Frequently asked questions and answers of blockchain exchange
(1) introction to price limit trading mode:
price limit buying / selling refers to that the user sets the price and quantity of a buying / selling currency to generate an order. The system will automatically match the buying and selling orders in the market. Once the price set by the user is reached, the transaction will be automatically executed according to the price priority time priority
(2) introction to market price transaction mode:
market price purchase refers to that the user sets a total amount and generates a commission order, from the beginning of selling to the completion of the total amount transaction. Selling at market price means that the user sets the total number of currencies to be sold, generates a commission document, and matches it from the beginning of buying to the completion of the total number of currencies transaction
(3) introction to currency transaction mode:
currency transaction is mainly aimed at the transaction between virtual digital assets and virtual digital assets, in which one currency is used as the pricing unit to purchase other currencies, and the currency transaction rule is also to complete matching transaction according to price priority and time priority< (4) introction of C2C transaction mode:
both parties of the transaction release the transaction information of buying or selling currency on the C2C transaction platform according to the demand. The buyer and the seller complete the transaction offline according to the agreed payment method, and the platform, as an intermediary, charges a certain proportion of the handling fee from each successful transaction< (5) introction to OTC OTC trading mode:
it is a set of platform for offline purchase of digital currency independent of the exchange. Businesses can publish purchase / sale advertisements on the platform, and purchase / sale users can purchase / sell through offline transfer. After the transfer, the platform will transfer the frozen digital currency to the buyer, The technical construction problems of the exchange can be found on the Internet
(6) introction to trading mining mode:
the exchange platform returns a certain proportion of the commission income to the platform users, and the platform coin is returned. According to the principle of distribution proportion, the exchange platform takes a certain proportion as the mining reward. Mining refers to trading on the platform to graally unlock the platform coin until all the platform coins are fed back. This kind of play has a strong attraction to attract users< (7) introction to futures / contract trading mode:
futures contract is an agreement that the buyer agrees to receive certain assets at a specific price after a specified period of time, and the Seller agrees to deliver certain assets at a specific price after a specified period of time. The price that both parties agree to use in future trading is called futures price. The designated r period in which both parties have to trade in the future is called the settlement date or delivery date. The assets agreed to be exchanged by both parties are called "subject matter"< (8) introction to the trading mode of perpetual contract:
perpetual contract is a new and unique contract. The goal of the contract is to allow high leverage to the market conditions of the spot market. The contract will not be delivered and can follow the reference price index through various mechanisms. The contract evolved from the traditional futures contract, but the perpetual contract has more obvious advantages and greater risks than the traditional futures contract, supporting long short two-way trading, opening a 100 times leverage, permanent position, premium and so on.
e to the use of Distributed Accounting and storage, there is no centralized hardware or management organization, the rights and obligations of each node are equal, and the data blocks in the system are jointly maintained by the nodes with maintenance function in the whole system.
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blockchain is a distributed account book technology, and digital currency is currently the main application mode of blockchain technology
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digital currency, based on the characteristics of blockchain, such as decentralization, traceability, non deletion and modification of records, confidentiality, convenient and rapid transaction, can be used as the carrier of asset digitization to a certain extent. Digital currency provides a feasible tool for asset digitization, safe, convenient and transparent transaction
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digital currency is illegal in China. In 2017, many ministries and commissions of the state have issued relevant issues, please search online
Relevant national leaders pointed out that blockchain technology is an important breakthrough for independent innovation of core technology. Therefore, more and more attention will be paid to the application of blockchain technology, and the central bank is also studying DCEP, but it is not clear when digital currency will enter the legal application -
a few countries, such as the United States, Japan and Singapore, are tolerant of digital currency:
1) the United States: there are usdt, ETH, and Libra in the future
2) Japan: in April 2017, Japan implemented the revised capital settlement law, stipulating that digital currency and Japanese yen are legal tender and can be traded with each other
3) Singapore: Singapore is tolerant of digital currency, and it has become a common practice for Singaporeans to invest in digital currency< br />
1. Decentralized: the left side of Figure 1 describes the centralized characteristics of today's financial system, and the right side describes the emerging decentralized financial system, which has no intermediary, and the rights and obligations of all nodes are equal. Any node that stops working will not affect the overall operation of the system
2. Trustworthiness: all nodes in the system can trade without trust, because the operation of the database and the whole system is open and transparent, and nodes cannot cheat each other within the rules and time range of the system
3. Collective maintenance: the system is maintained by all the nodes with maintenance function, and all the people in the system participate in the maintenance work together
4. Reliable database: every node in the system has the latest complete database , so it is invalid to modify the database of a single node, because the system will automatically compare and think that the same data record that appears most times is true
the blockchains of bitcoin, Ethereum and decent all have these characteristics.
