区块链预言机和随机数的区别,区块链预言机是什么意思

1. 10 important terms you need to know about blockchain! It is necessary to take a look

1. Smart contract

A smart contract is a computer protocol designed to spread, verify or execute contracts in an information-based manner. Smart contracts allow trusted transactions to be made without third parties, which are traceable and irreversible.

2. Timestamp

Timestamp refers to a string or encoded information used to identify the recorded time and date. The international standard is ISO 8601.

3. Turing completeness

Turing completeness refers to the ability of a machine to perform any calculation that any other programmable computer can perform. One example is the Ethereum Virtual Machine (EVM).

4. 51% attack

When a single individual or group exceeds half of the computing power, this individual or group can control the entire distributed network, if they have With some malicious ideas, they may issue conflicting transactions that damage the entire network.

5. Dapp - Decentralized Application

It is an open source application that runs automatically and stores its data on block L with cryptographic tokens in the form of incentives and operate on a protocol that displays proof of value.

6. DAO - Decentralized Autonomous Organization

It can be considered as a company that operates without any human intervention and hands all forms of control to one Set of unbreakable business rules.

7. DistributedLedger - Distributed Ledger

Data is stored through a distributed node network. A distributed ledger does not have to have its own token, it may be permissioned and private.

8. DistributedNetwork - Distributed Network

A network in which processing power and data are distributed on nodes rather than having a centralized data center.

9. Oracle

An oracle is a trusted entity that introduces information about the state of the external world through signatures, thereby allowing deterministic smart contracts to respond to uncertainty react to the external world. The oracle machine has the characteristics of non-tampering, stable service, and auditability, and has an economic incentive mechanism to ensure the power of operation.

10. Zero-knowledge proof

Zero-knowledge proof was proposed by S.Goldwasser, S.Micali and C.Rackoff in 20proposed in the early 1980s. It refers to the prover's ability to convince the verifier that a certain assertion is correct without providing any useful information to the verifier.

2. Are there 7 core technologies for blockchain operation that you should know?

How many of the 7 core technologies for blockchain operation do you know?
1. Blockchain links
As the name suggests, blockchain is a chain composed of blocks. Each block is divided into two parts: block header and block body (including transaction data). The block header includes the hash (PrevHash) value (also called hash value) of the previous block used to implement block linking and the random number (nonce) used to calculate the mining difficulty. The hash value of the previous block is actually the hash value of the header of the previous block, and the rules for calculating random numbers determine which miner can obtain the power to record the block.
2. Consensus Mechanism
Blockchain was born with Bitcoin and is the basic technical architecture of Bitcoin. Blockchain can be understood as a decentralized accounting system based on the Internet. A decentralized digital currency system like Bitcoin requires blockchain to ensure the consistency of accounting by each honest node without a central node. Therefore, the core of blockchain technology is a consensus mechanism that reaches a consensus on the legality of transactions among individuals who have no basis for trust in each other without central control.
There are currently four main categories of blockchain consensus mechanisms: PoW, PoS, DPoS, and distributed consensus algorithms.
3. Unlocking scripts
Scripts are an important technology for automatic verification and automatic execution of contracts on the blockchain. Each output of each transaction does not strictly point to an address, but to a script. A script is like a set of rules that govern how the recipient can spend the assets locked on this output.
The legality verification of transactions also relies on scripts. Currently it relies on two types of scripts: locking scripts and unlocking scripts. The locking script is a condition added to the output transaction, implemented through a script language, and is located at the output of the transaction. The unlocking script corresponds to the locking script. Only if the conditions required by the locking script are met, the corresponding assets on this script can be spent, which is located at the input of the transaction. Many flexible items can be expressed through scripting language. The interpretation script is similar to a "virtual machine" in our programming field, which is distributed and runs on every node in the blockchain network.
4. Transaction Rules
Blockchain transactions are the basic units that constitute blocks, and are also the actual effective content that the blockchain is responsible for recording. A blockchain transaction can be a transfer or other transactions such as the deployment of smart contracts.
In the case of Bitcoin, a transaction refers to a payment transfer. The trading rules are as follows:
1) The input and output of the transaction cannot be empty.
2) For each input of the transaction, if its corresponding UTXO output can be found in the current transaction pool, the transaction will be rejected. Because the current transaction pool is a transaction that has not been recorded in the blockchain.Transactions, and each input to a transaction should come from a confirmed UTXO. If found in the current transaction pool, it is a double spend transaction.
3) For each input in the transaction, its corresponding output must be UTXO.
4) Each input unlocking script must work with the corresponding output locking script to verify the compliance of the transaction.
5. Transaction Priority
The priority of blockchain transactions is determined by the blockchain protocol rules. For Bitcoin, the priority of a transaction being included in a block is determined by the time it takes for the transaction to be broadcast to the network and the size of the transaction. As the time it takes for a transaction to be broadcast to the network increases and the chain age of the transaction increases, the priority of the transaction is increased and will eventually be included in the block. For Ethereum, the priority of a transaction is also related to the transaction fee that the publisher of the transaction is willing to pay. The higher the transaction fee that the publisher is willing to pay, the higher the priority of the transaction being included in the block.
6.Merkle proof
The original application of Merkle proof is the Bitcoin system (Bitcoin), which was described and created by Satoshi Nakamoto in 2009. The Bitcoin blockchain uses Merkle proofs in order to store transactions in every block. This makes the transaction unable to be tampered with and makes it easy to verify whether the transaction is included in a specific block.
7.RLP
RLP (Recursive Length Prefix, recursive length prefix encoding) is a main encoding method for object serialization in Ethereum. Its purpose is to encode any nested sequence of binary virtual data. Lu Ji

3. Blockchain 100 questions: What information does the blockchain record?

The blockchain is the big ledger of the Bitcoin network, and each block is quite on a page in the ledger. So what information is recorded in the "account book

"? Currently, each block of Bitcoin mainly records data such as block header, transaction details, transaction counter, and block size.

