How many bits of bitcoin public key
Publish: 2021-05-28 06:09:16
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. Each person's wallet has more than one bitcoin address, and each bitcoin address represents a certain number of bitcoins. The bitcoin address is generated through a public key hash (rpiemd + Sha), and the public key is generated by the private key through elliptic curve (ECC). The private key is kept in the bitcoin wallet and should not be disclosed. The public key, together with the bitcoin address, needs to be publicly released through transaction records ring payment transactions, and the effectiveness of payment transactions is verified by the blockchain system.
3. The digital signature of bitcoin is an anti-counterfeiting string generated only by the transferor of bitcoin transfer. By verifying the digital string, on the one hand, it proves that the transaction is initiated by the transferor, on the other hand, it proves that the transaction information has not been changed in the transmission
digital signature shortens transaction information to a fixed length string through digital digest technology. For example, when Niuniu initiates a bitcoin transfer, it needs to first digest the transaction into a string, and then encrypt the digest with its own private key to form a digital signature. After the completion, Niuniu needs to broadcast the original (transaction information) and digital signature to the miner, and the miner uses Niuniu's public key for verification. If the verification is successful, it means that the transaction is indeed sent by Niuniu, and the information has not been changed
at the same time, the private key encrypted by digital signature is inconsistent with the public key decrypted by digital signature, so asymmetric encryption technology is adopted. It looks so complicated. In fact, you only need to input the private key to complete the transfer instantly!
digital signature shortens transaction information to a fixed length string through digital digest technology. For example, when Niuniu initiates a bitcoin transfer, it needs to first digest the transaction into a string, and then encrypt the digest with its own private key to form a digital signature. After the completion, Niuniu needs to broadcast the original (transaction information) and digital signature to the miner, and the miner uses Niuniu's public key for verification. If the verification is successful, it means that the transaction is indeed sent by Niuniu, and the information has not been changed
at the same time, the private key encrypted by digital signature is inconsistent with the public key decrypted by digital signature, so asymmetric encryption technology is adopted. It looks so complicated. In fact, you only need to input the private key to complete the transfer instantly!
4. Applications that support bitcoin protocol can correctly convert this string into the private key of bitcoin, and then convert the public key to get an address. If there is a corresponding bitcoin on the address, you can use the private key to spend the above bitcoin.
5.
There is no limit on the total amount of use, but there is a limit in theory. It depends on the number of public key digits. A simple high school permutation can calculate the number (an astronomical number); A public key is a very good random number generator. Under the restriction of long enough public key, it is impossible to have plicate public key in theory
the following is the calculation comparison of different length keys in intercepted professional books
6. 1. First of all, you need to know the concepts of public key and private key (you don't need to read this part already)
public key and private key are terms in asymmetric encryption of modern cryptography. They usually encrypt information with public key and decrypt information with private key. Why? Because when you watch TV dramas, telegrams are encrypted symmetrically. The disadvantages of this encryption method are obvious. If someone knows the key and encryption method, they can decrypt the telegrams according to the encryption method. Until asymmetric encryption, the situation has changed. Public key is the key that can be made public all over the world. For example, when you communicate with Google, you encrypt with the 1024 bit public key given by Google and send it to Google. Only he has the corresponding private key, and only he can decrypt it, so the communication security is ensured
2. Bitcoin mainly uses ECDSA, which is the elliptic curve signature algorithm, This algorithm has two characteristics. Note that these two points are very important to the following
A. as long as you know the private key, you can calculate the corresponding public key
B. If you have signed something with the private key, you can use the public key to calculate whether you signed it or not
3. After knowledge preparation, let's start with the transaction of bitcoin. In fact, bitcoin has no wallet, only transaction bills, and the whole bitcoin is a lot of transaction bills
for example:
bill 1 transfers from a to B to XXX bitcoin
Bill 2 transfers from B to C and D to XXX bitcoin
bill 3 transfers from C to e to XXX bitcoin
.... Anyone who downloads the client can receive all the bills from the day when bitcoin was established, so as long as all the bills are downloaded, they will naturally know how much money should be left on each account (think carefully here)
4. The account of bitcoin is the public key mentioned just now
5, Here is the core part!!! Each bill is a piece of data. After you sign it, it will be sent to the whole network, and the data structure will be reversed into easy to understand Chinese. The explanation is as follows:
from (who sent it, including two parts)
previous TX: the ID of the bill for which you want to spend the money, that is to say, any money you spend should have been transferred to you, You need to show the ID of the bill
scriptsig: your signature for this transaction is to hash the bill with your private key, only you can do this hash
to (who accepts, including two parts)
value: how much to send
scriptpubkey: the public key of the other party, and the bitcoin account is a public key
6, How to send it? Bitcoin communication is not so complicated. You can compare it to IRC channel, but different from ordinary "IRC", any client is an "IRC" server. When you start the client, you will receive the client address with public IP around, that is, the "server" list. This list is constantly refreshed, and it is all other bitcoin users, So when you shout a word in this "IRC", people around you will hear it and spread it all over the world
7. After sending the signature to the whole world, all the clients who receive this list will verify whether your signature is correct, whether you sent it, and whether you have so much money (according to the historical transaction, you can calculate how much money you have to spend)
if you have calculated this transaction, it's OK, Basically, the transfer is successful
8. In fact, the other party has accepted bitcoin, but in order to spend it, he must have the private key corresponding to the address (public key). So he can fill in the from header of a form. Previous TX is the serial number of the transaction just now. Scriptsig fills in the hash signed with his private key...
