Blockchain problems
blockchain refers to the technical solution of collective maintenance of a reliable database through centralization and distrust in the past, and it is a technical way for the whole people to participate in bookkeeping. Previous bookkeeping methods were all centralized and needed centralized intermediary, whether it was traditional government, financial institutions, notarization institutions or emerging e-commerce platform and online payment platform
in economic hypothesis, information is sufficient. In fact, it is precisely because of insufficient information that there are very large intermediaries. The existence of intermediaries increases the transaction cost and raises the transaction threshold. In essence, blockchain technology is a large-scale collaboration tool. It makes direct value transfer possible by using pure technology for the first time, and continues the trend of Internet decentralization and disintermediation. Disintermediated blockchain technology will greatly subvert the information intermediary instry
blockchain technology is the basic technology for building bitcoin data structure and encrypted transmission of transaction information, which realizes the issue and transaction of bitcoin. The core of blockchain technology is that all the current participating nodes jointly maintain the transaction and database, so that the transaction is based on the principle of cryptography rather than trust, so that any agreed parties can directly carry out payment transactions without the participation of a third party
technically, a block is a data structure for recording transactions, reflecting the capital flow of a transaction. In the system, the transaction blocks are connected to form a main chain, and all the nodes participating in the calculation record the main chain or part of the main chain
a block contains the following three parts: transaction information, hash formed by the previous block and random number. Transaction information is the task data carried by the block, including the private keys of both parties, the number of transactions, the digital signature of electronic currency, etc; The hash hash formed by the previous block is used to connect the blocks and realize the sequence of past transactions; Random number is the core of the transaction. All nodes compete to calculate the answer of the random number. The node that gets the answer the fastest generates a new block and broadcasts it to all nodes for updating, so as to complete a transaction.
The strict definition of blockchain refers to the distributed database technology that multiple nodes in peer-to-peer network jointly maintain a continuously growing list ledger constructed by time stamp and orderly record data blocks through consensus mechanism based on cryptography technology. This technical solution allows any number of nodes in the participating system to calculate and record all the information exchange data in the system in a period of time to a data block through cryptography algorithm, and generate the fingerprint of the data block for linking the next data block and checking. All participating nodes in the system jointly determine whether the record is true
blockchain is a technical solution similar to NoSQL (non relational database). It is not a specific technology, and can be implemented through many programming languages and architectures. There are many ways to realize blockchain, including pow (proof of work), POS (proof of stake), dpos (delegate proof of stake), etc
the concept of blockchain was first proposed in the paper "bitcoin: a peer-to-peer electronic cash system" by indivials (or groups) who call themselves Satoshi Nakamoto. Therefore, bitcoin can be regarded as the first application of blockchain in the field of financial payment
< H2 > [popular explanation]no matter how big the system or how small the website is, there is a database behind it. So who will maintain this database? In general, who is responsible for the operation of the network or system, then who is responsible for the maintenance. If it is wechat database, it must be maintained by Tencent team, and Taobao database is maintained by Alibaba team. We must think that this way is natural, but blockchain technology is not
if we think of the database as a book, for example, Alipay is a typical account book. Any change of data is bookkeeping. We can think of database maintenance as a very simple way of accounting. In the world of blockchain, everyone in the blockchain system has the opportunity to participate in bookkeeping. The system will select the fastest and best bookkeeper in a period of time, maybe within ten seconds or ten minutes. The bookkeeper will record the changes of the database and the account book in a block. We can think of this block as a page. After the system confirms that the records are correct, the system will record the changes of the database and the account book in a block, It will link the fingerprint of the past account book to this paper, and then send this paper to everyone else in the whole system. Then, over and over again, the system will look for the next person with fast and good bookkeeping, and everyone else in the system will get a of the whole ledger. This means that everyone as like as two peas in the system is called Blockchain. It is also called distributed account technology. P>
as like as two peas (computer) have identical accounting books, and everyone has the same rights, they will not collapse e to the loss of contact or downtime of a single person. As like as two peas, the data is transparent and everyone can see what changes are in every account. Its very interesting feature is that the data can't be tampered with. Because the system will automatically compare, it will think that the same number of books with the largest number are real books, and a small number of books with different numbers are false books. In this case, it's meaningless for anyone to tamper with his own account book, because unless you can tamper with most nodes in the whole system. If there are only five or ten nodes in the whole system, it may be easy to do so. However, if there are tens of thousands or even hundreds of thousands of nodes and they are distributed in any corner of the Internet, unless someone can control most computers in the world, it is unlikely to tamper with such a large block chain