you mean platform trading. Domestic illegal, international and mostly deceptive, you find the well-known ones. There is a special introction to blockchain network. Remember to be legal, otherwise you can't withdraw cash and it's useless to make money.
Let's suppose villagers Lao Wang and Xiao Li. Lao Wang borrowed some money from Xiao Li, who wrote it in an IOU signed by both parties. A few days later, Lao Wang denied the existence of borrowing money and claimed that Xiao Li forged the paper. Xiao Li can't argue because he finds it difficult to prove that Lao Wang actually owes him money
in this example, Lao Wang and Xiao Li are two nodes
now assuming the same scenario, there are many pairs of people trading with each other in the village. The only evidence for each pair is the IOU. If one party fails, it will be difficult to do so. Seeing this scene, the village head came up with a solution. He suggested using a common notebook for the whole village to record all the transactions. Due to the high prestige of the village head, the villagers unanimously decided to let the village head keep this important transaction book. Each transaction, the villagers go to the village head's home, let the village head witness and record, each transaction is written into a notebook, and then safely saved. That notebook can be called a database
because this notebook is very important, the village head locked it in the safe. However, there are always some problems. Sometimes, the village head will accidentally sprinkle ink on the paper, making some transaction records illegible. This is called a single point of failure. The thief knows that there is an important notebook in the safe of the village head's house. He tries his best to steal it. This is called hacking
until one day, the village head's son owed others a lot of money, so the village head secretly deleted his son's debt entry. In this way, the village head's son "does not owe money."
when the villagers knew this, they began to question the fairness and authority of the village head. So some people put forward a new idea:
abolish the power of the village head, which is called decentralization. Let all villagers keep a notebook, and the transaction records are copied and distributed, which is called distributed database. Therefore, if there are n people in the village, there are n notebooks, that is, n nodes. Every time there is a trade between any two people, all the people in the village get together and record it in their notebooks. And no one can cover the sky. This is called decentralization
they also decided that they would never delete the mentioned transactions from their notebooks, which is irreversible. For example, Lao Wang borrowed a sum of money from Xiao Li before, but in the twinkling of an eye, he wants to return the money. Then the transaction book will not delete the previous borrowing record, but write a new repayment record, so there are two records
next, let's try to break this rule. What if we bribe Lao Wang to change his notebook? It's not feasible, because the next time the villagers meet, they find that Lao Wang's notebook is different from everyone else's, so the villagers notice that Lao Wang may be engaged in an indescribable transaction, and decide to abolish Lao Wang's transaction record and kick Lao Wang out of the organization
What if you try to bribe all the villagers? It's too expensive
the characteristic of this model is that greedy people need to pay a lot to attack the rules. He will find it more profitable to follow the rules
a smart child in the village suggested that each transaction data be called "block" and linked into a "chain" in chronological order, which is called blockchain
the exchange I am familiar with uses the currency payment enterprise version, which is a digital asset security payment system. The general principle is to store the private key locally, bind the exchange's unique client with multiple encryptions, and the system itself does not save the private key, so as to prevent the possibility of digital currency theft from the source. It is also convenient to operate, with unified management of Multi Chain and multi currency and convenient reconciliation
hope to adopt.
