’ development capabilities, vision and research direction, covers three aspects: ① Possible development directions, as well as some potential and characteristic blockchains Platforms (EOS, Cardano, IOTA, etc.); ② Various issues that need to be considered in blockchain development, including technical limitations, various security issues and vulnerabilities, and countermeasures; ③ Blockchain evaluation, from 6 levels and 8 categories Quality indicators to design evaluation points and test cases for blockchain projects.

About the authors:

Zou Jun Yu Bin Zhuang Peng Xing Chunxiao Waiting: Zou Jun, CEO of Guangdian Express Blockchain Technology Co., Ltd. and deputy secretary-general of Zhongguancun Blockchain Alliance. He edited the best-selling technical book "Blockchain Technology Guide" and published more than 20 papers in leading international conferences and journals. Among them, the blockchain paper won the IEEE ICWS Best Paper Award, and the consensus algorithm paper was published by the top international journal "Transaction on Service". Computing" included and published. He has won the "Outstanding Alumni Award" from the Australia-China Alumni Association and the "President's Award" from Macquarie University.

Yu Bin is currently the president of Beijing Post Online Education Investment Group, a member of the Blockchain Committee of the China Institute of Electronics, an expert of the Zhongguancun Blockchain Industry Alliance, and a distinguished professor at Shanghai University of Finance and Economics and the Asian School of Finance and Economics. He holds a Ph.D. in communications and information systems from Beijing University of Posts and Telecommunications. He is the editor-in-chief of 4 monographs including "Introduction to Financial Technology". He has won the second prize of the National Science and Technology Progress Award and the first prize of the Ministry of Education. Experts in online education, financial technology, blockchain and other fields.

Zhuang Peng, senior consulting manager and senior architect of IBM Global Services Financial Services Department. 14 years of experience in financial industry structure design and strategic consulting planning. He has rich implementation experience in service transformation, large-scale enterprise-level distributed system architecture design, big data analysis, and financial payment. In the past three years, he has focused on blockchain and distributed ledger architecture research, blockchain-related applications and digital currency consulting research, and has served as a lecturer and training expert at blockchain summits many times.

Xing Chunxiao, deputy director of Tsinghua University Information Technology Research Institute and Internet Industry Research Institute, main research fields: computer software and theory, database and data warehouse, big data management and analysis, knowledge engineering and software engineering , blockchain and digital economy, smart cities (government affairs, business, culture and medical health) and other fields. He has published more than 350 academic papers, including more than 40 SCI papers, more than 150 EI papers, and 40 invention patents.

㈤ A brief analysis of the application of blockchain technology

A brief analysis of the application of blockchain technology
For the recently popular blockchain Technology, I believe many people do not understand its applicable scenarios. Although theoretically any industry related to digital networks can be applied, from the perspective of implementation costs, the following industries are more suitable for blockchain technology.
Since the essence of the blockchain is a distributed accounting ledger, digital currencies represented by Bitcoin and Ethereum are also a very simple and safe settlement method. The most important thing in the financial field is the accounting and clearing process. Blockchain technology can greatly improve the efficiency of traditional banks and the financial industry.
However, all of the above are the basic functions of blockchain, and there is still a lot of room for improvement. Currently, there is no mature blockchain financial project in the world. We still have a long way to go. Way to go.

