Bitcoin: A Peer-to-Peer Electronic Cash System

This paper asks how two people can agree that a digital payment happened first without asking a central mint to keep the ledger. Read it to see why signatures prove ownership but not uniqueness, how hash-linked proof of work makes one public history costly to rewrite, and why every confirmation still depends on an honest-compute majority assumption.

Reading focus: Why a valid digital signature can authorize two conflicting transfers, leaving double-spending as an ordering problem rather than a signature problem. How nodes validate transactions, compete to extend hash-linked blocks, and converge on the valid branch with the most accumulated proof of work. Why later blocks raise the cost of rewriting a payment, how the paper models attacker catch-up probability, and where honest-majority, privacy, and light-client limits remain.

Bitcoin white paper, 2008. Satoshi Nakamoto. 35 min read, easy difficulty.