How can we explain blockchain in a simple way?

　　Blockchain technology is considered to be the next disruptive core technology after steam engines, electricity, and the Internet. If steam engines released people’s productivity, electricity solved people’s basic living needs, and the Internet completely changed the way information is transmitted, then as a machine for constructing trust, blockchain may completely change the way value is transmitted in the entire human society.

　　Just starting to get to know blockchain, there are too many basic knowledge points that need to be understood and known. Everyone don’t be in a hurry, let’s popularize these knowledge points today. Today, let’s take a look at what public chain, private chain, consortium chain, and side chain are first.

　　I. What is blockchain?

　　Blockchain technology is a new type of distributed infrastructure and computational paradigm that uses block chain data structures to verify and store data, distributed node consensus algorithms to generate and update data, cryptographic methods to ensure the security of data transmission and access, and smart contracts composed of automated script code to program and operate data. It has characteristics such as decentralization, openness and transparency, non-tamperability, distributed storage, and smart contracts. In short, blockchain is a distributed public ledger technology. Everyone can view the content of this ledger and participate in the maintenance and update of the ledger.

　　II. Differences between public chains, private chains, and consortium chains

　　Blockchains can be divided into public chains, private chains, and consortium chains according to the degree of decentralization.

　　Public chains – completely decentralized, all users can read and write;

　　Consortium chains – partially decentralized, write participants are pre-screened, and read and write permissions are decided by the selected participants;online casino planClick to enter

　　Private chains – partially decentralized, write permissions are held by only one organization, and read and write permissions are decided by the organization.

　　Public chains are completely decentralized, with all data on the chain being publicly transparent and unchangeable. Anyone can read and write data through transactions or mining. The typical representative is the Bitcoin blockchain, where anyone can conduct transactions on the chain and view all transaction information on the chain. For example, Hunu can view the outgoing and incoming information of her BTC address on the chain (specific operations please click [Operation Guide] Recharge and withdrawal not arrived, don’t hurry); everyone can also see whether Satoshi has extracted Bitcoin from his BTC address (assuming you know Satoshi’s BTC address).

　　Consortium chains are partially decentralized, with limited openness and decentralization. Participants are pre-screened or directly designated, and the read permissions of the database may be public, or like the write permissions, limited only to system participants. The Ripple blockchain used for international remittances between Japan and South Korea and interbank transfers within Japan recently is a consortium chain. It provides cross-border payment services for financial institutions joining the consortium, and only members of the consortium who obtain the consent of the majority of the consortium members are eligible to write data on the chain. At the same time, whether the data on the chain is open to everyone or to only a part of people is also decided by the consortium.

　　Private chains are similar to consortium chains, with limited openness and decentralization. The rights to read and write, and the rights to book entries, are decided by the organization. The biggest difference from consortium chains is that consortium chains are for a consortium, such as a specific industry, while private chains are for an organization, such as an internal company service. According to the latest report from Daily News, the largest financial institution in Japan, Mitsubishi UFJ Group, plans to issue its own token (MUFG) to solve the problem that the transfer amount of electronic currency cannot exceed 1 million yen (about 60,000 RMB) without going through a bank. In this scenario, Mitsubishi UFJ Group uses a private chain that serves the company internally.

　　Three, sidechain

　　In a strict sense, ‘sidechain’ itself is not a blockchain, but can be understood as an extension protocol of blockchain. Early ‘sidechain’ was designed to solve the limitations of Bitcoin blockchain technology, first locking the assets on the main chain, and then making parameter modifications on the locked part of the assets on the sidechain (such as modifying, and conducting free trading and conversion. For example, modifying the account every 10 minutes, block size limit of 1M, etc., and giving the sidechain its own trading definition.

　　The current Lightning Network is based on some extensions of sidechain technology to achieve the purpose of fast transfers and transactions. Next, let’s briefly introduce how the Lightning Network operates.

　　If AB trade frequently, they can establish a channel between AB with 2 bitcoins, where AB each send 1 bitcoin to a multi-signature address, and then temporarily lock these coins on the main chain.