When it comes to the application of blockchain, the first thing we think of is the banking and financial industries. Since the essence of blockchain is a distributed accounting system, it is most suitable for the financial industry. Digital currencies based on blockchain can also be used in transactions, clearing and settlement, etc. The security and decentralization of blockchain are used to ensure the security of accounting. Currently, major countries are exploring this application.
In addition, many businesses of government agencies are also very suitable for the application of blockchain technology, such as the management of resident identity information, ownership records, product supervision, etc. Ensure the security and confidentiality of key information through distributed immutable records. Many countries such as Ireland have included this development plan as a short-term goal, and it is also one of the more common areas of use of blockchain.
Financial field: The financial field is the field where blockchain is most widely used besides Bitcoin. After all, financial development also involves currency and digital currency. Especially in the past two years, the development of digital currencies has also driven the application of blockchain.
Regarding blockchain deception, when blockchain first emerged, manyPeople’s doubts are called blockchain fraud. Now the chief economists of various countries in the region have begun to quit studying blockchain, proving that blockchain is gradually being accepted by the public.
In addition, due to the emergence of Ethereum smart contracts, blockchain can also better assist resource sharing related industries, such as our common shared bicycles and other products. Another example is the medical field. We can also use blockchain technology to improve efficiency and safety, which will bring about a qualitative change in this industry.
I believe everyone has a preliminary understanding of the practical application of blockchain. Looking back at the domestic ICO boom some time ago, a large number of unreliable projects such as dog chains forced speculation on the concept. Obviously, domestic investors There is not enough understanding of the blockchain application field, so stopping ICO not only regulates the industry, but also protects the investing public.

㈥ Can blockchain be written into a paper about data structure?

If you are admitted, can you write into a paper about data structure? Blockchain can be written into data Structure of the paper.

㈦ Can I cite literature at the end of a blockchain paper?

It is a very common practice to cite literature at the end of a paper, whether it is a blockchain paper or other types of papers. This approach can be used. When citing literature, you need to pay attention to the following aspects:

Citation format: When citing literature at the end of the paper, all literature materials need to be formatted according to the citation format specifications used. Commonly used citation formats include APA, MLA, Chicago, etc., which need to be formatted according to the title, author, publisher and other elements.

Citation content: When citing documents, you should only cite materials related to the topic of the paper and avoid citing content that is irrelevant to the topic. In addition, the quoted content needs to be consistent with the text and content of the paper, maintaining the logical relationship and coherence of the paper.

Number of citations: When citing references at the end of your paper, you should not cite too many references. The number of cited documents should be appropriately controlled based on actual needs to avoid citing too many irrelevant documents.

When citing literature at the end of a blockchain paper, you can refer to some typical blockchain papers or books and include them in the reference list. This helps to end with a hook, leads to a new research direction, and can also provide a more sufficient theoretical basis for analyzing the theme of the paper.

The following are some recommended papers and books about blockchain:

Nick Szabo: "Blockchain Applications: How It Works and Important Areas", O' Reilly Media, 2017

Anton Anderson and Don Tapscott: "The Blockchain Revolution: How It's Transforming Trade, Finance, Companies, and Our Future", Publisher: Portfolio , 2016

Jordan Dokanoski and Biseta Narayanan: "Blockchain Identification and Interpretation: Techniques, Tools, and Applications (Identification and Resolution)", Manning Publications, 2018

A.B. Călin, A. Turcanu, F. Drăgănescu: "Blockchain - A Primer", Publisher: Universe, 2019

Zulip Bank Group Economics Research team: "Blockchain: Diverse Applications for Creating Value", 2017.

These books and papers cover the application of blockchain technology in finance, trade, smart contracts, etc., as well as the essence and future development trends of blockchain technology. Reading these materials can help you gain an in-depth understanding of blockchain technology and its applications, master related technologies and concepts, and provide valuable reference materials for blockchain-related research and paper writing.

㈧ Intensive reading of blockchain papers - Pixel: Multi-signatures for Consensus

The paper mainly proposes a multi-signature algorithm Pixel for the consensus mechanism PoS.

All PoS-based blockchains as well as allowed blockchains have a common structure where nodes run a consensus sub-protocol to reach consensus on the next block to be added to the ledger. Such consensus protocols typically require nodes to check blocking proposals and express their agreement by digitally signing acceptable proposals. When a node sees enough signatures from other nodes on a specific block, it appends them to its view of the ledger.

Since consensus protocols typically involve thousands of nodes working together to reach consensus, the efficiency of the signature scheme is crucial. Furthermore, in order for outsiders to effectively verify the validity of the chain, signatures should be compact for transmission and should be verified quickly. Multisigs have been found to be particularly useful for this task because they enable many signers to create compact and efficient verifiable signatures on public messages.

