Proof-of-work is a system that can be used to prevent various forms of attacks of a network, such as denial of service or spam. The system forces someone connected to the network to perform a bit of computer work before they’re allowed to participate. By forcing an attacker’s computer to complete a few computations, it can become preventively expensive to spam the network on a continual basis. While there is a small bit of computing power required on the user’s end, the validity of the work is easy for the service provider to check. A proof-of-work system is used by Bitcoin to make sure that miners can prove their worth to the Bitcoin network. The computing power used by Bitcoin miners is basically a sacrifice to show that they’re willing to pay for large amounts of computing power in order to have the privilege of confirming the transactions on the network.

Hashcash

The proof-of-work system used by Bitcoin is known as hashcash. The idea of hashcash was first proposed by cryptographer and hacker Adam Back in 1997, and it was created to limit the amount of email spam and DoS attacks on the Internet. The easiest way to think about hashcash is through its application in email. The way it works is that a “stamp” is added to the header of each email. A small amount of computing power is used to generate that stamp, and the validity of the stamp can be checked rather quickly by the recipient of the email. This added cost is basically nothing to someone who is using email for its intended purposes, but spammers will quickly find out that the cost of sending thousands or millions of email is not worth it.

Proof-of-work in Bitcoin Mining

Although other systems for creating tokens based on proof-of-work had been created and tried out in the past, Bitcoin’s use of proof-of-work turned out to be the version that made the most sense for creating a sort of “e-cash”. Instead of using proof-of-work to create tokens on one’s own computer, the anti-spam mechanism is used to prove computing work to the Bitcoin network while mining for bitcoins. The main issue solved by Bitcoin is the double-spend problem. The problem of double-spending was basically a death sentence for every form of e-cash in the past because it meant the entire system had to rely on centralized servers. Those servers were the only available method for keeping a ledger of all the transactions involving any form of electronic money.

Securing the Blockchain

Although many people believe that Bitcoin mining is about creating new bitcoins, that’s not actually the reality of the situation. It is definitely true that new bitcoins are created through the mining process, but this has really been a method of bootstrapping the Bitcoin network more than anything else. After all, the network will supposedly be supported by nothing but transaction fees in the distant future. This means that the hashcash proof-of-work system is more about proving the validity of the votes towards each blockchain confirmation rather than generating tokens to be used on that network. At the end of the day, proof-of-work is the main security mechanism to make sure that the decentralized Bitcoin ledger is not easily attacked by a bad actor. As more computers add hashing power to the Bitcoin network in an attempt to earn bitcoins of their own, the blockchain becomes more secure. As it takes more computing power to launch an attack on the Bitcoin blockchain, it also becomes much more expensive.