The general problem of bitcoin
Publish: 2021-04-17 04:30:25
1. In order to understand the technical principle of bitcoin, we need to understand two important cryptographic techniques: hash code: it converts a long string into a fixed length string, and its conversion is irreversible, that is, it is impossible to guess the original string from hash code. Sha256 is mainly used in bitcoin protocol
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
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
2.
As for bitcoin's sharp rise and breaking the $48000 mark, I believe no one will expect that. What are the reasons for bitcoin's sharp rise? Will bitcoin continue to soar in the future? With these questions, let's analyze this problem. Here are my personal thoughts and opinions, for your reference and discussion only
the above has explained various factors of bitcoin soaring, but none of these factors is under our personal control, and when you invest, you can't guarantee that you can bear the loss, so when you choose to invest in bitcoin, you are doomed to pay for your decision, The world is so big and there are so many procts to invest in. Why choose bitcoin with such high risk? The above is my personal views and ideas, for reference only
3. Australia
in October 2013, bitcoin Bank of Australia was attacked by hackers, with a loss value of more than US $1 million. This incident has aroused the concern of bitcoin security in Australia. The Reserve Bank of Australia and the Australian tax office have said they want a virtual currency tax like a business transfer tax
Bangladesh
the Central Bank of Bangladesh banned the use of virtual currency in September 2014. Using bitcoin will be punished by law
Brazil
Brazil is one of the few countries in the world that has enacted laws related to electronic currency payment systems. Brazil has not banned bitcoin
Bolivia
for regulatory reasons, the Central Bank of Bolivia (BCB) has banned the use of bitcoin. BCB believes cryptocurrency will help business entities evade taxes
Canada
bitcoin is not considered legal, that is, bitcoin is not recognized by Canadian law. Canada's tax authorities plan to implement the same tax plan as barter trade and speculative trading for the bitcoin
China
China is one of the few countries in the world that ban bitcoin completely and prohibit financial institutions and banks from dealing with bitcoin transactions. In December 2013, the people's Bank of China issued a notice calling bitcoin & quot; Virtual goods;, And prevent it from becoming money
trading has been suspended
Ecuador has banned bitcoin, but it has chosen to set up a new state-owned electronic currency and monetary system, and the currency will be protected by the assets of the Central Bank of Ecuador
EU
at present, the EU still has different views on the classification of bitcoin. In October 2012, the European Central Bank's report on virtual currency concerns the legality of bitcoin under the EU legal framework. The European Banking Regulatory Authority issued a bitcoin risk warning, saying that the use of bitcoin has not been restricted at present
Finland
Finland has relevant regulations for the use of virtual currencies such as bitcoin. The relevant regulations are issued by the Finnish tax authority Vero skatt. Any gains arising from bitcoin transactions will be subject to capital gains tax
Hong Kong
Hong Kong has no regulations for bitcoin or any other virtual currency. However, the government is closely monitoring the use of bitcoin to prohibit money laundering, fraud and other illegal activities
India
India does not explicitly stipulate or prohibit the use of bitcoin. However, the Reserve Bank of India (RBI), equivalent to the Central Bank of India, has been forced to shut down India's largest bitcoin trading platform after it issued a notice that the use of bitcoin could cause money laundering and security problems
Israel
the Israeli tax authority is considering levying income tax on bitcoin transactions. Israeli banks even blackmail bitcoin payments
Kyrgyz
Kyrgyz central bank has banned the use of digital currency and bitcoin for the reasons of lack of centralized management, high currency risk and legal problems
Russia
the Central Bank of Russia believes that bitcoin may be used for money laundering and terrorist financing. Therefore, the Russian government banned the use of bitcoin
Taiwan
Taiwan's financial supervision commission is concerned about the uncertainty and speculation of bitcoin, so Taiwan opposes the installation of bitcoin ATM
UK
at present, there are no relevant regulations for the bitcoin. Profits or losses from bitcoin transactions are subject to capital gains tax, while the purchase of bitcoin is still subject to VAT
the U.S.
the U.S. is probably the most supportive country for virtual currencies such as bitcoin. There are no final rules on bitcoin. However, there are also many new rules for the establishment of bitcoin management framework.
