Blockchain technology of 51 credit card

1. Introction to seven core technologies of blockchain operation on January 15, 2018
1. Blockchain links
as the name suggests, blockchain is a chain composed of blocks. Each block is divided into block head and block body (including transaction data). The block head includes the prevhash value (also known as hash value) of the previous block used to realize the block link and the random number (nonce) used to calculate the mining difficulty. The hash value of the previous block is actually the hash value of the head of the previous block, and the random number calculation rule determines which miner can obtain the right to record the block
2. Consensus mechanism
blockchain is accompanied by the birth of bitcoin, which is the basic technology architecture of bitcoin. Blockchain can be understood as an Internet-based decentralized accounting system. A decentralized digital currency system like bitcoin requires the consistency of accounting of honest nodes without a central node, which needs blockchain to complete. Therefore, the core of blockchain technology is a consensus mechanism to reach a consensus on the legitimacy of transactions between indivials without mutual trust without central control
there are four main types of consensus mechanisms in blockchain: pow, POS, dpos and distributed consistency algorithm
3. Unlocking script
script is an important technology to realize automatic verification and contract execution on blockchain. Every output of every transaction does not point to an address in the strict sense, but to a script. A script is like a set of rules that constrain how the receiver can spend the asset locked on the output
the validation of transactions also depends on scripts. At present, it depends on two kinds of scripts: Lock script and unlock script. Locking script is a condition added to the output transaction, which is realized by a script language and located in the output of the transaction. The unlocking script corresponds to the locking script. Only when the conditions required by the locking script are met can the assets corresponding to the script be spent, which is located in the input of the transaction. Many flexible conditions can be expressed by script language. Interpretation script is similar to the "virtual machine" in our programming field, which runs in every node of the blockchain network in a distributed way
4. Transaction rules
blockchain transaction is not only the basic unit of a block, but also the actual effective content recorded by the blockchain. A blockchain transaction can be a transfer, or the deployment of smart contracts and other transactions
as far as bitcoin is concerned, a transaction refers to a single payment transfer. The transaction rules are as follows:
1) the input and output of the transaction cannot be empty
2) for each input of a transaction, if its corresponding utxo output can be found in the current transaction pool, the transaction will be rejected. Because the current transaction pool is the transaction not recorded in the blockchain, and each input of the transaction should come from the confirmed utxo. If it is found in the current trading pool, it is Shuanghua trading
3) for each input in a transaction, the corresponding output must be utxo
4) each input unlocking script must verify the compliance of the transaction together with the corresponding output locking script
5. Transaction priority
the priority of blockchain transaction is determined by the blockchain protocol rules. For bitcoin, the priority of a transaction to be included in a block is determined by the time when the transaction is broadcast to the network and the amount of the transaction. With the increase of transaction broadcast time on the network and the increase of transaction chain age, the priority of transaction will be improved and eventually be included by the block. For Ethereum, the priority of the transaction is also related to the transaction fee that the publisher is willing to pay. The higher the transaction fee that the publisher is willing to pay, the higher the priority that the transaction is included in the block
6. Merkle proof
the original application of Merkle proof is bitcoin, which was described and created by Satoshi Nakamoto in 2009. Bitcoin blockchain uses Merkle proof to store transactions in each block. So that the transaction can not be tampered with, but also easy to verify whether the transaction is included in a specific block
7. RLP
RLP (recursive length prefix) is one of the main encoding methods of object serialization in Ethereum. Its purpose is to encode the sequence of arbitrary nested binary data.

2. Blockchain technology is the underlying technology derived from big data, like a database recording all relevant important data. According to the research of jinwowo group, the characteristics of blockchain technology are as follows:
1-decentralization
2-transparency
3 - openness
4-autonomy
5 - information cannot be tampered with
6 - anonymity.