The "block header" contains all information except transaction information, mainly including the hash value of the previous block header:

Used to ensure that blocks are concatenated in order ; Timestamp: records the generation time of the block; random number: the answer to the arithmetic problem of the entire network mine

; Difficulty target: the difficulty coefficient score of the arithmetic problem.

"Transaction Details" records in detail the transferor, incomer, amount and digital signature of the transferor

of each transaction, which is the name of each transaction in each block. main content.

The "transaction counter" represents the number of transactions contained in each block.

"Block size" indicates the size of each block data. Currently, each block is limited to 1MB, and the possibility of expansion in the future cannot be ruled out

.

4. What are the three sets of metadata contained in the block header in blockchain technology?

1. The hash value of the previous block. Used for pre-index blocks
2. Mining difficulty, random value (for proof of work calculation), timestamp
3. Merkel tree, which can summarize and quickly summarize the verification blocks The root data of all transaction data.

5. Give an example of what is blockchain

Question 1: What is blockchain technology? What exactly is blockchain? What is blockchain? 1. Data blockchain is an important concept in the Bitcoin financial system. It records transaction record data on the entire Bitcoin network, and these data are shared by all Bitcoin nodes. Through the data block, we can query each transaction record. A look at the history of Bitcoin transactions. 2. Example: There are three persons A, B, and C. All funds of A and B are kept by C. And every financial transaction must be recorded by C. Now assume that A and B each have 1 million in custody of C. Then: A spends 80,000 yuan to B, then C's account book record will subtract 80,000 yuan from A's name, and add 80,000 yuan to B's name. If B transfers 50,000 yuan to A, C will add 50,000 yuan to A's name and subtract 50,000 yuan to B's name in the account book. A spends 50,000 yuan to B, then C's account book record will subtract 50,000 yuan from A's name, and add 50,000 yuan to B's name. 3. The role of the data blockchain is similar to that of C’s account record book. It records the user’s ownership of Bitcoin and the records of all users’ Bitcoin transactions. It’s just that this “account record book” is recorded by the mining software of every Bitcoin miner on the network. If a Bitcoin transaction is confirmed by the data blockchain, the relevant information will be recorded in the data blockchain. Bitcoin’s “account record book” is called the data blockchain. All data blockchains on the network form Bitcoin’s distributed network database system. 4. The essence of data blockchain technology is a decentralized and distributed structure of data storage, transmission and certification methods. It uses data blocks to replace the current Internet's dependence on central servers, so that all data changes or transaction items are recorded. On a cloud system, the self-certification of data during data transmission is theoretically realized. In a far-reaching sense, this transcends the traditional and conventional information verification paradigm that relies on a center and reduces the cost of establishing global "credit." This point-to-point verification will produce a "basic protocol", which is a new form of distributed artificial intelligence and will establish a new interface and shared interface between human brain intelligence and machine intelligence.

Question 2: What is the transaction process of the blockchain? Best to give an example 20 points 1. Definition
Blockchain is like an open networkNetwork ledger. It originated from Bitcoin and is the underlying technology of Bitcoin. In a Bitcoin transaction, all the information recorded in the transaction is packaged into a "Block" for storage. With the expansion of information exchange, blocks are linked to each other, forming a blockchain.
2. Characteristics
Digital currency represented by Bitcoin is a peer-to-peer electronic cash system. Among them, each transaction will be broadcast to all participants in the network, and will be recorded in the ledger after multiple confirmations. This ledger is the "blockchain". Each participant will have his own ledger. In this way, when false information occurs, it can be broken through mutual verification, thereby ensuring network security.
In the blockchain, every node is equal, and there is no centralized management organization. This "decentralization" feature makes the blockchain unnecessary to rely on third parties, and its operation does not require any human effort. intervention, capable of independent self-validation. In addition, the blockchain network is open to the world, and anyone can query data through the public port, so the entire system is highly transparent.
3. Application
In short, the blockchain is a trusted database and a reliable "ledger". In the future, it will be used in cross-border payments, securities, loans, voting, etc. For example, in cross-border payments, with the security provided by blockchain, money can be sent to the world anytime and anywhere, thus eliminating many intermediate links and high handling fees.

