The influence of cryptography on blockchain
bitcoin, Ruitai coin, Laite coin, Ethereum and other digital cryptocurrencies all use blockchain technology
blockchain is an important concept of bitcoin, which is essentially a decentralized database and the underlying technology of bitcoin. Blockchain is a series of data blocks generated by cryptography. Each data block contains the information of a bitcoin network transaction, which is used to verify the validity of the information (anti-counterfeiting) and generate the next block.
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 keybitcoin is a typical blockchain system, which can be studied carefully
Chinese Mahjong: the world's earliest blockchain project
first of all, a initiates an application. I want to play mahjong and set up a mahjong Bureau, which is equivalent to creating a block, and this block will be broadcast to B, C, D, a, B, C, C, C, C, C, D, D, D, D, D, D, D, D, D, D, D, D, D, D, D, D, D, D, D, D, D D...
in the process of playing mahjong, the above four people constantly play cards, which can be understood as mining, through what to mine? Mahjong machine can understand the mineralization machine. These four miners are the so-called miners. These four miners collide from 144 mahjong, and any right card can be Hu card. We can understand the 144 mahjong as a series of hash values (numbers). The process of Hu card is called computational power. Until Hu card, it means that the right hash value is collided and you can get a reward, Each person will pay the corresponding chips to C and put them in the blockchain. The reward is bitcoin or other virtual coins
Why do the other three people take the initiative to reward C? That's because these people have automatically reached a consensus that C has indeed won, and everyone has recorded the account, including the family members who are sitting next to buy horses. It's not good to deny it, otherwise when it comes out that the character is not good, no one will play with him again. After all, the circle is very important
when we reached a consensus, we didn't see any intermediary or third party judging that C had won, and the rewards given to C didn't need to be transferred to C through the third party. All of them were direct point-to-point transactions. This process was decentralization. The card players (miners) recorded their own achievements in the first game, and the third team won the first game, After the record is completed, a complete block is generated. But remember, this is only the first round. In the whole blockchain, this is just a node. The first eight rounds are finished, that is, eight nodes (blocks). Eight blocks are connected together to form a complete account book, which is the blockchain. Because everyone has one account book, it is a distributed account book. The purpose is to prevent someone from tampering with records. In the end, it is clear who wins or loses.
asymmetric encryption algorithm is a function that converts the original plaintext file or data into a series of unreadable ciphertext codes by using an encryption key. The encryption process is irreversible. Only holding the corresponding decryption key can the encrypted information be decrypted into readable plaintext. Encryption enables private data to be transmitted through the public network under the condition of low risk, and protects the data from being stolen and read by the third party
the core advantage of blockchain technology is decentralization, which can realize point-to-point transaction, coordination and cooperation based on decentralized credit in a distributed system without mutual trust by means of data encryption, time stamp, distributed consensus and economic incentive, so as to solve the high cost and low cost of centralized institutions Low efficiency and data storage insecurity provide solutions
the application fields of blockchain include digital currency, token, finance, anti-counterfeiting traceability, privacy protection, supply chain, entertainment, etc. with the popularity of blockchain and bitcoin, many related top domain names have been registered, which has a great impact on the domain name instry.
but there should be a place where people park their cars at the gate of the community, and then find a person stealing things at the gate of the community. Later, many owners reported that their battery car disappeared the next day, and they suspected that it was stolen< Then they called the police and asked them to deal with it
< / blockquote >later, after many times of investigation and surveillance video display by many police investigators there was a man about 50 years old who was pushing a battery car by and disappeared. Later, the police officers started a search at this intersection and finally found the stolen battery car in a corner
now they have been criminally detained by the local police department, and the rest of the time is still for further trial. As for how to sentence them in the future, we still need to know more about whether we should pay attention to the safety nearby when parking< this incident also makes many of us say that in normal times, if we have monitoring, we should also lock the car, even if we leave temporarily. If we have monitoring, we should also lock the car. Otherwise, we will cause serious losses to our property
Legislation, there is a law to follow, more or less to use
if we don't legislate and want to protect our own information, we don't have any
In fact, it's not so easy to protect personal information
in addition, I have registered a member of XX website before, so I won't mention it here. But soon after, there was a fraud call saying that I was selected as a lucky member by their website and wanted to give me a set of cosmetics
they can accurately say my address, phone number, and my ID. After hearing this, I asked him how much the cosmetics cost. They said it was free, but they charged a little postage, about 60 yuan
It is estimated that they think I am Xiao. In fact, I do Taobao, express delivery how much money, I can estimate. What's more, cosmetics are not so heavy, can't they be more than ten jin? Here in China, one of the best express delivery is Shunfeng. Generally, a kilogram of Shunfeng is about 22 yuan. They are not in what Xinjiang Tibet delivery to me, to 60 yuan freight, must be let express collectionI just said no, and the people who gave me the goods had to collect the transportation fee, so there must be no good goods, and then I hung up their phone
it's definitely not a good thing to charge dozens of yuan for express delivery. Before also heard some what sell tea, also say to want dozens of Yuan freight. There are also some people who sell jade and watches. They say they give them away free of charge, but they only charge dozens of yuan for freight. Ha ha, I didn't send the express. Generally, as long as the lighter things, it is absolutely impossible to charge dozens of yuan for freight
speaking of this, I believe there are many people who have the same experience as me. But usually when we get these calls, we can't collect evidence to sue the companies that leaked our information
Therefore, it is necessary to legislate to protect personal information security. More protection, more reassurance. Although it is difficult to stop these insiders from selling personal information. However, with the legal protection, I believe that these lawless elements will certainly suffer some hardships at that time