3. What can blockchain do? Blockchain, a great technology with the birth of bitcoin, can greatly rece transaction costs and improve efficiency in the financial field, which is enough to make Wall Street excited. However, this is only the tip of the iceberg, and its potential application prospects are very wide, which will subvert all aspects of our lives in the future. Internet is an information network with 0 and 1 flowing in it. Blockchain is a value network, which plays a role in value transmission, which is different from Internet in data transmission. When it comes to value transfer, there is a very simple scenario, such as payment. I have 100 yuan in hand. I want to transfer to the group by wechat red envelope or wechat transfer. In this transaction process, a third party is required to participate, while the transmission mode of blockchain is point-to-point transmission, without any intermediate node, This is a big difference between blockchain and our existing architecture. When it comes to point-to-point payment, many people think of bitcoin, because most people know about blockchain from bitcoin. What's the difference between blockchain and bitcoin? Blockchain is the technology behind bitcoin; Blockchain is a basic technical architecture. Through a specific data structure and consensus algorithm, an autonomous system with multi-party participation is designed and implemented. A specific data structure is actually the name of the blockchain itself, that is, its data is put in a block of data blocks, and then the data blocks are connected and implemented by a chain“ "Consensus algorithm" is a very important concept in blockchain. Without synchronic algorithm, there will be no blockchain. Introction to Bubi blockchain since its establishment, Bubi blockchain has been focusing on the R & D and innovation of blockchain technology and procts. It has a number of core technologies, and has made substantial innovation in many aspects, forming a number of core technology achievements, such as: mathematically proven distributed consensus technology, fast large-scale ledger access technology Multi Chain general ledger technology supporting business form expansion, interconnection technology between heterogeneous blockchains, etc. On April 25, "gege integral" introced the integral system into the concept of blockchain, opened up by multiple parties, issued and exchanged integral, and promoted the circulation of integral. All cooperative institutions can jointly participate in transaction verification, account book storage and real-time settlement; The third-party payment platform of the enterprise points issuer makes the points in and out more flexible. Bubi has developed its own basic blockchain service platform, which has been applied in equity, supply chain, credit and other fields. Bubi has been committed to building an open value circulation network with the core of decentralized (polycentric) trust, so that digital assets can flow freely. So far, let's analyze the difference between blockchain and bitcoin? 1. Essential difference. For the world, bitcoin is a digital currency based on cryptography, while blockchain, as we have just said, is a protocol of value transmission. There is an essential difference between the two, because one is digital currency and the other is a protocol of value transmission. 2. Algorithm. The consensus algorithm of bitcoin is based on a work algorithm called workload proof, pow. There are many different consensus algorithms in blockchain, including bitcoin POW algorithm, POS algorithm and DPS algorithm. 3. Transaction speed. Bitcoin has a maximum of seven transactions per second. Please note that we are talking about the maximum rather than the average, because this is a very strict definition. For blockchain, the number of transactions per second can reach tens of thousands or so, so this is also a major difference between blockchain and bitcoin. Because many people will confuse that the transaction speed of blockchain is seven transactions per second, which is wrong. This is a limitation of bitcoin. Blockchain can achieve very high transaction speed according to its different consensus algorithms and linking methods. 4. Link form. Bitcoin is a blockchain based on the Internet, that is to say, we call it public chain. Blockchain can be in the form of public chain, private chain or alliance chain. 5. Limitations. It is suggested that you do not touch some digital currencies related to blockchain. What is the reason? Bitcoin, as a digital currency, although it has very different characteristics, it does not comply with financial regulation. In other words, the 21 million bitcoins were issued without national authorization and national credit as a multiple. Blockchain also has some limitations. Although it is only a protocol and a technology, it is still a new technology in its infancy. To sum up, blockchain is a relatively low-level protocol and a technical infrastructure, on which there are various consensus algorithms. If the blockchain is 1, the consensus algorithm may be 10 to 20, but there may be 1000 or 2000 applications on it. In other words, bitcoin is only one implementation of many blockchain applications. Therefore, bitcoin and blockchain are not equal. Bitcoin is only a very primary implementation of blockchain. What can blockchain do? What about blockchain? In the bill market, the digital bill based on blockchain technology can become a safer, more intelligent and more convenient bill form. The point-to-point transaction with the help of blockchain can break the existing function of bill intermediary and realize the disintermediation of bill value transmission; The construction and data storage of the digital bill system do not need the central server, which saves the development cost of the central application and access system, reces the maintenance and optimization cost of the system under the traditional mode, and reces the risk of the system centralization; Based on the non tamperability of information in the blockchain, once the bill transaction is completed, there will be no default phenomenon, so as to avoid the behavior of "selling more than one vote" and asynchronous payment and endorsement, and effectively prevent the bill market risk. The securities exchange market is also a promising field of blockchain technology. At present, the traditional securities trading mode has the disadvantages of long trading process, low trading efficiency and high comprehensive cost, and there are strong intermediaries and regulatory agencies, so the rights of financial consumers are often not guaranteed. With the application of blockchain technology, buyers and sellers can directly pair through smart contracts, and the efficiency of transaction execution can be greatly improved. Through the distributed digital registration system, settlement and delivery can be automatically realized. Because the data entered into the block is irreversible and can be copied to each data block in a short time, the information entered into the block chain actually has the effect of publicity, so the occurrence of transactions and the confirmation of ownership will not be controversial. What can blockchain do? What about blockchain? Although at present, there is no mature underlying blockchain technology platform solution, technical problems such as capacity scalability, privacy protection, non net settlement and non recourse need to be solved, and large-scale application of blockchain technology also needs to reset it architecture and reengineer business process, these are only technical problems. The real test of blockchain technology rooted and growing in the financial field is the regulatory agencies and financial institutions. Will the inherent "de supervision" and "de centralization" characteristics of blockchain make the market players have no power to drive technological innovation. However, because the blockchain is a technology based on mathematical algorithm, the establishment of trust relationship between all parties does not need the help of intermediaries or authority centers, and the cost of establishing trust relationship is almost zero (on the premise of the establishment of blockchain financial infrastructure and ancillary infrastructure), and the blockchain code is open-source, no geographical restrictions, and the network pattern is distributed and interconnected, It lays a technical foundation for the establishment and development of Inclusive Finance and shared finance in the future, and creates material conditions for the integration and unification of global finance. From this point of view alone, blockchain technology is bound to establish a core position in the future financial development, and rely on and complement each other with finance, and win-win in the future.