Question 3: What is blockchain? What does it mean in layman’s terms? What is China’s attitude towards blockchain? What can blockchain do? Blockchain, a great technology that accompanied the birth of Bitcoin, is currently being used in the financial field to significantly reduce transaction costs and improve efficiency, which is enough to excite Wall Street. However, this is just the tip of the iceberg. Its potential applications are very broad and will subvert every aspect of our lives in the future.
Blockchain is an important concept of Bitcoin. It is essentially a decentralized database and serves as the underlying technology of Bitcoin. One of the most basic characteristics of Bitcoin is decentralization. In recent months, financial giants have gradually begun to pay attention to Bitcoin's technology and used it in non-monetary fields, such as stock trading, election voting, etc. (1) Art Industry
Artists can use blockchain technology to declare ownership and issue numberable, 100% edition works in digital form for any type of artwork. It even includes a marketplace where artists can buy and sell through their website without the need for any intermediary services.
(2), Real estate industry
Use blockchain technology to solve various problems faced by everyone involved in real estate, including the naming process, land registration, agency intermediaries, etc.
(3), InsuranceIndustries
The financial industry has always been the most sensitive to advanced technology. Traditional banking and securities industry giants have been involved in the booming blockchain venture capital investment since 2014, with total global investment reaching US$1 billion within two years.
(4) P2P wallet
Personal assets can be traded through this P2P wallet in the future without going through any central institution, such as Bitcoin.
Most blockchains are in their infancy, mainly overseas. There are very few good domestic blockchain projects, so it is not recommended for any non-professionals to invest in blockchain projects. If you are very interested in blockchain technology and have a technical or financial background, it is recommended that you consider starting a business in this area. In terms of the blockchain protocol system, the lowest layer is the underlying technology of the blockchain, including the technical protocols of the blockchain, as well as some platform routing and basic algorithms; in the middle layer, some application interfaces and some credentials must be solved Issuance and verification, including some industry platform services, big data analysis, etc. This is a very rough classification, and there should be more detailed classifications; the top ones are some applications of blockchain, including finance Some applications and some applications in other aspects, the Internet of Things and so on.
Introduction to Bubi Blockchain
Bubi Blockchain has been focusing on the research and development and innovation of blockchain technology and products since its establishment. It has a number of core technologies and has achieved substantial results in many aspects. Radical innovation has resulted in a number of core technological achievements, such as: mathematically provable distributed consensus technology, fast large-scale ledger access technology, multi-chain general ledger technology that supports business expansion, and interconnection technology between heterogeneous blockchains. wait. On April 25, "Gege Points" introduced the concept of blockchain into the points system, jointly opened it up with multiple parties, issued and redeemed points, and promoted the circulation of points. Each cooperative institution can jointly participate in transaction verification, ledger storage, and real-time settlement; the third-party payment platform of the enterprise points issuer makes the entry and exit of points more flexible. Bubi has developed its own basic blockchain service platform, which has been applied in equity, supply chain, points, credit and other fields. Bubi has been committed to building an open value circulation network with decentralized trust as the core, allowing digital assets to flow freely.
A simple understanding of blockchain is a technology at the bottom of Bitcoin, which is also a peer-to-peer electronic cash system that can realize peer-to-peer value delivery. We should distinguish between Bitcoin, Bitcoin blockchain, blockchain and blockchain. Blockchain technology and other concepts. In countries with relatively developed finance in the past, finance and blockchain technology have a long history, and the legislation of digital currencies and blockchain networks is also very important. With the advent of the financial era, large financial institutions are studying blockchain technology. They have their own teams and conceptual technologies. Slowly, banks in various regions are also participating in digital currency discussions. The application and support of this technology are not only that. The influence of blockchain on enterprises is also huge. For larger domestic enterprises, Bubi Blockchain is also used in variousIn the fields of equity, supply chain, points, etc., major domestic financial institutions and enterprises have taken a fancy to the value of new industries and developed their own blockchain platforms. Blockchain has instantly become a new innovative industry in China. In terms of overseas internationalization, the United States has already obtained 15 blockchain patents at the end of last year compared to China. Blockchain financial applications are entering a new stage in an all-round way. Various applications will become more and more in-depth, and related changes will also become more and more profound. It is attracting more and more attention and will form a huge new trend... >>

Question 4: What is blockchain technology? What is blockchain? How to explain the concept of blockchain? People in each industry have different understandings, and relevant explanations are gradually emerging due to more and more real-life applications. With the popularization of this blockchain technology, the related results are getting bigger and bigger. If we want to understand this technology, we must have an in-depth understanding of reality.
In the past six months, the concept of blockchain has gradually become popular in China, and a blockchain whirlwind has taken off in the financial circle. Blockchain has attracted the attention and favor of more and more people in the industry due to its unique technical advantages. Blockchain technology, which is decentralized (or multi-centered), highly transparent, cannot be tampered with, and has no single point of failure, is entering the field of vision of financial institutions and enterprises. It has at least been used in digital currency, payment exchange, registration and settlement, Digital assets, traceability and anti-counterfeiting, supply chain, Internet of Things and many other fields have moved from theoretical discussions to practical applications.
"Blockchain" was first introduced with "Bitcoin" released in early 2009. Blockchain has become the basic protocol and technical application for the launch, recording, and circulation of Bitcoin. Although Bitcoin has been controversial since its inception and cannot even be regarded as a "currency" by governments and monetary authorities, the blockchain technology used in Bitcoin has been recognized by governments, including governments and monetary authorities. extensive attention.
Why has blockchain become a rapidly heating up hot technology and topic?
The most important of these may be that the launch of Bitcoin based on blockchain technology has opened up a new relationship with traditional society ( The exploration and attempt of brand-new technologies and rule systems such as Internet user identity verification, wealth confirmation, transaction records, notarization and verification, which have little connection with offline) and are fully applied in the online world (online), provide people with the opportunity to adapt to the Internet society. Development provides alternative paths and unlimited imagination.
Judging from its application in Bitcoin, blockchain is a set of new network blocks (BLOCK, also called communities) formed by combining encryption technology with the Internet. Bitcoin configuration, netizen identity verification, and Bitcoin (value) confirmation formed by mining, Bitcoin transaction records, and extended encryption of Bitcoin cross-block flow (value transfer) (added block and transaction time identification, etc. Internet protocol rules and accounting including block chain (Blockchain), full encryption, mutual authentication, etc., including registration and verification(Ledger) system. Precisely because Bitcoin is not a substitute for offline legal currency, but is issued and managed by non-legal currency authorities, mainly imitating the model of gold, and is completely new and decentralized protected and supported by basic Internet protocols and strict encryption technology. Internet currency (virtual currency) has thus formed a new set of currency rules and systems that are different from and not subject to real social laws, and can be bought, sold or exchanged with legal currency. It has been more than 8 years since Bitcoin was launched. There has been no record of funds or user information being stolen. Its security has been verified, and its efficiency and cost of fund settlement also have obvious advantages. This has made people's confidence in the blockchain technology used in Bitcoin continue to increase, and people have become more and more aware that although blockchain is a technology and protocol pioneered and applied by Bitcoin, the blockchain Chain is not the same as Bitcoin, and its application is by no means limited to Bitcoin. The application of blockchain can be decentralized or centralized; it can be a public chain model or a private chain model. Therefore, after Bitcoin, blockchain technology is also constantly developing and innovating, and constantly exploring new application fields, especially in the financial field.
The reason why blockchain is valued highly by more and more people is because the development and widespread application of the Internet have caused more and more economic exchanges and transaction activities to be conducted online, and the online world (or online world) society) is rapidly expanding, enriching and active, and online transactions must solve the efficiency and security protection issues of the parties' identity verification, value verification, transaction records, inspection and verification, etc., and require strict intermediaries and agreements (rules or constitutions). In this regard, traditional thinking and customary practices are to follow the development trajectory of the transfer of offline transactions to online and push the common rules and practices of the real (offline) society to the online (network) society. However, in practice, it is increasingly It is difficult to adapt to the needs of online transactions.
For example, for the identity verification of the parties, the natural choice is to use the information on the identity documents protected by the laws of various countries as the basis, and then add account or transaction passwords, as well as facial recognition, iris, fingerprints and other biometrics to conduct online transactions. Verification, but this method first makes the citizen identity information in the cross-border interconnected online world subject to the administrative jurisdiction of real society... >>