Additional knowledge: Multi-signature
is a digital signature. In digital signature applications, multiple users are sometimes required to sign and certify the same file. For example, if a statement issued by a company involves the finance department, development department, sales department, after-sales service department and other departments, and needs to be signed and approved by these departments, then these departments need to sign the statement document. A digital signature scheme that enables multiple users to sign the same file is called a multi-digital signature scheme.
Multi-signature is an upgrade of digital signatures, which makes it possible to apply blockchain-related technologies to all walks of life. In actual operation, a multi-signature address can be associated with n private keys. When operations such as transfers are required, funds can be transferred as long as m private keys are signed, where m must be less than or equal to n, that is to say m/n is less than 1, it can be 2/3, 3/5, etc., it is necessary to establish this multi-signature addressDetermined when.

This article proposes the Pixel signature scheme, a pairing-based forward secure multi-signature scheme that can be used in PoS-based blockchains and can significantly save bandwidth and storage requirements. To support a total of T time periods and a committee of size N, multisig contains only two group elements, and verification requires only three pairings, one exponentiation and N -1 multiplications. Pixel signatures are almost as effective as BLS multi-signatures and also satisfy forward security. Additionally, just like in BLS multi-signatures, anyone can non-interactively aggregate individual signatures into a multi-signature.

Benefit:
To validate Pixel's design, the performance of Pixel's Rust implementation was compared with previous tree-based forward security solutions. Shows how to integrate Pixel into any PoS blockchain. Next, Pixel is evaluated on the Algorand blockchain, showing that it yields significant savings in storage, bandwidth, and block verification time. Our experimental results show that Pixel is effective as a stand-alone primitive and used in blockchains. For example, compared to a set of N = 1500 tree-based forward security signatures (for T = 232) with a 128-bit security level, a single Pixel signature that can authenticate the entire set is 2667 times smaller and can be verified 40 times faster . Pixel signing reduces the size of Algorand blocks of 1500 transactions by approximately 35% and reduces block verification time by approximately 38%.

The biggest difference compared to the traditional BLS multi-signature scheme is that BLS does not have forward security.

Compared with the tree-based forward security signature, the tree-based forward security signature can meet the security requirements, but the signature it constructs is too large and the verification speed needs to be improved. The design of this article reduces the signature size and verification time.

Supplementary knowledge: Forward security
is a security property of communication protocols in cryptography, which means that the leakage of a long-term master key will not lead to the leakage of past session keys. Forward security protects past communications from future exposure of passwords or keys. If a system has forward security, historical communications can be kept safe if the master key is compromised, even if the system is under active attack.

Build forward-secure signatures with Hierarchical Identity Based Encryption (HIBE) and add the ability to securely aggregate signatures on the same message and generate public parameters without a trusted set. To achieve:
1. Generate and update keys
2. Security against malicious key attacks
3. Invalid trust settings

For common post-attacks There are two variants:
1. Short-range variant: The adversary attempts to undermine committee members before a consensus agreement is reached. solve: Respond to short-range attacks by assuming the attack delay is longer than the running time of the consensus subprotocol.
2. Remote variant: solved by fork selection rules.
Forward secure signatures provide a clean solution to both attacks without the need for fork-choice rules or other assumptions about adversaries and clients. (Explain the advantages of forward secure signatures).

Permissioned blockchain consensus protocols (such as PBFT) are also at the core of many permissioned chains (such as Hyperledger), where only approved parties can join the network. Our signature scheme can be similarly applied to this setting to achieve forward secrecy, reduce communication bandwidth and generate compact block certificates.

In the traditional Bellare-Miner model, the forward security signature scheme FS of the message space M consists of the following algorithms:
1. Setup
pp ←Setup(T), pp is the parties Common parameters that are agreed upon by all, Setup(T) represents the distribution setting of fixed parameters within the T time period.

2. Key generation
(pk,sk1) ←Kg
The signer runs the key generation algorithm on the input maximum time period T to generate public verification for the first time period Key pk and initial secret signing key sk1.

