The concept of " blockchain " can be said to be extremely popular. It seems that no one talks about blockchain technology at the Internet Finance Summit. BAT and major banks and other financial institutions are starting their own blockchain research. For work, even IBM recently set up its own blockchain research laboratory, but what exactly is a blockchain? You may not know, and stay in the state of looking at flowers in the fog. From today, let's walk into the blockchain together and uncover the mystery of the blockchain!
Take the fast chain? You mean the blockchain, right?
To make the blockchain clear, let’s start with a story.
You must have heard the story of three people becoming tigers, right?
Suppose someone tells you, no, there is a tiger on the street, do you believe it?
I'm going, why don't you play cards according to common sense, you have to say you don't believe it!
Again! We're talking about real tigers!
Action!!!
Good! Very good!! Best actor-level performance!!!
Go ahead, it's time for a bunch of people to tell you this!
Let's change the scene again.
How would you feel if an old man with a high reputation and whom you trusted a lot told you about it?
Yes, this is called the power of trust. You don't trust a single individual who doesn't have enough credit,
But you will trust a bunch of individuals or a single individual with enough credit.
In the real society, the bank is the individual (center) with sufficient credit.
However, using a bank as a credit intermediary requires costs.
And we ordinary people have to pay for this huge credit cost.
Therefore, the financial industry is the most profitable industry.
Want to remove the credit endorsement of central institutions such as banks?
Then you can use the "bunch of individuals" we mentioned above, which is also the core of blockchain technology.
Blockchain is essentially a technical solution to solve the trust problem and reduce the cost of trust.
The purpose is to decentralize and remove credit intermediaries.
Blockchain is the underlying technology of Bitcoin.
The concept of Bitcoin (BitCoin) was originally proposed by Satoshi Nakamoto in 2009, and you can understand it as a digital currency.
Let's take Bitcoin transactions as an example to see how the blockchain works.
1. Broadcast each transaction on the entire network. For the whole network to recognize it as valid, it must be broadcast to every node.
2. After receiving the transaction information, the miner node must take out the account book to record the transaction.
一旦记录，就不可撤销，不能随意销毁。
矿工节点是通过电脑运行的比特币软件对交易的进行确认的。
为了鼓励矿工的服务，对于其所记录和确认的交易，
系统为矿工提供25个比特币作为奖励。(这个奖励数量，系统设定每4年减半)
奖励只有一份，那就看谁记录的快呗。
为了减少这种情况，系统会出一道十分钟的运算题，
谁能最快解出值，谁就将获得记录入账权利，并赢得奖励。
对了，这里可以给大家看一道据说是徐汇区幼儿园升小学的运算题。
别急啊，你试试看，我第一次反正是做错了。
……，好吧，我无力反驳。
说远了，我们再说回来。
前述区块链中所运用算法并不是简单的计算题，而是使用哈希散列(Hash)算法。
哈希散列是密码学里的经典技术，可以用来验证有没有人篡改数据内容。
3、获得记账权的矿工将向全网广播该笔交易，账簿公开，其他矿工将核对确认这些账目。交易达到6个确认以上就成功记录在案了。
矿工记录的时候，还会将该笔交易盖上时间戳，形成一个完整时间链。
4、当其它矿工对账簿记录都确认无误后，该记录就确认合法，矿工们就进入了下一轮记账权争夺战。
矿工的每个记录，就是一个区块(block)，会盖上时间戳，每个新产生的区块严格按照时间线形顺序推进，
形成不可逆的链条(chain)，所以叫做区块链(Blockchain)。
而且每个区块都含有其上一个区块的哈希值，确保区块按照时间顺序连接的同时没有被篡改。
这时候我们再看对区块链的原始定义就能理解了：区块链是一种分布式数据库，是一串使用密码学方法相关联产生的数据块，每个数据块都包含了一次网络交易信息，用于验证其信息的有效性和生成下一个区块。
若两个人同时上传，虽然这个概率很小，但是若发生，我们就看最后的区块链哪条更长，短的那条就失效。这就是区块链中的“双花问题”(同一笔钱花两次)。对于要制作虚假交易，除非你说服了全网里超过51%的矿工都更改某一笔账目，否则你的篡改都是无效的。
The greater the number of participants in the network, the lower the possibility of fraud.
This is also the advantage of collective maintenance and supervision, maximizing the cost of counterfeiting.
It is very difficult to convince 51% of fake people.
Well, let's summarize, the blockchain mainly has the following core contents:
1. Decentralization
This is the disruptive feature of blockchain. There is no central institution and central server, and all transactions take place in client applications installed on each person's computer or mobile phone.
Realizing point-to-point direct interaction not only saves resources, makes transactions autonomous and simplified, but also eliminates the risk of being controlled by centralized agents.
2. Openness
Blockchain can be understood as a technical solution for public bookkeeping. The system is completely open and transparent. The account book is open to everyone, enabling data sharing, and anyone can check the account. The opening effect looks like this:
3. Irrevocable, immutable and cryptographically secure
The blockchain adopts a one-way hash algorithm, and each newly generated block is advanced in strict accordance with the time-line sequence. The irreversibility and irrevocability of time make any attempts to intrude and tamper with the data information in the blockchain easy to be traced back, resulting in being hacked. The exclusion of other nodes, the cost of fraud is extremely high, which can limit related illegal activities.
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