Question 5: The so-called "district" What is "Blockchain"? Blockchain itself is a tool called decentralization and trustlessness. For example, when you graduate from university, the current practice is to have a certificate recognized and issued by an authoritative agency as your certificate. This setting is more troublesome, because this is a piece of paper, and paper can be forged, so there will be various gaps. The issuing authority is also a person, and there will be various gaps in the middle. As long as it is related to people, whoever There are various possibilities related to media. Blockchain provides a good opportunity. As soon as you graduate, you will have records on the blockchain.No one can change the record. This thing exists objectively. As a physical existence and as a data existence, the blockchain is born. In this case, anyone who wants to check where you graduated can easily solve the problem. This is similar to the big data often involved in social networking (WeChat) and payment platforms (Alipay, Yibao).

Question 6: What is blockchain? Can you explain the principle of 10-point blockchain in plain language: decentralized distributed accounting system
Blockchain The core of the technology is that all currently participating nodes jointly maintain transactions and databases. It makes transactions based on cryptographic principles rather than trust, so that any two parties who reach an agreement can directly conduct payment transactions without the participation of a third party.
?
Technically speaking, a block is a data structure that records transactions, reflecting the flow of funds for a transaction. The blocks of transactions that have been reached in the system are connected together to form a main chain, and all 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 hash formed by the previous block, and random number. Transaction information is the task data carried by the block, specifically including the private keys of both parties to the transaction, the number of transactions, the digital signature of electronic currency, etc.; the hash formed by the previous block is used to connect the blocks to realize the past The order of transactions; random numbers are the core of transaction completion. All miner nodes compete to calculate the answer to the random number. The node that gets the answer the fastest generates a new block and broadcasts it to all nodes for update, thus completing a transaction.
1.1 What is Blockchain
Blockchain (BlockChain) refers to a technical solution that collectively maintains a reliable database through decentralization and trustlessness. This technical solution mainly allows any number of nodes participating in the system to associate and generate a series of data blocks (blocks) using cryptographic methods. Each data block contains all the information exchange data of the system within a certain period of time, and generates The data fingerprint is used to verify the validity of its information and chain to the next database block.
?
In layman’s terms, blockchain technology refers to a way for all people to participate in accounting. Behind all systems there is a database, which is a big ledger. Then who will keep this ledger becomes very important. At present, it is whoever owns the system who keeps the accounts. Each bank’s account books are kept by each bank, and Alipay’s account books are kept by Alibaba. But now in the blockchain system, everyone in the system has the opportunity to participate in accounting. If there are new transaction data changes within a certain period of time, everyone in the system can do accounting. The system will judge the person who has the fastest and best accounting during this period, write the recorded content to the ledger, and Send the contents of the ledger during this period to all other people in the system.Backup. In this way, everyone in the system has a complete ledger. Therefore, this data becomes very safe. A tamperer needs to modify more than half of the system node data at the same time to truly tamper with the data. Such tampering would be extremely costly, making it nearly impossible. For example, Bitcoin has been running for more than 7 years. Countless hackers around the world have tried to attack Bitcoin, but so far there have been no transaction errors. It can be considered that the Bitcoin blockchain has been proven to be a safe and reliable system.
?
1.2 Why is there blockchain innovation?
Human beings need to communicate during their activities, and communication is based on information. In the past, information circulation was not convenient enough to satisfy market participants. There is a demand for information, so intermediaries and centers are born. This centralized system has problems such as high cost, low efficiency, value dispersion, "information islands" and insecure data storage. However, due to technical and environmental factors, this system continued to operate for many years until the emergence of the Internet. The starting point of the first generation of the Internet is the TCP/IP protocol, which is an open code that implements a unified format for peer-to-peer transmission of information by all nodes on the network, and brings the basic values ​​of freedom and equality required by a global unified market into programmed, protocol-based, and reliably Execution. The Internet eliminates low-value, high-cost intermediate chains and achieves low-cost and high-efficiency global information transmission in a decentralized manner.
?
However, the first generation of the Internet did not solve the problem of information credibility. Activities that can be decentralized on the Internet must be activities that do not require credit endorsement, and activities that require credit guarantee must be activities involving centralized third-party intermediaries. Therefore, Internet technology that cannot establish global credit has encountered great obstacles in its progress - people cannot participate in any value exchange activities on the Internet in a decentralized manner. To realize value exchange, people still need third-party intermediaries based on credit (such as banks, clearing agencies, exchanges). The global centralized credit system still has problems such as high operating costs, low efficiency, and vulnerability to attacks and damage. For example, each country's legal currency has different credit values ​​and incompatible clearing systems, which adds a lot of cost to global trade.
?
Therefore, what the second generation Internet must break through is: how to establish global credit in a decentralized manner? Let...>>

