Bitcoin, the first cryptocurrency

COMPUTER AND SOCIETY
Bitcoin, the first cryptocurrency Jean-Paul Delahaye1
Designed thanks to the progress of cryptography and made possible by peer-to-peer (P2P) networks, Bitcoin has been operating since 2009. Its capitalization now exceeds 5 billion euros.
States have always wanted to issue and control the currency. Local, private and complementary currencies are little used and monitored; moreover, they always depend on a central authority. Modern cryptography, which offers secure protocols and performs operations that were thought impossible (such as digital signatures), and the worldwide installation of infrastructures that allow the almost seamless functioning of a global network system, change the way given. A new form of money (the term is discussed but we will accept it) seems possible: purely digital, managed collectively without the intervention of any central authority, allowing secure, instantaneous transfers at a minimal cost from one point of the globe to another, it is the cryptographic or cryptocurrency currencies. After some unsuccessful attempts, the first robust version of this new type of currency, Bitcoin (whose capitalization today represents 92% of the capitalization of all cryptographic currencies) was born in 2009. It arouses the passion, as well of its detractors than those who want to believe in it and who have undertaken to build a economic sector linked to their existence. It would be possible to profoundly change the economy and even our societies.

1. University of Lille1, Sciences et Technologies, Laboratory of Computer Science of Lille, UMR 8022 CNRS, Bât M3-ext, 59655 Villeneuve d'Ascq Cedex. E-mail: delahaye @ li fl fr.
   1024- Bulletin of the computer company of France, number 4, October 2014, pp. 67-104
   68 JEAN-PAUL DELAHAYE ◦◦◦◦◦ • ◦◦ Is it not remarkable that all of the financial statements produced by a cryptographic protocol are now worth the equivalent of billions of euros (more than 5 billion euros on 27 August 2014? see http://cornmarketcap.com/). Bitcoin is the result of a subtle assembly of cryptographic protocols elaborated in the end of 2008 and carried out on January 3, 2009 by a researcher - or perhaps several? - hidden under the name of Satoshi Nakamoto. To understand the logic of this digital currency and to try to know if it can be used is our goal. We will see that the subject is both exciting - because of the originality, the mystery and success and this mathematical and computer construction - important - because it is undeniably a new type of currency that can play a role. central role - and particularly tricky - no one today really knows what this digital montage will become. The most extreme opinions are expressed about it2. Electronic currencies are not new and, in a way, all currencies are already electronic. For a long time now, all banking operations have been nothing more than writs played in computer memories. It is important to note this because it means that we know how to make robust computer systems handling money even when it comes to tens of billions of euros. While failures, "bug", viruses, hackers exist, but we managed pretty well to protect itself: the computerization of storage and massive money transfer is not the gateway to colossal fi nancial disasters. If we give ourselves the means - which is the case because when it comes to money, it's serious - we do it very well. Financial crises such as those in2009 did not have a major impact on the functioning of the financial system, but on the other hand, the mistakes made by the poor are often misleading in their economic and fi nancial analyzes, or are too voracious or even dishonest.
   Autoritécentrale Today all money rests on a central authority: a bank with, behind, a State or a set of associated States. This is also the case for all private electronic-currency systems, called complementary or alternative currencies. They allow online payments, trading within a game on the network (the Linden dollar of Second Life) or customer loyalty (airline miles, the points that your supermarket inscribed on your account each time you pass at the checkouts). The main feature of Bitcoins is that, conversely, they have been designed to self-regulate without central authority. The smooth functioning of trade is guaranteed by a general organization that everyone can examine
2. see Supplement 7 at the end of the article.
   1024- Bulletin of the computer company of France - number 4, October 2014
   Car • ◦◦ BITCOIN, FIRST CRYPTO-MONNAIE 69 because everything is public there: the basic protocols, the cryptographic algorithms used, the programs making them operational