Three types of blockchain

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. According to the classification of known blockchain technology applications, jinwowo group can be roughly divided into three categories:
1 - public blockchain; It means that anyone can read and send transactions for validity confirmation, and anyone can participate in the consensus process of the blockchain to jointly maintain the security, transparency and non tampering of the public blockchain data. For example,
2-community blockchain represented by bitcoin; It is also called alliance chain, which means that the nodes participating in the blockchain are selected in advance, and there are usually good network connections and other cooperative relationships between the nodes; Community blockchain is a practical application scenario of the combination of blockchain and physical goods, such as Domenech jewelry's Maobei mode
3-private blockchain: the participating nodes only have a limited range, the data access and use have strict permission management, the write permission is only in the hands of the participants, and the read permission can be opened to the outside world.

3. 1. Public chain, no official organization and management organization, no central server, participating nodes freely access to the network according to the system rules, not controlled, and work based on consensus mechanism among nodes Subversive: absolutely credible and open) < br > typical case: digital currency represents bitcoin < br > 2. The private chain is built within a group. The operation rules of the system are set according to the requirements of the group, and the modification or read permissions are limited to some extent, while maintaining the authenticity and partial decentralization of the blockchain Typical case: R3 < br > 3. Alliance chain, jointly initiated by several institutions, is between the public chain and the private chain, and has the characteristics of partial decentralization. The read permission on the fast chain in this area may be public or partially public, that is to say, multiple pre selected nodes are designated as bookkeepers internally, and the pre selected nodes compete for bookkeeping permission, Other access nodes can participate in the transaction, but not the accounting process The abilities of the candidates should not be uneven< Br > (relatively credible and open) < br > existing cases: Super ledger < br > example:? In the case of loan diversion, when the user jumps to the other party's website for registration through our link, the docking party can choose to cheat and say that it has not received the user's registration request. However, if we put the user registration behavior into the block, if the docking party wants to receive the user registration behavior, it must pay us at the same time.

4. The general classification of Chongqing jinwowo analysis blockchain technology is as follows:
1 - Open blockchain
2 - Collaborative blockchain
3 - private blockchain.

5. A new resolution initiated by representative Adam kinzinger, a Republican from Indiana, has been submitted to the US House of Representatives, calling on the government to formulate national policies on emerging technologies, including digital currency and blockchain technology
the resolution calls on the idea of bitcoin, but does not directly mention its name. Instead, it calls it "alternative illegal currency". Blockchain technology is the key point, which points out that this technology has the potential to "fundamentally change" the way trust and security are built on online transactions
but in fact, the United States has not taken action to formulate this rule. However, there is a global blockchain alliance R3 in the process of formulating the standard for the use of blockchain. Of course, blockchain is just a technology that can be used by any enterprise. In China, there is a project called decent, which is more avant-garde. It uses blockchain technology to build a decentralized content publishing platform, but it may encounter some problems in China.

6. It can be roughly divided into three categories:
1 - public blockchain: it refers to the blockchain that anyone can read and send transactions for validity confirmation, and anyone can participate in its consensus process, so as to jointly maintain the security, transparency and non tampering of public blockchain data
2-community blockchain: also known as alliance chain, it means that the nodes participating in the blockchain are selected in advance, and there are usually good network connections and other cooperative relationships between the nodes
3-private blockchain: the participating nodes only have a limited range, the access and use of data have strict permission management, the write permission is only in the hands of the participants, and the read permission can be opened to the outside world.

7. According to the classification of known blockchain technology applications, jinwowo group can be roughly divided into three categories:
1 - public blockchain
2 - community blockchain
3 - private blockchain.