Hello fellow Steemians and welcome to my Home Work post on Consensus Algorithm submitted to Prof @alphafx. I will be talking about Proof of Capacity.

PROOF OF CAPACITY

Proof of capacity (PoC) is a consensus mechanism algorithm used in blockchain to arrive at the necessary agreement on one state of the network amongst distributed processes is such as crypto. This proof of capacity (PoC) allows the mining devices in the blockchain to use the available hard drive space to decide Valid transactions and mining rights.

The PoC authentication systems make use of spare space on a device had drive to store solutions to a hashing problem in cryptocurrency.

Drawing an analogy from Investopedia,

" if lottery rewards are based on matching the most numbers on the mining ticket, then a player with longer list of possible solutions will have better chance of winning". And to add to that, such player is allowed to keep using the lottery ticket block numbers again and again repeatedly.

Top Project using PoC

BurstCoin
Chia
Spacemint

UNDERSTANDING THE CONCEPT OF PoC

PoC came out as one of the many alternative solutions to the problem which is high energy consumption in proof of work systems and Crypto hoarding in proof of stake systems. PoC give room for the mining devices also called nodes on the blockchain, to use empty space on the hard drive to mine the available cryptocurrency.

PoC does it work by storing a list of possible solutions on the mining device's hard drive even before the mining commences, unlike Proof of Work method of repeatedly altering the numbers in the block header and repeatedly hashing for the solution.

How proof of capacity works plotting and mining
The PoC protocol makes use of a two step-process that is, Plotting and Mining.

First, the hard drive is plotted: A compilation of all possible nonce (a number, usually generated randomly or from the time, used once in a cryptographic protocol, to prevent replay attacks) values are created through repeated hashing of data which includes a miner's account.

Each of such nonce contains 8192 hashes and are numbered from 0 to 8191. All these hashes are paired in to what is known as a scoop. This means that hashes that are adjacent to each other are combined to form one pair of two. For example has 0 and 1 constitutes scoop 0, as 2 and 3 make up scoop 1 etc.

The second step has to do with the actual mining exercise in which in the miner calculates a scoop number, Lets say for instance, a miner begins the mining activity and generate get scoop number 20, the miner would then go to scoop 20 of nonce 1 and use that scoop's data to calculate a deadline value.

This process is repeated when calculating the deadline for each nonce that is being held on the miner's hard drive. After following the calculation of every deadlines, the one what's the minimum deadline will be chosen by the miner.

Deadline value means the duration of time (always in seconds) that must elapse from when the last block was forged before the miner is allowed to forge a new block.

For example, if miner Ochang comes up with a minimum deadline of 31 seconds and in that 31 seconds no other miner can forge the block, Ochang will secure the chance to forge the block and also Ochang will get rewarded.

Comparison Between Proof of Work and Proof of Capacity

While PoC allows the mining devices in the blockchain to use their available hard drive space, Proof of Work and Proof of Stake does not work like that.

Proof of Work uses ASICS (an Application Specific Integrated Circuit) and computation to check if transactions are correct. PoW objective is to deter cyber-attacks such as a distributed denial of service attack (DDoS) whose purpose is exhausting the resources of the computer by sending multiple fake requests.

ADVANTAGES AND DISADVANTAGES OF PoC

Proof of Capacity has many Pros over Proof of Work and Proof of Stake systems, it also has some important cons also, let us look at this Advantages and disadvantages.

ADVANTAGES

1. Proof of Capacity can make use of any regular hard drive including the ones that has Android base system.

2. It is up to 30 times more energy friendly than the ASIC based mining of the BTC cryptocurrency from reports.

3. There is focus no need for constant upgrade of hard drive neither is there need to use a particular dedicated hardware.

4. The hard drive can be reused for any other data storage purpose as mining data can be wiped-off with ease.

DISADVANTAGES

1. The system has not been adopted by many developers

2. Mining activities can be affected by malware

3. Widespread of Proof of Capacity will lead to production of higher capacity hard drives which could lead to "arms race".

CONCLUSION

After going through my research, from my findings I can say that PoC is indeed a very unique protocol, because it secured the network by only using inexpensive, low power hard drives, instead of the more expensive, and power hungry processors and ASICS.

THE END

References

1. investopedia
2. medium
3. coinbureau