The main points of the underlying technology of Bitcoin: node/transaction process/block/block header/block formation/block bifurcation
Bitcoin does not exist
Bitcoin does not exist anywhere, including your computer hard drive or any other storage device. The bitcoin you hold is just the address that owns the bitcoin. Such an address only serves as a bank account, and there is no physical object or a certain data file called Bitcoin.
All Bitcoin transactions are stored in a huge ledger file, and this ledger is the blockchain. The balance of your "bank account" (Bitcoin address) is not directly stored in the address, but calculated.
UTXO is the basic unit of Bitcoin transactions
First, let's take a picture of the pretense in the "Father of Bitcoin" Satoshi Nakamoto's white paper
UTXO (Unspent Transaction Outputs) is unspent transaction output, which is a core concept of Bitcoin transaction generation and verification.
What is UTXO anyway?
An example of an account-based payment system:
Zhang San has an account with a balance of 100 yuan, and Li Si has an account with a balance of 50 yuan. When Zhang San wants to pay Li Si 20 yuan, do the following:
Check whether Zhang San’s account balance is sufficient. If it is less than 20 yuan, terminate the transaction and report “Insufficient balance” to Zhang San
Deduct 20 yuan from Zhang San’s account
Add 20 yuan to Li Si’s account
An example of UTXO's payment system:
Zhang San dug 12.5 bitcoins. A few days later, he paid 2.5 of them to Li Si. A few days later, he and Li Si each contributed 2.5 bitcoins to make 5 bitcoins to pay Wang Wu. Then, the account changes of the three persons are recorded using UTXO as follows:
For Bitcoin's blockchain ledger, only 3 transaction records are recorded. The source of funds is the transaction input of each transaction, and the destination of funds is the transaction output of each transaction. Every transaction spends an input and produces an output, and the output produced is the "unspent transaction output", which is UTXO.
Three great innovations of Satoshi Nakamoto, who were evaluated as "extremely brilliant" by Dan Boneh, professor of cryptography and computer security at Stanford University: one is the design of blockchain, one is UTXO, and the other is smart contract
Bitcoin private key
The Bitcoin address is a string of randomly generated strings, like a transparent piggy bank, which anyone can see. The private key is also a string of confidential strings, like a key, only the person holding the private key can open the piggy bank.
Why does the transaction need to wait 10 minutes?
The Bitcoin protocol sets the approximate time for completion of mining to be 10 minutes. Therefore, the merchant may wait until the block of your exchange is confirmed before shipping it to you. But there are also merchants who will not let you wait. Based on the trust in you, I believe that you will not take the same amount of money and spend it elsewhere before the transaction is confirmed. But generally this only applies to small transactions.
10 minutes is the time designed by Satoshi Nakamoto. Considering that it takes a few minutes to calculate and verify a transaction and spread to the entire Internet, in order to avoid "miner A and miner B sending at the same time without knowing that the other party has calculated the result. In the case of "calculation result", it is assumed that it takes 10 minutes to complete the calculation.
Handling fees during the transaction
Currently, many miners do not charge fees. However, as the coins awarded to miners by the system for each successful mining operation continue to decrease, more miners will surely collect fees in the future. Some wallets allow you to manually set the handling fee. The part of the transaction that was not received by the other party and the change was not returned is the handling fee. This money will eventually be obtained by the lucky miner who has the right to bookkeeping.
This article was originally published by @ 块链老垚 to everyone is a product manager. Reprinting without permission is prohibited.
The picture is from Pixabay
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