区块链 防篡改,区块链有什么技术,可以实现“防篡改”?

㈠ How is the security of blockchain? What are the risks of blockchain?

The hottest topic at the beginning of the new year is blockchain, but there are also Many people are skeptical about its security and risks. So what is the security of blockchain? What are the risks of blockchain? Below we will give you the answers one by one. I hope it will be helpful to you after reading them.
How is the security of blockchain Anyuan?
First of all, blockchain is a distributed database technology. Distributed technology mainly refers to storage architecture. The distributed architecture adopted by the blockchain not only stores the ledger data on each node, but also each node must contain the data of the entire ledger. This completely distributed architecture brings extremely high security, and no one can destroy all nodes at the same time.
Secondly, blockchain technology can achieve tamper resistance through "blocks" and "chains". The unit of data storage in the blockchain is the block. When each block is generated, it must contain the unique "characteristic value" of the previous block (which can be regarded as the ID card of the block). Each block is generated strictly according to the The order of time is lined up to form a "chain".
Security is a major feature of blockchain technology. However, from the perspective of privacy protection, the block chain emphasizes openness and transparency, and any node has the right to operate according to the consensus algorithm, so it is not suitable for scenarios where data privacy needs to be protected.
What are the risks of blockchain?
1. Technical risks: For example, the launch of Ethereum was once popular, but because it is a digital currency with smart contracts, it brings the risk of hacker attacks due to possible loopholes in smart contracts. THEDAO, the largest crowdfunding project in Ethereum, was hacked and lost more than $60 million.
2. Legal risks: The legality issues of digital currency issuance, notarization and confirmation of rights, and legality issues of proof, including legality issues of smart contracts, digital bills, accounting and liquidation, and equity crowdfunding, are currently in my country and The rest of the world is still legally blank.
3. Crime risks: Using digital currencies to abscond with the money, using digital currencies to launder money and illegal gambling, using smart contracts and digital bills designed to defraud profits, using blockchain technology to commit anonymous crimes, etc. Due to the current regulatory gap, there may be huge criminal risks.
The above is what the editor brings to you. How about the security of blockchain? What are the risks of blockchain? all content.

㈡ What is blockchain technology and how does it change business and financial models

What is blockchain technology and how does it change business and financial models? According to reports, since the end of March, the tour guide team led by Yang Feihu has been receiving inquiries from out-of-town individual tourists. "There are many families traveling to Wuhan from out of town. Several families come together by car or by high-speed rail," Yang Feihu said. , Yellow Crane Tower, Hubei Provincial Museum, and East Lake Scenic Area are still places to check in. "It's hard to get a ticket for the Hubei Provincial Museum now, and all the seats for the May Day period have been reserved." He and many people seeking the museum said.My parents went to Shuidun Town, Zijin County, Heyuan City. Because Zhang Weiping once confessed that this was the place where Aunt Mei lived, and it was also the place where 8 of the 9 abducted children in the "Aunt Mei Case" were sold.

㈢ What is blockchain technology? What is blockchain? A chained data structure composed of sequential connections, and a cryptographically guaranteed distributed ledger that cannot be tampered with or forged.

Broadly speaking, blockchain technology uses block chain data structures to verify and store data, uses distributed node consensus algorithms to generate and update data, and uses cryptography to ensure data transmission and access. It is a new distributed infrastructure and computing method that uses smart contracts composed of automated script codes to program and operate data securely.

[Infrastructure]

Generally speaking, the blockchain system consists of data layer, network layer, consensus layer, incentive layer, contract layer and application layer composition. Among them, the data layer encapsulates the underlying data blocks and related basic data and algorithms such as data encryption and timestamps; the network layer includes distributed networking mechanisms, data dissemination mechanisms, and data verification mechanisms; the consensus layer mainly encapsulates network nodes Various consensus algorithms; 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 encapsulates various scripts, algorithms and smart contracts, and is the core of the blockchain The basis of programmable features; the application layer encapsulates various application scenarios and cases of the blockchain. In this model, the chain block structure based on timestamps, the consensus mechanism of distributed nodes, economic incentives based on consensus computing power, and flexible programmable smart contracts are the most representative innovations of blockchain technology.

