In bitcoin key

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

2. I'll give you my address (address). You can find my zip code (public key). You can write to me with my zip code (public key) + address. The mail will be sent to my mail cabinet. I'll open the mail cabinet (private key) with the key I have. The key of express cabinet is stored in my wallet (wallet)
1. The mail cabinet is stolen (the database is stolen)
2. The key is stolen (the private key is stolen)
3. Knowing my home address (the public key is stolen), the lock of the mail cabinet is opened violently (the private key is cracked violently).

3.

Bitcoin, as a virtual encrypted network data currency, has been soaring in recent years, and has been concerned by many people. Criminals also focus on this piece of fat, using bitcoin to start a new type of crime

In my opinion, bitcoin, a virtual currency, still needs to be more cautious in investment to avoid falling into the trap of criminals

4. First of all, let's talk about the background. The basic principle of bitcoin "account" is key public key address. You can roughly understand it as "key box box number". Now is to start from the box number or box to crack the key
there are basically two kinds of attacks, one is dictionary attack, the other is brute force attack
dictionary attack is to use common passwords and their simple variants as keys one by one. As long as your pass phrase is not hard enough, the possibility of successful attack is very high. So if you want to use this, you need to popularize the knowledge of cryptography first, and don't think it's very safe to add a long password
if you don't use the wallet generated by pass phrase, you can only crack it violently, which is equivalent to enumerating all the possible keys. At present, this is impossible, even if the electronic computer is becoming more and more powerful. However, quantum computer can do it theoretically, but don't worry too much. If such a powerful quantum computer comes out, it will not only endanger bitcoin
at the same time, bitcoin has a second layer of protection: if an address only accepts bitcoin but does not output it, its public key is confidential, that is to say, no one else can see the box, only the box number. At present, the process of decing the box from the box number can't even be done by quantum computer. In other words, if there is a quantum computer, bitcoin has a last line of Defense: it's temporarily safe to transfer your money to a new address
finally, some time ago, the wallet generated by the Android client was attacked because of a bug in the underlying random number generator. In fact, this function is not random securerandom, which Google quickly admitted and fixed. It's hard to say whether this kind of thing will happen again, but I don't think we need to worry too much.

5. I'll give you my address (address). You can find my zip code (public key). You can write to me with my zip code (public key) + address. The mail will be sent to my mail cabinet. I'll open the mail cabinet (private key) with the key I have
1. The mail cabinet is stolen (the database is stolen)
2. The key is stolen (the private key is stolen)
3. Knowing my home address (the public key is stolen), the mail cabinet lock is opened violently (the private key is cracked violently).

6. It depends on what wallet you use.
bitcoin QT generally has 100

7. The private key is a secret data block that proves that you have the right to consume bitcoin from a specific wallet. It is implemented through a cryptographic signature. If you are using wallet software, your private key is stored in your computer; If you are using an online wallet, your private key is stored on a remote server. Don't disclose private keys, because they allow you to consume the bitcoin in the corresponding bitcoin wallet
digital currencies such as Ruitai, doggy and Wright all have private keys.