Bitcoin is a set of ideas.
A set of concepts much older than Bitcoin itself. In this article I will report some "key concepts" of other authors which Satoshi Nakamoto (and / or Craig Wright) then elaborated.
-First cryptographic system for making untraced payments was theorized by David Chaum (1982)
- eCash: the system drawn up by Chaum was born in 1992. David also introduced the concept of anonymous digital currency and pseudonym
-Cryptography and digital protocols in this sector are due to ideas of Tim May (Cyphernomicon, 1994)
-Nippon Telegraph And Telephone Corporation (NTT). In the 90s Tatsuaki Okamoto and Kazuo Ohta describe a revolutionary system:
1) The security of the system must be independent of the physical conditions of the system itself and must allow money to be transferred through the network
2) It must not be possible to clone money
3) Nobody should be able to track the transaction
4) Transactions must also be possible online
5) Money can be sent to other users
6) Money can be divided into smaller units
According to some, if Satoshi was Japanese it could be Okamoto or Ohta (or maybe both)
-E-Gold: this payment system (which exploited the circulation of gold and silver) was launched in 1996 by Douglas Jackson. However phishing attempts and Ponzi scheme will decree the end of E-Gold. Jackson will be arrested for circulating money without licenses
-Smart Contract, Blockchain and (almost) Proof Of Work: the concept and operation behind Bitcoin are ideas of Nick Szabo (1993-1997). The Hungarian also presents the "Bit Gold" project which however is not successful. Although somewhat different, this system already uses a chain and proof of work (money is created by solving cryptographic problems)
-Proof Of Work: the real Proof Of Work was born in 1997 thanks to Adam Black (Hashcash). However, this system was already used a few years earlier to combat spam and DDoS attacks
-Not traceability and decentralization (1998): these concepts are due to Wei Dai (inspired by Tim May). Basically we are talking about a non-traceable decentralized network, in which the senders and recipients of money are identified only by public keys and each transaction is digitally signed. Furthermore Dai gives reasoning on how to create a money issue mechanism linked to some computational burden to be fulfilled
-Bitcoin: the birth of the crypto takes place in late 2008
