In recent years, financial giants, including JPMorgan Chase, Citigroup, Goldman Sachs, Nasdaq and so on, have expressed enthusiasm for blockchain technology. The blockchain technology that these giants are keen on, also known as distributed books, what exactly is a distributed account book? Let's start with another thing.
Block chain and cyclists
A cyclist on Wall Street
Before NASDAQ was founded, people cycled around on Wall Street carrying a bag full of bonds in order to complete the settlement as soon as possible. Then the business became more and more, the bicycle was too busy. In the 1960s, Wall Street traded only four days a week, four hours a day, in order to keep up with the speed of clearing. This development, people think not ah, bicycles must not run computer. In 1971, when someone said, "Let's do something about it, we came up with a DTC liquidation system." The system's approach is that all transactions take place within the system, including the broker's access to the system, which is still in use by Nasdaq.
Central DTC liquidation system
The system improves the efficiency of transactions, but does not change the central structure of transactions. When there are enough trades and enough brokers, the system is in danger of collapsing or even collapsing. So experts wondered if autonomous, distributed systems would be better? The answer is yes. The block chain is a distributed ledger, each node can display the ledger, then maintain the ledger, and can not tamper with the account, unless you control more than 51% of the node, but this is not possible. To make it easier, if you have a book in your house, you can keep it. In the past, it was Mom and Dad who gave you their wages and put them in your books. In case you are gluttonous and want to buy something delicious, you may have a dozen less notes on the books, and then you want to buy a cell phone, and thousands of dollars less on the books. This is just one example. I believe that when I was a child, everyone wanted to spend some money from my parents' pockets.
A central family ledger
Once there is a distributed ledger, the problems mentioned above will not arise, because you are keeping accounts, your father is also keeping accounts, and your mother is also keeping accounts. They can all see the general ledger. You can't change it, neither can your parents. There's nothing you can do about dad who wants to buy a cigarette or someone who wants to eat like this.
Distributed family account book
The block chain is essentially a decentralized distributed account book, which itself is a series of interrelated blocks of data generated using cryptography, each of which contains multiple pieces of information effectively confirmed by the bitcoin network transaction. Centralization and decentralization before we talked about the nature of the block chain is a decentralized distributed account, so, what is the so-called centralization? Let's start by thinking about the question, "what is the process of buying a book online?" Step 1: after you place an order, you call Alipay. The second step: payment of payment after the seller can notify the delivery. Step 3: the seller receives the notice to deliver the goods to you. Step 4: you are satisfied after receiving the goods, so confirm receipt. Step 5: Alipay receives your notice and calls the seller.
Centralized trading process
We can see, in this process, although you are trading with the seller, but the entire transaction is around Alipay. Therefore, if something goes wrong with the Alipay system, for example, if a meteorite is dropped from the sky, and the Alipay server is completely smashed, or because of the global economic crisis, Alipay goes bankrupt, the helpless Alipay has to say quietly that there is no such transaction. Then the deal will end in failure, when the buyer and seller will be entangled, both sides can not prove themselves.
The failure of the central node can cause the transaction to fail
To simulate a block chain small city to illustrate how the decentralized block chain works, we first simplify the entire decentralized distributed structure into an extreme case to explore. Let's say we have a small, decentralized city, where there are five lovely and lively little friends who do this when they borrow money from each other: let's say B borrows $1 from A, and at this time, What about the people in the city? A yelled in the crowd: "I am A. I lent B1 yuan!" "B also shouted in the crowd:" I am BBA A lent me a dollar! "the other people in the city, C, D, E, heard the news. They took out their small books and wrote them down in silence:" A loaned B1 yuan one year, one month, one day. "
To centralize the city's bookkeeping
When we simplify an extremely decentralized model, we find that in a city with only five people, a decentralized system has been established that does not require banks or Alipay. The model does not require a trust relationship or a credible organization. When everyone in a distributed architecture records accounts, it is not feasible to tamper with the books. For example, B suddenly denied it: "I don't owe $1 for A!" "at this time, the masses C or D or E will stand up and say," No, my account clearly recorded that you borrowed one yuan from A in a certain year, month, day, and did not find a record of your repayment. "
Decentralized books can't be tampered with.
Now, have you found a problem in this model, where the so-called $1 is not important, and nobody cares, "$1" has become a variable, and it can be replaced with any concept? Just admit it's a valuable thing. For example, A shouted in the city: "I created a Bharara energy!" "the rest of the city heard it, so everyone wrote down in their little book," someone has a Bharara energy, "you don't even have to know what Bharara energy is. What else can I do? A can shout again: "I gave B a Bharara energy." "as long as the city's B, C, D, E, that is, everyone in the city admits the deal, then the deal really works, even if there's no Bharara energy in real life. N.
