Only two keys are needed to work, which the system will issue during registration.
Unlike banks and electronic accounts, where too much confidential information is required for work, the blockchain does not require anything from users.
Each person who wants to take part in the blockchain has his own public key, with which he signs the transaction (as it were, closes it to the key and writes “send to John"), as well as a private key with which he can open the package that John sent him back.
A public key is a certain phrase of numbers and symbols, available for viewing to everyone. If we draw an analogy with Bitcoin (like shown here https://nsbroker.com/xrp-usd), then the public key is a wallet number that can be sent to anyone to transfer funds.
The private key is the most valuable thing. With the help of it, all transactions are signed within the personal wallet, and therefore it must be stored in a confidential place. For example, like passwords from online banks.
Decentralization and distribution
We have already found that maintaining a network requires the constant and continuous operation of several powerful computers. Blockchain has the most computing engagement on the planet today. Even giants like Google, Amazon and Apple cannot compete with this network in terms of power.
The more people use blockchain, the more powerful and secure it becomes.
Anyone can become a member of the network: just install the official wallet and download the full node to your disk. From this point on, the computer will become a full-fledged node on the network.
For example, one person has a copy of the blockchain on his computer. There is another computer on which there is another copy of the blockchain, and there are tens of thousands of them all over the world. If any intruder wants to hack into the system and "draw" a million for himself, not only will he have to recalculate all these blocks on his own, he will also have to do it in every computer, on every node. And this, of course, is impossible - the system is completely decentralized and does not have control nodes. And every day there are more and more such nodes, and the chances of hacking are less and less.
In a centralized system, all information is stored on the server, and if something happens to it, you can say goodbye to valuable data. In the case of a centralized system, it is also easier for attackers to find vulnerabilities in order to attack host computers. It could be a simple breach in software security or the irresponsible work of a bank security officer - see Wikipedia for reference.
Such a big security issue can only be solved with an equally large network. And the blockchain system is just suitable for these criteria, where each block with information is copied simultaneously to thousands of devices without systems dominating in the structure.