in October 2013, bitcoin Bank of Australia was attacked by hackers, with a loss value of more than US $1 million. This incident has aroused the concern of bitcoin security in Australia. The Reserve Bank of Australia and the Australian tax office have said they want a virtual currency tax like a business transfer tax
Bangladesh
the Central Bank of Bangladesh banned the use of virtual currency in September 2014. Using bitcoin will be punished by law
Brazil
Brazil is one of the few countries in the world that has enacted laws related to electronic currency payment systems. Brazil has not banned bitcoin
Bolivia
for regulatory reasons, the Central Bank of Bolivia (BCB) has banned the use of bitcoin. BCB believes cryptocurrency will help business entities evade taxes
Canada
bitcoin is not considered legal, that is, bitcoin is not recognized by Canadian law. Canada's tax authorities plan to implement the same tax plan as barter trade and speculative trading for the bitcoin
China
China is one of the few countries in the world that ban bitcoin completely and prohibit financial institutions and banks from dealing with bitcoin transactions. In December 2013, the people's Bank of China issued a notice calling bitcoin & quot; Virtual goods;, And prevent it from becoming money
trading has been suspended
Ecuador has banned bitcoin, but it has chosen to set up a new state-owned electronic currency and monetary system, and the currency will be protected by the assets of the Central Bank of Ecuador
EU
at present, the EU still has different views on the classification of bitcoin. In October 2012, the European Central Bank's report on virtual currency concerns the legality of bitcoin under the EU legal framework. The European Banking Regulatory Authority issued a bitcoin risk warning, saying that the use of bitcoin has not been restricted at present
Finland
Finland has relevant regulations for the use of virtual currencies such as bitcoin. The relevant regulations are issued by the Finnish tax authority Vero skatt. Any gains arising from bitcoin transactions will be subject to capital gains tax
Hong Kong
Hong Kong has no regulations for bitcoin or any other virtual currency. However, the government is closely monitoring the use of bitcoin to prohibit money laundering, fraud and other illegal activities
India
India does not explicitly stipulate or prohibit the use of bitcoin. However, the Reserve Bank of India (RBI), equivalent to the Central Bank of India, has been forced to shut down India's largest bitcoin trading platform after it issued a notice that the use of bitcoin could cause money laundering and security problems
Israel
the Israeli tax authority is considering levying income tax on bitcoin transactions. Israeli banks even blackmail bitcoin payments
Kyrgyz
Kyrgyz central bank has banned the use of digital currency and bitcoin for the reasons of lack of centralized management, high currency risk and legal problems
Russia
the Central Bank of Russia believes that bitcoin may be used for money laundering and terrorist financing. Therefore, the Russian government banned the use of bitcoin
Taiwan
Taiwan's financial supervision commission is concerned about the uncertainty and speculation of bitcoin, so Taiwan opposes the installation of bitcoin ATM
UK
at present, there are no relevant regulations for the bitcoin. Profits or losses from bitcoin transactions are subject to capital gains tax, while the purchase of bitcoin is still subject to VAT
the U.S.
the U.S. is probably the most supportive country for virtual currencies such as bitcoin. There are no final rules on bitcoin. However, there are also many new rules for the establishment of bitcoin management framework.
