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⑴ What is the main chain?

It can be understood as an officially launched, independent blockchain network; the side chain is not. It does not refer to a specific blockchain, but is a collective name for all blockchains that comply with the side chain protocol.

⑵ What are side chains and main chains in blockchain?

Main chain: that is, an officially launched, independent blockchain network. It can be said that the entity that stores data in the blockchain is generally considered to be the main chain network itself. For example, BTC mainnet, ETH mainnet and EOS mainnet are all main chains.

Sidechain: First of all, the essence of the sidechain protocol is a cross-blockchain solution. Simply put, this solution allows data information to be transferred between two blockchains. Sidechains were originally proposed to enable the transfer of Bitcoin and other digital assets between multiple blockchains.

In layman’s terms, side chains are like pathways that connect different blockchains to each other to achieve the expansion of the blockchain. The side chain is completely independent of the main chain, but the two ledgers can "interoperate" and achieve interaction.

Sidechain protocol - Sidechain protocol refers to (taking Bitcoin as an example): it allows Bitcoin to be safely transferred from the Bitcoin main chain to other blockchains, and from other blockchains A protocol for securely returning to the Bitcoin main chain. The same goes for exchanging Bitcoin for Ethereum or other blockchains. So, why do we need side chains, or what are the benefits of side chains?

The functions that the main chain lacks are provided by the side chain.

For example, the Bitcoin network does not have the function of smart contracts, but this function can be realized through side chains.

If the operation efficiency of the main chain is low, some functions of the main chain can be transferred to the side chain for implementation.

For example, the transfer speed of the main chain is very slow and there is no way to meet daily payment needs. We can develop the Lightning Network as a side chain to meet daily payments. Also due to low performance, Ethereum cannot support large-scale commercial-level DAPPs (decentralized applications), which can be achieved through side-chain development.

If you put aside the technical rigor, you can use another simpler way to understand the side chain. All networks that provide support or services for the original main network can be called side chains. No need to Care about whether this side chain uses blockchain technology. For example:

Third-party payment network (Alipay/WeChat), you can think of the bank network as the main chain, and third-party payment is a side chain.

Cryptocurrency trading considers free networks such as Bitcoin and other virtual currencies as the main chain, and the exchange can be regarded as a side chain.

RSK and Loom are separately developed side chains for the Bitcoin and Ethereum main chains respectively.

In the first application, the main chain and side chains are centralized

In the second application, the main chain is decentralized.The side chain is centralized

The third application is that the main chain is decentralized and the side chain is also decentralized. With the deepening of blockchain technology, we can see that human beings Value exchange activities will slowly transition from the first application to the third application.

The Xueshuo Innovation Blockchain Technology Workstation under Lianqiao Education Online is a school planning and construction development project of the Ministry of Education of China. The "Smart Learning Workshop 2020-Master's Degree Innovation Workstation" launched by the center is the only approved "blockchain technology professional" pilot workstation. The professional base is based on providing students with diversified growth paths, promoting the reform of the training model integrating professional degree research, production, and research, and building an applied and compound talent training system.

⑶ Common blockchain cross-chain technologies

Common blockchain cross-chain technologies include: 1. Ripple Interledger protocol. 2. Side-chain technology BTCRelay. 3. Relay technology Polkadot and COSMOSPolkadotCOSMOS; 4 hash locking technology Lightingnetwork.5 distributed private key control technology WanChain. Among the many problems faced by blockchain, the interoperability between blockchains greatly limits the application space of blockchain. Regardless of whether it is a public chain or a private chain, cross-chain technology is the key to realizing the Internet of Value. It is a good medicine to save the blockchain from scattered islands and a bridge for the blockchain to expand and connect outwards.

⑷ What are the core blockchain technologies of blockchain technology?

What is the hottest Internet topic at the moment? You don’t need to explain it to the editor to know that it is the blockchain. Blockchain technology, but many friends have only heard of this technology and do not have much in-depth understanding of it. 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 decryption of the block)The value of the answer to the block-related math question), the target hash value of the current block, the root value of the Merkle number 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 ultimately generates a unified hash value of all transaction information in the block. Any change in transaction information in the block will cause Merkle tree changes.
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 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:
The consensus mechanism is all accounting nodesHow to reach a consensus among account nodes to determine 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 longest chain age has a greater chance of obtaining 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) to solve non-Byzantine problems, detailed algorithmThe text does not explain. 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 contract:
Smart contract is a set of programmed rules and logic that respond to scenarios. Implemented by decentralized, trusted shared script code 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 introduced to the core technology of blockchain.