< H2 > [elements]combined with the definition of blockchain, we think that we must have the following four elements to be called public blockchain technology. If we only have the first three elements, we will consider it as private blockchain Technology (private chain)
1, peer-to-peer network (power equivalence, physical point-to-point connection)
2, verifiable data structure (verifiable PKC system, non tampering database)
3, distributed consensus mechanism (Solving Byzantine general problem, solving double payment)
4 Game design of Nash equilibrium (cooperation is the strategy of evolutionary stability)
combined with the definition of blockchain, blockchain will realize four main characteristics: decentralized, trustless, collective maintenance and reliable database. And the other two will be derived from the four characteristics Features: open source Privacy. If a system does not have these characteristics, it can not be regarded as an application based on blockchain technology
Decentralized: there is no centralized hardware or management organization in the whole network. The rights and obligations of any node are equal, and the damage or loss of any node will not affect the operation of the whole system. Therefore, it can also be considered that the blockchain system has excellent robustnesstrustworthiness: there is no need to trust each other when participating in the data exchange between each node in the whole system. The operation rules of the whole system are open and transparent, and all data contents are also open. Therefore, within the specified rule range and time range of the system, nodes cannot and cannot cheat other nodes
collective maintenance: the data blocks in the system are maintained by all the nodes with maintenance function in the whole system, and these nodes with maintenance function can be participated by anyone
reliable database: the whole system will enable each participating node to obtain a of the complete database in the form of sub databases. Unless more than 51% of the nodes in the whole system can be controlled at the same time, the modification of the database on a single node is invalid, and the data content on other nodes cannot be affected. Therefore, the more nodes and computing power in the system, the higher the data security in the system
Open Source: since the operation rules of the whole system must be open and transparent, the whole system must be open source for the program
Privacy Protection: since there is no need to trust each other between nodes, there is no need to disclose the identity between nodes, and the privacy of each participating node in the system is protected
1-contains a distributed database
2-distributed database is the physical carrier of blockchain, blockchain is the logical carrier of transaction, all core nodes should contain full copies of the blockchain data
3-blockchain serializes blocks according to time, And blockchain is the only body of the whole network transaction data
4-blockchain is only effective for addition, but not for other operations
5-public and private key verification based on asymmetric encryption
6-accounting node requires that Byzantine general problem can be solved / avoided
7-consensus progress is evolutionarily stable, That is, in the face of a certain amount of contradictions between different nodes, the data will not collapse
8-consensus process can solve the problem of double spending
from the perspective of data: blockchain is a kind of distributed database. The "distributed" here is not only reflected in the distributed storage of data, but also reflected in the distributed records of data (that is, it is collectively maintained by system participants). In short, blockchain can realize distributed recording of global data information (which can be collectively recorded by system participants rather than centralized recording by a centralized organization) and distributed storage (which can be stored in all nodes participating in recording data rather than centralized storage in centralized organization nodes)
from the perspective of effect: blockchain can generate a set of time sequence, tamper proof and trustworthy database, which is decentralized storage and data security can be effectively guaranteed<
the working principle of blockchain technology
today's blockchain technology can be summarized as a technology to collectively maintain a reliable database through centralization and de trust in the past. In fact, blockchain technology is not a single and brand-new technology, but the result of the integration of a variety of existing technologies (such as encryption algorithm, P2P file transfer, etc.), which are cleverly combined with the database to form a new way of data recording, transmission, storage and presentation. In short, blockchain technology is a technology that everyone participates in recording and storing information. In the past, people entrusted the work of data recording and storage to the centralized organization, while the blockchain technology allows everyone in the system to participate in the data recording and storage. Under the distributed peer-to-peer network without central control point, blockchain technology uses the method of distributed collective operation to build a P2P self-organizing network. Through the complex verification mechanism, the blockchain database can maintain the integrity, continuity and consistency. Even if some participants commit fraud, the integrity of the blockchain cannot be changed, let alone tamper with the data in the blockchain
the source of blockchain technology principle can be summarized as a mathematical problem: Byzantine general problem. Byzantine general problem extends to Internet life, and its connotation can be summarized as: under the background of Internet, when we need to exchange value with unfamiliar opponents, how can we prevent people from being deceived and confused by malicious saboteurs, so as to make wrong decisions. The Byzantine general problem is further extended to the technical field. Its connotation can be summarized as: in the absence of trusted central nodes and trusted channels, how to reach a consensus among the nodes in the network. Blockchain technology solves the well-known Byzantine Generals Problem - it provides a way to create consensus networks without having to trust a single node<
Application of blockchain technology
blockchain technology overlaps three fields:
1, currency: issuance mechanism, distribution mechanism, adjustment mechanism
2, contract: equity, mutual insurance, right registration and transfer, smart contract, etc.
