Blockchain/Level I · Money/1.2 The cypherpunk road/Lesson 5
b-money and bit gold
The two designs that solved the math but missed the network
MaterialsWei Dai, ‘b-money’ (November 1998)Nick Szabo, ‘Bit gold’ (2005 blog post)Satoshi Nakamoto, ‘Bitcoin: A Peer-to-Peer Electronic Cash System’ (October 2008)
Wonder
- Why did a system where money is created by computation still require a trusted server to prevent cheating?
- How does the cost of solving a mathematical puzzle change over time, and why does that break fungibility?
- What specific mechanism allows an open, anonymous set of participants to agree on a single ledger without a known quorum?
Explore
- Wei Dai posted ‘b-money’ in November 1998. It proposed money created by solving computational problems, with the cost broadcast to all participants. Version one required every user to keep a full copy of all balances, which was impractical at scale. Version two delegated account-keeping to a subset of servers who posted deposits that could be fined for cheating. Dai never implemented it.
- Nick Szabo developed ‘Bit Gold’ ideas in 1998 and published them as a blog post in 2005. It used a chain of proof-of-work solutions where each new challenge derived from the previous solution, creating a timestamped record. Szabo framed it as a digital analogue of gold: costly to produce and impossible to fake.
- Szabo identified a critical flaw: fungibility. As hardware improved, later hash solutions cost less to produce than earlier ones, making them unequal in value. He proposed bundling solutions of different vintages into standard units through a separate market layer. Bitcoin sidestepped the problem: the protocol issues identical coins on a fixed schedule, and proof of work only decides who earns them.
- Bit Gold relied on a distributed property-title registry run by a Byzantine quorum of servers to verify the chain. While robust against some failures, this architecture required a coordinated set of known nodes to maintain consensus. That left open how an unknown, changing set of participants could agree.
- Satoshi Nakamoto cited b-money as reference [1] in his October 2008 whitepaper and emailed Wei Dai in August 2008. Bitcoin shared ideas with both (signed transfers and a chain of proofs of work) but removed the trusted servers. The result was a system where consensus emerged from cumulative work rather than institutional authority.
- Neither design settled how an open network resists the Sybil attack. An attacker could create unlimited identities to outvote honest participants unless each ‘vote’ carried a tangible cost. Bitcoin solved this by making each block’s proof of work expensive to produce but cheap to verify, allowing probabilistic finality without a central arbiter of truth.
Key facts
- Wei Dai proposed b-money in November 1998; it used computational work for money creation but required trusted servers or full replication.
- Nick Szabo’s Bit Gold (1998/2005) chained proof-of-work solutions into a costly, unforgeable digital commodity.
- Szabo acknowledged that falling hashing costs made early units non-fungible relative to later ones.
- Bit Gold relied on a Byzantine quorum of servers for consensus, limiting it to known participants.
- Satoshi cited b-money in the whitepaper and, in a 2010 forum post, described bitcoin as an implementation of both b-money and Bit Gold.
- Both designs lacked a mechanism for an open, unknown set of participants to agree on one ledger without trusted intermediaries.
Exercise nine, six, three, one
9CollectList 9 key components or constraints from the b-money and Bit Gold proposals: work creation, storage models, consensus mechanisms, fungibility issues, trust assumptions, scaling limits, attack vectors, implementation status, and legacy impact.
6ClusterGroup these 9 items into 6 categories based on their function in a monetary system: value generation, ledger maintenance, consensus formation, unit stability, security against fraud, and network scalability.
3DistillReduce the 6 groups to 3 reasons neither design became working peer-to-peer cash.
1CrystallizeWrite 1 sentence on what bitcoin added that both designs lacked.
Fact check
Dates, figures and claims checked against the published sources listed below.