The development of the Internet has enabled the development of electronic business. One way of payment in electronic business is via electronic cash. The money thus becomes information stored on a microprocessor or in a database containing data on account status, personal information, PINs, transaction information, etc. Adapting to new trends contributes to the development of crypto currencies as a digital means of exchange, i.e. digital equivalent money. Their main characteristic is the absence of a central institution that issues them or manages them. Currently, the most popular crypto currency is Bitcoin. Bitcoin is based on a computer network that provides stability by cryptography. The way in which that system works is presented for the first time in 2008, in the article "Bitcoin - A Peer-to-Peer Electronic Cash System". The author of the article is Satoshi Nakomoto, although is considered that that was just the pseudonym and the true identity is not revealed. You can get Bitcoin in two ways- first is buying it on the stock market or retailers, and the other way is by mining. Mining can be defined as an economic incentive for participants competing for each prize in the Transaction Verification Event or as award for the solution of the cryptographic problem. It is estimated that in Croatia there are about 25,000 Bitcoin users while in 2017 there were 15,000 registered users.