3, Governance: identity authentication, health management, notarization, judicial arbitration, decentralized autonomous organization, Voting, etc.
blockchain is like a "trust creating machine". What Bubi blockchain needs to do is a new technology and proct to realize real value circulation and make the Internet reach a new height
when it comes to blockchain technology, we have to mention bitcoin. Many people know that electronic currency bitcoin is not issued by a specific monetary institution, but generated by a large number of calculations of a specific algorithm. In fact, the core of real support for bitcoin is blockchain technology
How can invisible and intangible bitcoin operate through blockchain technology? The popular interpretation in the instry is that blockchain can be seen as a technical solution to collectively maintain reliable databases through "decentralization" and "distrust". Generally speaking, this technology can be understood as the technology of all participants in bookkeeping. In the past, people used a centralized server for bookkeeping. In the blockchain technology system, everyone can participate in bookkeeping and jointly identify the authenticity of records
"through this technology, even if there is no neutral third-party organization, the two sides who do not trust each other can cooperate. In short, blockchain is like a "trust creating machine."“ Blockchain technology is widely used in the era of big data. " At present, in addition to the field of Internet finance, blockchain technology has been applied in many fields and has shown great prospects
in addition, blockchain technology is also of great significance in law. Especially in the field of assets, whether it is physical assets such as real estate and automobile, or intangible assets such as health and reputation, we can use this technology to complete registration, transaction and tracking. It can be said that blockchain technology will be useful in any field of proction and life that lacks trust. "
blockchain technology concept stocks
it is recommended to pay attention to it manufacturers with blockchain technology and applications. We think that blockchain is more like a mechanism or technical solution. In the future, manufacturers who can combine this mechanism into different scenarios for promotion and application are expected to achieve subversive success. Blockchain technology can ensure that the data structure will not be tampered and forged, and has broad application prospects in the field of financial payment. Bubi blockchain has set up a special team around digital currency, focusing on the development trend of digital currency for a long time, and has set up a special team to carry out relevant work around the instry development demand of digital currency, including the research on blockchain technology.
the development of blockchain application technology is more in the use of its decentralized and tamper proof technology. These two characteristics successfully push the blockchain application technology to the world. People suddenly realize that in this lack of trust society, there can be a technology to change the status quo, and do not need to go through a third party, Completely decentralized technology
if this technology can be popularized, it will be a breakthrough, so the development of blockchain application technology has become the focus of research and development in various countries and regions.
although POW is not optimal, it is now the most practical consensus algorithm. For example, bitcoin, lightcoin and decent all adopt the pow proof mechanism.
imagine that in Byzantine times, there was a rich city-state with all kinds of gold, silver, jewelry, silk and satin, and its Lord Doraemon enjoyed all the luxury and glory. On the outskirts of the city-state, four Byzantine Generals, Daxiong, panghu, Xiaofu and Jingxiang, coveted Doraemon's wealth, so they decided to join hands to capture Doraemon's city-state. According to the strength comparison between the two sides, more than half of the generals must attack at the same time to defeat the enemy, so the winning condition is that at least three of the four can agree on the attack time. What are the odds of the four generals
the answer to this question depends on the cooperation mode of the four people. If it is a centralized system and there is an alliance leader, such as panghu (equivalent to a central server), then there is no doubt about their victory, because it is very easy to reach an agreement on the attack time. As long as panghu calls Daxiong, Xiaofu and Jingxiang to have a meeting to discuss it, Even if we have different opinions, panghu can make a final decision. Now let's go back to the assumption of Byzantine Generals. In a distributed network without trust, what are the odds of four generals winning< br />
?
first of all, e to the lack of trust between the four generals, the possibility of gathering in a small dark room for a conspiracy meeting is ruled out (what if they are kidnapped by panghu in a small dark room?); Secondly, since there is no leader, the opinions of all four people will be equally valued. In this case, the four generals could only negotiate the attack time by sending messages between their camps by messenger. For example, if Daxiong thinks 6 a.m. is a good time to launch an attack, he will send messengers to tell panghu, Xiaofu and Jingxiang their opinions. At the same time, panghu may think it's better to launch a surprise attack at 9 p.m., Xiaofu prefers to launch an attack at 3 p.m., and Jingxiang hopes that it will be 10 a.m., and the three of them will send their own messengers at the same time. In this way, after the first round of communication, each of the four generals had four attack times to choose from, and each of them had to inform the other three of their chosen time in the next round of communication. Because four people make decisions independently, there are 256 possible final choices. Only when more than three people choose the same time can consensus be reached, and there are only 64 such results, that is to say, the probability of reaching consensus is only 1 / 4. This is only the case of four generals. What if the number of generals is 10, 100 or 1000? With a little calculation, we can see that as the number of people increases, the hope of reaching a consensus will become increasingly dim
change the general in the above example into the node in the computer network, the messenger into the communication between nodes, and the attack time into the information that needs to reach a consensus. Then you can understand the dilemma described by the consensus problem. The ability to reach a consensus is self-evident for a payment system. If you remit a sum of money to your family to buy a car and go to the bank the next day for verification, the counter will tell you "about how much money you remit, there are three versions of records in our system". Obviously, you dare not deposit money in such a bank. Before the emergence of bitcoin, the consensus problem is difficult to be solved perfectly. In order to reach a consensus, we need to adopt a centralized system (unless the nodes meet certain conditions), and in order to decentralize the consensus, we can't guarantee it. So how does blockchain technology solve this problem Pay attention to the official account weoption, reply to "block chain", you can view the full text.