Nakamoto Consensus and Blockchains
Stub. Beyond the basic hash-chain/proof-of-work/51%-attack picture already covered: a formal treatment of Nakamoto consensus (what it is, Bitcoin's setup assumption, a full security proof, the selfish-mining attack, and the latency-capacity tradeoff in fast-block regimes); and the surrounding blockchain concepts — what a blockchain actually is, the first blockchain (timestamping), what blockchains are genuinely useful for, checkpointing, payment channels as the simplest layer-2 solution, fine-grained censorship-resistance (strong chain quality), additional on-chain-market properties (hiding, simultaneous binding, accountable last look), and player replaceability.
blockchain-and-cryptocurrency-security already covers the basic hash-chain/proof-of-work construction, 51% attacks, and smart contracts; this note covers Nakamoto consensus formally as a Byzantine agreement protocol in its own right — a genuinely new form of agreement (probabilistic, not deterministic; permissionless, not fixed-committee) compared to the classical protocols elsewhere in this topic, related in spirit to the probabilistic termination of asynchronous-agreement-protocols. Covers Bitcoin’s specific setup assumption, a full security proof of the protocol, selfish mining analyzed as a genuine incentive attack (not just a definition), and the latency-capacity tradeoff that emerges when blocks are produced fast. The blockchain-concepts half asks what a blockchain even is at a definitional level, traces the idea back to pre-Bitcoin digital timestamping, and is honest about what blockchains are and aren’t actually useful for. Checkpointing, payment channels (the simplest layer-2 scaling solution), strong chain quality (a fine-grained, high-throughput-compatible censorship-resistance property, with a matching latency lower bound), further on-chain-market properties (hiding, simultaneous binding, accountable last look — needed for fair on-chain trading), and player replaceability (achieving sub-quadratic, committee-based communication, with an adaptive-security extension) round out the modern research agenda — see blockchain-systems-and-applications for the applied/systems-building side of this same agenda.
Outline (TODO — flesh out each)
- What is Nakamoto consensus?
- Bitcoin’s setup assumption
- Security proof of Nakamoto consensus
- The problem of selfish mining
- Latency and block capacity — the fast-block-regime tradeoff
- What is a blockchain? The first blockchain (timestamping)
- What are blockchains useful for, really?
- Checkpointing a blockchain
- Payment channels — the simplest L2 solution
- Strong chain quality; a matching latency lower bound
- Hiding, simultaneous binding, and accountable last look
- Player replaceability — committee-based sub-quadratic protocols
- Adaptive security for player replaceability