Blockchain Shuanghua 6

1. This is not a rigid rule. It has nothing to do with blockchain. There is a relationship between the algorithm of this currency. The confirmation method of each currency is different, so this is not a rigid rule
the confirmation times of bitcoin are different from that of Ruitai coin, Laite coin and doggy coin.

2.

Blockchain includes public blockchain, joint (instry) blockchain and private blockchain. Public chain point-to-point e-cash system: bitcoin, smart contract and decentralized application platform: Ethereum

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. In essence, it is 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 bitcoin network transaction information, Used to verify the validity of its information (anti-counterfeiting) and generate the next block

extended data

according to the different degree of blockchain network centralization, three kinds of blockchains under different application scenarios are differentiated:

1. The blockchain with the whole network open and without user authorization mechanism is called public chain

2. The authorized nodes are allowed to join the network, and the information can be viewed according to the authority. It is often used in the inter agency blockchain, which is called alliance chain or instry chain

3. All the nodes in the network are in the hands of one organization, which is called private chain

alliance chain and private chain are also called licensing chain, and public chain is called non licensing chain

blockchain features

1, decentralization. Blockchain technology does not rely on additional third-party management institutions or hardware facilities, and there is no central control. In addition to the self-contained blockchain itself, each node realizes information self verification, transmission and management through distributed accounting and storage. Decentralization is the most prominent and essential feature of blockchain

2. Openness. Blockchain technology is based on open source. In addition to the private information of all parties involved in the transaction is encrypted, the data of blockchain is open to everyone. Anyone can query blockchain data and develop related applications through the open interface, so the information of the whole system is highly transparent

3. Independence. Based on consensus specifications and Protocols (similar to various mathematical algorithms such as hash algorithm used by bitcoin), the whole blockchain system does not rely on other third parties, and all nodes can automatically and safely verify and exchange data in the system without any human intervention

4. Safety. As long as 51% of all data nodes cannot be controlled, the network data cannot be arbitrarily manipulated and modified, which makes the blockchain itself relatively safe and avoids subjective and artificial data changes

5. Anonymity. Unless there are legal requirements, technically speaking, the identity information of each block node does not need to be disclosed or verified, and the information can be transferred anonymously

3. In the process of learning blockchain, you will hear the word "double flower", which means double payment, or more directly, a sum of money has been spent twice. In this article, we will briefly analyze why there are double flowers and how bitcoin can avoid double flowers

in the traditional transaction, there is no double spending problem because there is a centralized institution such as a bank: every payment will be dected from your bank account, and all details will be recorded in the bank. But in bitcoin, because there is no concept of account, utxo is introced, that is, no transaction output is spent. Because there is no guarantee from centralized institutions such as banks, when a transaction occurs, there may be a risk of double spending: for example, a has a bitcoin, and then he constructs two transactions T1 and T2 at the same time to spend the bitcoin, one of which is given to B, to buy a suit from B, one is given to C, and to buy a pair of shoes from C. If we do not introce some mechanism to avoid this situation, bitcoin, as a digital currency, will not have any meaning of existence. Next, let's analyze how bitcoin can prevent this "double flower" attack

(1) normal situation

first of all, let's look at the normal situation. To put it bluntly, most of the time, the consensus mechanism of blockchain can nip Shuanghua in the bud. Let's illustrate with the above examples:

suppose that a constructs two transactions T1 and T2, and transfers its own value of 1btc utxo to B and C respectively, in an attempt to obtain benefits from B and C at the same time. Then a broadcasts the two constructed transactions to the network almost at the same time

suppose that the miner node in the network receives the transaction T1 first, and finds that the source of funds for the transaction has not been spent, so it adds T1 to its own memory transaction pool and waits to be packaged into the block

in most cases, the miner node will receive transaction T2 soon. At this time, the miner node will refuse to process the transaction because the transaction input that T2 points to is the same as T1 that has been added to the transaction pool. Other miner nodes in the network are similar, so a's attempt to double flower is stillborn

(2) bifurcation

the above is normal, but there are also abnormal cases to consider: suppose that the miner nodes M1 and M2 dig out the block almost at the same time, and unfortunately M1 only receives transaction T1 when digging in the block, while M2 only receives transaction T2 when digging in the block, so transaction T1 and T2 are packed into two blocks respectively. Because these two blocks were g out at about the same time, resulting in the bifurcation of the blockchain:

some nodes in the network (which may be close to M1) received the block blk1 packed by M1 first, so they used the block to extend their own blockchain, while other nodes (which are close to M2) received the block blk2 packed by M2 first, and used the block to extend their own blockchain, So the whole blockchain network

4. I wrote a lot of blockchain project analysis before and after, from the initial bitcoin, Ethereum and EOS to various application-oriented projects, such as exchange, currency, u like and other content-based projects, including the project party's draft. I have formed a set pattern for project analysis in my mind. I know this framework after reading my project analysis articles. I analyze the project white paper according to "project introction, launch background, project innovation, project team, development trends, token and market, project risk, competitive proct analysis, suggestions and summary", or match the content and framework in the white paper, Some will be filled in, others will not be written out; Next is the supplementary information as evidence, combing ideas, and then according to their own understanding to write project analysis, so as to be regarded as their own project analysis. For project analysis, I can summarize three steps: the first step is to collect information (see white papers, search engines, official articles, etc.); The second step is to set the frame template; The third step is to delete the content to form one's own understanding.

5. Because it comes from money. Virtual money is bought with real money. So it's also called coin there.

6. Tencent and Taobao have always been incompatible. But both of them are Internet giants in China and even in the world. Wechat blocked Taobao, and Ma Yun built his own contacts against wechat. WeChat's micro payment is also aimed at competing with Alipay. The pat Network was eventually sold to Jingdong, because competition was not Taobao. Taobao block QQ currency is also expected.

7. QQ coin is a kind of virtual currency issued by Tencent in order to facilitate users to purchase the virtual goods and services it provides. Its official price is: 1q coin = 1 yuan. However, if the amount of recharge is large, there will be a certain amount of discount on some recharge platforms
it should be noted that this is the recharge price. If it's selling q-coin, because q-coin recycling is now done by some third-party platforms, there will be a certain cost. Therefore, the recovery price of Q coin is generally lower than the recharge price, remember!

8. QQ currency is a virtual currency issued by Tencent. The official issue price of Tencent is: 1q currency = 1 yuan. However, if the amount of recharge is large, there will be different discounts in different recharge platforms
if you want to exchange Q currency for RMB, it's a bit complicated. Because Tencent does not support q-coin exchange at present, it is now doing q-coin recovery and exchange on some third-party platforms. Therefore, there will be a certain discount. Therefore, in the recovery of Q currency, 1q currency can not be converted into 1 yuan RMB.