Читать книгу Blockchain Data Analytics For Dummies - Michael G. Solomon - Страница 48

Nakamoto’s original blockchain proposal described a public blockchain. After all, blockchain technology is all about providing trusted transactions among untrusted participants. Sharing a ledger of transactions among nodes in a public network provides a classic untrusted network. If anyone can join the network, you have no criteria on which to base your trust. It’s almost like throwing a $20 bill out your window and trusting that only the person you intend to pick it up will do so.

Public blockchain implementations, including Bitcoin and Ethereum, depend on a consensus algorithm that makes it hard to mine blocks but easy to validate them. PoW is the most common consensus algorithm in use today for public blockchains, but that may change. Ethereum is in the process of transitioning to the Proof of Stake (PoS) consensus algorithm, which requires less computation and depends on how much blockchain currency a node holds. The idea is that a node with more blockchain currency would be affected negatively if it participates in unethical behavior. The higher the stake you have in something, the greater the chance that you’ll care about its integrity.

Because public blockchains are open to anyone (anyone can become a node on the network), no permission is needed to join. For this reason, a public blockchain is also called a permissionless blockchain. Public (permissionless) blockchains are most often used for new apps that interact with the public in general. A public blockchain is like a retail store, in that anyone can walk into the store and shop.