⑸ What are the classifications of blockchain and what is the structure of the blockchain?

The concept of blockchain has been quite popular recently. It comes from Bitcoin and so on. The implementation of cryptocurrency, but this technology has been gradually used in various fields. So do you know what the classifications of blockchain are? What is the structure of blockchain? Let’s follow us to find out more.
What are the classifications of blockchain?
1. Public Blockchains (PublicBlockChains)
Public blockchain refers to: any individual or group in the world can send transactions, and the transactions can be obtainedValid confirmation of this blockchain, anyone can participate in its consensus process. The public blockchain is the earliest blockchain, and it is also the most widely used blockchain at present. The virtual digital currencies of all major bitcoins series are based on the public blockchain. There is one and only one corresponding to this currency in the world. Blockchain.
2. Consortium (Industry) Blockchain (ConsortiumBlockChains)
Industry Blockchain: Multiple preselected nodes are designated within a certain group as bookkeepers, and the generation of each block is jointly performed by all preselected nodes. Decision (pre-selected nodes participate in the consensus process), other access nodes can participate in transactions, but do not participate in the accounting process (essentially still managed accounting, but become distributed accounting, how many slag points are pre-selected, how to decide each The bookkeeper of each block becomes the main risk point of the blockchain), and anyone else can conduct limited queries through the open API of the blockchain.
3. Private Blockchain (privateBlockChains)
Private Blockchain: Only uses the general ledger technology of the blockchain for accounting. It can be a company or an individual, and has exclusive access to the writing of the blockchain. With access permissions, this chain is not much different from other distributed storage solutions. At present (Dec2015), conservative giants (traditional finance) want to experiment with private blockchains, while public chain applications such as Bitcoin have been industrialized, and private chain application products are still being explored.
4. Sidechain (Sidechain)
Sidechain is a blockchain used to confirm data from other blockchains. Through the two-way peg (TwoWayPeg) mechanism, various assets such as Bitcoin and Ripple coins can be Transfers are realized on different blockchains at a certain exchange rate.
What is the structure of blockchain?
1. Basic network layer: The basic network layer consists of a data layer and a network layer. The data layer includes underlying data blocks and related data encryption and timestamp technologies; the network layer includes distributed networking mechanisms, Data dissemination mechanism and data verification mechanism, etc.
2. Intermediate protocol layer: The intermediate protocol layer consists of a consensus layer, an incentive layer, and a contract layer. The consensus layer mainly includes various consensus algorithms of network nodes; the incentive layer integrates economic factors into the blockchain technology system. , mainly including the issuance mechanism and distribution mechanism of economic incentives; the contract layer mainly includes various scripts, algorithms and smart contracts, which is the basis of the programmable features of the blockchain.
3. Extension layer: This layer is similar to a computer driver and is designed to make blockchain products more practical. There are currently two categories. One is various trading markets, which are important channels for exchanging fiat currencies for cryptocurrency. They are simple to implement, get money quickly, and have low costs, but the risks are also high. The second is the expansion implementation in a certain direction. For example, based on the Yishu side chain, it can provide customized services for third-party publishing organizations, forum websites and other content producers.
4. Application service layer: As the most important link in the blockchain industry chain, the application service layer includes various application scenarios and cases of blockchain.Including programmable currency, programmable finance and programmable society.
The above are the blockchain classifications brought to you by the editor? What is the structure of blockchain? all content.

⑹ Chain classification of blockchain

Two days ago, a friend asked a lot of questions about blockchain on WeChat. One of the questions is what is the chain of blockchain? Go to categories. Blockchain can currently be divided into four categories: public chain, private chain, alliance chain and side chain. Beijing Muqi Mobile Technology Co., Ltd., a professional blockchain outsourcing development company, welcomes discussions for cooperation. The following will help you understand the characteristics of these blockchain chains and how to apply them. I hope it will be helpful to you.

1. Public chain - everyone can participate

Public chain means that anyone can read it, anyone can send transactions, and transactions can be effectively confirmed A blockchain in which anyone can participate in the consensus process.

The public chain adopts the proof-of-work mechanism (POW), proof-of-stake mechanism (POS), and share authorization proof mechanism (DPOS), and combines economic rewards and encrypted digital verification. And establish a principle that the economic rewards that each person can obtain are proportional to the workload. These blockchains are often considered to be completely decentralized.