Question 7: Explain clearly what is blockchain in an easy-to-understand manner. The English name for blockchain is Blockchain. Block literally means block, block, and chain means chain, chain. Therefore, together they are translated into blockchain.
1. Use cryptography technology to encrypt and decrypt so that records cannot be tampered with. Common blockchain encryption methods include hash algorithm, RSA algorithm, elliptic curve algorithm, etc.;
2. The huge amount of calculation needs to be supported by a reasonable reward mechanism. Because every transactionAll transactions must be recorded, so so far, the Bitcoin blockchain has more than 60 G. Every new transaction requires confirmation of the information related to the trading account to ensure that the transaction is valid. The huge amount of calculation requires a computer with powerful computing power to complete.
In order to encourage the participation of powerful computing power, Bitcoin provides two rewards: one is to issue a certain number of Bitcoins to these computers every day; instead, all transfer fees are awarded to these computers. (The technical term for these computers is "mining machines", and the people who hold the mining machines are called "miners".)
Biying China is working hard on the digitization of assets and has launched the digital currency crowdfunding platform Biying China.

Question 8: What is blockchain? Blockchain is a new application model of computer technology such as distributed data storage, point-to-point transmission, consensus mechanism, and encryption algorithm. The so-called consensus mechanism is a mathematical algorithm that establishes trust and obtains rights and interests between different nodes in the blockchain system.
In May 2016, the Currency Blockchain Research Center published the first book in China that introduces blockchain in simple terms, "Blockchain: Defining a New Pattern of Future Finance and Economics." It introduces the impact of blockchain technology on future finance and economy

Question 9: What is blockchain? For the time being, this is a relatively high-end technology. It connects all nodes (which can be understood as servers) through p2p network technology. Complete data (blocks) are stored on each node. The addition and withdrawal of any node will not affect the normal operation of the chain. Data is embodied in the form of data blocks. Blocks are connected to each other and can be understood as a one-way linked list. The hash value of the nth block is generated based on the hash of the n-1th block, the transaction recorded in the current block, and the random number as parameters. In this way, if you want to modify the data of the historical block, you have to modify all the blocks from the modified block to the final block. The difficulty can be imagined.
The blockchain also introduces a consensus mechanism and an incentive mechanism. There is no way to describe it too comprehensively here. I hope everyone can discuss and learn together

Question 10: What is blockchain: This explanation of blockchain is more understandable. Blockchain (Blockchain) refers to the method of decentralization and trustlessness. A technical solution for collectively maintaining a reliable database.
In layman’s terms, blockchain technology refers to a way for all people to participate in accounting. There is a database behind all systems. You can think of the database as a big ledger. Then who will keep this ledger becomes very important. Currently, whoever owns the system keeps the accounts. Tencent keeps the accounts of WeChat, and Alibaba keeps the accounts of Taobao. But now in the blockchain system, everyone in the system has the opportunity to participate in accounting. If there are any data changes within a certain period of time, everyone in the system can record them.Accounting, the system will judge the person who has the fastest and best accounting during this period, write the contents of his records into the ledger, and send the contents of the ledger during this period to all other people in the system for backup. In this way, everyone in the system has a complete ledger. In this way, we call it blockchain technology.
Blockchain technology has become the darling of the financial community in China and has become a hot topic. Domestic Puyin Group has launched Puyin, a tea-based digital currency.

6. Blockchain Series 5 - Oracle

1. Why is a decentralized oracle needed?

① Connect real-world data

Oracle is a bridge that collects real-world data to provide data for blockchain smart contracts. This is an important function of combining blockchain technology with the real world. Before, Bitcoin actually only stayed in the virtual realm. It was a completely digital asset and had no connection with the real world. It was somewhat self-talk, but in the actual real world All economic behaviors will generate data, and the connection between technology and actual data can be generated through oracles. This is just like the previous blockchain technology is an independent closed pool. Its own waves cannot affect other water systems, but through oracles It is equivalent to opening up a closed pool and turning it into living water, which rises and falls with the real sea of ​​reality.

