Digital Currency Proposals
The concept of a purely digital currency preceded Bitcoin. One prominent concept, B-money, was proposed by Wei Dai on the cypherpunks mailing list in November of 1998.
B-money proposed using a Proof of Work concept to generate currency, transmitting in a broadcast to all users, similar to the later Bitcoin proposal.
- B-money Paper: http://weidai.com/bmoney.txt
bit gold is a proposed decentralized currency proposed in 1998 by Nick Szabo that uses PoW to create a chain of transactions. The proposal is notable because of the proposal's similarity to the later Bitcoin system.
In the bit gold proposal, Byzantine Fault tolerance is achieved by depending on a majority of network addresses. This component of the proposal has been criticized as being vulnerable to a Sybil attack in which an attacker can cheaply acquire many network addresses to disrupt the system.
- Blog post describing Bit gold: http://unenumerated.blogspot.com/2005/12/bit-gold.html