At present, there are several sections of blockchain

3. Blockchain mainly solves the trust and security problems of transactions, so it proposes four technological innovations to solve this problem:
(1) distributed ledger, that is, transaction bookkeeping is completed by multiple nodes distributed in different places, and each node records complete accounts, so they can participate in monitoring the legitimacy of transactions, At the same time, they can testify together
different from traditional distributed storage, the uniqueness of distributed storage of blockchain is mainly reflected in two aspects: one is that each node of blockchain stores complete data according to block chain structure, while traditional distributed storage generally stores data in multiple copies according to certain rules. Second, the storage of each node in the blockchain is independent and has the same status, which relies on the consensus mechanism to ensure the consistency of storage, while the traditional distributed storage generally synchronizes data from the central node to other backup nodes[ 8]
no single node can record the account data separately, so as to avoid the possibility that a single bookkeeper is controlled or bribed to record false accounts. In theory, unless all the nodes are destroyed, the accounts will not be lost, so as to ensure the security of the account data
(2) asymmetric encryption and authorization technology, the transaction information stored on the blockchain is public, but the account identity information is highly encrypted, which can only be accessed under the authorization of the data owner, thus ensuring the data security and personal privacy
(3) consensus mechanism is how to reach a consensus among all accounting nodes to determine the validity of a record, which is not only a means of identification, but also a means of preventing tampering. Blockchain proposes four different consensus mechanisms, which are suitable for different application scenarios and achieve a balance between efficiency and security
the consensus mechanism of blockchain has the characteristics of "the minority is subordinate to the majority" and "everyone is equal", in which "the minority is subordinate to the majority" does not completely refer to the number of nodes, but also can be the computing power, the number of shares or other characteristics that can be compared by computers“ "Everyone is equal" means that when the nodes meet the conditions, all nodes have the right to put forward the consensus results first, and then directly recognized by other nodes, and finally may become the final consensus results. Taking bitcoin as an example, the workload proof is adopted. Only when more than 51% of the accounting nodes in the whole network are controlled can a nonexistent record be forged. When there are enough nodes in the blockchain, this is basically impossible, thus eliminating the possibility of fraud.
(4) smart contract, which is based on these trusted and tamperable data, can automatically execute some pre-defined rules and terms. Take insurance as an example. If everyone's information (including medical information and risk occurrence information) is true and reliable, it is easy to carry out automatic claim settlement in some standardized insurance procts

4. 1. Public chain, no official organization and management organization, no central server, participating nodes freely access to the network according to the system rules, not controlled, and work based on consensus mechanism among nodes Subversive: absolutely credible and open) < br > typical case: digital currency represents bitcoin < br > 2. The private chain is built within a group. The operation rules of the system are set according to the requirements of the group, and the modification or read permissions are limited to some extent, while maintaining the authenticity and partial decentralization of the blockchain Typical case: R3 < br > 3. Alliance chain, jointly initiated by several institutions, is between the public chain and the private chain, and has the characteristics of partial decentralization. The read permission on the fast chain in this area may be public or partially public, that is to say, multiple pre selected nodes are designated as bookkeepers internally, and the pre selected nodes compete for bookkeeping permission, Other access nodes can participate in the transaction, but not the accounting process The abilities of the candidates should not be uneven< Br > (relatively credible and open) < br > existing cases: Super ledger < br > example:? In the case of loan diversion, when the user jumps to the other party's website for registration through our link, the docking party can choose to cheat and say that it has not received the user's registration request. However, if we put the user registration behavior into the block, if the docking party wants to receive the user registration behavior, it must pay us at the same time.

5. Currently known blockchain technology classification, jinwowo Group believes that it can be roughly divided into three categories:
1 - public blockchain: refers to the blockchain that anyone can read, send transactions for validity confirmation, and anyone can participate in its consensus process, so as to jointly maintain the security, transparency and tamper proof of public blockchain data
2-community blockchain: also known as alliance chain, it means that the nodes participating in the blockchain are selected in advance, and there are usually good network connections and other cooperative relationships between the nodes
3-private blockchain: the participating nodes only have a limited range, the access and use of data have strict permission management, the write permission is only in the hands of the participants, and the read permission can be opened to the outside world.

6. A new resolution initiated by representative Adam kinzinger, a Republican from Indiana, has been submitted to the US House of Representatives, calling on the government to formulate national policies on emerging technologies, including digital currency and blockchain technology
the resolution calls on the idea of bitcoin, but does not directly mention its name. Instead, it calls it "alternative illegal currency". Blockchain technology is the key point, which points out that this technology has the potential to "fundamentally change" the way trust and security are built on online transactions
but in fact, the United States has not taken action to formulate this rule. However, there is a global blockchain alliance R3 in the process of formulating the standard for the use of blockchain. Of course, blockchain is just a technology that can be used by any enterprise. In China, there is a project called decent, which is more avant-garde. It uses blockchain technology to build a decentralized content publishing platform, but it may encounter some problems in China.

7. Blockchain is a kind of technology, which can accelerate the instrial upgrading and open up the upstream and downstream of the instry. Anyone can do it.