in a narrow sense, blockchain is a kind of chained data structure, which is composed of data blocks connected in sequence according to the time sequence, and is a distributed account that can not be tampered with and forged by cryptography. In a broad sense, blockchain technology is a new distributed infrastructure and computing paradigm, which uses blockchain data structure to verify and store data, uses distributed node consensus algorithm to generate and update data, uses cryptography to ensure the security of data transmission and access, and uses intelligent contract composed of automated script code to program and operate data
blockchain and big blockchain are not the same concept. Big blockchain should be the name of a company. Bitcoin, Ethereum and decent are all successful cases of blockchain technology.
of course, blockchain developers can also take some measures
one is to use professional code audit services,
the other is to understand the security coding specifications and take preventive measures
the security of cryptographic algorithm
with the development of quantum computer, it will bring great security threat to the current cryptosystem. Blockchain mainly relies on elliptic curve public key encryption algorithm to generate digital signature for secure transactions. Currently, the most commonly used ECDSA, RSA, DSA, etc. can not withstand quantum attacks in theory, and there will be greater risks. More and more researchers begin to pay attention to cryptographic algorithms that can resist quantum attacks
of course, in addition to changing the algorithm, there is another way to improve the security:
refer to bitcoin's treatment of public key address to rece the potential risk of public key disclosure. As users, especially bitcoin users, the balance after each transaction is stored in a new address to ensure that the public key of the address where bitcoin funds are stored is not leaked
security of consensus mechanism
the current consensus mechanisms include proof of work (POW), proof of stake (POS), delegated proof of stake (dpos), practical Byzantine fault tolerance (pbft), etc
POW faces 51% attack. Because POW depends on computing power, when the attacker has the advantage of computing power, the probability of finding a new block will be greater than that of other nodes. At this time, the attacker has the ability to cancel the existing transaction. It should be noted that even in this case, the attacker can only modify his own transaction, but not the transaction of other users (the attacker does not have the private key of other users)
in POS, attackers can only attack successfully when they hold more than 51% of the token, which is more difficult than 51% of the computing power in pow
in pbft, when the malicious nodes are less than 1 / 3 of the total nodes, the system is secure. Generally speaking, any consensus mechanism has its own conditions. As an attacker, we also need to consider that once the attack is successful, the value of the system will return to zero. At this time, the attacker does not get any other valuable return except destruction
for the designers of blockchain projects, they should understand the advantages and disadvantages of each consensus mechanism, so as to select an appropriate consensus mechanism or design a new consensus mechanism according to the needs of the scene
security of smart contract
smart contract has the advantages of low operation cost and low risk of human intervention, but if there are problems in the design of smart contract, it may bring great losses. In June 2016, the Dao, the most popular funding project of Ethereum, was attacked. The hacker obtained more than 3.5 million Ethereum coins, which later led to the bifurcation of Ethereum into Eth and etc
there are two aspects of the proposed measures:
one is to audit the security of smart contracts, and the other is to follow the principles of smart contract security development
the security development principles of smart contract are: be prepared for possible errors to ensure that the code can correctly handle the bugs and vulnerabilities; Release smart contracts carefully, do well in function test and security test, and fully consider the boundary; Keep smart contracts simple; Pay attention to the threat intelligence of blockchain and check and update in time; Be clear about the characteristics of blockchain, such as calling external contracts carefully
security of digital wallet
there are three main security risks in digital wallet: first, design defects. At the end of 2014, a user lost hundreds of digital assets e to a serious random number problem (repeated r value). Second, the digital wallet contains malicious code. Third, the loss of assets caused by the loss or damage of computers and mobile phones
there are four main countermeasures:
one is to ensure the randomness of the private key
the second is to verify the hash value before software installation to ensure that the digital wallet software has not been tampered with
the third is to use cold wallets
the fourth is to back up the private key.