This story still has to start with Bitcoin
Bitcoin, an electronic cash system, is simultaneously disintermediated (electronic cash between individuals does not require a trusted third-party intermediary) intervention) and decentralized (maintained by an organization) (the two parties can complete the transaction without establishing a trust relationship)
Hash function: convert any long string into Fixed-length output (the calculation process cannot be too complicated), as long as the input string changes slightly, the output of the hash function will be completely different.
Blockchain: Divide large things into many blocks for storage. As long as one thing is tampered with and the data below are different, it will be discovered
It uses blockchain (data structure hash function) to ensure that the ledger cannot be tampered with, uses digital signature technology to ensure that only you can use your own account, and uses p2p network and POW authentication mechanism to ensure decentralized operation. Method
Blockchain uses block chain data structure to verify and store data, uses distributed node authentication algorithm to generate and update data, and uses cryptography to ensure data transmission and access security. A new distributed infrastructure and computer paradigm.
Three elements:
The essence of blockchain is a distributed ledger and a database. The blockchain uses a hash algorithm to ensure that information cannot be tampered with, uses public keys and private keys to identify identities, and collectively maintains a reliable database in a decentralized and disintermediated manner.
The differences between big data and blockchain are mainly reflected in the following aspects.
(1) Data volume. Blockchain technology is a new application model of computer technologies such as distributed data storage, point-to-point transmission, authentication mechanism, and encryption algorithm. The amount of data processed by blockchain is small and has a meticulous processing method. Big data manages massive amounts of data, which requires breadth and quantity, and the processing methods will be rougher.
(2) Structured and unstructured. Blockchain is a block with a rigorously defined structure. The chain composed of pointers is a typical structured data, while big data needs to process more unstructured data.
(3) Independence and integration. In order to ensure security in the blockchain system, information is relatively independent, while the focus of big data is the integrated analysis of information.
(4) Direct and indirect. Blockchain is a distributed ledger, which is essentially a database, while big data refers to in-depth analysis and mining of data, which is a kind of indirect data.
(5)CAP theory. C (Consistency) means consistency, which means that any read operation can always read the result of the previously completed write operation. That is, in a distributed environment, data at multiple points is consistent. A (Availability) refers to availability, which refers to obtaining data quickly and returning operation results within a certain time. P (Tolerance of Network Partition) is partition tolerance, which means that when a network partition occurs (that is, some nodes in the system cannot communicate with other nodes), the separated system can still operate normally. CAP theory tells us that a distributed system cannot meet the three requirements of consistency, availability, and partition tolerance at the same time. It can only meet two of them at the same time. As the saying goes, "You can't have your cake and eat it too." Big data usually chooses to implement AP, and blockchain chooses to implement CP.
(6) Basic network. The underlying infrastructure of big data is usually a computer cluster, while the infrastructure of the blockchain is usually a P2P network.
(7) Source of value. For big data, data is information, and value needs to be extracted from the data. For blockchain, data is an asset and the inheritance of value.
(8) Calculation mode. In the big data scenario, one thing is assigned to multiple people to do. For example, in the MapReduce computing framework, a large task will be decomposed into many subtasks and assigned to many nodes for calculation at the same time. In the blockchain scenario, multiple people are allowed to do one thing repeatedly. For example, many nodes in the P2P network record a transaction at the same time.