4. The credit problem of central system
5. Tianlong spirit, set three functions in one, automatic planting, automatic play strange, automatic business. Fully adapt to any window, use the process can be moved to adjust the size of the window
Tianlong genie is a script program made by key Genie 8. X
[function description]
Tianlong spirit, automatic planting, automatic strange fighting, automatic business running
[instructions for use]
for detailed setting instructions and version update download, please see
auto mining start key Ctrl + Shift + home
note that it is better to keep a window size when starting this script
changing the window size will change the acquisition point
upload and download 6 minutes ago (25.14 KB)
collection settings
after the start of mining and mining
after the start of mining, only mining is needed
after the start-up of mining, only mining without mining
F10 stealth
No, not used
you need to put the stealth skill in the F10 column. After you find the collection, you will hide first and then collect it
F9 plus red
No, not used
Qingxin is suitable for the Qingxin and Chongxu of Emei
red medicine is suitable for medicine and symbiosis
Red percentage%
according to the percentage of blood strips, if it is lower than this value, red will be added< No, do not use it
red medicine is suitable for adding blue medicine
percentage of adding Blue%
according to the proportion of blue bars, if it is lower than this value, add blue
Q fishing coordinate points are separated
enter the coordinates that can be fished on the current collection map, and when the collection has no energy, it will automatically go fishing to hang energy< The first time you start the automatic mining system, a window will appear, as shown in the figure:
upload and download 15 hours ago (4.47 KB)
after you confirm, the big map will be opened automatically. At this time, you can right-click 20 acquisition points on the map in order. Click the script of 20 collection points to start the collection
when you start again, the following window will appear. You can choose whether to relocate. If it is in the same map, the same window size can keep the original acquisition point
upload and download 15 hours ago (5.05 KB)
Tianlong genie is a script program made by key Genie 8. X
[function description]
Tianlong spirit, automatic planting, automatic strange fighting, automatic business running
[instructions for use]
for detailed setting instructions and version update download, please see
auto mining start key Ctrl + Shift + home
note that it is better to keep a window size when starting this script
changing the window size will change the acquisition point
upload and download 6 minutes ago (25.14 KB)
collection settings
after the start of mining and mining
after the start of mining, only mining is needed
after the start-up of mining, only mining without mining
F10 stealth
No, not used
you need to put the stealth skill in the F10 column. After you find the collection, you will hide first and then collect it
F9 plus red
No, not used
Qingxin is suitable for the Qingxin and Chongxu of Emei
red medicine is suitable for medicine and symbiosis
Red percentage%
according to the percentage of blood strips, if it is lower than this value, red will be added< No, do not use it
red medicine is suitable for adding blue medicine
percentage of adding Blue%
according to the proportion of blue bars, if it is lower than this value, add blue
Q fishing coordinate points are separated
enter the coordinates that can be fished on the current collection map, and when the collection has no energy, it will automatically go fishing to hang energy< The first time you start the automatic mining system, a window will appear, as shown in the figure:
upload and download 15 hours ago (4.47 KB)
after you confirm, the big map will be opened automatically. At this time, you can right-click 20 acquisition points on the map in order. Click the script of 20 collection points to start the collection
when you start again, the following window will appear. You can choose whether to relocate. If it is in the same map, the same window size can keep the original acquisition point
upload and download 15 hours ago (5.05 KB)
6. It doesn't matter. Chain and currency can be separated. Currency is the financing means of R & D chain. But now people are keen on hyping currency. The technology financing of chain has not been well realized, or they simply forget what the purpose of issuing currency is. The result is that the chain or the country takes the lead, and the currency or the country's reputation has real value, The essence of all virtual currency trading is to earn money with national reputation.
7. No, these bitcoins are just out of circulation. The total amount remains unchanged
8. POW relies entirely on the use of economic incentives to increase a large number of accounting participants, so as to dilute the proportion of evil nodes, or significantly increase the cost of evil, and those who make false accounts need to control or bribe more nodes. This is a simple and crude consensus mechanism, which has not been optimized in algorithm, but is very feasible. Now the two largest blockchains, bitcoin and Ethereum, are all mined by pow
although POW is not optimal, it is now the most practical consensus algorithm. For example, bitcoin, lightcoin and decent all adopt the pow proof mechanism.
although POW is not optimal, it is now the most practical consensus algorithm. For example, bitcoin, lightcoin and decent all adopt the pow proof mechanism.
9. The formal expression of Byzantine general problem (hereinafter referred to as "consensus problem") is: how to reach a consensus on information in a distributed network that is not based on trust? This statement sounds obscure, but its essence is not complicated. Although the following examples are not completely consistent with the consensus issue, they are helpful for our understanding [9]
imagine that in Byzantine times, there was a rich city-state with all kinds of gold, silver, jewelry, silk and satin, and its Lord Doraemon enjoyed all the luxury and glory. On the outskirts of the city-state, four Byzantine Generals, Daxiong, panghu, Xiaofu and Jingxiang, coveted Doraemon's wealth, so they decided to join hands to capture Doraemon's city-state. According to the strength comparison between the two sides, more than half of the generals must attack at the same time to defeat the enemy, so the winning condition is that at least three of the four can agree on the attack time. What are the odds of the four generals
the answer to this question depends on the cooperation mode of the four people. If it is a centralized system and there is an alliance leader, such as panghu (equivalent to a central server), then there is no doubt about their victory, because it is very easy to reach an agreement on the attack time. As long as panghu calls Daxiong, Xiaofu and Jingxiang to have a meeting to discuss it, Even if we have different opinions, panghu can make a final decision. Now let's go back to the assumption of Byzantine Generals. In a distributed network without trust, what are the odds of four generals winning< br />
?
