Will the central banks' monopoly on minting money disappear? Be careful, one battle can hide another. Sino-American quarrels over monetary dumping and the spat between Donald Trump and Mario Draghi, the president of the ECB, over the alleged undervaluation of the euro are taking centre stage. But there is another currency war that is more insidious and for which states agree, as their finance ministers and central bank governors will say this week at the IMF's 2019 Annual Meeting in Washington. This is the almost existential threat that cryptocurrencies, and not just the libra in the making, pose to the currencies of sovereign states as they exist today. Bitcoin and its insane speculative leaps, which everyone has heard about since 2017 without always understanding how it works, have done great harm to cryptocurrencies. It is the exotic tree discredited by its excesses that hides the forest growing slowly but surely. Similarly, the media success achieved by Libra, the project announced by Facebook last spring to launch a " stable digital currency", is misleading. It makes us forget that there are already " stablecoins " (stable cryptocurrencies), such as the USD Coin, issued by a private company owned in part by Goldman Sachs and which is now circulating in 85 countries. " Stablecoin " is a word to remember. Because whatever the fate of Libra, Facebook's pharaonic and quasi-imperialist project that could fail for strictly regulatory reasons, the concept of " stable cryptocurrency" is promised a great future. It could be adopted by the central banks of the States themselves in order to counter private initiatives. All " stablecoins ", including USD Coin or Libra share the following two characteristics. As cryptocurrencies, they use blockchain technology, in other words " a tamper-proof computer notebook open to all and whose participants communicate with each other in real time and live, without going through an intermediary " according to the experts' description. As for stability, it can be achieved in several ways, including by pledging each monetary unit by one or more central bank currencies. Cryptocurrencies are the latest find in the abundant world of means of payment that has continued to make its honey of technological innovations over the centuries. Starting from barter, never completely disappeared, money took the form of countless products, marine (shells), vegetable, metallic, before becoming fiat money based on trust and therefore unrelated to the real value of the support product. From the Renaissance, the race for dematerialization was permanent : scriptural money (negotiable bills, checks), fiduciary (notes) with the appearance of the first central bank in Sweden (1668), electronic (cards), then digital (payments by telephone of which Kenya is the leader, M-Pesa). Insane volatility If the vectors are protean, the three functions of money have never changed since the philosopher Aristotle identified them 2,350 years ago: unit of account to measure the price of goods, store of value for savers and means of payment to trade. Obviously, bitcoin, because of its insane volatility, does not meet this specification that " stablecoins " meet. Their great merit is to constitute a decentralized, direct and instantaneous means of payment, in accordance with blockchain technology that can put the inhabitants of the entire planet in immediate contact. Theoretically, and subject to privacy and computer security issues, " stablecoins " are a very convenient and probably the least expensive payment instrument due to the absence of intermediaries. But this is not their true originality compared to the currencies of central banks and the system of deposits and credits intermediated by banks, The Copernican revolution of " stablecoins " is very well analyzed by Benoît Coeuré, one of the directors of the ECB, by this observation : " It is probably easier to connect a new currency to an existing network - the case of libra, than to build a new network on an existing currency - the case of the euro " (speech of Luxembourg, 17 September). If Libra were to be launched, it would have overnight the Facebook network of 2.4 billion members, much more than the 500 to 600 million users of the euro in the world since it was created in 1999, by including foreigners to the euro area. Will Libra and " stablecoins " be the real alternative to the dollar as an international currency to date without any real competitor ? The question is asked, hence the great reluctance of the Fed and the US Treasury towards them. Benoît Coeuré has been instructed by the G7 to draw up regulatory recommendations on the prudential problems for the international monetary system and the security of savers raised by these new instruments. He will present them this week before the G7 in Washington. It should be noted that it will not be a question, at this stage, of proposing to central banks to develop digital currencies themselves (Central bank digital currency, SBDV), which the People's Bank of China is working hard to do. A solution also advocated by Bruno Le Maire, our Minister of Finance : " We cannot accept that a private company acquires the instruments of sovereignty of a state ," he said last month. Creations of private origin or public monopoly as we wish in Beijing and Paris, the " stablecoins " are not about to disappear. Whatever the fate of Libra, Facebook's pharaonic and quasi-imperialist project, the concept of "stable cryptocurrency" is promised a great future