Although many people understand the blockchain and may participate in some projects, they may not have seen or read the Bitcoin white paper. Next, I’m going to talk to you about what a white paper is, especially to give you an intensive reading of the Bitcoin white paper.
foreword
Through the Bitcoin white paper, you can understand what the real white paper should look like . Because many people may have read the white papers of many projects, all kinds of gorgeous rhetoric, and all kinds of hype technologies. In fact, after reading the Bitcoin white paper, you will findIt turns out that the white paper is so simple and unpretentious, and it is so technical, it is all dry goods, as it is only a few pages and not many words. Therefore, the article does not need to be long, the key is to have connotations , especially dry goods.
originalSummarypart
Abstract：
A purely peer-to-peer version of electronic cash would allow online
payments to be sent directly from one party to another without going through a
financial institution. Digital signatures provide part of the solution, but the main
benefits are lost if a trusted third party is still required to prevent double-spending.
We propose a solution to the double-spending problem using a peer-to-peer network.
The network timestamps transactions by hashing them into an ongoing chain of
hash-based proof-of-work, forming a record that cannot be changed without redoing
the proof-of-work. The longest chain not only serves as proof of the sequence of
events witnessed, but proof that it came from the largest pool of CPU power. As
long as a majority of CPU power is controlled by nodes that are not cooperating to
attack the network, they’ll generate the longest chain and outpace attackers. The
network itself requires minimal structure. Messages are broadcast on a best effort
basis, and nodes can leave and rejoin the network at will, accepting the longest
proof-of-work chain as proof of what happened while they were gone.
form
In fact, the white paper is a bit similar to the paper, and the paper also has an abstract. However, the thesis is different. The thesis must have a detailed argument , that is, if you put forward a point of view, or propose a system, you will have to develop layers of arguments around this point of view later. That is to say, there must be an argument for everything. But the white paper is different. The white paper can have no argument at all , it can be just a concept, or an overview, and then the technology, each link, and the innovation point will be mentioned.
peer to peer
The first sentence of the abstract reads: " This paper proposes an electronic cash system fully realized through peer-to-peer technology ". This sentence is very typical, straight to the point and said what it does. This sentence is very important. It is going to be an electronic cash system , so what are the characteristics of this electronic cash system? It is implemented entirely through peer-to-peer technology, so peer-to -peer has become a very critical keyword here.
We may ask at this time: What is peer-to-peer? Look at the last sentence, " It enables online payment to be initiated directly by one party and paid to another party without going through any financial institutions ." These two sentences are very typical. The previous sentence fully explained what a peer-to-peer electronic cash system is, that is, it does not require an intermediate, and it does not require a third party. One party can initiate and pay the other party directly online without any financial institution in between. Get straight to the point and say what it does, and what it is.
Then he went on to say, " Although digital signatures partially solve this problem, if the support of a third party is still required to prevent double payment, then this system will lose its value ." He said that although digital signatures solve some of the problems of this system, such as solving the problem of others knowing that I sent the information, but if the support of a third party is still required to prevent double spending, then centralization still exists, and it still depends on third party. Then this kind of system loses its value. So, later he said, " We propose a solution here, which is that the cash system operates in a peer-to-peer environment and can prevent double payment problems ." This sentence makes it clear that if a peer-to-peer cash system is to be realized, what is the important problem that needs to be solved? It is to prevent the double spending problem.
double spending problem
There are many people talking about Bitcoin and blockchain. But he doesn't know the main business of the blockchain, what kind of problem Bitcoin solves . In fact, it solves adouble spending problem. Because in the case of peer-to-peer, that is, there is no central system in the middle, no bank, and no third party. How to ensure that one point can go to another point to ensure that the double spending problem does not exist? This is critical.
