What sets apart blockchain apart maybe than anything else is its element of decentralization. This means that any change to the blockchain network must be verified by a majority or all of its members before any changes can be made. To do this, a consensus has to be reached, which as the name suggests, is a majority opinion. In blockchain, this is achieved through a blockchain protocol. In this article, we'll look at two of the most well-known protocols used in blockchain - proof of work and proof of stake.
Proof of Work
Proof of work (POW) is the first blockchain consensus protocol. It was pioneered by Bitcoin and is also used in many other cryptocurrencies. In a proof of work system, network members compete to be the fastest to solve the cryptographic puzzles needed to add a new block to the blockchain. The input to these puzzles consists of all earlier noted messages on the blockchain, together with the new set of trades to be attached in the next block. Thus, the amount of information becomes larger and the calculation more complex over time, constraining increased processing power.
When the puzzle is solved, the machine involved proves that it has finished the work, and is rewarded in any given system with a token of benefit. In the Bitcoin blockchain, this comes in the sort of a newly-minted Bitcoin. It should be noted that while successful mining is rewarded with new bitcoins, one does not have to own any bitcoins as a prerequisite to joining in the process of Bitcoin mining.
Proof of Stake
Proof of stake (POS) is the most general agreement protocol after proof of work. We have decided to illustrate its functionality with the example of the NXT cryptocurrency, which uses a pure proof-of-stake system in transaction validation.
In the NXT system, anyone can set up a joint and buy NXT cryptocurrency. A validator must prove ownership of a certain amount of NXT in order to participate in forcing, i.e., transaction validation. The validator’s probability of forging the next block is equal to its share of all NXT in existence. This is a clear distinction from proof of work, in that NXT ownership is a prerequisite to participation in “forging” and therefore to earning the associated fees. Note that transaction fees earned by the validator are paid by the transacting parties. Torquing creates no new tokens, as all NXT is pre-mined.
“Transparent forcing" constitutes a recent advance to the protocol, its aim being to improve the threshold for an attack from 51 to 90, for example, with transparent forcing, a bad actor would have to own over 90 of all NXT in issue in order to manipulate the ledger. Under this system, the node which will validate the next block is randomly selected in advance, but only the next 10 validators are known. A node that fails to take up its position is penalized by temporary exclusion from forcing.
One node forges each block, which allows data to be sent directly to it, speeding up the forcing process. Unlike proof-of-work mining, forcing requires little computing power and electricity. Even the simplest computers, such as the Raspberry Pi, can forge.
Proof-of-stake systems such as NXT's can thus deliver transaction speeds approaching those of the Visa network, and may, therefore, prove useful in driving wider adoption of cryptocurrency. In those circumstances, it is worth noting that Ethereum is expected to start using the proof of stake consensus in the next few months.
A range of other mechanisms exists, such as proof of activity, proof of burn, proof of capacity or proof of elapsed time, which we'll look at another time. Keep looking here on the Bybit website for more great content!