Blockchain epidemic security card

1. Security in blockchain comes from some attributes< Mining blocks need to use resources< Br > 2. Each block contains the hash value of the previous block< Br > imagine if the attacker wants to change the chain by changing the transaction five blocks ago. If they tamper with the block, the hash value of the block changes. Then the attacker must change the pointer from the next block to the changed block, and then change the hash value of the next block... This will continue until the end of the chain. This means that the farther the block is behind the chain, the greater the resistance to change. In fact, the attacker has to simulate the hash capability of the whole network up to the front end of the chain. However, when the attacker tries to attack, the chain continues to move forward. If the attacker's hash value is lower than the rest of the chain (< 50%), they will always chase and never proce the longest chain. Therefore, this type of blockchain can resist attacks, where the attacker's hash value is less than 50%< Br > when attackers have 51% hash value, they can rewrite the network history with a list of valid transactions. This is because they can recalculate the hash value of any block sort faster than the rest of the network, so they can ultimately guarantee a longer chain. The main danger of 51% attacks is the possibility of double spending. This simply means that an attacker can buy an item and show that they have paid with any number of confirmations on the blockchain. Once they receive the item, they can reorder the blockchain so that it doesn't include the send transaction and get a refund< Br > even if the attacker has more than 50% hash value, the attacker can only do so much damage. They can't do things like transfer money from the victim's account to their account or print more coins. This is because all transactions are recorded by the account?? Account owners sign, so even if they control the entire network, they cannot forge account signatures.

2. Tencent must be the security leader of the blockchain, with security guaranteed, and refine the public components of the city level blockchain application to meet the landing needs of the trusted blockchain instry in different scenarios.

3. 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.

4. Blockchain technology has a natural trend of weakening and avoiding centralized supervision, but it will promote the generation of virtual power, which also needs compliance supervision. Tencent's security is particularly important to lead the blockchain, strengthen the supervision of the application of blockchain technology, and ensure the legality and compliance of activities and transactions in the chain.. Are you satisfied with my answer? Please accept if you are satisfied

5. What class, please? Safety. It's not safe to work anywhere ring the epidemic? But also can not go to work, so as long as you want to be safe, it must be your own safety measures to take good

6.

It's too boring to be at home. I don't know what to do, when to get up, and when to go to bed. The most important thing is that I don't know when to return to work. I see less and less money in the bank card, and the time to return to work is far away. Since I can't open up the source, I need to cut down. As a professional auto man, since you can't go out, you should study various configurations of vehicles at home. With the continuous development of the automobile instry, there are more and more car configurations, such as ACC, AEB, BSW and many other security configurations. Don't mention that you are dizzy, even the ghost sister of an Autobot is dizzy

bullshit: what you think is easy to use may not be so easy to use, but those functions you don't know can save your life at the critical moment. At home, don't always tiktok to learn. p>

this article comes from the author of car home, which does not represent the standpoint of car home

7. Micro three cloud replied: blockchain developers can 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.

8. Ah? A liar
that's not necessarily true. Generally speaking, it's impossible without definite evidence
most of the QQ reminders are only for epidemic prevention and control.