4. Blockchain is a technology that can completely change the underlying design of the financial system, because it can realize the undifferentiated record between the ownership of all assets in the market and the transaction records of all market participants, so it can completely eliminate the intermediate links of clearing and trusteeship, which are used to confirm the ownership before, ring and after the transaction; In addition, as an electronic information record, blockchain can be combined with computer algorithm to realize the automation of transactions, that is, intelligent contract. There are many derivative applications of blockchain combined with other financial technologies, each of which can replace a kind of market intermediary. Blockchain is to financial services what TCP / IP is to the Internet: once the underlying standards are recognized and popularized, specific applications like bitcoin and R3 will appear in every corner of financial services. Bitcoin uses blockchain technology to query and record. For example, if I register an account in haobtc and transfer the money, I need to query the status in the block browser in the account or the block browser in BTC. In this way, the blockchain technology helps me solve the problem of daily transfer currency query.

5. Chongqing jinwowo analysis: blockchain also comes with the technology of transaction confirmation. To realize the automatic confirmation of movable property rights for all participants in the supply chain, and form a common non tamperable record on the block chain, so as to solve the pain points in the existing right registration and right realization.

6. College students have no right to sign labor contracts, but they can establish labor relations with employers, and the corresponding wages can not be delayed.

7. 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,

8. Explain blockchain with scientific language --- blockchain is a permanent and irreversible modified record generated by superimposing encrypted data (blocks) in chronological order. Many financial institutions in the world, including JPMorgan Chase, HSBC, Citibank and New York Mellon bank, have also cooperated with blockchain companies to study the application of blockchain technology in the financial market. The person in charge of the blockchain Technology Laboratory of Shanghai Heshu software said that when there is no trusted third party in blockchain, all transaction data will be stored in a data block, and the transaction information will form a complete chain and be included in the blockchain, which is a more reliable ultimate solution than the trusted third party.