[Block chain] consensus algorithm (POW, POS, DPOS, PBFT) presentation and experience
POW: Proof of Work, work to prove.
POW coin mechanism bits used in the generation of the Block, a meet the requirements of the Hash Block consists of N leading zeros, the number of zeros depends on the difficulty level value of the network. To get a reasonable Block Hash need to go through a lot trying to calculate, calculate the time depends on hashing speed of the machine. When a node provides a reasonable Block Hash value, indicating that the node did after a lot of trying to calculate, of course, does not follow the number in absolute terms, because to find a reasonable hash is a probability event. When a node has n% of the total network operator force, i.e., the probability of the node n / 100 found Block Hash.
POS: Proof of Stake, proof of ownership.
POS: also known as proof of ownership, similar to property stored in the bank, and this model will be based on the amount of time you hold the digital currency, you are assigned the appropriate interest.
Simply put, according to the amount and a time to hold your money, give your hair a system of interest at stake to prove POS mode, there is a term called Age coins, each coin produces 1 coin age every day, for example, you hold there are 100 coins, holds a total of 30 days, then your money at this time to the age of 3000, this time, if you found a POS block, your age coins will be cleared to 0. You are cleared every 365 coins age, you will get money from the interest on 0.05 blocks (assuming that interest may be understood as an annual interest rate of 5%), then in this case, 5% interest = 3000 * / 365 = 0.41 currency, which under very interesting, wait-there interest.
DPOS: Delegated Proof of Stake, appointed proof of interest. For details on this agreement, it may refer to the latest Bowen, " [Block Chaining] DPoS official consensus mechanism (BTS / EOS) Detailed "
DPoS mechanism bits stocks, shares of Chinese name is called proof of authorization mechanism (also known as the trustee mechanism), its principle is to make every bit shares held by the people to vote, thereby producing 101 delegates, we can be understood as 101 super nodes or mineral pool, which is 101 according to another supernode are exactly equal. Points of view, DPOS a bit like a parliamentary system or the People's Congress system. If the representative is unable to perform their duties (when it is their turn, failed to generate block), they will be removed, the network will elect a new super node to replace them. DPOS the emergence of the most important is generated because mining machine, a large number of operators in force do not understand nor care about Bitcoin of people who, similar to cattle concert tickets and a lot of store did not care about the content of the concert.
PBFT: Practical Byzantine Fault Tolerance, practical Byzantine fault-tolerant algorithms. See supra Byzantine fault tolerance algorithm description .
PBFT is a state machine replica replication algorithm, a service modeled as a state machine, a copy machine to copy the state at different nodes of a distributed system. A copy of each state machine are preserved state services, but also to achieve operational services. The set of all the copies of the composition R represents uppercase, using 0 to | R | -1 represents an integer of each copy. For convenience of description, it is assumed | R | = 3f + 1, where f is the maximum number of copies may fail. Although there may be more than copy 3f + 1, but in addition to extra copies can not improve reliability than degrade performance.
Above mainly is the mainstream consensus algorithm.
From the time point of view, this order is according to the consensus algorithm from birth to the popular order given.
For POW, directly Bitcoin become a reality, and put into use. POS exists primarily from considerations of economics and innovation. The final due to professional miners and mining machine, so this community advertised decentralized algorithm has been substantial center of concerns that the rumors of 60% to 70% of the count forces are concentrated in China. So later appeared DPOS, this calculation does not consume a lot of extra power to allocate rights of way ore output was the pool. But to say that can play a substitute role, DPOS instead POW alone, POS or POW + POS is unlikely, after all, there is reasonable. Each algorithm has its own considerations and significance in a particular period of time, whether it is technical, or business.
If the angle technology's jump, combined with more political and economic way of thinking on the inside, perhaps even more out of the consensus algorithm, such as the concept of PPP in conjunction with a similar way of consensus, not only to achieve the punitive nature of the offenders, but also Operators achieve most efficient power savings instead.
As for the selection algorithm, where the total quoted this passage as the end of the season:
In short, the consensus best design is modular, such as highly relevant selection and application scenarios Notary, consensus algorithms, trusted environment using paxos or raft, with permission of the Union can be used pbft, unlicensed chain can be pow , pos, ripple consensus, etc., according to the counterparty confidence rating, the freedom to choose a consensus mechanism, which is really the best.