Features:

1. Open source, because the operating 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 the public domain Program developers in the chain have no right to interfere with users, so the blockchain can protect users who use the programs they develop; 3. The access threshold is low and anyone with sufficient technical capabilities can access it, that is, as long as there is a computer that can connect to the Internet Computers can meet the access conditions; 4. All data is public by default, although all associated participants hide their true identities. This phenomenon is very common. They generate their own security through their public nature, where every participant can see all account balances and all their transaction activity.

Case: There are many familiar figures in the public chain: BTC, ETH, EOS, AE, ADA, etc.

2. Private chain - rights are in the hands of a few people

A private chain refers to a blockchain whose write permission is only in the hands of one organization. Read permissions are either open to the public or arbitrarily restricted. Relevant applications include database management, auditing, and even a company. Although in some cases it is desirable to have public auditability, in many cases public readability is not necessary.

Features:

1. Fast transaction speed. The transaction speed of a private chain can be faster than any other blockchain, or even close toIt is not the speed of a regular database that is a blockchain. This is because even a small number of nodes have a high degree of trust, and each node does not need to verify a transaction. 2. Good privacy, giving better privacy protection The private chain makes the data privacy policy on that blockchain exactly the same as in another database; there is no need to deal with access permissions and use all the old methods, but at least it says , this data is not publicly available to anyone with an internet connection. 3. Low transaction costs. Transaction costs are significantly reduced or even zero. Transactions can be carried out completely free or at least very cheaply on the private chain. If one entity controlled and processed all transactions, they would no longer need to charge fees for their work.

Case: The Linux Foundation, R3CEV Corda platform, and Gem Health network’s Hyperledger project are either developing or using private chains.

3. Alliance chain - partial decentralization

The degree of openness and decentralization of the alliance chain is limited. The participants are screened out in advance or designated directly. The read permission of the database may be public, or it may be limited to the participants of the system like the write permission.

Features:

1. Low transaction costs, transactions only need to be verified by a few trusted high-computing nodes without the need for confirmation by the entire network; 2. Nodes Easy to connect, if something goes wrong, the consortium chain can be quickly repaired through manual intervention, and allows the use of consensus algorithms to reduce block times, thereby completing transactions faster; 3. Flexible, if necessary, run a private blockchain community or Companies can easily modify the rules of this blockchain, revert transactions, modify balances, etc.

Case: Ripple has established an alliance chain for international remittances between Japan and South Korea and inter-bank remittances in Japan. At the same time, Xunlei Link, which has been popular for a while, is also a semi-open alliance chain.

4. Side chain - extended protocol

Strictly speaking, "side chain" is not a blockchain itself, but can be understood as an extension of the blockchain. Protocol. The early "side chain" was to solve the limitations of Bitcoin blockchain technology. Side chains are like pathways that connect different blockchains to each other to achieve the expansion of the blockchain. Side chains Completely independent of the Bitcoin blockchain, but the two ledgers can "interoperate" and interact.

Features:

1. Independence, side chain The advantage of the architecture is that the code and data are independent, which does not increase the burden on the main chain and avoid excessive data expansion. The side chain has an independent blockchain, an independent trustee or witness, and an independent node network, that is, a Blocks generated by side chainsBroadcasting will only occur between all nodes that have the sidechain installed. 2. Flexibility. All blockchain parameters of the side chain can be customized, such as block intervals, block rewards, transaction fee destinations, etc. Advanced users can also modify the consensus algorithm.

Case: LSK, RDN, ARDR and other currencies use side chain technology.

For the current entire digital currency field, this year may still be a competition for the underlying public chain projects. The reason is that the current public chain as the infrastructure of the blockchain still has obvious shortcomings and is still unable to be realized. Truly safe, reliable and efficient. This also obviously restricts the development of the entire blockchain industry.

⑺ What is the relationship between the side chain and the main chain?

The side chain is another blockchain outside the main chain, anchoring a certain node in the main chain. The computing power is used to maintain the authenticity of the side chain and realize the transfer of the value on the public blockchain and the value on other account books in multiple blockchains. The most representative implementation is Blocksteam. The main chain in this blockchain architecture where the main chain and side chain cooperate is sometimes called the parent chain (Parentchain)

⑻ The difference between the main chain and side chain in the blockchain

According to the degree of independence of the blockchain network, it is divided into two types: main chain and side chain. The difference between the two is as follows:

1. The main chain refers to a blockchain network that is officially online and can operate independently. The main chain is also called the main network and the mother chain. Simply put, it is the mother of all chains. The chain that can generate chains is called the parent chain.

