Proof of work, a “weak” but desired protocol

by Lumai Mubanga

The proof of work protocol has been in use for some time and notably for good reasons. Despite its deficiencies in terms of delayed transaction processing speeds, proof of work is considered a deliberate design meant to win the trust of network users. How so?

The Weakness

As pointed out in another article, the biggest weakness of proof of work protocol is its inability to scale. Transaction speeds take longer than current non-blockchain systems such as VISA. Whereas VISA systems can complete close to 70000 transactions per second, the proof of work protocol could only process less than 60 transactions per second. This, among other factors, led to the search for other protocols that could up the processing speed of transactions. However, other factors could still keep this protocol on several networks even when better solutions are designed to replace it.

The Desired Weakling

Despite the above weakness that definitely affects the rate at which some businesses complete transactions on the blockchain, proof of work is seen as a desired weakling in two aspects. It could be described as a tradeoff between transactional speed and the need for security.

Security Enhanced by Immutability

It is often pointed out that proof of work was a deliberate design to enforce security. One fact that stands out is that, since its inception, proof of work has never been hacked into as many times as it should be in comparison to conventional systems. Why is it hard to break in? Immutability.  

The idea that this protocol is consensus-based and that all the nodes on the network, potentially tens of thousands of nodes, are asked to copy and keep the same data makes it secure. To repeat the same work, then periodically come together, and agree on whatever the majority select as the right version of the truth creates trust that is unmatched. That gives PoW based blockchains high level of security. To alter any data on such networks demands altering thousands of the same data on thousands of nodes.

Disincentivizing Bad Behavior

Proof of work disincentivises bad behaviour. This means that public anonymous networks have to take extra steps to disincentivize bad behaviour. On a public and open blockchain, making users anonymous can have undesirable behaviour. Many are likely to be dishonest if they believe they are anonymous. During consensus, for example, all nodes on the network periodically need to compare the latest block of transactions that they’ve recorded. Every node on the network competes to guess a random piece of data called the nonce. The first node to guess the correct nonce gets to share its copy of the most recent block. If the majority of the nodes on the network have the same block, that node wins a prize. But what happens when one node is dishonest? PoW ensures a node owner who decides to be dishonest will only raise their electricity bill while ensuring that they never earn any funds by participating or mining on the network.

Thus, despite the weakness, PoW still has desirable qualities that may allow it to be there longer.