Same issue of 28 bitcoin

1. On November 1, 2008, a self styled Satoshi Nakamoto posted a research report on a secret cryptography discussion group. The report expounded his new idea of electronic currency bitcoin came out
on January 3, 2009, Nakamoto g up the first batch of 50 bitcoins on a small server in Helsinki, Finland
on May 21, 2010, the first bitcoin transaction: Laszlo hanyecz, a Florida programmer, bought a $25 pizza coupon with 10000 BTC
on July 16, 2010, the price of BTC rose by US $0.08 from US $0.008. The first sharp price fluctuation shows the rise of new things
on July 17, 2010, the first bitcoin platform was established
on November 6, 2010, the price on mtgox reached $0.5, and the bitcoin economy reached $1 million
on December 7, 2010, the first portable device to portable device transaction was realized on Nokia 900, with a transaction volume of 0.42btc
on February 9, 2011, the price reached US $1 for the first time, which is equivalent to US $1. The news that BTC is equivalent to us dollar has been widely reported by the media, which has aroused people's great attention, and the number of new users has increased greatly. In the next two months, bitcoin and pound sterling, Brazilian currency, Polish currency exchange trading platform has opened
on March 18, 2011, the BTC / USD exchange rate hit a seven week low, falling to US $0.7
on August 20, 2011, the first bitcoin conference and World Expo were held in New York. Among Google trend counties, bitcoin's attention reached a new high, with a price of $11 at that time
on November 14, 2011, the price of bitcoin hit a new half year low of $1.99
on September 15, 2012, the bitcoin conference was held in London. At this time, the price of bitcoin was $11.8
on September 27, 2012, bitcoin fund was founded, and the price of bitcoin was $12.46
on November 25, 2012, the first bitcoin conference in Europe was held in Prague, Czech Republic. At this time, the price of bitcoin was $12.6
on February 19, 2013, bitcoin client v8.0 was released. At this time, the price of bitcoin was $28.66
on April 10, 2013, BTC set a record high price of $110
on May 9, 2013, BTC Chinese, the largest bitcoin reporting website www.sosobtc.com The company obtained the investment fund Union Square's US $5 million round a investment, and the price of bitcoin was US $112.09 at this time< On May 28, 2013, the Department of Homeland Security banned the virtual currency service of Liberty Reserve, a Costa Rican exchange company, for its suspected xiqian and unlicensed fund transfer business, U.S. prosecutors said that this will become the largest international xiqian lawsuit in history, with the scale of absorbing money reaching 6 billion US dollars. A large number of users, including China, will lose all their money. At this time, the price of bitcoin is 128 US dollars
in June 2013, Netcom said that the United States will withdraw from qe3, deflationary bitcoin and quantitative easing monetary policy, which are the relationship between the two
on June 27, 2013, the German Conference made a decision: holding bitcoin for more than one year will be tax-free, which is considered by the instry to recognize the legal status of bitcoin. At this time, the price of bitcoin is $102.24
on June 28, 2013, mtgox obtained the monetary service license issued by the financial crime enforcement network office of the U.S. Department of the Treasury. Transaction standardization may mean that bitcoin is on the right track, government risk is reced, and its pace of integration into the display economy will be accelerated. At the same time, it will play an exemplary role in other virtual currencies. At this time, the price of bitcoin is $97.99
on November 28, 2013, the bitcoin trading price of Mt. GOx, a popular bitcoin exchange, broke through $1000, reaching a record high of $1073
on November 29, 2013, the trading price of bitcoin on Mt. GOx, a popular exchange, hit a record high of US $1242, while the price of gold was US $1241.98 an ounce, surpassing that of gold for the first time.

2. 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

3. 1. The smallest bitcoin unit is 1 Cong, or 0.00000001btc
2. The concept of bitcoin was first proposed by Nakamoto in 2009. According to Nakamoto's idea, open source software was designed and released, and P2P network was built on it. Bitcoin is a kind of P2P digital currency. Point to point transmission means a decentralized payment system
3. Unlike most currencies, bitcoin does not rely on specific currency institutions. It is generated by a large number of calculations based on specific algorithms. Bitcoin economy uses a distributed database composed of many nodes in the whole P2P network to confirm and record all transactions, and uses cryptography design to ensure the security of all aspects of currency circulation. The decentralized nature and algorithm of P2P can ensure that it is impossible to artificially manipulate the value of bitcoin through mass proction. The design based on cryptography can make bitcoin only be transferred or paid by the real owner. This also ensures the anonymity of money ownership and circulation transactions. The biggest difference between bitcoin and other virtual currencies is that the total amount of bitcoin is very limited and it has a strong scarcity. The monetary system used to have no more than 10.5 million in four years, after which the total number will be permanently limited to 21 million.