Extended information:

[Blockchain core technology]

Blockchain mainly solves the trust and security issues of transactions, so it addresses this issue Four technological innovations:

1. Distributed ledger means that transaction accounting is completed by multiple nodes distributed in different places, and each node records a complete account, so they all Can participate in supervising the legality of transactions and can also jointly testify for them.

The uniqueness of blockchain’s distributed storage is mainly reflected in two aspects: First, each node of the blockchain stores complete data according to the block chain structure. Traditional distributed storage generally stores The data is divided into multiple parts for storage according to certain rules. Second, the storage of each node in the blockchain is independent and of equal status, relying on the consensus mechanism to ensure storage consistency, while traditional distributed storage generally synchronizes data to other backup nodes through the central node.

No node can record ledger data independently, thus avoiding the possibility of a single bookkeeper being controlled or bribed to record false accounts. Also because there are enough accounting nodes, theoretically speaking, unless all nodes are destroyed, the accounts will not bewill be lost, thus ensuring the security of account data.

2. Asymmetric encryption and authorization technology. Transaction information stored on the blockchain is public, but account identity information is highly encrypted and can only be accessed with authorization from the data owner. , thus ensuring data security and personal privacy.

3. The consensus mechanism is how all accounting nodes reach a consensus to determine the validity of a record. This is both a means of identification and a means of preventing tampering. Blockchain proposes four different consensus mechanisms, which are suitable for different application scenarios and strike a balance between efficiency and security.

The consensus mechanism of the blockchain has the characteristics of "the minority obeys the majority" and "everyone is equal". "The minority obeys the majority" does not entirely refer to the number of nodes, but can also be the computing power and the number of shares. Or other characteristic quantities that the computer can compare. "Everyone is equal" means that when a node meets the conditions, all nodes have the right to give priority to the consensus result, which will be directly recognized by other nodes and may eventually become the final consensus result.

4. Smart contracts. Smart contracts are based on these trustworthy and non-tamperable data and can automatically execute some predefined rules and terms. Take insurance as an example. If everyone's information (including medical information and risk occurrence information) is true and trustworthy, it will be easy to automate claims settlement in some standardized insurance products.

In the daily business of insurance companies, although transactions are not as frequent as those in the banking and securities industries, the reliance on trusted data continues unabated. Therefore, the author believes that using blockchain technology from the perspective of data management can effectively help insurance companies improve their risk management capabilities. Specifically speaking, it is mainly divided into risk management of policyholders and risk supervision of insurance companies.

Blockchain-Network

㈣ Problems with Blockchain

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

There are two main problems with blockchain.

1 The blockchain cannot verify the authenticity of information outside the system. If the information uploaded to the blockchain itself is false, the anti-counterfeiting and anti-tampering of the blockchain will be worthless. To ensure that the uploaded information is authentic, there still needs to be an authoritative agency to check it. Since we all trust the information uploaded by this authoritative organization, why should we be afraid of it tampering with the information? What difference does it make if we use blockchain or not?

2 In the blockchain world, code is the law, and the system can run automatically. However, once it interacts with the real world, the real world may not necessarily agree with the law of the code. For example, a contract is signed on the blockchain and will be automatically executed when it expires and assets will be transferred. However, if there is a bad guy in reality who does not execute the real asset transfer in accordance with the contract on the blockchain, the contract will be a piece of paper. It is also necessary for the actual courts and other institutions to take action.

The first blockchain to be implementedThe reason why the application, Bitcoin, has such a huge influence is that it can avoid the above two problems.

Bitcoin is completely self-contained. All information is generated within the Bitcoin system and is closed and verifiable. Bitcoin is not linked to any real assets, so it can be easily passed through The program runs automatically.