　　As long as AB signs the transaction, these two currencies can be transferred freely between the two parties. The reason why it can be free is that these 2 bitcoins have not moved at all, but have only transferred the ownership of the currency outside the blockchainonline casino local and The latest method. When the channel is finally closed, the transaction will be written to the blockchain, and both parties can get their own part of the currency.

　　On the Lightning Network, when transferring between AB without establishing a channel, for example, when A pays to D who has not established a channel, it can be propagated through nearby nodes, from A to B to C to D, and A only needs to pay a small amount of transaction fee to B and C. If there is already a channel between BC, another transaction fee can be saved. It should be noted that if this operation is performed on the main chain, all nodes in the network need to synchronize this information, which will result in a much higher transaction fee and slower speed; while on the Lightning Network, because only ABCD nodes need to be propagated, the speed will be much faster, and the transaction fee will also be much cheaper.

　　A simple summary of the characteristics of sidechain:

　　1. Sidechain is a kind of extension protocol, designed to solve the limitations of the main chain (such as Bitcoin blockchain) technology;

　　2. Generally, lock the assets on the main chain first, and then make parameter modifications on the locked part of the assets on the side chain;

　　3. Used to achieve the purpose of low transaction fees, high transfer speed, and so on.

　　One of the consensus algorithm series: the RAFT algorithm of private chain and the PBFT algorithm of consortium chain

　　To reach a consensus on the order of data is the essential problem that many consensus algorithms need to solve

　　The implementation of Fabric’s PBFT algorithm

　　The consensus algorithms in the current stage can be mainly divided into three categories: public chain, consortium chain, and private chain

　　Private chain, all nodes are trustworthy

　　Consortium chain, there are peer-to-peer untrusted nodes

　　Private chain: The consensus algorithm of private chain, which is the traditional distributed system consensus algorithm before the concept of blockchain was popularized, is similar to the Paxos algorithm, such as the Zab protocol of Zookeepersports betting and How to find it. The applicable environment of private chain generally does not consider malicious nodes in the cluster, but only considers fault nodes caused by system or network reasons.

　　Consortium chain: In the consortium chain, the classic representative project is the Fabric project under the Hyperledger organization, which uses the pbft algorithm in Fabric 0.6 version. In addition to considering the existence of faulty nodes in the cluster, the consortium chain also needs to consider the existence of malicious nodes. For the consortium chain, each new node joining needs to be verified and audited.

　　Public chain: In addition to considering the existence of faulty nodes in the network, public chains also need to consider malicious nodes, which is similar to consortium chains. The biggest difference with consortium chains is that nodes in public chains can join or exit very freely, without strict verification and audit.online casino method and The latest website

　　The most commonly used algorithms in public chains are pow algorithm and pos algorithm, which are directly related to the interests of participants and use interests to restrict the honest work of nodes, solving the Byzantine problem in distributed systems. Byzantine fault-tolerant algorithm is a state machine replica replication algorithm, through multi-round message passing between nodes, all honest nodes in the network can reach a consensus.

　　Using Byzantine fault-tolerant algorithms does not require the issuance of encrypted currency, but can only be used for private chains or consortium chains, and node joining needs to be controlled for permissions; it cannot be used for public chains because all nodes in public chains can join or exit at will, and cannot resist Sybil attacks (Sybil attack).

　　The raft algorithm includes three roles, namely: follower (follower), candidate (candidate) and leader (leader). A node in the cluster can only be one of these three states at a time, and these roles can transform into each other with the change of time and conditions.

　　The raft algorithm mainly includes two processes: one is leader election, and the other is log replication, among which the log replication process is divided into two stages: recording logs and submitting data. The raft algorithm supports the maximum fault-tolerant fault nodes is (N-1)/2, where N is the total number of nodes in the cluster.

　　There is an animation in foreign countries that introduces the raft algorithm very thoroughly, the link address is:. This animation mainly includes three parts of content, the first part introduces the process of simple leader election and log replication, the second part introduces the detailed process of leader election and log replication, and the third part introduces how the raft algorithm recovers network consistency when encountering network partition (brain split).

