As is well known, in 2009 the first article on the Bitcoin concept as an electronic transaction system "A peer-to-peer Electronic Cash System" [1] appeared, which, unlike other predecessor systems, brings the great novelty of being based on a transaction history or "Ledger" following the Blockchain concept [2]. We can consider Bitcoin as digital hard money or as its white paper [1] (Nakamoto's article) says: "An electronic cash system".