first of all, e to the lack of trust between the four generals, the possibility of gathering in a small dark room for a conspiracy meeting is ruled out (what if they are kidnapped by panghu in a small dark room?); Secondly, since there is no leader, the opinions of all four people will be equally valued. In this case, the four generals could only negotiate the attack time by sending messages between their camps by messenger. For example, if Daxiong thinks 6 a.m. is a good time to launch an attack, he will send messengers to tell panghu, Xiaofu and Jingxiang their opinions. At the same time, panghu may think it's better to launch a surprise attack at 9 p.m., Xiaofu prefers to launch an attack at 3 p.m., and Jingxiang hopes that it will be 10 a.m., and the three of them will send their own messengers at the same time. In this way, after the first round of communication, each of the four generals had four attack times to choose from, and each of them had to inform the other three of their chosen time in the next round of communication. Because four people make decisions independently, there are 256 possible final choices. Only when more than three people choose the same time can consensus be reached, and there are only 64 such results, that is to say, the probability of reaching consensus is only 1 / 4. This is only the case of four generals. What if the number of generals is 10, 100 or 1000? With a little calculation, we can see that as the number of people increases, the hope of reaching a consensus will become increasingly dim
change the general in the above example into the node in the computer network, the messenger into the communication between nodes, and the attack time into the information that needs to reach a consensus. Then you can understand the dilemma described by the consensus problem. The ability to reach a consensus is self-evident for a payment system. If you remit a sum of money to your family to buy a car and go to the bank the next day for verification, the counter will tell you "about how much money you remit, there are three versions of records in our system". Obviously, you dare not deposit money in such a bank. Before the emergence of bitcoin, the consensus problem is difficult to be solved perfectly. In order to reach a consensus, we need to adopt a centralized system (unless the nodes meet certain conditions), and in order to decentralize the consensus, we can't guarantee it. So how does blockchain technology solve this problem Pay attention to the official account weoption, reply to "block chain", you can view the full text.
imagine that in Byzantine times, there was a rich city-state with all kinds of gold, silver, jewelry, silk and satin, and its Lord Doraemon enjoyed all the luxury and glory. On the outskirts of the city-state, four Byzantine Generals, Daxiong, panghu, Xiaofu and Jingxiang, coveted Doraemon's wealth, so they decided to join hands to capture Doraemon's city-state. According to the strength comparison between the two sides, more than half of the generals must attack at the same time to defeat the enemy, so the winning condition is that at least three of the four can agree on the attack time. What are the odds of the four generals
the answer to this question depends on the cooperation mode of the four people. If it is a centralized system and there is an alliance leader, such as panghu (equivalent to a central server), then there is no doubt about their victory, because it is very easy to reach an agreement on the attack time. As long as panghu calls Daxiong, Xiaofu and Jingxiang to have a meeting to discuss it, Even if we have different opinions, panghu can make a final decision. Now let's go back to the assumption of Byzantine Generals. In a distributed network without trust, what are the odds of four generals winning< br />
?