　　The proposal of the pbft algorithm is mainly to solve the Byzantine general problem.

　　In order for this problem to have a solution, there is an extremely important prerequisite, that is, the channel must be reliable. If the channel cannot guarantee reliability, then the Byzantine problem has no solution. The issue of channel reliability will lead to the two-army problem. The conclusion of the two-army problem is that it is basically impossible or extremely difficult to reach a consensus through communication on an unreliable communication link.

　　The Byzantine Generals Problem was first proposed by Leslie Lamport and two others in the 1982 paper ‘The Byzantine Generals Problem’. It proved that when the total number of generals is greater than 3f, and traitors are f or fewer, loyal generals can reach a consensus on orders, that is, 3f+1=n. The algorithm complexity is o(n^(f+1)). In 1999, Miguel Castro (Castro) and Barbara Liskov (Liskov) first proposed the pbft algorithm in their paper ‘Practical Byzantine Fault Tolerance’, which also meets the condition of 3f+1=n for fault tolerance, and the algorithm complexity is o(n^2).

　　First, let’s think about a question, why is the maximum number of fault-tolerant nodes in the pbft algorithm (n-1)/3, while the maximum number of fault-tolerant nodes in the raft algorithm is (n-1)/2?

　　For the raft algorithm, the fault tolerance of the raft algorithm only supports fault-tolerant faulty nodes and does not support fault-tolerant malicious nodes. What is a faulty node? It is a node that becomes unresponsive due to system busy, failure, network problems, or other abnormal conditions. A node that appears in this situation is a faulty node. What is a malicious node? A malicious node, in addition to not responding to the requests of other nodes in the cluster on purpose, can also deliberately send incorrect data or send different data to different other nodes, causing the nodes in the entire cluster to ultimately fail to reach a consensus. Such nodes are malicious nodes.

　　The raft algorithm only supports fault-tolerant faulty nodes. Assuming the total number of nodes in the cluster is n, and the number of faulty nodes is f, according to the principle of majority rule, the normal nodes in the cluster only need to be one more than f nodes, that is, f+1 nodes, so the number of correct nodes will be more than the number of faulty nodes, and the cluster can reach a consensus. Therefore, the maximum number of fault-tolerant nodes supported by the raft algorithm is (n-1)/2.

　　For the pbft algorithm, in addition to supporting fault-tolerant faulty nodes, the pbft algorithm also needs to support fault-tolerant malicious nodes. Assuming the number of nodes in the cluster is N, and the number of faulty nodes is f. Among the faulty nodes, they can be both faulty and malicious, or only faulty or only malicious. This will lead to the following two extreme cases:

　　In the first scenario, if there are f faulty nodes that are also malicious, then according to the principle of majority rule, the normal nodes in the cluster only need to be one more than f nodes, that is, f+1 nodes, so the number of correct nodes will be more than the number of faulty nodes, and the cluster can reach a consensus. That is to say, the maximum number of fault-tolerant nodes supported in this case is (n-1)/2.

　　In the second case, the faulty nodes and the malicious nodes are different nodes. There will be f faulty nodes and f faulty nodes. When a node is found to be a faulty node, it will be excluded from the cluster, leaving f faulty nodes. Then, according to the principle of majority rule, the normal nodes in the cluster only need to be one more than f nodes, that is, f+1 nodes, so the number of correct nodes will be more than the number of faulty nodes, so the cluster can reach consensus. Therefore, the total number of all types of nodes is f+1 correct nodes, f faulty nodes, and f faulty nodes, that is, 3f+1=n.

　　Combining the above two cases, therefore, the maximum number of fault-tolerant nodes supported by the pbft algorithm is (n-1)/3

　　The basic process of the pbft algorithm mainly includes the following four steps:

　　The client sends a request to the master node

　　The master node broadcasts a request to other nodes, and the nodes execute the three-stage consensus process of the pbft algorithm.

　　After the node completes the three-stage process, it returns a message to the client.

　　After the client receives the same message from f+1 nodes, it represents that consensus has been correctly completed.