3. Key update
skt+1←Upd(skt) The signer uses the key update algorithm to update the secret key skt of time period t to skt + 1 of the next period. This scheme can also provide a "fast-forward" update algorithm skt0←$Upd0(skt,t0) for any t0 > t, which is more efficient than repeatedly applying Upd.

4. Signing
σ ←Sign(skt,M), when inputting the current signature key skt message m∈M, the signer uses this algorithm to calculate the signature σ.

5. Verification
b ← Vf(pk,t,M,σ) Anyone can verify the message M within the time period t under the public key pk by running the verification algorithm The signature of signature M. This algorithm returns 1 indicating that the signature is valid, otherwise it returns 0.

1. Relying on asymmetric bilinear groups to improve efficiency, our signature is located in G2×G1 instead of G2^2. This way, it is enough to give public parameters into G1 (which we can then use hash curve instantiation without trust setup) without having to generate "consistent" public parameters (hi, h0 i) = (gxi 1, gxi 2) ∈G1×G2.

2. Key generation algorithm, the public key pk is smaller, refer toNumber settings improve security.

In addition to the algorithm of the forward secure signature scheme in Section 3, the forward secure multi-signature scheme FMS in the key verification model also has a key generation that additionally outputs the public key Proof of π.
Added Key aggregation, Signature aggregation, and Aggregate verification. It also proves its correctness and security on the premise of meeting the multi-signature function of forward security.

1. PoS is protected from subsequent damage
Subsequent damage: Post-verified nodes attack and destroy the previous consensus verification state.
In situations where many users propagate many signatures (such as transaction blocks) on the same message, Pixel can be applied to all of these blockchains to protect against follow-on attacks and potentially reduce bandwidth, storage and computation cost.

2. Pixel integration
In order to vote on block B, each member of the sub-protocol signs B using a Pixel with the current block number. Consensus is reached when we see the set of N committee members signing on the same block B, where N is some fixed threshold. Finally, we aggregate these N signatures into a single multi-signature Σ, and the pair (B, Σ) forms a so-called block certificate and append block B to the blockchain.

3. Register a public key
Every user who wants to participate in the consensus needs to register a participating signing key. Users first sample Pixel key pairs and generate corresponding PoPs. The user then issues a special transaction (signed under her consumption key), registering a new participation key. Transactions include PoP. Select the PoS validator that reached agreement in round r to check (a) the validity of the special transaction and (b) the validity of the PoP. If both checks pass, the user's account is updated with the new participation key. From this point, if checked, the user will use the Pixel login block.
That is, constantly changing its own participation key to achieve forward security.

4. Propagation and aggregation of signatures
The signatures of each committee will be propagated through the network until the signatures of N committee members are seen on the same block B. Note that Pixel supports non-interactive and incremental aggregation: the former means that signatures can be aggregated by any party after broadcast without contacting the original signer, while the latter means that we can add new signatures to a multisig to obtain new of multi-signatures. In practice, this means that the propagating node can perform intermediate aggregation on any number of committee signatures and propagate the results until a block certificate is formed. Alternatively, nodes can aggregate all signatures before writing the block to disk. That is, after receiving enough block proof votes, the nodeThe signatures of N committee members can be aggregated into a multisig, and then the block and certificate are written to disk.

5. Key update
When using Pixel in the blockchain, time corresponds to the block number or sub-step in the consensus protocol. When relating time to the block number, it means that all eligible committee members should update their pixel keys every time a new block is formed and the round number is updated.

Conduct an experimental evaluation on the Algorand project, and compare it with the Algorand project's own solution to prevent post-corruption attacks, BM-Ed25519, and the BLS multi-signature solution.

Storage space:

Bandwidth saving:
Algorand uses a relay-based propagation model, where the user’s nodes are connected to the relay network (nodes with more resources ). Without aggregation during propagation, the bandwidth pixel savings for relays and regular nodes come from smaller signature sizes. Each relay can serve dozens or hundreds of nodes, depending on the resources it provides.

Save verification time