first of all, e to the lack of trust between the four generals, the possibility of gathering in a small dark room for a conspiracy meeting is ruled out (what if they are kidnapped by panghu in a small dark room?); Secondly, since there is no leader, the opinions of all four people will be equally valued. In this case, the four generals could only negotiate the attack time by sending messages between their camps by messenger. For example, if Daxiong thinks 6 a.m. is a good time to launch an attack, he will send messengers to tell panghu, Xiaofu and Jingxiang their opinions. At the same time, panghu may think it's better to launch a surprise attack at 9 p.m., Xiaofu prefers to launch an attack at 3 p.m., and Jingxiang hopes that it will be 10 a.m., and the three of them will send their own messengers at the same time. In this way, after the first round of communication, each of the four generals had four attack times to choose from, and each of them had to inform the other three of their chosen time in the next round of communication. Because four people make decisions independently, there are 256 possible final choices. Only when more than three people choose the same time can consensus be reached, and there are only 64 such results, that is to say, the probability of reaching consensus is only 1 / 4. This is only the case of four generals. What if the number of generals is 10, 100 or 1000? With a little calculation, we can see that as the number of people increases, the hope of reaching a consensus will become increasingly dim
change the general in the above example into the node in the computer network, the messenger into the communication between nodes, and the attack time into the information that needs to reach a consensus. Then you can understand the dilemma described by the consensus problem. The ability to reach a consensus is self-evident for a payment system. If you remit a sum of money to your family to buy a car and go to the bank the next day for verification, the counter will tell you "about how much money you remit, there are three versions of records in our system". Obviously, you dare not deposit money in such a bank. Before the emergence of bitcoin, the consensus problem is difficult to be solved perfectly. In order to reach a consensus, we need to adopt a centralized system (unless the nodes meet certain conditions), and in order to decentralize the consensus, we can't guarantee it. So how does blockchain technology solve this problem Pay attention to the official account weoption, reply to "block chain", you can view the full text.
10. The formal expression of Byzantine general problem (hereinafter referred to as "consensus problem") is: how to reach a consensus on information in a distributed network that is not based on trust? This statement sounds obscure, but its essence is not complicated. Although the following examples are not completely consistent with the consensus issue, they are helpful for our understanding [9]. Imagine that in Byzantine times, there was a rich city-state with all kinds of gold, silver, jewelry, silk and satin. Its Lord Doraemon enjoyed all the luxury and glory. On the outskirts of the city-state, four Byzantine Generals, Daxiong, panghu, Xiaofu and Jingxiang, coveted Doraemon's wealth, so they decided to join hands to capture Doraemon's city-state. According to the strength comparison between the two sides, more than half of the generals must attack at the same time to defeat the enemy, so the winning condition is that at least three of the four can agree on the attack time. What are the odds of the four generals? The answer to this question depends on the cooperation mode of four people. If it is a centralized system and there is an alliance leader, such as panghu (equivalent to a central server), then their victory is not in doubt, because it's very easy to reach an agreement on the attack time, as long as panghu calls Daxiong, Xiaofu and Jingxiang to have a meeting to discuss, Even if we have different opinions, panghu can make a final decision. Now let's go back to the assumption of Byzantine Generals. In a distributed network without trust, what are the odds of four generals winning? First of all, e to the lack of trust among the four generals, the possibility of gathering in a small dark room for a conspiracy meeting was ruled out (what if they were kidnapped by panghu in a small dark room?); Secondly, since there is no leader, the opinions of all four people will be equally valued. In this case, the four generals could only negotiate the attack time by sending messages between their camps by messenger. For example, if Daxiong thinks 6 a.m. is a good time to launch an attack, he will send messengers to tell panghu, Xiaofu and Jingxiang their opinions. At the same time, panghu may think it's better to launch a surprise attack at 9 p.m., Xiaofu prefers to launch an attack at 3 p.m., and Jingxiang hopes that it will be 10 a.m., and the three of them will send their own messengers at the same time. In this way, after the first round of communication, each of the four generals had four attack times to choose from, and each of them had to inform the other three of their chosen time in the next round of communication. Because four people make decisions independently, there are 256 possible final choices. Only when more than three people choose the same time can consensus be reached, and there are only 64 such results, that is to say, the probability of reaching consensus is only 1 / 4. This is only the case of four generals. What if the number of generals is 10, 100 or 1000? With a little calculation, we can see that as the number of people increases, the hope of reaching a consensus will become increasingly dim. Change the general in the above example to the node in the computer network, the messenger to the communication between nodes, and the attack time to the information that needs to reach a consensus. Then you can understand the dilemma described by the consensus problem. The ability to reach a consensus is self-evident for a payment system. If you remit a sum of money to your family to buy a car and go to the bank the next day for verification, the counter will tell you "about how much money you remit, there are three versions of records in our system". Obviously, you dare not deposit money in such a bank. Before the emergence of bitcoin, the consensus problem is difficult to be solved perfectly. In order to reach a consensus, we need to adopt a centralized system (unless the nodes meet certain conditions), and in order to decentralize the consensus, we can't guarantee it. So how does blockchain technology solve this problem?
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