② Reduce intermediary fees and automatically execute the contract content

Since the blockchain cannot be tampered with data, the accuracy of the data is objectively guaranteed and the contract content can be automatically executed. Imagine that in the past, if two companies jointly signed a contract worth 100,000, Company A breached the contract, but Company B was very likely to give up its rights protection, because it knew that legal rights protection would require more money and time. Then for Company B next time, after the evaluation , it is very likely that the 100,000 contract will not be signed because the risk is too high. But smart contracts guarantee automatic execution, and as long as company A defaults, company B can be compensated. This will greatly facilitate the further development of the transaction.

③ Can prevent hacker attacks

Imagine that if data recording is centralized, you only need to attack a certain website or port, and the relevant record information will be tampered with, but decentralization The oracle machine now extracts data from multiple parties for comparison. Instead of trusting one port in the past, there is now an additional multi-port comparison link to see if the port information is consistent. In the past, hackers attacked one port, but now hackers have to attack multiple ports, and hackers do not know which ports are called, so the difficulty is greatly increased.

2. In what fields can the oracle be applied?

① Can be better applied to areas with clear quantitative standards

For example, gambling, goods transactions, mortgage loans, the results of transactions are very easy to judge, winning or losing games, delivery of goods, etc. Whether the loan is repaid as scheduled?Function contracts can automatically execute the corresponding contract content. It is somewhat similar to the Taobao platform. When I buy an apple, I first give the money to the Taobao platform, the merchant delivers the goods, the buyer confirms receipt, and the Taobao platform transfers the money to the merchant. But now the decentralized oracle machine connects the data of our peer-to-peer transactions, and the smart contract assumes the role of the platform and reduces the fees of the intermediary platform.

② It cannot be well applied to non-quantitative standard transaction fields

For example, in the design industry, Party B provided a plan, but Party A believed that it did not meet the standards and required continued modification, but Party B revised it many times. After Party A still does not agree with its design, then there will be problems in the judgment of the smart contract. It is not easy to judge whether Party B failed to complete the work according to the standards or Party A wants to get more results of labor for a dollar, and the execution of the contract will also be a problem. Hence it comes.

7. Can encryption technology really rebuild social trust? -

In the blockchain industry, different people have different definitions of the word "trust". For software engineers, trust usually refers to "zero-trust interactive systems", "trustless transactions" and other trust-minimizing technologies. Still, trust has been key to helping us truly understand crypto.

Trust comes from the Old Norse word "traust", which means confidence and protection. The word has always meant trusting that people and processes will deliver on their promises. Trust is the cornerstone of a functioning society – societies that trust each other often develop more prosperous economies and harmonious societies because counterparties are less exposed and dispute resolution processes are fairer.

Unfortunately, the public has begun to lose trust in the core institutions responsible for keeping our society and economy functioning. According to Gallup polls, American people's confidence in major U.S. institutions has been declining over the past 45 years. Although the degree of trust breakdown varies across industries and countries, judging from the public’s negative sentiment towards the existing system, it is clear that everyone is seeking a fairer solution.

New technologies such as blockchain, Cryptocurrency, smart contracts and oracles are constantly emerging to coordinate social and economic affairs in a more secure, transparent and accessible way. More importantly, these technologies prove that cryptographic guarantees, often referred to as “cryptographic truth”, will effectively rebuild people’s trust in daily social and economic activities.

Note: The term "application" in this article broadly refers to any interface that interacts with companies, governments, or other users on the same platform, including applications downloaded on mobile phones or websites. In addition, the blockchains mentioned in this article mostly refer to permissionless blockchains (i.e., Ethereum and Bitcoin blockchains), because the application scope of such blockchains is much larger than that of permissioned blockchains (i.e., : Alliance chain and private chain).

The public has lost trust in traditional institutions and processes. This problem is reflected in all aspects of modern society. The following lists four reasons that lead to the collapse of trust. These problems directly affect people’s quality of life and social and economic development.

Centralization of ownership of data and processes

The initial design architecture of the Internet determines that applications are centralized to a large extent. Typically, a centralized entity owns the intellectual property of an application, controls its back-end algorithms, determines its future development direction, and profits from the data and revenue generated by the application. This centralized model creates an unequal relationship between users and applications. Apps can easily extract value from users, which also leads to users losing trust in the apps.

For example, apps often censor users' actions without their consent. There may be some actions that do violate the terms of service, such as illegal conduct. But many times the review has no clear basis and is subjective. This makes people question the neutrality of the platform. Neutral platforms should not treat or discriminate against anyone, especially because of self-interest, external political or social pressure, or differences in values. The public also holds very polarized views on whether social media, financial services, streaming media and other social platforms have the right to censor platform content.

If blockchain and oracles are used to build a network of trust, the above problems can be effectively solved - the world can operate based on objective facts, all people and processes operate in full compliance with the agreement, and all data is obtained Keep accurate records.

Data is owned by individuals and process ownership is decentralized

One of the biggest advantages of blockchain technology is that it can decentralize applications or institutions responsible for running social and economic activities. Blockchain technology can create a completely neutral platform that cannot arbitrarily censor user content due to any economic, political or social pressure. Once the terms are written into the smart contract and stored on the blockchain, the relationship between the user and the dApp can be viewed by anyone and cannot be tampered with by either party, not even the administrator.

Decentralized systems also eliminate intermediary custodians. The blockchain is more of a non-custodial facilitator, and all data generated by the dApp is publicly viewable and cannot be tampered with by anyone. Users can directly control their data and assets through the private key, and the private key can only be owned by the user. For example, anyone can view the complete transaction history of the Bitcoin ledger, and can host and send Bitcoins in their own account to other users on the network, without the need for banks to participate in the entire process.

