Knowledge Base

Overview

“Bitcoin: A Peer-to-Peer Electronic Cash System” is the founding 2008 whitepaper by Satoshi Nakamoto ([email protected], www.bitcoin.org) that introduced Bitcoin. It proposes a purely peer-to-peer form of electronic cash that lets two parties transact directly without a trusted financial intermediary. Its central contribution is a decentralized solution to the double-spending problem: a network timestamps transactions by hashing them into an ongoing chain of hash-based proof-of-work, producing a public transaction history that cannot be altered without redoing all subsequent work. The system replaces institutional trust with cryptographic proof, and remains secure as long as honest nodes collectively control a majority of CPU power.

Key points

• Coins are modeled as a chain of digital signatures: each owner transfers a coin by signing a hash of the previous transaction plus the next owner’s public key, letting any payee verify the chain of ownership.
• A distributed timestamp server hashes a block of items and chains each timestamp into the previous one; because publishing proves the data existed at that time, the chain reinforces every earlier record. This section directly generalizes prior digital time-stamping work by Haber and Stornetta.
• Proof-of-work (a Hashcash-style search for a SHA-256 hash with a required number of leading zero bits) makes consensus “one-CPU-one-vote”; the longest chain represents the majority decision and is expensive to rewrite. Difficulty auto-adjusts via a moving average targeting a fixed number of blocks per hour.
• Block transactions are hashed into a Merkle tree with only the root stored in the block header, so spent transactions can be pruned to reclaim disk space; a block header runs about 80 bytes, and Simplified Payment Verification (SPV) lets lightweight clients verify using only headers plus a Merkle branch.
• Incentives (a coinbase block reward plus transaction fees) fund honest participation and coin issuance without a central authority, aligning a would-be attacker’s economics toward playing by the rules.
• A Gambler’s Ruin / Poisson analysis shows an attacker’s probability of overtaking the honest chain drops exponentially with the number of confirmation blocks z; the paper tabulates, for example, that at q=0.1 an attacker’s catch-up probability falls below 0.1% by z=5.

Relevance to Truestamp

The whitepaper’s timestamp-server and Merkle-tree constructions are direct antecedents of Truestamp’s design: transactions hashed into a per-block Merkle tree, the antecedent of Truestamp’s own tree, with only the root committed into a hash-chained ledger. Truestamp records its block hashes onto the public Bitcoin blockchain as an external block commitment, inheriting Bitcoin’s proof-of-work immutability to prove a Truestamp block existed before a given point in time. See also the item vs block commitment distinction and the Bitcoin glossary term.

Citations

1. Bitcoin: A Peer-to-Peer Electronic Cash System. Satoshi Nakamoto, 2008 (9 pages, 8 references including Hashcash, Haber and Stornetta digital time-stamping, and Merkle).