　　Why does receiving the same message from f+1 nodes represent that consensus has been correctly completed? From the derivation in the previous section, it can be known that whether it is the best case or the worst case, if the client receives the same message from f+1 nodes, it means that there are enough correct nodes that have reached consensus and completed the processing.

　　3. The core three stages of the algorithm process

　　The core three stages of the algorithm are respectively the pre-prepare stage (preparation stage), the prepare stage (preparation stage), and the commit stage (commitment stage).

　　In terms of process comparison, for leader election, the essence of the raft algorithm is that the one who is faster is elected, while the pbft algorithm is to rotate the master node in order according to the number. For the consensus process and the leader reshuffling mechanism, in order to more vividly describe these two algorithms, the consensus process of raft and pbft will be compared to how a team executes commands. From this perspective, we can understand the differences between raft algorithm and pbft.

　　A team must have a leader and ordinary members. For the raft algorithm, the consensus process is: as long as the leader is not down, whatever the leader says, we (ordinary members of the team) will do, and we will implement it resolutely. When should we reshuffle the leader? Only when the leader is down should we reshuffle the leader, otherwise, we are the people of the leader in life and the ghost of the leader in death.

　　For the pbft algorithm, the consensus process is: when the leader sends a command to me, if I think the leader’s command is problematic, I will refuse to execute it. Even if I think the leader’s command is correct, I will still ask other members of the team whether the leader’s command is correct. Only when a majority (2f+1) of the members agree that the leader’s command is correct will I go ahead and execute the command. When should we reshuffle the leader? Of course, we should reshuffle if the leader is down. If most people think the leader is incompetent or has a problem, we will also reshuffle the leader.

　　IV. Conclusion

　　Raft algorithm and pbft algorithm are classic consensus algorithms in private chains and consortium chains. This article mainly introduces the process and differences between raft and pbft algorithms. There are two fundamental differences between raft and pbft algorithms:

　　The raft algorithm from nodes will not reject the request of the master node, while the pbft algorithm from nodes may reject the request of the master node in some cases;

　　The raft algorithm can only tolerate faulty nodes, and the maximum number of tolerated faulty nodes is (n-1)/2, while the pbft algorithm can tolerate both faulty nodes and malicious nodes, with a maximum number of tolerated nodes of (n-1)/3.

　　The pbft algorithm achieves consensus through voting and can effectively solve problems including forks while improving efficiency. However, it is only suitable for consortium chains and private chains because the communication volume between two nodes is O(n^2) (which can be reduced through optimization), and generally cannot be applied to more than 100 nodes.

　　The premise of having a solution for pbft is that the channel must be reliable, and the existing problem is poor scalability (scalability).

　　Partly from:

　　What are the three major public chains of blockchain designed for?

　　The three major public chains of blockchain refer to BTC, ETH, and ADA

　　Blockchain public chain is also known as blockchain common chain. The meaning of public chain is that anyone can read the data in the system at any time. Public chains are often completely decentralized, and this feature makes it impossible for anyone or any institution to control or tamper with the data on the chain.

　　Extended Information:

　　Blockchain is a term in the field of information technology. In essence, it is a shared database in which the data or information stored has characteristics such as ‘unforgeable’, ‘full traceability’, ‘traceable’, ‘open and transparent’, and ‘collective maintenance’. Based on these features, blockchain technology has laid a solid ‘trust’ foundation, created a reliable ‘cooperation’ mechanism, and has broad application prospects.

　　Type

　　1. Public Blockchain

　　Public Blockchains (PublicBlockChains) refer to: Any individual or organization in the world can send transactions, and these transactions can obtain effective confirmation from the blockchain. Anyone can participate in its consensus process. Public blockchains are the earliest blockchain and the most widely used blockchain. All virtual lotteries of the bitcoins series and How to find it are based on public blockchains, and there is only one blockchain corresponding to this currency in the world.

　　2. Joint (Industry) Blockchain

　　Industry blockchain (ConsortiumBlockChains): Multiple pre-selected nodes are designated as bookkeepers within a certain group, and the generation of each block is decided by all pre-selected nodes (pre-selected nodes participate in the consensus process). Other access nodes can participate in transactions but do not interfere with the bookkeeping process (essentially still托管记账, just changed to distributed bookkeeping, the number of pre-selected nodes, and how to determine the bookkeeper of each block becomes the main risk point of this blockchain), and anyone else can perform limited queries through the open API of the blockchain.

