Academy Lesson sha256-preimage-resistance-assumption

Summary

SHA256 remains preimage resistant for practical adversaries.

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What is Bitcoin?

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Bitcoin is pseudonymous: addresses are public identifiers without built-in real names, but flows can still be traced and clustered.

Nodes enforce consensus rules by validating blocks/transactions. Miners order transactions into blocks and compete in proof-of-work.

Wallets store and manage cryptographic keys used to sign spends. The bitcoin itself exists as UTXOs on the blockchain state.

Bitcoin base layer optimizes final settlement and security. Lightning optimizes speed and cost for day-to-day payment flow.