A permissionless network lets anyone join and participate in consensus without obtaining extra permission. It contrasts with a permissioned network, whose participants are known and fixed. section 12.1.3
Permissionless participation changes how consensus handles membership and leadership:
- Bitcoin uses proof of work: miners solve cryptographic puzzles to become participants and possible block leaders. section 12.1.3
- Unknown participants make censorship harder because an attacker cannot easily predict or prevent the next leader. section 12.1.3
- Proof-of-stake systems can dynamically select a smaller participant set; Algorand selects participants and leaders according to currency holdings. section 12.1.3
- Open participation can introduce forks, while leaderless systems such as Avalanche let anyone propose changes. 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 permissionless participation with centralized, decentralized, distributed, and permissioned network structures. section 12.1.3