2. Compared with the concept of the main chain, the side chain can be called a side chain as long as it abides by the side chain protocol and anchors a node on the main chain.

There is a cooperative relationship between the main chain and the side chain. The main chain is like the larger gear in a bicycle. It is an independent blockchain network that does not require power from other gears and can turn on its own.

⑼ What are the blockchain technologies?

The concept of blockchain can be said to be very popular. At the Internet Finance Summit, no one said anything about blockchain Chain technology is out. What is blockchain technology?

Blockchain technology can be either a public classification (anyone can see it) or a permissioned network (only permissioned people can see it), solving supply chain challenges. Because it is An immutable record, so it is shared among network participants and updated in real time.

Blockchain technology - data layer: Designing the data structure of the account book

Core technology 1. Block_ _;Chain:

Technically, a block is a data structure that records transactions, reflecting the capital flow of the transaction. The transaction blocks that have been reached in the system are connected to form the main chain, and all nodes participating in the calculation are It records the main chain or a part of the main chain.

Each block is composed 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 transaction quantity and transaction details. BlockThe header includes the current version number, the previous block address, a timestamp (recording the time when the block was generated, accurate to seconds), a random number (recording the answer value to the mathematical problem related to decrypting the block), the target hash value of the current block, Information such as the root value of the Merkle number source. From a structural point of view, most functions of the blockchain are implemented by the block header.

Core technology 2. Hash function:

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The hash function can convert data of any length from the Hash algorithm to a fixed-length code. The principle is a one-way hash function based on cryptography. This function is easy to verify, but difficult to interpret. The industry usually Expressed in the form of y=hash(x), this hash function implements the hash value y of the operation x.

Commonly used hash algorithms include MD5, SHA-1, SHA-256, SHA- 384, SHA-512, etc. Taking the SHA256 algorithm as an example, input any data into SHA256 and you will get a 256-bit Hash value (hash value). Its characteristics: the same data input will get the same result. The input data changes a little (for example , 1 becomes 0) will get completely different results, the results are measured. The forward calculation (the Hash value corresponding to the data calculation) is very simple. The reverse calculation is extremely difficult and is considered impossible under the current scientific and technological conditions.

Core technology 3. Merkle tree:

Merkle tree is a hash binary tree that can quickly verify the integrity of large-scale data. In the blockchain network, Merkle_黄髂jumimifu The sculls and weapons are the erkle trees.

Core technology 4. Asymmetric encryption algorithm:

Asymmetric encryption algorithm is a key confidentiality method that requires a key and a key. The public key and the private key are a pair. If you use the public key to encrypt data, you can only use the corresponding key. Decrypt the private key to obtain the corresponding data value. If you use the private key to sign the data, you can only use the corresponding public key to verify the signature. The sender of the verification information is the owner of the private key.

Due to encryption and decryption Using two different keys, the algorithm is called an asymmetric encryption algorithm, while symmetric encryption uses the same key in the encryption and decryption processes.

Blockchain Mitigation Technology - Network Layer: Implementing Charging Centralization of nodes

Core technology 5, P2P network:

P2P network (peer-to-peer network), also known as point-to-point technology, is an Internet system without a central server and user groups exchanging information . Different from the central network system with a central server, each client of the peer-to-peer network is a node and also has the function of a server. Domestic Xunlei software uses P2P technology. The P2P network has the characteristics of centralization and reinforcement.

< p>Blockchain technology - consensus layer: allocate the task load of charging nodes

⑽ The difference between main chain and side chain in blockchain

Usually blockchain, especially public chain Both have mainnet and testTest network. The main network is a trusted blockchain network recognized by the blockchain community, and its transaction information is recognized by all members. Valid blocks will be appended to the main network's block ledger after consensus on the blockchain network.
Many people don’t understand what sidechains are. This concept comes from the Bitcoin community and was proposed in December 2013. There are some questions about whether its birth is due to Bitcoin itself or the mechanism of a certain blockchain. But if you modify it directly on the Bitcoin protocol or chain, it is easy to make mistakes. And because Bitcoin blocks are constantly being operated, if something goes wrong, the amount of funds involved will be huge, and this is not allowed.
Sidechains actually do not refer to a specific blockchain, but all blockchains that comply with the sidechain protocol. This term is relative to the main chain of Bitcoin.
For more information browse what are sidechains