Digital signature, encrypted payment

Imagine if Xiao Ming now wants to pay Xiaofang 2 coins, so he writes "Xiaoming pays Xiaofang 2 coins". Similarly, if A wants to pay B N coins, A can write "A pays B N coins". That's the problem. If Xiao Ming is very dishonest, he can write "Xiao Fang pay Xiao Ming 20 coins" at will. How to ensure the reliability of payment?

Bitcoin or other encrypted currencies use digital signatures to encrypt payments. When users join the Bitcoin ecosystem, each user will get a Bitcoin Address and Bitcoin Wallet. The wallet is actually a pair of keys, including the public key. And private key (public & private key), the private key is used to generate a digital signature, and the public key is used together for asymmetric encryption. To put it simply, asymmetric encryption can ensure that only Xiao Ming himself (essentially the person who owns Xiao Ming's private key) can use Xiao Ming's Bitcoin for payment. Therefore, it is not so much Xiao Ming's Bitcoin, it is better to say Xiao Ming's private key Bitcoin, which is one of the reasons why Bitcoin is anonymous.

Another reason is that the users of the Bitcoin network are composed of Bitcoin addresses, which means that when you want to pay, the Bitcoin network records "[a Bitcoin address] pay [a Bitcoin address]" , Instead of directly recording "something pays for something". The owner of the address is certified by its private key.

Therefore, it is very important to protect your private key. In fact, the private key may disappear due to various reasons (the computer is invalid, the memory is lost, etc.). When the private key disappears, the corresponding Bitcoin can no longer be found.