Proof-of-X

General

Goal: Secure updating of a state

Block time: trade off between time

Proof of Work

• Right to create new block: be the first to solve a puzzle based on consumption of a resource external to the system
• Miners choose one of all possible forks to contribute to (or splits among chains but with reduced efficiency per chain)

Proof of Stake

Disadvantages

• Nothing at stake: Miners (voters) can vote on all forks of a blockchain