Block chain background
In 2008, a pseudonym Satoshi people, in an article for the "Bitcoin: a point to point electronic cash system," the paper first proposed bitcoins. Nakamoto binding a plurality of digital money previous invention, as a HashCash and B-money, to create a completely centralized electronic cash system, the central authority does not depend on the currency or security settlement authentication security. Subsequent Ethernet Square and other projects start to appear, it triggered a wave of "money" and "chain" tide.
The underlying core technology is technology Bitcoin block chain, ether Fong projects employed. Block chain may reshape society as a mode of operation of "subversive" innovative technology, highly individual countries and social concerns, has developed into eco-system has a greater influence.
The block chain brings innovation and application technology is divided into the block chain block chains 1.0, 2.0 block chains, chain block 3.0.
1, a block chain 1.0: non-programmable bits credits representative of the "virtual money";
2, block chains 2.0: based on the financial block chain of programmable "smart contract";
3, block chains 3.0: The Area block chain extended to other applications.
Current issue
1, technology architecture: high efficiency, security challenges, higher resource consumption issues, particularly inefficient data throughput and consensus mechanism;
2, the industry regulatory issues;
3, "killer" application not found commercial application scenarios.
Concepts and core technology
1, a block chain concept definition
In block chain is a peer to peer network environment, transparent and credible rules (in order of timestamp) Construction unforgeable, can not be altered and the block chain traceability data structures, implementation, and transaction management (transaction) processing mode. Application of computer technology is a new model of a distributed data storage, transmission point, consensus mechanism, encryption algorithm, a distributed peer to peer, block chain, unforgeable and tamperproof, transparent and reliable, high reliability key feature.
Three kinds of block chain deployment models:
1, public chain: customers can use any, any node can enter, all nodes participate consensus and read and write data to the center features a strong, Case: Bitcoin and Ethernet Square ;
2, the Union chain: only interested customers to use, only authorized permission to access node, the access node according to the rules of participation and consensus to read and write data, weak decentralized features, case: Hyperledger Fabric;
3, private chain: individual customers, only authorized nodes to access and participate in consensus and read and write data in accordance with the rules.
Object block recorded on the block chain A transaction set is packaged state occurring within a period of time;
A transaction is an operation state change of each change, and has a unique transaction identifier (e.g., hash value).
2, consensus mechanism
It means to achieve consensus mechanism to build trust between the different nodes trust body, a mathematical algorithm to obtain rights, provided to the distributed network nodes to identify parameters used to confirm data changes caused by movement in trading books, and can reach a final consistency.
(1) Pow (workload proof): PoW weak and needs to be Regulated whole network participation agreement calculation, performance efficiency is not high, only 50% of the whole network node failure problems, PoW consensus of the bits of credits used;
(2 ) PoS (proof of interest): requires network node must provide a certain number of tokens prove, more than listed companies similar replacement ticket, node prove to hold more tokens, the right to obtain billing higher the probability. Performance and security has improved, the regulatory weak, still only allow 50% of the entire network node failure problem;
(3) DPOS (shares proof of authorization): In order to prevent large mineral pool the entire network monopoly operator force, holding money several number of nodes elections proxy node authentication and accounting, similar to the board of directors voting system. Advantages may effectively reduce the time involved in the consensus verification, block enhance production rate can be similar in terms of performance and regulatory desire the PoS fault tolerance mechanism, the EOS on the use of consensus DPoS mechanisms;
(. 4) PBFT (Practical Byzantine Fault Tolerant): PBFT the system needs to be deployed at least on the 3f + 1 nodes, can tolerate up to f malicious Byzantine failure occurs nodes, wherein the system state is 2f + 1 nodes determined.
(5) If in good condition, trusted network environment without malicious nodes, etc., the system platform can be used Raft and other distributed a sexually mature solution, colleges and universities to complete the transaction and to reach a consensus, uses less resources and high performance .
3, security
(1) hashing algorithm
(2) symmetric encryption algorithm
(3) asymmetric encryption algorithm
4, storage mechanism
Typically present data block chain comprises a key KV databases, relational databases, flat files.
5, P2P communication mechanism
6, can be intelligent about
status quo
1, bit coin
2, Ethernet Square
3, Hyperledger Fabric