Based on consensus, execution is guaranteed through encryption technology

Since the blockchain is based on a decentralized consensus mechanism to verify transactions in the network, any party can No special treatment will be given. Not in the blockchainThere are administrators, so dApps in crisis cannot be rescued, nor can they press the reset button at will. Blockchain replaces administrators with a decentralized network that ensures security based on encryption technology and economic incentive mechanisms, making it almost impossible to tamper with consensus or previously stored data.

Blockchains and dApps can also change, but changes usually require many independent users to reach a social consensus, rather than just one person making decisions like centralized applications. For this reason, many dApps use decentralized autonomous organizations (hereinafter referred to as DAOs) for governance, and all users vote together to initiate changes. In fact, many dApps have their own native tokens and use these tokens in the DAO, using a token-weighted voting mechanism to decide whether proposals are passed.

Executing digital contracts on a globally accessible and highly tamper-proof blockchain platform can significantly reduce counterparty risk. Many blockchains and dApps have also introduced automatic penalty mechanisms to punish participants for their bad behavior. For example, the PoS blockchain will confiscate some of the tokens pledged by malicious nodes as punishment. dApps can also temporarily hold user funds in custody until certain conditions are verified before releasing the funds. This way, it is almost impossible for the losing party to avoid payment.

Decentralized oracle networks achieve the same guarantee by creating authoritative facts. Each dApp can clearly define how they want to obtain facts from the outside world and develop clear boundary conditions. In other words, oracles can more flexibly verify external events for smart contracts. Users can choose to trust different data sources, or they can choose to spend more money to improve the decentralization level of the oracle network. No matter how users design the oracle mechanism, they must first reach a consensus on the facts transmitted by the oracle and recognize its authority. The agreement reached between the user and the oracle can be written into a service level agreement (hereinafter referred to as SLA) smart contract to prevent anyone from tampering with the content of the agreement, and automatically execute the reward and punishment mechanism when the task is completed.

Chainlink Verifiable Random Function (hereinafter referred to as VRF) is a service that creates authoritative facts through oracles. Chainlink VRF uses oracle technology to generate random numbers and cryptographic proofs off-chain, and then sends both to the chain. The blockchain will use cryptographic proofs to verify that the random numbers have not been tampered with by any oracle. NFT and gaming applications use random numbers generated by Chainlink VRF to perform various on-chain functions, such as picking winners of special NFT airdrops and determining the contents of treasure chests. It is worth mentioning that users can independently verify the fairness and impartiality of the entire process, and even game developers or NFT creators have no right to influence the generation of random results.