Because Bitcoin is completely virtual and operates entirely on procedures and rules, it has no borders, is not subject to regulatory control, does not require exchange, circulates freely, cannot be frozen or confiscated, is available to everyone, and will not be over-issued or devalued. , which is its advantage over legal currency.

However, because Bitcoin completely relies on fixed rules and procedures to operate automatically, the supply of Bitcoin is inelastic. If the private key is stolen, the property will be lost and cannot be recovered. This is why it Shortcomings.

Similarly, when using blockchain technology in reality, if we really pursue that code is the law and the private key proves everything, if the private key is stolen, the assets will inevitably be lost and cannot be recovered. For example, if shares are mapped to the blockchain, is it possible that if a major shareholder loses his private key, all his shares will become unusable? This is also an unavoidable problem with blockchain.

In summary, the real killer application of blockchain is actually cryptocurrency. Developing a currency-less blockchain is not that disruptive, and we must be wary of some scammers using the banner of blockchain to defraud money and subsidies.

#digital currency# #BTC[超话]#

㈤ How to prevent tampering of the initial data of the blockchain

Data fraud, untrustworthy data, etc. The existence of the problem has brought serious challenges to many application scenarios such as financial supervision and risk control, and is also becoming a major obstacle to large-scale data interconnection and sharing. The issue of data authenticity and credibility has long affected all areas of society. In the era of artificial intelligence that relies more on data, this impact will be more prominent.

Data falsification may occur at any stage. Among them, falsification during data storage is often easier: because under existing data storage technology, the owner, manager or entrusted storage party of the data has the ability to unilaterally tamper with or delete the data at will.

Since an important reason for the untrustworthiness of data is that one party can tamper with and delete data without authorization, how to avoid this problem has naturally attracted a lot of attention in the industry. The birth of blockchain and decentralized storage technology has played a certain role in curbing data tampering, and has also achieved preliminary verification in the market.

Many companies are beginning to try to use blockchain to store data, such as in cargo traceability and other scenarios. The approach is often to write important data directly into the block. This simple and crude approach does solve the need to prevent data from being deleted, and then satisfies the trustworthy sharing of some data, but there are many problems:

First of all, it is unable to store massive data: within the blockIt is not suitable for storing big data including multimedia data, otherwise the block size will be difficult to control, making the scalability of the blockchain worse. This leads to the need to filter and select raw data in the business, and only select a small amount of necessary data to store in the block, but this will reduce the richness of trusted data.

The second is the low efficiency of data access: First, due to the existence of the packaging process, blockchain data storage is generally not used for high-speed data writing. Secondly, due to the traversal data reading method, the blockchain cannot support fast indexing, let alone SQL.

The data maintenance efficiency is low again: due to its sequential reference characteristics, the blockchain does not support the deletion and modification of individual historical data (unless the entire chain is regenerated, but this is not what the blockchain should do) encouraged behavior). It should be noted here: "Put an end to unilateral private tampering" and "No deletion at all" are two completely different things. The former is a technical means to ensure mutual trust, but the latter may be a loss of necessary function points.

Finally, there is the risk of data loss: this risk refers solely to the PoW blockchain system that adopts the longest chain principle of Satoshi Nakamoto consensus. In this type of blockchain, when a chain fork occurs, the longest (or heaviest) chain branch will be retained, and other branches will be discarded, which makes the data in the block actually exist forever and be "subverted" ”, the risk of being discarded. The existence of attacks such as selfish mining will exacerbate this risk. This is unacceptable in data storage applications.

It is precisely because of the above reasons that directly using traditional blockchain for data storage obviously cannot meet the needs for trusted data storage in a large number of practical scenarios. This issue has also triggered a lot of discussions, such as "what data should be stored on the chain and what data should be stored off the chain." The root cause of these problems is due to the limited storage efficiency and capabilities of the blockchain itself. After all, in the database era, we never talk about "what data should be stored outside the database".

