The encyclopedia · Software & IT · Technical decision · 2008–2009
Bitcoin made computational work the basis of trust, so strangers could trade without one
Satoshi Nakamoto's 2008 design replaced banks and trusted third parties with a chain of hashes that no one can rewrite without redoing the work.
Bitcoin
the move
Every earlier attempt at digital cash had needed a trusted third party to prevent double spending, which reintroduced the bank that cryptocurrency was trying to remove. Satoshi Nakamoto's 2008 whitepaper proposed a peer-to-peer network where nodes agree on one history without trusting anyone.
The trick is proof of work: producing a valid block requires finding a hash below a target, a random search that takes real computation. A block includes the hash of the block before it, so any attempt to alter history means redoing the computational work of every later block. The honest chain grows by accumulating the most work, and changing it would require outrunning the entire network.
The mechanism also pays for itself: the block reward gives miners new coins as incentive, so the security is self-funded. An individual block is unpredictable to win, but the network as a whole produces one roughly every ten minutes by design, which gives everyone a shared, tamper-evident clock.
why it works
- Proof of work makes fraud cost more than it could ever return, so honest mining is the rational strategy.
- The chain of hashes makes every transaction's history checkable by anyone with the software.
- The block reward funds the work without any central authority collecting fees.
- Difficulty adjustment keeps block time stable as computing power grows, so the system does not speed up or stall.
what transfers
When you cannot make parties honest, make dishonesty expensive—price misbehavior in something real, like computation.
what came after
The Bitcoin network went live in January 2009 and became the first working decentralized currency. Proof of work was adopted by many later blockchains, and the design has been studied as the canonical solution to Byzantine agreement over open networks, though its energy cost remains a live criticism.
references
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