Algorand's PPoS Protocol Approach To Fight Selfish Mining And Mining Inequality.

Cryptocurrency mining is a reward-based activity where people join to earn some passive income, but some mining algorithms not only help to grow inequality but also give more chances to powerful miners to take part in block creation, hence selfish mining starts. For instance, the PoW (Proof of Work) mining algorithm used for Bitcoin mining gives more opportunity to powerful miners to take part in block creation. Powerful miners can earn high rewards while the person who has a less powerful computer can't able to take part in the mining is at a disadvantage. In PoS (Proof of Stake) mining, the person who holds less coins is again prohibited. This means that the more coins owned by a miner, the more mining power he or she has.  {Reference}{Reference}.

Because of selfish mining and mining inequality, the number of miners decreasing gradually causes the centralization of a blockchain. PPoS (Pure Proof of Stake) is a permissionless blockchain that can solve many problems beyond selfish mining and mining inequality{Reference}.

Pure proof-of-stake (PPoS) protocol:

Algorand uses a pure proof-of-stake (PPoS) protocol built on Byzantine consensus. Pure proof-of-stake (PPoS) protocol built on Byzantine consensus affords all users the ability to take part in creation of new blocks.. The number of Algo's a user holds will increase the probability to get chosen to propagate new blocks.

Algorand’s consensus protocol does not require participants to solve cryptographic puzzles in order to propose or validate blocks. Any user who is online and possesses stake is eligible to participate in the consensus protocol. And block generation does not require any expensive computation. Participation cost—both computational and financial—is very low and therefore not a barrier to participation. Like PoS protocol, PPoS doesn't give the control of the entire system to a small subset.  Block producers and validators get selected randomly by the system {Reference}. 

Working procedure of PPoS:

This protocol has two phases to complete the entire process of block creation where the block proposer and the committee of validators get selected through the cryptographic lottery.
Phase-1:
  1. A user is randomly selected among all coin holders.
  2. His public key is revealed to all users.
  3. The user proposes the block.
Phase-2:
  1. A committee of 1000 users is randomly selected.
  2. This committee validated the block.
  3. Then the Block gets attached to the main chain.

Let’s compare PPoS with other mining protocols:

PPoS vs PoW: PoW is the oldest mining protocol where the user who can first solve the cryptographic puzzle will receive the reward.  Solving the puzzle first requires high computational power.  PoW is an expensive protocol,  consumes high power, is complex to set up, and transactions are slow to process.  

PPoS doesn’t require high-cost hardware to mining  and doesn’t require high-cost electricity to take part in the mining and because of cryptographic lottery everybody gets an equal chance to propose a block.
PPoS vs PoS (Proof of Stake): In case of PoS protocol your stake will define weather you can take part in the mining or not and the person with huge stake gets maximum chance to produce blocks and there is a fixed numbers of validators but in PPoS there is not fixed numbers of validators and it is independent of you stakes everyone can participate and no any penalty and lock period. 

Some other benefits of PPoS:

1.No barrier to participation: As PPoS requires very negligible criteria for its users to take part in block creation, so where everyday people are getting out from PoW and PoS but PPoS more people can easily join.
2.Untampered decenralization: As block proposers and validators are getting selected by cryptographic lottery, it is impossible to dominate the network by a single person or institution hence we get untampered decentralization.
3. Limitless scalability: The PPoS consensus protocol can occur multiple  time in parallel shards, hence more conjugation in the network we will get more numbers of shards to process transactions.

Conclusion:

As the Blockchain network grows it cannot solve the Blockchain Trilemma and cannot achieve all three characteristics of decentralization, scale and security. The few validators and miners who have enormous stacks of coin and powerful miners now have the advantage and power. The minority reap the benefits.  Lower mining pools result in exclusion and prohibit mining because the main profits are distributed to the few, powerful miners only. {Reference-1,2}.

We need a system that can keep its basic properties without affecting mining behavior and according to me, PPoS is the solution. Selecting block proposers and validators randomly eliminates inequality and the dominance of a person or group in the network.