Blockchain technology is in a mess recently. If you carefully check the information on the Internet, you will find that the principle of blockchain technology is a typical American way of thinking. Everyone has the right to vote, and each node (computing power) has a ledger. The bad guy (bad debt) is chosen, and the whole system is paralyzed.
A blockchain system consists of many nodes, which are generally a computer. In this system, each participating node has the opportunity to compete for bookkeeping, that is, to update database information. The system will select the fastest and best node for bookkeeping within a period of time (maybe ten minutes or one second), and let him book the account within this period of time. Data changes are recorded in a data block, which we think of as a page. After the accounting is completed, the node will send the ledger of this page to other nodes. Other nodes will verify whether the ledger on this page is correct, and if there is no problem, they will put it into their own ledger. In the system, the data representation of this page of the ledger is called a block. This block records the changes of the entire ledger data during this period of time. This update result is then sent to every node in the system. Therefore, each node of the entire system has exactly the same ledger.
We refer to this accounting method as blockchain technology or distributed ledger technology.
safety
So why take this approach? What advantage does he have? Because usually everyone's intuition is that this method seems to be a waste of bandwidth and storage space, and is not a desirable solution. However, the blockchain builds extremely high security through this highly redundant method.
First of all, the rights of each node are the same, and the destruction of any node will not affect the security of the entire system, nor will it cause data loss. Its weight in the whole system is consistent. The system selects bookkeepers among the nodes linked to the system every time, so even if one or part of the nodes is destroyed or crashes, it will not affect the operation of the entire system.
Secondly, the ledger data of each node is exactly the same, which means that data tampering of a single node is meaningless. Because if the system finds that the two ledgers do not match, it considers that the version of the node with a relatively large number of the same ledgers is the real version of the data. Those few inconsistent node ledgers are not real, but tampered with. The system will automatically discard this part of the ledger that is considered tampered, which means that if you want to tamper with the data content on the blockchain, unless you can control most of the nodes in the entire system. This is commonly referred to as a 51% attack to initiate changes to the ledger data.
However, when the number of nodes in the entire system is as high as tens of thousands, or even hundreds of thousands, then the possibility of data tampering is greatly reduced. Because these nodes are likely to be distributed in every corner of the world, in theory, unless you can control most of the computers in the world, you have no chance to tamper with the data on the blockchain.
In addition, another 51% attack method is to build as many nodes (computing power) as the original system to attack the blockchain system (although it is important to build enough computing power, not only It is only the number of nodes, but considering that the concept of computing power is more complex, the number of nodes is used as an analogy here). For example, if the system originally had 10,000 nodes, the attacker deployed another 10,001 nodes and added them to the system in the blockchain. Since the attacker has gained more than 50% control, it has been able to launch the attack. Obviously, the cost of such an attack also depends on the original size of the system. It turns out that the more nodes in the system, the greater the cost to the attacker. Since Bitcoin is currently the largest blockchain network, according to statistics, the cost of building a network system as large as the existing Bitcoin is as high as 27 billion US dollars.
But the attacker also faces another dilemma. Once it successfully launches the attack, it will cause the value of the system to instantly drop to zero. That is to say, once the attacker successfully tampered with the ledger, since the entire network can immediately identify the inconsistency of the ledger data, everyone realizes that the system ledger is already an unreliable ledger, which means that the data recorded in the ledger becomes unreliable. value, the tokens in the system will also become worthless. That is, the attacker will be unprofitable. For the state, it seems that there is no need to attack a network like Bitcoin in this way. The state can simply achieve the purpose of banning Bitcoin by directly declaring that Bitcoin is illegal.
value
大多数人都知道区块链和比特币关系密切，甚至有人会把区块链等同于比特币技术。事实上区块链仅仅是比特币的底层技术，是在比特币运行很久之后，才把它从比特币中抽象地提炼出来。从某种角度来看，也可以把比特币认为是区块链最早的应用。
比特币的创造者---中本聪在其2008年发表的经典论文《比特币:一种点对点网络的电子现金》中明确指出:传统金融体系不可避免地要依赖“第三方”机构（传统银行），这种传统的中心化金融机构是很难让货币像其他信息那样免费的进行传输。正是为了解决这些问题，中本聪创造性的提出了通过区块链技术建立一个去中心化、去第三方、集体协作的网络体系设想，而无需中心化的平台做信任的桥梁，区块链通过全网的参与者作为交易的监督者，交易双方可以在无需建立信任关系的前提下完成交易，实现价值转移。如果说互联网TCP/IP协议是信息高速公路，那么区块链的诞生意味着货币的高速公路第一次建设已经初步完成。