b-money

b-money is a 1998 proposal by computer engineer Wei Dai for an anonymous, distributed electronic cash system. Published in a short paper titled B-money: an anonymous and distributed electronic cash system and circulated in cypherpunk circles, it described how participants could create money, exchange value, and enforce contracts without a central authority — a full decade before Bitcoin launched. Satoshi Nakamoto cited b-money as the very first reference in the Bitcoin whitepaper, making Wei Dai one of the named intellectual predecessors of the network.

Core ideas

Dai outlined two related models. In the first, every participant maintains a copy of a collective ledger recording how much money belongs to each pseudonymous identity — each identity being a public key, with messages signed and authenticated cryptographically. New money is created by demonstrating the solution to a computational problem whose cost can be objectively verified, an early articulation of proof-of-work issuance: money tied to provably expended effort rather than decree. In the second, more pragmatic model, a subset of "servers" holds the ledger on everyone's behalf, bound by security deposits that can be forfeited for misbehavior — an idea that reads, in hindsight, like a rough sketch of economic-penalty consensus. Both versions anticipated themes now central to Bitcoin: a shared ledger instead of a bank, pseudonymous keys instead of accounts, and computational effort as the root of monetary credibility. The proposal even sketched contract enforcement with arbitration, foreshadowing later smart-contract ambitions.

Why it was never built

b-money remained a proposal. Dai himself acknowledged it left hard problems open, and they were precisely the fatal ones: how the network would agree on the difficulty and value of the computational work as technology improved, and how to keep every participant's copy of the ledger consistent when nodes disagree or act maliciously — the consensus problem, unsolved. The first model assumed an idealized, synchronous broadcast channel that does not exist on real networks; the second reintroduced trusted parties through the server class. Money creation pegged to the cost of computation also implied an elastic supply with no fixed cap — a different monetary philosophy from Bitcoin's eventual hard limit of 21 million.

The bridge to Bitcoin

Bitcoin's contribution was not inventing these concepts from scratch but assembling them into a system that actually reaches consensus: SHA-256 proof-of-work ordering transactions into timestamped blocks, the longest-chain rule resolving disagreement, and a difficulty adjustment answering Dai's open question about calibrating work automatically, every 2016 blocks, forever. Where b-money treated proof-of-work as a mint, Bitcoin's deeper move was using it as a clock — the mechanism by which strangers agree on history. The lineage matters to how we tell the story: Bitcoin stands on the shoulders of b-money, Hashcash, and Bit Gold, and honest history credits the giants. For the fullest contrast between the 1998 sketch and the 2008 solution, read Dai's short paper alongside the Bitcoin whitepaper — the gap between them is exactly the invention.