What does bitcoin rely on
behind the scenes, the entire bitcoin network shares a public ledger called "blockchain.". This general ledger contains every transaction processed, so that the user's computer can verify the validity of each transaction. The authenticity of each transaction is protected by the electronic signature corresponding to the sending address, which enables users to have complete control over the bitcoin transferred out from their own bitcoin address. In addition, anyone can use the computing power of specialized hardware to process transactions and get a bitcoin reward for it. This service is often referred to as "mining."
bitcoin mining has gone through three stages of development. When bitcoin was just born, the price of bitcoin was very low. People just took bitcoin as a game and used their ordinary computers to mine. However, in 2012, with the rise of bitcoin price, people found that the mining speed of graphics cards was fast, so, People began to buy a large number of graphics cards and assemble them for mining, commonly known as "burning graphics cards"; The third stage is the well-known ASIC miner mining. Since Avalon proced the world's first ASIC bitcoin miner, bitcoin mining has been completely subverted, and mining has become a special professional thing.
public key system: corresponds to a public key and a private key, keeps the private key in the application and publishes the public key. When Party A transmits information to Party B, it can use Party A's private key to encrypt the information, and Party B can use Party A's public key to decrypt the information, so as to ensure that the third party cannot impersonate Party A to send the information; At the same time, when Party A transmits information to Party B, it is encrypted with Party B's public key and sent to Party B, and then Party B decrypts it with his own private key, so as to ensure that the third party cannot eavesdrop on the communication between the two people. RSA is the most common public key system, but the lliptic curve digital signature algorithm is used in bitcoin protocol. What's the difference between cash and bank account? Bitcoin is an electronic currency in BTC. In this article, it is also used to refer to the whole bitcoin system. Like opening an account in a bank, the corresponding concept in bitcoin is address. Everyone can have one or more bitcoin addresses, which are used to pay and collect money. Each address is a string that starts with 1. For example, I have two bitcoin accounts, and. A bitcoin account is uniquely determined by a pair of public key and private key. To save the account, you only need to save the private key file. Unlike bank accounts, banks keep all transaction records and maintain the book balance of each account, while bitcoin's transaction records are jointly maintained by the whole P2P network through a pre agreed protocol. How much money is in my account address? Although the current account balance can be seen by bitcoin software, unlike banks, there is no place to maintain the book balance of each address. It can only calculate the account balance in real time through all historical transactions. How do I pay? When I pay from address a to address B of the other party, the payment amount is e. at this time, both parties will announce the transaction information to each network node, telling address a to pay to address B, and the payment amount is e. In order to prevent the third party from forging the transaction information, the transaction information will be encrypted with the private key of address A. at this time, the network node receiving the transaction information can use the public key of address a to verify that the transaction information is indeed sent by address a. Of course, trading software will help us do these things, we just need to input the relevant parameters in the software. What will the network node do after receiving the transaction information? This is the most important part of the bitcoin system, which needs to be elaborated. For the sake of simplicity, only bitcoin protocol has been implemented. In the current version, each network node will save all transaction information synchronously. There are two kinds of transaction information in history, one is & quot; Verified & quot; The transaction information, that is, the verified transaction information, is stored in a series of "blocks". Each & quot; block" Is the previous & quot; bock" The ID of each block is the hash code of the hash code of the block and the new transaction information (see an actual block). The other category refers to those who also & quot; Unverified & quot; The transaction information just paid above belongs to this category. When a network node receives new unverified transaction information (possibly more than one), it can calculate the book balance of each address at that time because the node keeps all the transaction information in history, so it can calculate whether the transaction information is valid, that is, whether there is enough balance in the payment account. After eliminating the invalid transaction information, it first takes out the last & quot; block" Then, the unverified transaction information is combined with the ID, and a verification code is added to form a new "block". It needs a lot of calculation to build a new block, because it needs to calculate the verification code, so that the above combination becomes a block, that is, the first several bits of the hash code of the block are 1. At present, the first 13 bits need to be 1 (generally, the specific method is uncertain), which means that if the block is generated by enumeration method, the average number of enumerations is 16 ^ 13. Using CPU resources to generate a block is called "gold mining", because the proction of the block will get a certain reward, and the reward information has been included in the block. When a network node generates a new block, it will broadcast to other network nodes. However, this network block may not be accepted by the network, because it is possible that other network nodes have proced the block earlier. Only the earliest block or the block with the largest number of subsequent blocks is valid, and the remaining blocks are no longer used as the initial blocks of the next block. How does the other party confirm that the payment is successful? When the payment information is distributed to the network node, the network node begins to calculate whether the transaction is valid (that is, whether the account balance is enough to pay), and attempts to generate blocks containing the transaction information. When six blocks (one direct block and five subsequent blocks) contain the transaction information, the transaction information is considered "verified", so that the transaction is formally confirmed, and the other party can confirm the successful payment. A possible problem is that I will pay the balance of address a to address B, and at the same time pay to address C. If I only verify that the single comparison transaction is valid. At this point, my way of cheating is to generate six blocks including B to B and six blocks including C to C before the truth is revealed. Because I need a very long CPU time to generate a block, compared with the whole network, the probability of my cheating success is very small. What is the motivation of network nodes to proce blocks? As can be seen from the above description, in order to make the transaction information effective, the network node needs to generate 1 and 5 subsequent blocks to contain the transaction information, and such block generation is very CPU intensive. How to let other network nodes help to proce