In recent years, some products have also appeared, providing useful practices to solve the above-mentioned inefficiency problem of blockchain data storage, such as:

Interplanetary File System IPFS, R3’s Corda , Tencent TrustSQL, etc. However, these products still have more or less problems in the trusted storage of data. Specifically:

IPFS generates a hash summary of the data content and performs distributed storage among multiple nodes. A single The holder does not have complete data, thus protecting data privacy to a certain extent. However, IPFS can only be modified and known (because the hash value will change due to content changes), and there are no data security measures such as access control. Overall, it is still difficult to meet the needs of enterprise-level services.

Corda is a storage product tailored for the privacy needs of financial transactions, focusing on the privacy of data storage. For this reason, Corda does not have a global ledger and requires the existence of witnesses. It is a private but not secure and trustworthy data storage solution.

TrustSQL and other similar domestic products adopt a simple and intuitive design idea, which is currently the most common practice in China, that is, first store the data in the database (or IPFS), and then store the operation records, data hashes, etc. on the chain. . Compared with TrustSQL, some similar products such as Zhongxianbit’s ChainSQL have further improved their support for SQL. This type of product meets the needs of "auditable" and "transparent supervision" of data, but the disadvantage is that it still cannot prevent the deletion and modification of the data itself, but can only make the "deletion and modification visible"; in addition, the preservation of key data requires participation. The storage cost of full copy storage of nodes is slightly higher. And the design in terms of data privacy is still insufficient.

In view of the shortcomings in the above products, Wuyuan Technology has explored a different path through original technological innovation and launched an independent intellectual property product "ImSQL", aiming to provide a method that can truly ensure data integrity. Trusted storage products that have been tampered with or deleted without permission.

ImSQL (Immutable SQL Database) is a new type of trusted data storage solution based on blockchain and distributed storage technology, and perfectly solves the problem of "preventing private deletion" and "protecting data privacy" , "reducing storage costs" and other core issues provide a reliable technical path for trusted storage and data sharing in the big data era.

Compared with existing products, ImSQL has the following outstanding advantages:

1. Completely prevent unilateral unauthorized tampering and deletion of data. By conducting multi-party verification in both storage and retrieval processes and preventing tampering and deletion during the storage process, the authenticity and credibility of the data are fully guaranteed, so that participants in the application can trust each other and adopt other parties' data with confidence, so that the data can Support accurate traceability and accountability.

2. Eliminate single points of failure. While multiple parties share data, they also jointly maintain the data. The data does not only exist in one party, and fundamentally realizes a trusted sharing pool of distributed data, which not only avoids the risk of single point failure, but also improves the efficiency of data sharing.

3. Fragmented storage meets data privacy requirements and prevents any party from mastering complete data, thus solving the data privacy issues that exist in traditional cloud computing’s centralized storage or blockchain full copy storage. Complete data is not available to any storage custodian other than the data owner.

4． Excellent data access performance: ImSQL can achieve a writing speed of 3,000 TPS and a reading speed of 10,000 QPS on a single node. In addition, ImSQL also has the following advantages: supports SQL language, can be horizontally expanded, has excellent access performance and user experience, and can make full use of cluster expansion to further increase the above indicators several times.

5. It meets the efficient access requirements for big data such as multimedia, supports efficient access, efficient indexing, and efficient expansion, and is truly competent in big data business scenarios. It can achieve both trustworthy and efficient storage of video and other data, thereby providing video surveillance and other services.The scene provides an unprecedented trustworthy security experience.

6. The adoption of a sharded design greatly reduces the storage pressure and cost of each storage participant, giving more participants the opportunity to join and participate in the ecosystem of trusted data sharing.

7. Distributed architecture, compatible with light nodes, encourages more nodes to participate. There are no super nodes, and the nodes participating in storage have the same status, which better ensures the reliability and invulnerability of the system. In addition, if a node chooses to run in light copy mode, it can only store part of the data, greatly reducing its own storage pressure. Although its obligations are reduced, its power will not be affected in any way.