　　3. Private blockchain

　　Private blockchain (PrivateBlockChains): Only uses the total account technology of blockchain for bookkeeping, can be a company or an individual, enjoys the writing permission of this blockchain alone, and there is no great difference between this chain and other distributed storage solutions. Traditional finance is trying to experiment with private blockchain, while the application of public chain such as Bitcoin has been industrialized, and the application products of private chain are still in the exploration stage. What is the public chain in blockchain?

　　Public chain, also known as ‘public chain’, refers to the blockchain where anyone in the world can enter the system at any time to read data, send confirmable transactions, and compete for bookkeeping. Public chains are usually considered ‘fully decentralized’ because no individual or institution can control or tamper with the reading and writing of data. In terms of application, blockchain public chains mainly include Bitcoin, Ethereum, Hyperledger, most altcoins, and smart contracts, among which the ancestor of blockchain public chains is the Bitcoin blockchain, with the following characteristics:

　　1. Code open source

　　Code is uploaded to github, and everyone can download the complete blockchain data to undergo public scrutiny.

　　2. Fully decentralized

　　Anyone can become a node, and each node is public, allowing everyone to participate in the calculation of the blockchain. No node is permanent, but阶段性, and no center has mandatory power over nodes. Anyone can read, send transactions, and transactions can be effectively confirmed on the blockchain. Anyone can participate in the consensus process. The consensus process determines which block can be added to the blockchain and the exact current state. Everyone can receive economic rewards proportional to their contributions in the consensus process. These public chains are usually considered to be ‘fully decentralized’.

　　3. Develop decentralized applications

　　Program developers can easily develop decentralized applications through this public chain. Public chains can protect user rights and interests from the influence of program developers. Blockchain chain classification

　　A few days ago, a friend asked many questions about blockchain on WeChat, one of which was how to classify the chain of blockchain. Currently, blockchain can be divided into four categories: public chain, private chain, consortium chain, and side chain. Beijing Muqi Mobile Technology Co., Ltd., a professional blockchain outsourcing development company, welcomes cooperation. Below, let’s understand the characteristics and applications of these chains of blockchain, hoping it will be helpful to everyone.

　　1. Public chain – everyone can participate

　　A public chain is a blockchain that anyone can read, anyone can send transactions, and transactions can be effectively confirmed, and anyone can participate in the consensus process.

　　Public chains adopt mechanisms such as Proof of Work (POW), Proof of Stake (POS), and Delegated Proof of Stake (DPOS), and combine economic rewards with encrypted digital verification, establishing a principle that everyone can obtain economic rewards proportional to the amount of work.

　　Features:

　　1. Open source, since the operation rules of the entire system are open and transparent, this system is an open-source system; 2. Protect users from the influence of developers, in public chains, developers have no right to interfere with users, so the blockchain can protect the users of the programs they develop; 3. Low access threshold, anyone with sufficient technical ability can access it, that is, as long as there is a computer that can connect to the Internet, it can meet the conditions for access; 4. All data is publicly available by default, although all participants hide their real identities, this phenomenon is very common. They generate their own security through their public nature, where each participant can see all account balances and all transaction activities.

　　Cases: Many familiar figures in public chains: BTC, ETH, EOS, AE, ADA, etc.

　　2. Private chain – power is in the hands of a few

　　A private chain refers to a blockchain where the write permission is in the hands of a single organization. Read permissions or openness may be limited to varying degrees. Related applications include database management, auditing, and even a company, although in some cases, it is hoped that it can have public audibility, but in many situations, public readability is not necessary.

