1 In the 1980s, a group of talented programmers discussed this difficult problem in a password email group. In 1982, David Chaum proposed an untraceable encrypted network payment system. Eight years later, he extended this idea to an encrypted anonymous cash system, namely Ecash.

2 1998, Wei Dai's paper expounds an anonymous distributed electronic cash system: b-money. At the same time, Nick Szabo invented Bitgold and put forward a workload proof mechanism, in which users solve mathematical problems competitively, and then publish the answers in series with encryption algorithm to build a property right authentication system. Hal Finney perfected the mechanism as "reusable workload proof".

On the basis of predecessors' work, in 2008, the little-known "Satoshi Nakamoto" published "Bitcoin: A Peer-to-Peer Cash Payment System" in metzdowd.com's cryptography mailing list. On June 3rd, 2009, the Bitcoin network was born, and Satoshi Nakamoto himself released the first open source version of the Bitcoin client.

Since then, the history of human currency has turned a new page.