8. What are the core technologies of blockchain technology?Introduction to technology

What is the hottest Internet topic right now? You don’t need to tell me that it is blockchain technology. However, many friends have only heard of this technology and have no idea about it. Too much in-depth understanding, so what are the blockchain technologies? Below we will bring you an introduction to the core technology of blockchain for your reference.
What are the core elements of blockchain technology?
Blockchain technology can be a public ledger (visible by anyone) or a permissioned network (visible only by those authorized), which solves supply chain challenges , because it is an immutable record that is shared among network participants and updated in real time.
Blockchain technology----data layer: designing the data structure of the ledger
Core technology 1. Block + chain:
Technically speaking, block is a data structure that records transactions. Reflects the flow of funds for a transaction. The blocks of transactions that have been reached in the system are connected together to form a main chain, and all nodes participating in the calculation record the main chain or part of the main chain.
Each block consists of a block header and a block body. The block body is only responsible for recording all transaction information in the previous period, mainly including the number of transactions and transaction details; the block header encapsulates the current version number, previous A block address, timestamp (recording the time when the block was generated, accurate to seconds), random number (recording the value of decrypting the answer to the math question related to the block), target hash value of the current block, and Merkle number Root value and other information. From a structural point of view, most functions of the blockchain are implemented by the block header.
Core technology 2. Hash function:
The hash function can convert data of any length into a set of fixed-length codes through the Hash algorithm. The principle is based on a cryptographic one-way hash function. This kind of function is easy to verify, but difficult to crack. Usually, the industry uses y=hash(x) to represent it. This hash function implements operations on x to calculate a hash value y.
Commonly used hash algorithms include MD5, SHA-1, SHA-256, SHA-384 and SHA-512, etc. Taking the SHA256 algorithm as an example, inputting any string of data into SHA256 will result in a 256-bit Hash value (hash value). Its characteristics: the same data input will get the same result. As long as the input data changes slightly (for example, a 1 becomes a 0), a completely different result will be obtained, and the result cannot be predicted in advance. Forward calculation (calculating the corresponding Hash value from the data) is very easy. Reverse calculation (cracking) is extremely difficult and is considered impossible under current technological conditions.
Core technology 3. Merkle tree:
Merkle tree is a hash binary tree, which can be used to quickly verify the integrity of large-scale data. In the blockchain network, the Merkle tree is used to summarize all transaction information in a block, and finally generates a unified hash value of all transaction information in the block.Any change in transaction information will cause the Merkle tree to change.
Core technology 4. Asymmetric encryption algorithm:
Asymmetric encryption algorithm is a key secret method that requires two keys: public key and private key. The public key and the private key are a pair. If the public key is used to encrypt the data, only the corresponding private key can be used to decrypt it, thereby obtaining the corresponding data value; if the private key is used to sign the data, then only the corresponding public key can be used to sign the data. In order to verify the signature, the sender of the verification information is the holder of the private key.
Because encryption and decryption use two different keys, this algorithm is called an asymmetric encryption algorithm, while symmetric encryption uses the same key in the encryption and decryption processes.
Blockchain technology----network layer: realize the decentralization of accounting nodes
Core technology 5. P2P network:
P2P network (peer-to-peer network), also known as point-to-point technology, is no Central server, Internet system that relies on user groups to exchange information. Unlike a centralized network system with a central server, each client in a peer-to-peer network acts as both a node and a server. Domestic Xunlei software uses P2P technology. The P2P network has the characteristics of decentralization and robustness.
Blockchain technology----Consensus layer: allocate the task load of accounting nodes
Core technology 6. Consensus mechanism:
Consensus mechanism is how to reach consensus among all accounting nodes to identify The validity of a record is both a means of identification and a means of preventing tampering. There are currently four main types of consensus mechanisms: PoW, PoS, DPoS and distributed consensus algorithms.
PoW (Proof of Work, proof of work): PoW mechanism, which is like Bitcoin’s mining mechanism, miners package existing transactions that have not been recorded by the network into a block, and then continue to traverse and try to find a random number , so that the hash value of the new block plus the random number meets certain difficulty conditions. Finding a random number that meets the conditions is equivalent to determining the latest block of the blockchain, and is also equivalent to obtaining the current round of accounting rights of the blockchain. Miners broadcast blocks that meet the mining difficulty conditions in the Yuanfu network. After verifying that the block meets the mining difficulty conditions and that the transaction data in the block meets the protocol specifications, other nodes in the entire network will each Blocks are linked to their own version of the blockchain, thereby forming a network-wide consensus on the current network state.
PoS (ProofofStake, Proof of Stake): PoS mechanism requires nodes to provide proof of a certain number of tokens to obtain a distributed consensus mechanism for competing for blockchain accounting rights. If you rely solely on the token balance to determine the bookkeeper, you will inevitably make the rich win, which will lead to the centralization of bookkeeping rights and reduce the fairness of the consensus. Therefore, different PoS mechanisms use different methods to increase the amount of money based on the proof of equity. The randomness of accounting rights avoids centralization. For example, in the PeerCoin PoS mechanism, the Bitcoin with the largest chain age will be rewardedThe greater the chance of accounting rights. NXT and Blackcoin use a formula to predict the next accounting node. The more tokens you own, the greater the probability of being selected as an accounting node. In the future, Ethereum will also switch from the current PoW mechanism to a PoS mechanism. Judging from the information currently available, Ethereum's PoS mechanism will use nodes to place bets on the next block. The winner of the bet will receive an additional Ethereum currency award. Those who do not win will be deducted Ether coins to reach consensus on the next block.
DPoS (DelegatedProof-Of-Stake, share authorization certificate): DPoS is easy to understand and is similar to the modern corporate board of directors system. The DPoS mechanism adopted by BitShares is that shareholders vote to select a certain number of witnesses. Each witness has two seconds of authority to generate blocks in order. If the witness cannot generate a block within the given time slice, The block generation authority is given to the witness corresponding to the next time slice. Shareholders can replace these witnesses at any time by voting. This design of DPoS makes the generation of blocks faster and more energy-saving.
Distributed Consistency Algorithm: Distributed Consistency Algorithm is based on traditional distributed consistency technology. Among them are Byzantine fault-tolerant algorithms that solve the Byzantine Generals problem, such as PBFT (Byzantine fault-tolerant algorithm). In addition, distributed consensus algorithms (Pasox, Raft) that solve non-Byzantine problems are not explained in this article. This type of algorithm is currently a commonly used consensus mechanism in alliance chain and private chain scenarios.
Taken together, POW is suitable for public chains. If you build a private chain, it is more suitable to use POS because there is no trust problem in verification nodes; and because there are untrustworthy local nodes in the alliance chain, it is more suitable to use DPOS.
Blockchain technology----Incentive layer: Develop a "salary system" for accounting nodes
Core technology 7. Issuance mechanism and incentive mechanism:
Take Bitcoin as an example. Bitcoins are initially rewarded by the system to miners who create new blocks, and this reward is halved approximately every four years. At the beginning, miners were rewarded with 50 Bitcoins for each new block recorded, and this reward is halved approximately every four years. By analogy, by around AD 2140, newly created blocks will no longer receive rewards from the system. By then, the total number of Bitcoins will be approximately 21 million. This is the total number of Bitcoins, so it will not increase indefinitely.
Another source of incentives is transaction fees. When there are no system rewards for newly created blocks, the miners' income will change from system rewards to transaction fees. For example, when you transfer, you can specify 1% of it as a handling fee to be paid to the miner who records the block. If the output value of a transaction is less than the input value, the difference is the transaction fee, which will be added to the incentive for that block. As long as a given amount of electronic currency has entered circulation, the incentive mechanism can gradually be converted to rely entirely on transaction fees, so there is no need to issue new currency.
Blockchain technology----Contract layer: giving the ledger programmable features
Core technology 8. Smart contractAbout:
Smart contracts are a set of scenario-based programmed rules and logic, which are implemented through decentralized, trustworthy and shared script codes deployed on the blockchain. Normally, after the smart contract is signed by all parties, it is attached to the blockchain data in the form of program code, and is recorded in a specific block of the blockchain after being propagated through the P2P network and verified by nodes. Smart contracts encapsulate a number of predefined states and transition rules, scenarios that trigger contract execution, response actions under specific scenarios, etc. The blockchain can monitor the status of smart contracts in real time, and activate and execute the contract by checking external data sources and confirming that specific trigger conditions are met.
The above is what blockchain technologies the editor has brought to you? All content of the introduction to the core technology of blockchain.