ImSQL takes into account database attributes such as massive storage, fast indexing, and horizontal expansion, as well as the blockchain characteristics of data being stored and solidified. It is expected to be used in many fields that focus on trusted data storage and sharing. It brings unprecedented user experience and convenience, such as: realizing the interoperability and mutual trust of data from all parties in the supply chain, realizing the interconnection and interoperability of data between various departments of the government or large enterprises, and supporting the storage of massive data related to trusted traceability, etc.

Take government big data construction as an example. Achieving efficient data interconnection among the many different government departments and entities has always been a difficult problem. The current practice often requires the establishment of an independent big data department and an independent data storage system, which pulls relevant data from different entities, analyzes it, reconstructs it, and then visualizes it. This often brings about large upfront expenses, including explicit expenses such as people, finances, and materials, as well as implicit expenses such as staffing, rights, responsibilities, interests, time costs, and department walls. At the same time, the existence of an independent big data department also implies the need for a trusted third party to endorse or even assume responsibility. If ImSQL is used as the underlying platform for data interoperability in this scenario, this task can be completed more efficiently, as shown in:

There is no need to rely on third-party entity endorsement: data between different entities can be Write directly to ImSQL, and the data will be preserved as soon as it is written. The data can no longer be tampered with or deleted privately by any party, ensuring the availability, consistency and credibility of the data when other entities access it at any time;

No need to Establish and maintain additional data storage systems: Data is jointly stored and maintained by all participating entities. It is naturally shared and connected, which reduces system implementation and maintenance costs without reducing usage efficiency. At the same time, ImSQL's data fragmentation storage technology can realize data sharing while also taking into account privacy protection. That is, the data stored by all entities can be incomplete fragments, and only those entities with access rights can search for fragmented data. , keys to combination and interpretation.

In summary, as a reliable and tamper-proof data storage technology, ImSQL fully inherits the advantages of blockchain data preservation, and breaks through the efficiency weaknesses of blockchain, providing a Users are provided with the same efficient data access experience as the database. ImSQL is a new category created by the combination of blockchain and database technology, and it is the best choice to achieve trusted data storage.

㈥ Blockchain: DefenseTampered Hash Encryption Algorithm

Students A and B toss a coin in the classroom and bet on who will clean the house. If it comes up heads, then A will clean; if it lands tails, then B will clean. There is nothing wrong with this strategy.

However, if the scenario is transferred to an online chat room, and A and B also play a coin-tossing game, B will probably not agree, because when A tosses a coin, B will not guess.

Heads or tails, A can say that B guessed wrong.

How to solve this problem? How about encrypting the result of the coin toss first, and then B guesses? You can try this method.

Assume that any odd number represents the front side of the coin, and any even number represents the tail side. A wants a number 375, then multiplies it by 258, tells B the result is 96750, and declares that the 375 A wants is the key, which he keeps for safekeeping.
When verifying the result next, A can lie and claim that 258 is the number he wants and 375 is the key, and A is still invincible. What if A tells B the key in advance? B can directly calculate the original number, losing the confidentiality function.

This method of knowing the encryption method and knowing the decryption method obviously does not work. Is there a way to know the encryption method and still not be able to recover the original text?

Obviously there is, it is OK to add irreversible operations to the encryption process. A designs a new encryption method:

Assume that the number A wants is 375 and encrypts it:

B gets the result 120943, but he can hardly calculate the key 375 based on 120943.
If B wants to verify whether A is lying:

Finally, he can flip a coin...

This encryption method that loses part of the information is called "one-way encryption". Also called hash algorithm.

There is a problem:

This is possible, but it can be solved by increasing the difficulty of the above algorithm so that A is difficult to find.

According to the above statement, a reliable hash algorithm should satisfy:

The hash function in cryptography has three important properties, namely collision resistance and irreversibility of the preimage. , problem friendliness.

Collision means that student A can find out an odd and an even number in advance to make the hash results consistent, which is computationally infeasible.

First of all, if the news about the large space sauna is compressed into a small space, there will definitely be a collision. Assume that the length of the hash value is fixed to 256 bits. If the order is 1, 2,...2 256 + 1, these 2 256 + 1 input values, and the hash values ​​are calculated one by one, you will definitely be able to find two input values ​​that make the hash The values ​​are the same.