public key and private key are terms in asymmetric encryption of modern cryptography. They usually encrypt information with public key and decrypt information with private key. Why? Because when you watch TV dramas, telegrams are encrypted symmetrically. The disadvantages of this encryption method are obvious. If someone knows the key and encryption method, they can decrypt the telegrams according to the encryption method. Until asymmetric encryption, the situation has changed. Public key is the key that can be made public all over the world. For example, when you communicate with Google, you encrypt with the 1024 bit public key given by Google and send it to Google. Only he has the corresponding private key, and only he can decrypt it, so the communication security is ensured
2. Bitcoin mainly uses ECDSA, which is the elliptic curve signature algorithm, This algorithm has two characteristics. Note that these two points are very important to the following
A. as long as you know the private key, you can calculate the corresponding public key
B. If you have signed something with the private key, you can use the public key to calculate whether you signed it or not
3. After knowledge preparation, let's start with the transaction of bitcoin. In fact, bitcoin has no wallet, only transaction bills, and the whole bitcoin is a lot of transaction bills
for example:
bill 1 transfers from a to B to XXX bitcoin
Bill 2 transfers from B to C and D to XXX bitcoin
bill 3 transfers from C to e to XXX bitcoin
.... Anyone who downloads the client can receive all the bills from the day when bitcoin was established, so as long as all the bills are downloaded, they will naturally know how much money should be left on each account (think carefully here)
4. The account of bitcoin is the public key mentioned just now
5, Here is the core part!!! Each bill is a piece of data. After you sign it, it will be sent to the whole network, and the data structure will be reversed into easy to understand Chinese. The explanation is as follows:
from (who sent it, including two parts)
previous TX: the ID of the bill for which you want to spend the money, that is to say, any money you spend should have been transferred to you, You need to show the ID of the bill
scriptsig: your signature for this transaction is to hash the bill with your private key, only you can do this hash
to (who accepts, including two parts)
value: how much to send
scriptpubkey: the public key of the other party, and the bitcoin account is a public key
6, How to send it? Bitcoin communication is not so complicated. You can compare it to IRC channel, but different from ordinary "IRC", any client is an "IRC" server. When you start the client, you will receive the client address with public IP around, that is, the "server" list. This list is constantly refreshed, and it is all other bitcoin users, So when you shout a word in this "IRC", people around you will hear it and spread it all over the world
7. After sending the signature to the whole world, all the clients who receive this list will verify whether your signature is correct, whether you sent it, and whether you have so much money (according to the historical transaction, you can calculate how much money you have to spend)
if you have calculated this transaction, it's OK, Basically, the transfer is successful
8. In fact, the other party has accepted bitcoin, but in order to spend it, he must have the private key corresponding to the address (public key). So he can fill in the from header of a form. Previous TX is the serial number of the transaction just now. Scriptsig fills in the hash signed with his private key...
7. The wallet will be decrypted before 18:20:00. Permanent decryption may be able to back up the wallet when it is decrypted I haven't tried it. You can try it.)
8. Bitcoin
private key
is a 256 bit
random number
, which is generated by SHA-256 algorithm
private key
is a 256 bit
random number
, which is generated by SHA-256 algorithm
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