blocks as soon as possible? The answer is very simple. The agreement stipulates that BTC will be rewarded for the address where the block is proced, as well as the Commission promised by both parties. At present, the reward for procing a block is 50btc, which will be halved every four years in the future. For example, the reward will be 25btc from 2013 to 2016. Is the transaction anonymous? Yes, and No. All bitcoin transactions are visible. We can check all transaction records of each account, such as mine. But what's different from the banking monetary system is that everyone's account itself is anonymous, and everyone can open many accounts. In general, anonymity is not as good as it claims. But bitcoin has another advantage in doing black market trading: it can't be frozen. Even if the police trace a bitcoin address, there is nothing they can do unless they trace the computer used by the exchange based on the Internet address. How to ensure that bitcoin does not depreciate? Generally speaking, in the case of equivalent trading activities, the value of money is inversely proportional to the amount of money issued. Unlike the traditional money market, the central bank can determine the amount of money issued. Bitcoin does not have a central issuing institution. Only by procing blocks can we get a certain amount of BTC currency. Therefore, bitcoin's new amount of money depends on: 1. The speed of procing blocks: bitcoin's agreement stipulates that the difficulty of procing blocks is fixed at an average of 2016 every two weeks, about 10 minutes. Moore's law of doubling CPU speed every 18 months will not speed up the proction of block. 2. The number of rewards for block proction: at present, 50 BTC is awarded for each block proced, which is halved every four years. In 2013, 25 BTC is awarded, and in 2017, 12.5 BTC is awarded. Considering the above two factors, bitcoin's currency issuing speed is not controlled by any single node in the network. Its protocol makes the currency stock known in advance, and the maximum stock is only 21 million BTC
1. Mining can not only proce bitcoin, but also guarantee transaction information
similarly, a mathematical system contains 21 million mathematical problems, so we need to constantly seek the special solution of each mathematical problem through a huge amount of calculation. In addition, the special solution is unique
mining can not only increase the supply of bitcoin money, but also protect the security of bitcoin transactions and prevent fraulent transactions. In terms of process, bitcoin network is a point-to-point payment system, and anyone can trade through the transaction program
in order to ensure that the transaction process is truthfully recorded, the role of "miner" is required to be responsible for recording bitcoin transaction information. The time interval is 10 minutes. The best recorded transaction records among miners will be packaged and stored in a new block, and the corresponding miners will also receive a certain amount of bitcoin rewards
2. The mining process is extremely complex, which is beyond human power
the specific process is as follows. When a miner listens to the transaction, he will first verify the transaction information. The verified transactions will be recorded by miners and stored in their own database. There may be thousands of miners in the world doing the same thing, but every ten minutes, only one miner has the right to create a new block, so that the transaction information recorded by himself can be recognized and stored permanently
next, miners need to fight for the right to keep accounts. This is a competition of computing power. The core of this competition is to use computers to complete a large number of calculation tasks and find a super difficult random number. This random number is the special solution of the equation mentioned in the first paragraph. The miner who calculates the correct random number first wins. According to the rules of the game, the probability of a miner getting the accounting right is directly proportional to the proportion of his computing power in the total computing power of the whole network. In other words, the probability of finding the random number is equivalent to throwing out 100 million dice, and the total number of dice is less than 150 million. Therefore, mining requires a large number of computers, installation of specific algorithm software, repeated operation day and night, not human
3. Bitcoin mining is actually "villagers' bookkeeping"
maybe some netizens still don't understand, let's take an example. In a village, the villagers often borrow money from each other, even if they write a written document, there is a risk of default. Then, every time there is a loan behavior in the village, we will use the village trumpet to inform everyone that all the villagers (miners) will record all the transaction records in their own account books.
renrenfu financial and business school tells you that every bitcoin node will collect all unconfirmed transactions and gather them into a data block, which will be integrated with the previous data block. The miner node will attach a random adjustment number and calculate the SHA-256 hash value of the previous data block. The mining node keeps trying again and again until it finds the random adjustment number so that the generated hash value is lower than a specific target
because hash operation is irreversible, it is very difficult to find the required random adjustment number, which requires a continuous trial and error process that can predict the total number. At this time, the workload proof mechanism will play a role. When a node finds a satisfactory solution, it can broadcast its results to the whole network. Other nodes can receive the new data block and check whether it meets the specification. If other nodes do meet the requirements by calculating the hash value, then the data block is valid, and other nodes will accept the data block and attach it to their own chain
bitcoin mining uses SHA-256 hash value operation. This algorithm will carry out a large number of 32-bit integer circular right shift operations
exhaustive verification until it finds a data that meets the requirements. This meaningless data is a dollar
In fact, the mining calculation of bitcoin is to do math problems together. The problem stem is the transaction that needs to be recorded. By doing the problem, everyone grabs the bookkeeping right, and the miners can get system rewards and transaction fees. The feature of sha256 algorithm used in bitcoin is that it is easy to verify the known answers correctly, but it is very troublesome to get the answers, and it needs to try one by one. The miner who got the answer first was recognized by everyone as having snatched the right to keep accounts, and the reward was given to him. Let's continue to grab the bookkeeping right of the next question. In short, the significance of these calculations is only to ensure the stability and safety of the whole system, and there is no more significance
it is not comprehensive to regard bitcoin as a by-proct of computing. The generation and issuance of bitcoin, all the transactions and circulation in the bitcoin chain, and the stability of the bitcoin system are the purpose of computing and are integrated. Of course, in addition to maintaining the system, it does not proce other value and procts. This is also a black spot where bitcoin is accused of not being environmentally friendly and wasting resources. In general, bitcoin, as a milestone blockchain digital currency, is e to the huge value of a large amount of computing power investment and user trust. There is no doubt about that