Student A, when you see this, please don’t be too happy too early. Because you have to have time to figure it out before it's yours. Why do you say that?

According to the birthday paradox, if 2 130 +1 inputs are randomly selected, there is a 99.8% probability of finding at least one pair of collision inputs. Then for a hash function with a hash value length of 256 bits, an average of 2128 hash calculations need to be completed to find the collision pair. If a computer performed 10,000 hash calculations per second, it would take approximately 10 27 years to complete 2 128 hash calculations.

Student A, don’t think about cheating. You probably won’t live this long. Of course, it is possible if computer computing power is greatly improved.

So what other uses does integrity have?

Used to verify the integrity of the information, because if the information is not tampered with during transmission, the hash value obtained by running the hash calculation will be different from the original hash value.

Therefore, in the blockchain, the collision resistance of the hash function can be used to verify the integrity of blocks and transactions.

Because a hash value corresponds to countless plaintexts, theoretically you don't know which one it is. For example, the results of 4+5=9 and 2+7=9 are the same. I know that the result I entered is 9, but can I know what number I entered?

If, when performing hash calculation on message m, a random prefix r is introduced, and based on the hash value H(r||m), it is difficult to recover message m, which means that the hash function The value hides message m.

Therefore, student B, it is impossible to deduce the original data based on the results. It is like finding a needle in a haystack.

Problem friendliness means that there is no convenient way to generate a hash value that meets special requirements. What does it mean? In layman's terms, there is no shortcut, you need to figure it out step by step. If the required hash result starts with several 0s, then the number of hash calculations required to find the hash value where the first 3 digits are all 0 and the hash value where the first 6 digits are all 0 is calculated. Quantitative relationship.

How can this be used? In the blockchain, it can be used as proof of work in the consensus algorithm.

Mainly describes three important properties of the hash function: collision resistance, preimage irreversibility, and problem friendliness.

Because of these important properties, functions such as integrity verification of blocks and transactions in the blockchain and workload proof of the consensus algorithm are implemented using hash functions.

[1]. Zou Jun, Zhang Haining. Blockchain Technology Guide [M]. Beijing: Mechanical Press, 2016.11
[2]. Chang Chai, Han Feng. Blockchain From digital currency to credit society [M]. Beijing: CITIC Press, 2016.7
[3]. Zhang Jian. Blockchain defines the new future financial and economic landscape [M]. Beijing: Machinery Industry Press, 2016.6

㈦ What are the core blockchain technologies of blockchain technology?

What is the hottest Internet topic at the moment? You don’t need to tell me that it is blockchain technology. However, many friends have only heard of this technology and do not have too much in-depth understanding of it. So blockchain What are the 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 the second), random number (recording the value of decrypting the answer to the math question related to the block), the target hash value of the current block, and the 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 the transaction information in a block, and finally generates a unified hash value of all the transaction information in the block. Any change in the transaction information in the block willCauses 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 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 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) 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 programmable features to the ledger
Core technology 8. Smart contract:
Smart contract isA set of scenario-responsive programmed rules and logic is implemented through decentralized, trustworthy and 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.

Is blockchain reliable?

With the development of the times, many science and technologies are now used in people’s lives, and blockchain is used in a very wide range of applications. As an Internet technology, the purpose of blockchain is to verify the validity of information, so it has an anti-counterfeiting function. Blockchain is a combination of many data blocks in a chain structure in time order to maintain the reliability of the database. The application fields of blockchain are also relatively wide, and are often used in finance, the Internet, insurance, and some public welfare fields. Blockchain is divided into public and private. Its biggest features are high transparency, decentralization and collective maintenance. Because it is used too widely, many people have doubts about blockchain in daily life. I don’t know. Is it reliable?

Generally speaking, blockchain technology is not a scam. It is reliable, but it also has certain disadvantages. Blockchain technology can have great benefits if applied in legal fields, but once it goes astray and is introduced into illegal fields, it will have very serious consequences.