Proof of authority

As explained in Real-World Cryptography

Proof of authority is a consensus-participant selection mechanism that relies on authorized identities or authorities.

Proof of authority (PoA) selects consensus participants in advance. It fits permissioned networks, where a known and fixed group participates, rather than permissionless networks, where anyone may join. section 12.1.3 section 12.5

PoA matters because consensus protocols must control who participates:

• Known participants make classical Byzantine fault-tolerant consensus practical, while large participant sets increase communication, leader-election, and speed problems. section 12.1.3
• PoA contrasts with proof of stake, which selects participants dynamically according to the currency they hold. section 12.1.3
• It also contrasts with Bitcoin’s proof of work, which lets participants compete probabilistically to become participants and leaders. section 12.1.3

Figure 12.1 A centralized network can be seen as a single point of failure, whereas a distributed and decentralized network are resilient to a number of servers shutting down or acting maliciously. A permissioned network has a known and fixed set of main actors, while in a permissionless network, anyone can participate.

Compare permissioned networks with fixed main actors against permissionless networks where anyone can participate. section 12.1.3

How Real-World Cryptography covers it

How deep it goes

Defines participant selection and contrasts alternatives, but stops short of detailing authority assignment or protocol execution.

Examples

Contrasts a fixed participant set with dynamically selected proof-of-stake participants and permissionless proof-of-work miners.

What it assumes

Assumes basic consensus vocabulary while introducing permissioned and permissionless network distinctions.

What you can do after

Evaluate how a consensus design controls participation and distinguish PoA from proof of stake and proof of work.

How it connects

Connects Byzantine fault tolerance, permissioned networks, permissionless networks, proof of stake, and proof of work.

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Related concepts

• permissioned networkconfigures · A network in which participation in consensus is restricted to a fixed or authorized set of participants.
• Byzantine fault-tolerant consensus algorithmconfigures · A Byzantine fault-tolerant consensus algorithm enables distributed participants to agree on a system state despite arbitrary or malicious behavior by some participants.

This explainer was generated by Manning's knowledge graph from the text of Real-World Cryptography. The section links point to the parts of the book it draws on.