Difficulty of blockchain system attack

1.

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 a major 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 attack successfully only when they hold more than 51% token, which is more difficult than 51% 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 greater 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 contract, and the other is to follow the principle of smart contract security development

the security development principles of smart contract are: to 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 check the hash value before installing the software to ensure that the digital wallet software has not been tampered with

The third is to use cold wallet

The fourth is to back up the private key

2.

Blockchain is a new application mode of distributed data storage, point-to-point transmission, consensus mechanism, encryption algorithm and other computer technologies. Blockchain is an important concept of bitcoin. It is essentially a decentralized database. At the same time, as the underlying technology of bitcoin, it is a series of data blocks generated by using cryptographic methods. Each data block contains a batch of information about bitcoin network transactions, Used to verify the validity of its information (anti-counterfeiting) and generate the next block

if such technology wants to be put into application, the biggest problem is the "Impossible Triangle problem"

that is, scalability, decentralization and security cannot be achieved at the same time, and only two of them can be achieved

most of the existing public chain projects in the market are difficult to put into use on a large scale

3.

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

4. If your blockchain system refers to a decentralized point-to-point system, its characteristics are as follows:
1. The point-to-point system allows members to join freely without middleman, and nodes can interact freely
2. The point-to-point system can speed up information processing and rece costs by replacing middleman

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6. In a simple explanation, 51% attack is also called majority attack. It means that malicious miners control more than 50% of the hash rate of the blockchain network, and then attack the network and take over the blockchain network, so that criminals can reverse transactions, stop payment or prevent new transactions from being confirmed
for more information about 51% attacks, you can learn about them on the password finance network,

7. In fact, it's not very difficult. Technology is the second. It's mainly about whether we can explore a new business model in combination with the enterprise's own operation. In this regard, we can go to the micro three clouds of the blockchain research center to see if they can combine the blockchain with the shopping mall and content payment scenarios, and have formed blockchain systems and landing application cases.

8. 1. It's not too hard. Implementation technology is the second. It is mainly to understand the idea of centralized design. 2. You can go to the Internet to find the programming language that you are good at to implement blockchain.

9. Heteromorphic attack, also known as address pool pollution, refers to the intrusion and pollution of nodes between similar blockchain systems. This is an attack that most public chains are likely to face. The opportunity of this attack is that many public chains have handshake protocols with similar chains, and then the system can not identify whether the node belongs to its own chain. The attacker can use this point to collect the address of the public chain and make a malicious handshake, contaminate the address pool through the node handshake, so that the nodes of different chains shake hands with each other and push the known nodes in their respective address pools to each other, causing more nodes to contaminate each other and eventually spread to the whole network. The communication performance of the node under heteromorphic attack will decline, and the node will be blocked, which will eventually lead to the abnormality of the main network. The security of blockchain system is not only provided by technology itself, but also provided by developers. The more careful the program logic designed by developers, the lower the possibility of being broken. Therefore, if you need to develop a system, you must find a reliable development company. Xuanling technology is a reliable blockchain development company. Their strength and experience in blockchain development are trustworthy. If you have any intention, you can consult their company.

10. The result of these two attacks is that the other party's system is out of service or crashed e to information overload. But DoS attack is a single server attack, while DDoS attack is distributed multiple servers attack, the success of the attack is higher. The application of blockchain technology should be more and more, so it is necessary to understand the knowledge of blockchain. It is recommended that you go to the official website of Xuanling technology. This website has many popular science and application posts of blockchain technology, which should be of great help to blockchain learning.