In my understanding, there are following block chain consensus building mechanisms.
Proof of Work
It comes from the big amount of calculation work is needed for adding new node.
Confirming calculation is easier, but adding calculation is more difficult.
According to that reason, the participant who calculate much can get the floor, Proof of work.
Bit Coin, Mona Coin, Ethereum
Proof of Stake
Participant who has the most coin can get the floor.
If he cheat, the amount of his coin decreases.
Peercoin, Blackcoin
Social Network
When 80% of approvers approve the transaction, it gets confirmed.
Someone who wants to be recognized as an approver, has to be join the approver group. But the group is on approval system, and if the member is not trustworthy, then he will be expelled.
Proof of Activity
This mechanism is composed of PoW and PoS.
The block generated by miner can't be used as it is, after getting confirmation by members who were chosen randomly among participants.
Proof of Burn , Proof of Deposit
This mechanism is composed of PoW and PoS.
Proof of Importance
NEM
Proof of Stake Velocity
Makes use of social aspects, such as density of communications directed toward each of the nodes in the network.
Reddcoin
Proof of Capacity
Burstcoin
Proof of Reputation
Proof of Work
I will show some explanation for proof of work.
A block contains hash value, some transaction data and nonce.
- hash value
- some transaction data
- nonce
nonce
nonce is seed of next block hash value.
Work, calculation, is to detect the nonce.
Required condition
next hash value must have some zero from start, in terms of hexadecimal. normally, 16 zeros are required in BitCoin (but it varies according to the circumstance).
(example)
00000000000000000000fc1373684ddbba7385729485789456...
so miner have to discover specific nonce by mass calculation.
and if miner discovered the nonce, he can get coin. It is PoW.
This mass calculation requirement makes it difficult to falsify blocks.
If someone changes data in the block, he must change every nonce and hash of later. But it is impossible because of the difficulty of its calculation.