Mergen tree in blockchain
hash algorithm is a cryptographic algorithm that can only encrypt, but not decrypt. It can convert any length of information into a fixed length string
this string has two characteristics:
1. Even if the input value changes only a little, the output hash value will be very different
2. Only exactly the same input value can get exactly the same output value
3. There is no rule between the input value and the output value, so the input value cannot be calculated by the output value. In order to find the specified output value, we can only use enumeration method: constantly change the input value to find the output value that meets the conditions
hash algorithm ensures that the results of bitcoin mining can not be deced reversely. Therefore, the miner's continuous operation is essentially brutally cracking the correct input value. Whoever finds the first one will get the bitcoin reward.
core analysis:
1. Transparency, 2. Openness, 3. Information can not be tampered with, 4. Decentralization,
5. Detailed analysis
blockchain is a new application mode of distributed data storage, point-to-point transmission, consensus mechanism, encryption algorithm and other computer technologies. The so-called consensus mechanism is a mathematical algorithm to establish trust and obtain interests between different nodes in the blockchain system
1. In a narrow sense, blockchain is a kind of chained data structure composed of data blocks connected in sequence according to the time sequence, and it can not be tampered with and forged by cryptography
2. Broadly speaking, blockchain technology uses blockchain data structure to verify and store data, uses distributed node consensus algorithm to generate and update data, and uses cryptography to ensure the security of data transmission and access It is a new distributed infrastructure and computing method to program and operate data by using intelligent contract composed of automated script code.
Public chain, also known as "public chain", refers to the blockchain that anyone in the world can enter the system at any time to read data, send confirmatory transactions and compete for bookkeeping. The public chain is generally considered to be "completely decentralized", because no indivial or institution can control or tamper with the reading and writing of data in it. In terms of application, blockchain public chain mainly includes bitcoin, Ethereum, super ledger, most counterfeit currencies and smart contracts. The ancestor of blockchain public chain is bitcoin blockchain, which has the following characteristics:
1, open source code
upload the code to GitHub, and everyone can get complete blockchain data by downloading, Accept the test of the public
2, complete decentralization
anyone can become a node, each node is open, everyone can participate in the calculation of the blockchain, any node is not permanent, but phased, and any center is not mandatory for nodes. Anyone can read and send transactions, and transactions can be effectively confirmed on the blockchain. Anyone can participate in the consensus process. The consensus process determines whether a block can be added to the blockchain and the exact current state. Everyone can get financial reward from it, which is proportional to their contribution to the consensus process. These public chains are generally considered to be "completely decentralized"
3. Developing decentralized applications
through this public chain, developers can easily develop centralized applications. Public chain can protect the rights and interests of users from the influence of program developers

Generally speaking, Merkel tree is a way to hash a large number of "chunks" of data. It depends on splitting these data "chunks" into data chunks with smaller units (buckets). Each bucket block contains only a few data "chunks", and then takes each bucket unit data chunk for hashing again to repeat the same process, Until the remaining total number of hashes is only 1: root hash
the most common and simplest form of Merkel tree is binary mekle tree, in which the data block of a bucket unit always contains two adjacent blocks or hashes. Its description is as follows:
decent, bitcoin and Ethereum smart contract are all this structure
there are many changes in the form of Dao, which can be a kind of digital currency, or a system or institution, such as e- community, focusing on the idea of Dao.
Baas (backend as a service) is a back-end service. Service providers provide customers (developers) with integrated cloud back-end services, such as file storage, data storage, push service, authentication service and other functions, to help developers develop applications quickly

