Blockchain involves sensitive issues

1. The relationship between blockchain and big data is not very big. The main purpose of big data is to manage massive data, and the core of blockchain is to achieve high security and high reliability of data without centralized intermediary accounting. Therefore, blockchain and big data do not conflict with or replace each other. They are completely different solutions for data in different scenarios.

2.

Although driven by the influx of capital and talents, the blockchain instry ushered in rapid development, but as an emerging instry, the frequent warning of its security vulnerabilities caused people to worry about the risk of blockchain

Yu Kequn, director of the national information technology security research center, pointed out that the emergence of blockchain has brought people a lot of expectations for privacy exposure, data leakage, information tampering, network fraud and other issues. However, there are still many challenges in the security of blockchain

Li Bin, assistant director of China Information Security Evaluation Center, analyzed that the current blockchain is divided into three types: public chain, private chain and alliance chain. No matter which type, it faces security challenges in algorithm, protocol, use, time limit and system. What is particularly critical is that the current blockchain is still facing 51% attack problem, that is, nodes can successfully tamper and forge blockchain data by mastering more than 51% of the network examples

it is worth noting that in addition to external malicious attack risk, blockchain also faces the threat of its endogenous risk. Yu Kequn reminded that how to build a complete security application system around the equipment, data, application, encryption, authentication and authority of the application system of the whole blockchain is an important problem that all parties must face

Wu Jia also analyzed that as an emerging instry, employees in the blockchain instry are lack of safety awareness, which leads to the low safety factor of the software and hardware related to the blockchain and a large number of security loopholes. In addition, there are many ecological links in the whole blockchain. In contrast, the strength of the relevant security employees is scattered and it is difficult to form a joint force to solve the problem. A systematic solution is needed to meet the above challenges

content source: zhongxin.com

3.

Blockchain technology is widely used. Under the integration of new technologies, the main application scenarios of blockchain include finance and insurance, intelligent manufacturing, intelligent environmental protection, energy and power, health care, ecation, culture and innovation, smart city, social welfare, agriculture and many other fields

1. blockchain + finance

   blockchain can help financial institutions solve problems such as trust and data sharing

3. blockchain + right art

   Tianhe Guoyun's blockchain right system

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3. Blockchain + government

in statistics, voting, budget management and other aspects, blockchain can rece costs, improve efficiency, and increase transparency, so as to prevent the risk of failure of centralized system

4. Blockchain + insurance

fraud identification and risk prevention: by placing insurance claims under an unchangeable general ledger, blockchain helps to eliminate the common sources of fraud in the insurance instry

property insurance and accidental injury insurance: policies and shared ledgers recorded in the form of smart contracts can improve the efficiency of property insurance and accidental injury insurance

Health Insurance: blockchain technology enables medical records to be encrypted and shared among health service providers, thus improving the interoperability of the health insurance ecosystem

Reinsurance: the information security of reinsurance contracts on the blockchain platform can be ensured through the form of smart contracts, which can rece the amount of information and simplify the payment process between insurers and reinsurers

4. Here we need to mention that the basic system structure of blockchain includes the following
① network routing ② cryptographic algorithm ③ script system ③ consensus mechanism
the security problem of blockchain is mainly the script system completed by script system, which is an abstract concept and an extremely important function in blockchain technology, The reason why a valuable network can be formed depends on the script system, which is driven like an engine and continuously sends and receives data. The so-called script refers to the program of some systems in the rule reconfirmation system, and the rules are fixed. For example, in the bitcoin system, only bitcoin can be sent and received, The system allows users to edit the program rules by themselves, and then they can deploy them to the blockchain ledger. In this way, the functions of the whole blockchain system can be expanded. For example, Ethereum realizes the function of smart contract through this set of custom script system, Then specific scenario applications or real life cases, such as order logistics information and supply chain information.

5. One of the characteristics of blockchain projects (especially public chains) is open source. Through open source code, to improve the credibility of the project, so that more people can participate. But the open source code also makes it easier for attackers to attack blockchain system. In the past two years, there have been a number of hacker attacks. Recently, the anonymous currency verge (xvg) was attacked again. The attacker locked a vulnerability in the xvg code, which allowed malicious miners to add false timestamps on the block, and then quickly dig out new blocks. In a few hours, the attacker obtained nearly $1.75 million worth of digital currency. Although the subsequent attack was successfully stopped, no one can guarantee whether the attacker will attack again in the future
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.

6. I choose Chinese currency! Low operation delay, idle can also save money mining EOS, very suitable.

7. Security risks include three points:
loss of private key
error implementation
the protocol was attacked
at this stage, it can only be prevented, and it is unrealistic to completely solve it. After all, blockchain is just a newborn baby. Bitcoin and Ethereum are often attacked. Recently, decent, a relatively active blockchain content publishing platform, will encounter the same technical problems.

8. There are two main problems
the first is that blockchain generally establishes a decentralized security maintenance mechanism through incentive system, but there is a disadvantage that the general incentive system will issue money, which is not supported in China
the second is the technical bottleneck, and the TPS of blockchain is generally not high, which can not support the landing of a large number of applications