Is it logical to use “Proof-of-Authority” for a “public” blockchain?

Question

According parity.io website:

Proof-of-Authority is a replacement for Proof-of-Work, which can be used for private chain setups.

And also:

The chain has to be signed off by the majority of authorities, in which case it becomes a part of the permanent record. This makes it easier to maintain a private chain and keep the block issuers accountable.

And also:

PoA networks are well-suited to regulated industries where entities responsible for maintaining the network (authorities) need to be known, rather than remain anonymous as in mining-based chains like Bitcoin and Ethereum.

It is underlined to use Proof-of-Authority for a private chain.

What is the reason? And Is it logical to use "Proof-of-Authority" for a "public" blockchain, in sense of keeping decentralization?

Answer 1

What is the reason? And Is it logical to use "Proof-of-Authority" for a "public" blockchain, in sense of keeping decentralization?

Proof of Authority is, by definition, centralised. If the authority nodes go rogue, or fail to reach consensus, the network is useless.

You could use it in public networks (some of the ethereum testnets are PoA), but it would not be a decentralized network. The value of a PoA mainnet would have to come from some benefit of its centralization, and a very high level of trust in the trusted authorities.

Answer 2

Proof Of Authority was developed primarily as a solution to the problem of spam attacks on Ethereum’s Ropsten test network.It's the optimised version of Proof Of Stake by leveraging identity as the form of stake.

The basic principle behind this is

"It takes 20 years to build a reputation and 5 minutes to ruin it. If you think about that, you’ll do things differently."

POA consensus aren't 100% decentralised but rather a compromise between decentralization and the efficiency afforded by centralization.

Disadvantage is some people simply do not care about their reputation .If validators that is limited in number, they are subjected to outside influence from third parties, especially if those third parties have a significant interest in seeing the network fail then it may lead to disaster.

So in a nutshell POA is good for private blockchains with centralized trusted authority.