The flow of energy in Bharara
A few problems in a small city, of course, the world of block-chain is not so simple, it has other rules to restrict each other, let's solve the following questions: question 1: why help you keep accounts? Why do you shout at the sky, others will help you keep accounts, other people's time do not want money? Don't you want money in someone else's notebook? So, in order for everyone to help me keep my books, I added a new rule, and I decided to reward the first person who heard my call and put it in a small book. The reward mechanism is also simple. The first person to hear me shout and write it down is a Bharara energy reward. This Bharara energy is not for nothing, it is the reward for your work, just like working can make money, you help me keep the account, the whole system will pay you. There are several things you have to do: first, you have to hear my voice and put it in your little book before everyone else, and then you have to tell the whole city right away-- I'm done with it. If you don't use any more records, others will give up the lucrative business. At the same time, you have to do one thing: add a unique number to your record, and shout out the record and number together, so, When the next person rerecords, he will continue with this record and a unique number.
Bookkeeping is rewarded
When this new rule comes into effect, there must be people who, in order to get Bharara's energy, begin to hold their breath and listen to the sounds made around them, so that they can write down a new record in the first place. At this point, does a reader who knows the block chain think of the term-"Bitcoin mining"? Yes, that's the simple explanation for mining bitcoin. On the topic of Bitcoin mining, an article by Zhihu's user, "Linglong Monk," gave a more vivid example: single men looking for girlfriends, "National Mother-in-law," said. I have a lot of beautiful white skin, cute daughter, so, I give you a problem in the world, a solution to give you one of the girls Wechat ID.
The difficult problem of "National Mother-in-law"
As a result, single men crazily compete, trying to break their heads to solve this world-famous problem. As long as one of the single men to solve a problem, immediately proudly extolled the world, demonstration all single men, this girl Wechat ID is mine, first come first served, you give up. Although the other single men have reached half, but there is no way, the speed is not fast enough, had to immediately solve the next problem.
Get a reward for solving a problem
At the same time, not only did the lucky single man, the first successful solution to the world-famous problem, not pay a dowry of 12,000 yuan, but the "national mother-in-law," who was conquered by his talent, will also make a dowry for the single man's huge fortune. This is the Bitcoin reward for mining in bitcoin. Question 2: who listens to the question of bifurcation? In this paragraph, we quote Zhihu user "Wang Le-LaiW3n". In this vast small city, there must be such problems as B and C are almost simultaneously recorded, and at the same time shouted to the sky, "this number 89757 Bharara energy is mine." However, because the city is so vast, some people will think that the Bharara energy of the number 89757 belongs to B; others think that the Bharara energy of the number 89757 belongs to C.But there is only one Bharara energy of the number 89757, ah. What if only one person can get it? Half a person? Of course not, at this time we will adopt more primitive and simple rules to solve the problem, who will listen to who is who. Without any restrictions, the event will develop into something like this: some people think it's B, and when they hear it, they start to keep an account. Then everything they did was based on the fact that B had Bharara's energy number 89757, and as the message passed on, the chain of information grew longer and longer; Another group of people who think C said this first will follow this trend.
Who listens to the question of bifurcation?
This matter is serious, originally is a unique, the numbering sequence rigorous total information chain, after B and C shouted "this number 89757 Bharara energy belongs to me" this sentence, forks forcefully!!! If this continues, everyone's books will be different, and there's no way to be sure which one is true! To solve this problem, small cities have added a new block chain rule, which must be written on top of the record, and to ensure that the center is 0.89757 millimeters from the edge of the field, so, Everyone writes with a scale before writing. This is very difficult. It takes five minutes for each person to write, so the time used to write this sentence is different. So, as long as someone shouted, "I'm done!" The other people who are writing this sentence will stop writing it and start writing it again in a small book. "that sentence was written by so and so. The number of the last sentence is × × ×".
The rules of accounting are complicated every time.
Problem 3: the double flower problem refers to the phenomenon that a digital cash is used repeatedly in the transaction. What if I shout to both B and C and I give you a Bharara energy? There is only one Bharara energy. How can you ensure that a Bharara energy is paid only once in a real transaction? Let's take Bitcoin as an example, as Nakamoto said in subsection 5 of the Bitcoin White Paper. The steps to run the bitcoin network are as follows: 1. New transactions are broadcast across the network; 2. Each node brings the received transaction information into a block; 3. Each node tries to find a single one in its own block with. When a node finds a workload proof, It broadcasts to the whole network; 5.If and only if all transactions contained in the block are valid and have not existed before, the other nodes recognize the validity of the block; 6.The other nodes indicate that they accept the block, The accepted method is to follow the end of the block, create a new block to extend the chain, and treat the random hash value of the block as the random hash value of the new block. That is, from the moment the transaction occurs, the Bitcoin transaction data is time-stamped; when the transaction data is packaged into a block, one confirmation is completed; after six consecutive confirmations, The deal is irreversible; in Bitcoin, each acknowledgment requires "a complex puzzle", meaning that each confirmation takes a certain amount of time.
Irreversibility after 6 confirmations
In this case, when I try to make two payment transactions with one fund, because the confirmation is longer, it is almost impossible for the latter to be confirmed at the same time as the previous transaction. The funds could not be confirmed at the second transaction after the first transaction was confirmed. The whole network accounting of the block chain needs to reach a consensus in the whole network, and the problem of double spending can not be generated.