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　　1. The transaction speed is fast, a private chain can be faster than any other blockchain, even approaching the speed of a conventional database that is not a blockchain. This is because even a small number of nodes have a high level of trust, and it is not necessary for each node to verify a transaction. 2. Good privacy, private chains provide better privacy protection, making the data privacy policy on that blockchain consistent with that of another database; there is no need to handle access permissions and use all the old methods, but at least, this data will not be publicly obtained by anyone with network connections. 3. Low transaction costs, transaction costs are significantly reduced, even to zero, and transactions can be completely free or at least very inexpensive on a private chain. If an entity controls and processes all transactions, they no longer need to charge for their work.

　　Cases: The Hyperledger project of the Linux Foundation, R3CEV Corda platform, and GemHealth network, or private chains are being developed or used.

　　3. Consortium Chain – Partial Decentralization

　　The openness and decentralization of the consortium chain are limited. The participants are pre-screened or directly designated, and the read permissions of the database may be public, or like the write permissions, may be limited to the participants of the system.

　　Features:

　　1. Low transaction costs: Transactions only need to be verified by a few trusted high-computation nodes, without the need for network-wide confirmation; 2. Easy to connect nodes: If there is a problem, the consortium chain can quickly repair it through manual intervention and allow the use of consensus algorithms to reduce block time, thereby completing transactions faster; 3. Flexibility: If needed, communities or companies running private blockchains can easily modify the rules of the blockchain, restore transactions, modify balances, and so on.

　　Cases: Ripple established a consortium chain for international remittances in Japan and South Korea, as well as domestic interbank remittances in Japan, and the Xunlei chain coin, which was popular for a while, is also a semi-open consortium chain.

　　4. Sidechain – Extension Protocol

　　In a strict sense, ‘sidechain’ itself is not a blockchain, which can be understood as an extension protocol of blockchain. Early ‘sidechain’ was created to address the limitations of Bitcoin blockchain technology. Sidechains act like channels that connect different blockchains together to achieve blockchain expansion. Sidechains are completely independent of the Bitcoin blockchain, but these two ledgers can ‘interact’ with each other to achieve interaction.

　　Features:

　　1. Independence: The benefit of the sidechain architecture is that the code and data are independent, without increasing the burden on the main chain and avoiding excessive data expansion. Sidechains have their own independent blockchain, independent trustees or witnesses, and also have their own independent node network, which means that the blocks generated by a sidechain will only be broadcast among all nodes that have installed the sidechain. 2. Flexibility: All blockchain parameters of the sidechain can be customized, such as simple ones like block interval, block reward, and the destination of transaction fees, and advanced users can also modify the consensus algorithm.

　　Cases: LSK, RDN, ARDR, and other currencies are using sidechain technology.

　　For the entire field of ‘lottery and How to find it’, this year may still be a competitive tournament for bottom-level public chain projects. The reason is that public chains, as the infrastructure of blockchain, still have obvious deficiencies and cannot yet achieve true security, reliability, and efficiency. This also obviously restricts the development of the entire blockchain industry. What is a public chain?

　　Public chain is also known as ‘public chain’, and public chain refers to the blockchain that anyone in the world can read, send transactions, and have transactions confirmed effectively, and can also participate in the consensus process. According to the degree of centralization of the blockchain network, three different application scenarios of blockchain are differentiated:

　　1. Publicly available, without user authorization mechanisms, blockchain is known as a public chain;

　　2. Nodes authorized to join the network can view information according to their permissions and are often used in blockchain between institutions, known as consortium chains or industry chains;

　　3. All nodes in the network are controlled by a single institution, known as a private chain.

　　Expanded information:

　　According to the degree of centralization of the blockchain network, three different application scenarios of blockchain are differentiated:

　　(1) Publicly available, without user authorization mechanisms, blockchain is known as a public chain;

　　(2) Nodes authorized to join the network can view information according to their permissions and are often used in blockchain between institutions, known as consortium chains or industry chains;

　　(3) All nodes in the network are controlled by a single institution, known as a private chain.

　　Consortium chains and private chains are also collectively referred to as permission chains, while public chains are referred to as non-permission chains.

　　Reference source:百度百科 – Public Chain

　　The reason for the failure of blockchain connection verification

　　Strategy failure. The reason for the failure of blockchain connection verification is strategy failure. Blockchain (English: blockchain or blockchain) is an intelligent peer-to-peer network that identifies, disseminates, and records information using a distributed database. The problems of blockchain

　　Blockchain has its uses, but it is by no means omnipotent.

