Blockchain consensus mechanisms
summary
Starts with permissioned consensus (synchronous vs partially synchronous models, one‑third Byzantine bound) and shows rotating leaders plus Byzantine broadcast as a concrete solution. Presents Nakamoto’s proof-of-work lottery: hash puzzles, longest‑chain rule, waiting ~5–6 blocks for probabilistic finality, high energy cost. Describes Algorand’s verifiable random function sortition, small committees running BFT to get fast finality, mitigation for nothing‑at‑stake and long‑range attacks via ephemeral participation keys, plus notes about relay‑node centralization and required large stakeholder participation.
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chapters (17)
- 0:00Blockchain introduction
- 2:58Consensus in blockchains
- 7:23Layered architecture
- 12:33Cryptographic tools
- 18:57Permissioned consensus
- 26:27Byzantine broadcast
- 37:17Partial synchrony model
- 44:24Permissionless challenge
- 49:29Nakamoto consensus
- 55:42Proof of work mechanism
- 1:04:32Network security
- 1:24:24Forks and finality
- 1:33:05Proof of work limitations
- 1:42:10Proof of stake
- 1:51:49Stakeholder consensus
- 1:59:24Verifiable random functions
- 2:09:27Algorand overview
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