timestamp
Then, immediately after he said, " The network hashes all transactions withtimestamp", this sentence shows how to add a timestamp. It is passedhash function. The hash function, as we all know, is equivalent to a data digest. Therefore, through the hash function, all transactions can be timestamped. Because after all transactions have passed through a timed sequence, we can guarantee to avoid double spending, which is the basis. Of course, it must be used in conjunction with other technologies to solve the double-spending problem. So he said, the hash function time-stamps all transactions, merging them into an ever-extending, hash-based, proof-of-work, chain as a transaction record. Unless the full proof-of-work is re-completed, the resulting transaction record willunchangeable。
blockchain
This explains how the entire blockchain is formed. After all the transactions are timestamped through the hash function, they are added to a chain based on the proof-of-work of the hash function, and as a transaction record, there is a block. Formed transaction records cannot be changed unless the full workload is re-done . Then here it is explained that the workload proof mechanism is a consensus, which is very important. In addition, it follows that the longest chain will not only be used as a proof of the observed sequence of events, but also be regarded as the maximum value from the computing power of the CPU . So, this is the longest chain and is considered the most expensive. Is this chain safe? He made an assumption that as long as most of the CPU computing power does not plan to cooperate to attack the entire network (what is the majority? More than 50% is the majority), then the honest nodes will generate the longest chain . The infrastructure required by the system itself is very little, and the information can be disseminated throughout the network as much as possible. Nodes (Note) can leave and rejoin the network at any time (since it is a P2P network) and take the longest chain of work as proof of transactions that occurred while the node was offline.
Summarize
This summary is written very clearly. He told readers what problems he found and how to solve them, and explained the main ways and advantages of solving this problem . This is very important, and the paper is a routine. In fact, as long as you carefully read the abstract of the Bitcoin white paper, you will know that the question raised by Satoshi Nakamoto is: a peer-to-peer electronic cash payment system that requires third-party support is worthless . He wants to construct a decentralized peer-to-peer electronic cash system. However, if you want to construct a decentralized point-to-point electronic cash payment system, although the current digital signature guarantees certain mechanisms, the double-spending problem cannot be solved. So how to solve double spending? It becomes a very critical place for such a system.
Through the summary, we know that the **Bitcoin system solves two main problems, one is a decentralized point-to-point payment system, and the other is to solve the double spending problem. **Actually it is a belonging. Therefore, the technical solutions mentioned in the entire white paper revolve around these two issues. The former problem is the final goal, and the transition to the final goal is only possible after the double spend is resolved. Well, when Satoshi Nakamoto wrote this white paper, he already had a relatively complete solution for the decentralized peer-to-peer system. Because in the field of cryptography, there were some papers in the 1980s, and in the 1990s and 2000, some very complete systems were formed, but they all had a center.
So, about the decentralized peer-to-peer electronic cash system. The focus of the white paper is on how to solve the double spending problem through P2P, which is a peer-to-peer system. Then to solve the double-spending problem, it is necessary to check the accounts. How can bookkeeping be recognized in a peer-to-peer system without a center? Who keeps the account can be recognized by everyone? How to recognize? How to reach a consensus? Bitcoin introduces a timestamp-based hash function and makes it form a context-dependent sequence, which is why it is called a blockchain. That is, it has many transactions, which are then packaged into a package and recorded in a block. Well, the first piece, and then the second piece and the third piece. Each block forms a sequential order.
Order is very important. Because only with the sequence, can we know which transaction comes first and which transaction comes after. Now because the bank manages the accounts for us, the records of the bank are very clear, which transaction occurred at what time, minutes and seconds, and which transaction occurred again at what time, minutes and seconds, it is all in order. So here, bookkeeping is immutable, which is a by-product of Bitcoin. Here we want to say, first of all, there is a premise that blockchain accounting cannot be changed. It is often referred to as a 51% attack, that is, according to the sentence in the abstract of the original text, "Unless the entire workload is re-completed, the formed transaction records will not be changed." Due to the complex POW (workload proof calculation), changing transaction records will be very time-consuming and require a lot of calculations. Objectively achieve the unchangeable purpose. But from the perspective of business design, this is sometimes a defect. If the change is agreed by both parties to the transaction and is legal, or agreed by the majority of nodes? Here, there is a situation where most nodes agree, so it can be forked, which is a later story. In addition, some later facts about Bitcoin proved that the abuse of Bitcoin was also due to this defect. For example, illegal transactions based on the dark web, network extortion, including hackers' theft of Bitcoin, etc. If you take advantage of this defect, you cannot change it.
In fact, according to the justice of the majority, these transactions should be revoked, that is, they need to be rolled back. But in Bitcoin, it does not allow tampering. So, that makes it have a very unique side to it in certain scenarios. But from another point of view, traceability, this is exactly what is needed. In the information, an important feature of a Bitcoin system is also disclosed. The system itself requires very little infrastructure, because there is no centralized server, and the related maintenance, backup, disaster recovery, management and other costs It will be greatly reduced, which is explained in the Bitcoin white paper. So as for the specific basic solution, it is the beginning of the white paper, and the first part of the white paper is the introduction.