Questions about digital currency

1.

Yin Zhentao, deputy director of the law and Finance Research Office of the Financial Research Institute of the Chinese Academy of Social Sciences, said that digital currency faces two risks. The first is the technical level. Digital currency relies on blockchain technology and a system, which will make it suffer from security impact, such as hacker attacks on computer systems. We have seen many practical problems in this process

Zhao Zhanzhan, a special researcher of intellectual property research center of China University of political science and law, believes that digital currency has anonymity, quickness and irrevocability. In addition, bitcoin and other digital currencies have high circulation in the world, so many criminals use digital currency as a new money laundering channel. Moreover, there are many different ways to realize money laundering through digital currency. Generally speaking, the probability of new money laundering being found and investigated is lower than before. Many countries have no effective means and technology to combat money laundering through digital currency. These factors lead to criminals prefer this way of money laundering

2. Legal risks faced by digital currency: (1) at the macro level, there are legal risks, systematic risks and consumer protection. At present, the legislative problems of e-commerce and e-payment have not been solved, the concept of e-currency and related provisions need to be clarified, and many laws and regulations have not been followed up. Secondly, there is a systemic risk caused by the collapse of a single issuing institution. If a certain issuing institution loses confidence in e-money e to its poor management, other e-money issuing institutions will also face run risk. Moreover, in the absence of standardized supervision, it is difficult for the public to effectively identify the qualification and credit level of issuers. How to effectively prompt risks and protect the rights and interests of the public has become a difficult problem. In addition, the concealment, rapidity and cross-border nature of Internet payment make e-money an inevitable money laundering tool for criminals 2 At the micro level, there are technical risks and credit risks in the main body of e-money issuance. The issuers of e-money in China include banks, non bank financial institutions, Internet enterprises and other enterprises. Due to the weak financial professional foundation of some issuers, especially the lack of mandatory technical security standards in China, there are serious management loopholes and security risks in e-money issuers. System software or hardware failures will affect the availability of e-money. Secondly, the unreasonable structure of assets and liabilities and high concentration of investment will lead to the lack of liquidity and the risk of default. In addition, the payment and circulation of e-money rely heavily on all kinds of networks, and there are all kinds of operational risks, such as deliberate embezzlement of other people's accounts, internal crimes of issuing institutions and malicious intrusion of hackers, which will damage the interests of e-money holders. Bitcoin, Ruitai and other digital currencies are suitable.

4. Digital currency does not worry about counterfeit money. If it is paper money, it worries about counterfeit money. I don't worry. I didn't take any money with me.

5. Hacker attack
bitcoin can exist only because both sides of the transaction recognize its transaction value, so anyone can design virtual currency independently. Ars technica, for example, announced this week that it would create its own cryptocurrency, arscoin[ 2]

Cohen believes that the main threat to digital cryptocurrency is how to keep it safely, and the loss of mt.gox bitcoin once again highlights this problem. Recently, the US Congress has also launched a debate on digital cryptocurrency. Some members believe that the supervision of the bitcoin should be strengthened to avoid risks. Another congressman, Jared polis, believes that the US dollar has similar defects to bitcoin, so if bitcoin is banned, then the US dollar note should also be banned[ 2]

digital currency has a short history of development in the world, but it develops rapidly. Many countries are trying to sum up experiences and lessons through official or non-governmental efforts.

6. Version of block version

hash value of previous block: prev_ Hash

the hash tree value of the transaction to be written: Merkle_ Root

update time: ntime

current difficulty: nbits
the process of mining is to find x to make
sha256 (version + prev)_ hash + merkle_ root + ntime + nbits + x )) < Target

the range of X in the above formula is 0 ~ 2 ^ 32, which can be calculated according to the current difficulty. In addition to x, you can also try to change Merkle_ Root and ntime. Because of the hash feature, finding such an X can only be brute force search

once you find x, you can broadcast a new block, and other clients will verify whether your block is legal. If your block is accepted, the first transaction in each block must be to send the newly generated 25 bitcoins to an address. Of course, you will set the address to your own address to get the 25 bitcoins< Every transaction record of bitcoin from the beginning to now has been saved on the network. The whole bitcoin network maintains a huge transaction record file (about 12g now). The average update cycle of this file is 10 minutes. The newly added transaction record is called a block, and this huge file is composed of a series of blocks, called block chain.

Why are 25 bitcoins
this is the rule. At first, there are 50 bitcoins. For each half of the remaining bitcoins, the income will be halved. In this way, the total amount of bitcoins that can be generated will approach 21 million. If you still claim to have g up 50 bitcoins, it will not be accepted by other clients, and the block will be g up in vain

how to ensure that the average update cycle is 10 minutes
the smaller the target, the more difficult it is to solve X. for every 2016 blocks (about 14 days) generated, the network will adjust the target according to the average interval of new blocks generated ring this period

is it the fastest person who always solves it first
No. You always want to take the mining income as your own, so when everyone calculates, the address to send the mining income is different, so Merkle_ Root is different, that is to say, everyone starts to solve from a different initial state

how to solve it at the same time
there will be a fork in the block chain. Some clients accept a and some accept B. until a branch becomes longer, everyone will choose the longer branch. If what you dig is unfortunately not selected, your mining income will be invalid

since I choose a longer branch, how can I solve it with very low difficulty
the client finds the most difficult and longest branch among many branches

are these calculations wasted
if you want to spend a sum of money twice, you need to do so. Dig a new block, but hide not broadcast, and continue to mine. Find merchant a, pay bitcoin, and let others on the network dig the block and write the transaction record. Find merchant B, pay bitcoin, and write the block you g. If you can get two blocks first and broadcast them, everyone will take your longer branch as the current block chain, and the bitcoin received by merchant a will not be recognized. In this way, the probability of successful attack depends on the speed of hash calculation. If the computing power of the whole network is high enough, the success rate of such attacks is very low or the cost is very high.

7. I can tell you that the so-called digital currency is that the swindlers try to change the real gold and silver in your pocket into the digital currency that they say is inferior to even the Ming coin. At least the Ming coin can be seen and touched. What kind of people sell it to you!