MDP of blockchain

1. blockchain encrypts the transaction information in a transaction block by hash algorithm, and compresses the information into a hash string composed of a string of numbers and letters. Jinwowo group analyzes the functions of its hash algorithm as follows: the hash value of the blockchain can uniquely and accurately identify a block, and any node in the blockchain can obtain the hash value of the block through simple hash calculation, and the calculated hash value does not change, which means that the information in the blockchain has not been tampered with.

2. 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.

3. From an academic point of view, blockchain is a new application mode of distributed data storage, point-to-point transmission, consensus mechanism, encryption algorithm and other computer technologies. Blockchain is essentially a decentralized database

for example, if you are a woman, every time your boyfriend says something to you or promises to buy something for you, you immediately record it and send it to you and all his friends, classmates, colleagues, as well as various groups and circles of friends, so that he can no longer deny it. This is called blockchain

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, low 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.

4. Traditional transactions on the Internet need to rely on trusted third-party institutions to process electronic payment information, and both parties trust the third-party institutions However, the third-party intervention also has many disadvantages:< Br > - high transaction cost (a certain handling charge)< Br > - Privacy exposure (the third party needs to provide the information of both parties in order to verify the information)< Br > -... < br > imagine that if the third-party organization is removed and the two parties trade directly, how can the transaction take effect? The emergence of blockchain technology is to solve this problem. Blockchain is based on the principle of cryptography rather than trust mechanism, which makes the two parties reach an agreement to trade directly and publish it to all witnesses.

5. The projects of jinwowo network technology analysis blockchain are divided into three levels:

the top and easiest thing to do is the application layer. I can see two or three such projects every day, accounting for more than 95% of the whole market. But such companies often write a lot of technical things in the white paper. In fact, they also write in vain. This is purely for the purpose of collecting pages, because they don't need to talk about technology at all

the second type is the intermediate operation level, such as quantum chain and ant. This kind of project is similar to the operation procere, called the basic chain, which is used to run the application. This category is relatively small, and the proportion has dropped to less than 5%

the third category is more downward extension and lower level, such as standard chain and arcblock. This kind is even less. It's good to see two or three in a month. And some of them are not necessarily true, because there is really nothing to write about, and all fields are occupied by others, so someone will go in this direction.

6. Firstly, we need to know that blockchain is a new application mode of computer technology such as distributed data storage, point-to-point transmission, consensus mechanism and encryption algorithm. Secondly, as for the composition architecture of blockchain system, jinwowo Group believes that it is composed of data layer, network layer, consensus layer, incentive layer, contract layer and application layer

1. Data layer: encapsulates the underlying data block and related data encryption and timestamp technologies

2. Network layer: includes distributed networking mechanism, data propagation mechanism and data verification mechanism

3. Consensus layer: it mainly encapsulates various consensus algorithms of network nodes; The incentive layer integrates economic factors into the blockchain technology system, mainly including the issuance mechanism and distribution mechanism of economic incentives

4. Contract layer: it mainly encapsulates all kinds of scripts, algorithms and smart contracts, which is the basis of the programmable characteristics of blockchain; At present, jinwowo in Southwest China has taken the lead in big data research with blockchain as the underlying technology, and also provides big data services with blockchain as the underlying technology

5. Application layer: encapsulates various application scenarios and cases of blockchain. In this model, chain block structure based on timestamp, consensus mechanism of distributed nodes, economic incentive based on consensus computing power and flexible and programmable smart contract are the most representative innovations of blockchain technology

7. What is the common chain in the block chain
A: the public chain is open to the public. Users can participate anonymously without registration, and can access the network and blockchain without authorization. Nodes can choose to freely access the network. The blocks on the public chain can be viewed by anyone, and anyone can also be on the public chain