What is blockchain? Blockchain Technology
Blockchain is an important concept of bitcoin. It is essentially a disintermediated database. At the same time, as the underlying technology of bitcoin, it is a series of data blocks generated by using cryptographic methods. Each data block contains the information of a bitcoin network transaction, which is used to verify the effectiveness of its information (anti-counterfeiting) and generate the next block
blockchain is a new application mode of distributed data storage, point-to-point transmission, consensus mechanism, encryption algorithm and other computer technologies
in a narrow sense, blockchain is a kind of chain data structure that combines data blocks in a sequential way according to the time sequence, and it can not be tampered with and forged by cryptography
broadly speaking, blockchain technology uses blockchain data structure to verify and store data, uses distributed node consensus algorithm to generate and update data, and uses cryptography to ensure the security of data transmission and access It is a new distributed infrastructure and computing method to program and operate data by using intelligent contract composed of automated script code
extended data:
the evolution mode of blockchain is as follows:
& 9642; Blockchain 1.0 - digital currency
▪ Blockchain 2.0 - digital assets and smart contracts
▪ Blockchain 3.0 - Implementation of distributed applications in various instries
blockchain features:
1. Disintermediation. Due to the use of Distributed Accounting and storage, there is no centralized hardware or management organization in the system, the rights and obligations of any node are equal, and the data blocks in the system are jointly maintained by the nodes with maintenance function in the whole system
2. Openness. The system is open. In addition to the private information of all parties to the transaction is encrypted, the data of the blockchain is open to all. Anyone can query the blockchain data and develop related applications through the open interface, so the information of the whole system is highly transparent
3. Autonomy. Blockchain adopts consensus based specifications and Protocols (such as a set of open and transparent algorithms) to enable all nodes in the whole system to exchange data freely and safely in a de trusted environment, so that the trust in "people" is changed into the trust in machines, and any human intervention does not work
The information can not be tampered with. Once the information is verified and added to the blockchain, it will be stored permanently. Unless more than 51% of the nodes in the system can be controlled at the same time, the modification of the database on a single node is invalid. Therefore, the data stability and reliability of the blockchain are extremely high5. Anonymity. Because the exchange between nodes follows a fixed algorithm, the data interaction does not need to be trusted (the program rules in the blockchain will judge whether the activity is effective). Therefore, the counterparties do not need to make the other party trust themselves by disclosing their identities, which is very helpful for the accumulation of credit
The way in which people keep accounts together is also known as "distributed" or "decentralized", because everyone keeps accounts, and the accuracy of the account book is determined by the program algorithm, not by an authoritative organization
this is the blockchain, the core is finished, blockchain is so simple, a common account book
six core algorithms of blockchain Technology:
blockchain core algorithm 1: Byzantine agreement
the story of Byzantine is like this: the Byzantine Empire has great wealth, and the surrounding 10 neighbors have been around for a long time, but the Byzantine walls stand tall and firm, No single neighbor has been able to successfully invade. Any single neighbor's invasion will fail, and at the same time, it may be invaded by other nine neighbors. Byzantine Empire's defense ability is so strong that at least more than half of its ten neighbors attack at the same time before it can be broken. However, if one or several of the neighbors agree to attack together, but betray in the actual process, then the invaders may be annihilated. So each side was careful and could not easily trust its neighbors. This is the question of Byzantine Generals
blockchain core algorithm 2: asymmetric encryption technology
in the above Byzantine agreement, if several of the 10 generals send messages at the same time, it is bound to cause confusion in the system, resulting in different attack time schemes and inconsistent actions. Anyone can send the message of attack, but who will send it? In fact, it only needs to add a cost, that is, only one node can spread information in a period of time. When a node sends a unified attack message, each node must sign and seal to confirm its identity when receiving the message from the initiator
blockchain core algorithm 3: fault tolerance problem
we assume that in this network, messages may be lost, damaged, delayed and sent repeatedly, and the order of receiving is inconsistent with the order of sending. In addition, the behavior of nodes can be arbitrary: they can join or exit the network at any time, they can discard messages, forge messages, stop working and so on, and they may also have all kinds of human or non-human failures. Our algorithm provides fault tolerance for consensus system composed of consensus nodes, which includes both security and availability, and is suitable for any network environment
blockchain core algorithm 4: Paxos algorithm (consistency algorithm)
the problem solved by Paxos algorithm is how a distributed system can reach an agreement on a certain value (decision). A typical scenario is that in a distributed database system, if the initial state of each node is consistent, and each node performs the same operation sequence, then they can finally get a consistent state. In order to ensure that each node executes the same command sequence, it is necessary to execute a "consistency algorithm" on each instruction to ensure that the instructions seen by each node are consistent. A general consistency algorithm can be applied in many scenarios, which is an important problem in distributed computing. There are two models of node communication: shared memory and message passing. Paxos algorithm is a consistency algorithm based on message passing model
blockchain core algorithm 5: consensus mechanism
blockchain consensus algorithm is mainly workload proof and equity proof. Take bitcoin as an example. In fact, from a technical point of view, POW can be regarded as a reusable hashcash, and the generation workload proves to be a random process in probability. When mining a new secret currency and generating a block, the consent of all participants must be obtained, and the miner must obtain the pow work proof of all data in the block. At the same time, miners have to constantly observe and adjust the difficulty of this work, because the requirement for the network is to generate a block every 10 minutes on average
blockchain core algorithm 6: distributed storage is a kind of data storage technology, which uses the disk space of each machine through the network, and forms a virtual storage device with these scattered storage resources, and the data is stored in every corner of the network. Therefore, distributed storage technology does not store complete data in each computer, but stores the data in different computers after cutting. It's like storing 100 eggs, not in the same basket, but separately in different places. The total number is 100. Want to learn more, you can make more use of network search, network search results - small knowledge