　　Blockchain mainly has two problems.

　　Blockchain cannot verify the authenticity of information outside the system. If the information uploaded to the blockchain is itself false, the anti-counterfeiting and anti-tampering capabilities of the blockchain are of no value. To ensure the authenticity of the uploaded information, an authoritative institution must be in charge. Since we trust the information uploaded by this authoritative institution, why should we be afraid of it tampering with the information? What difference does it make whether we use blockchain or not?

　　In the blockchain world, code is law, and the system can operate automatically. However, once interacting with the real world, the real world may not necessarily recognize the legality of the code. For example, if a contract is signed on the blockchain and is automatically executed upon expiration, transferring assets, but in reality, if there are defaulters who do not execute the asset transfer as per the blockchain contract, the contract becomes null and void, and the real-world court or other institutions need to take action.

　　The first practical application of blockchain, Bitcoin, has such a significant impact because it can circumvent the aforementioned two problems.

　　Bitcoin is a completely independent system, with all information generated internally within the Bitcoin system. It has the characteristics of closure and verifiability, and is not linked to any real-world assets, which allows it to be conveniently operated automatically through programs.

　　Bitcoin, being completely virtual and operated solely by programs and rules, is borderless, unregulated, and does not require currency exchange. It circulates freely, cannot be frozen or seized, is accessible to everyone, and does not suffer from inflation or over issuance. This is its advantage over fiat currency.

　　However, because Bitcoin operates completely based on fixed rules and programs automatically, there is no flexibility in the supply of Bitcoin. If private keys are stolen, property will be lost and cannot be recovered, which is also its drawback.

　　Similarly, in the real application of blockchain technology, if one really pursues code as law and private keys prove everything, if private keys are stolen, it will inevitably lead to asset loss that cannot be recovered. For example, if shares are mapped to the blockchain, what if a major shareholder loses his private key, and his shares will no longer be usable? This is also a problem that blockchain cannot avoid.

　　In summary, the real killer application of blockchain is actually cryptocurrency. Creating a blockchain without currency does not have such a disruptive effect, and it is necessary to be cautious about some scammers who use the blockchain as a pretext to defraud money and subsidies.

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　　Blockchain electronic invoice cannot receive a verification code

　　If you cannot receive a verification code because your mobile phone has installed an interception software, it is recommended that you remove the SMS interception of the application software or try a different mobile phone.

　　If you cannot receive a verification code or SMS due to your mobile phone being turned off, out of signal, unpaid, or suspended, it is recommended that you recharge and restart your mobile phone to try.

　　If you are using a mobile phone overseas or receiving an SMS verification code with an overseas mobile phone, it is recommended that if you are experiencing network delay, you can try to obtain it again later.

　　CAPTCHA (an automatic Turing test to distinguish computers from humans) is an abbreviation, a public automatic program to distinguish whether a user is a computer or a human. What does chainvalidationfailed mean in a can?

　　Chainvalidation is an information technology term, referring to blockchain verification. Chainvalidationfailed is a simplified form of chainvalidationisfailed, meaning blockchain verification failure.

　　The blockchain is a distributed ledger in which each block contains some transaction information. In the blockchain, each node has its own copy, and nodes maintain the consistency of the ledger through consensus algorithms. When conducting transactions, transactions must pass a series of verifications, including digital signature verification and transaction validity checks.

　　When a transaction fails to pass verification, it is considered invalid and rejected. This means that the sender of the transaction cannot record the transaction information on the blockchain, and the recipient cannot obtain the transaction information. If the sender wishes to resend the transaction information, it may be necessary to change the content of the transaction or resend it.

　　There may be multiple reasons for blockchain verification failure. For example, invalid digital signatures, incomplete transaction data, or duplicate transactions. In addition, since transactions on the blockchain must strictly follow coding rules, any illegal operation will be automatically rejected. It is crucial for transaction participants to be familiar with the blockchain verification process and ensure the accuracy of transaction information to avoid verification failure.