Definition and characteristics of blockchain
1-decentralization
2-transparency
3 - openness
4-autonomy
5 - information cannot be tampered with
6 - anonymity.
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
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
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
e to the use of Distributed Accounting and storage, there is no centralized hardware or management organization, the rights and obligations of any node are equal, and the data blocks in the system are jointly maintained by the nodes with maintenance function in the whole system
openness
the system is open, in addition to the private information of all parties to the transaction is encrypted, the data of the blockchain is open to all, and anyone can query the blockchain data and develop related applications through the open interface, so the information of the whole system is highly transparent
autonomy
blockchain adopts consensus based specifications and Protocols (such as a set of open and transparent algorithms) to enable all nodes in the whole system to exchange data freely and safely in a de trusted environment, so that the trust in "people" is changed into the trust in machines, and any human intervention does not work
information cannot be tampered with
once the information is verified and added to the blockchain, it will be stored permanently. Unless more than 51% of the nodes in the system can be controlled at the same time, the modification of the database on a single node is invalid, so the data stability and reliability of the blockchain are extremely high<
anonymity
since the exchange between nodes follows a fixed algorithm, their data interaction does not need to be trusted (the program rules in the blockchain will judge whether the activity is effective by themselves), so the counterparties do not need to trust themselves by disclosing their identities, which is very helpful for credit accumulation
Characteristics of blockchain
one of the four characteristics of blockchain: tamper proof
the most easily understood characteristic of blockchain is tamper proof
tamper proof is based on the unique account book of "block + Chain": the blocks with transactions are added to the end of the chain in time order. To modify the data in a block, you need to regenerate all blocks after it
one of the important roles of consensus mechanism is to make it almost impossible to modify a large number of blocks at high cost. Take the blockchain network (such as bitcoin and Ethereum) with workload proof as an example, only with 51% of computing power can all blocks be regenerated to tamper with data. However, the destruction of data is not in line with the self-interest of players with large computing power. This practical design enhances the reliability of data on the blockchain
generally, the transaction data in the blockchain ledger can not be "modified", it can only be "modified" through the new transactions that are approved. The process of correction will leave traces, which is why the blockchain can not be tampered with. Tampering refers to changing or misinterpreting by means of forgery
in today's common files and relational data, unless a special design is adopted, the system itself does not record modification traces. Blockchain ledger adopts a design different from that of files and databases. It draws on the design of ledger in reality, that is, to retain the traces of records. Therefore, we can not "modify" the account book without leaving traces, but can only "modify" the account book (see Figure 2)
Figure 6: bitcoin is centralized in the organization and logically centralized
when we imagine the future organization, the ideal prototype in our mind is often bitcoin organization: completely decentralized autonomous organization. But in practice, for the sake of efficiency and advancement, we will move closer to the centralized organization and finally find a suitable balance point
nowadays, in the blockchain projects that are created and issued through the smart contract of Ethereum and run in a community or ecological way, the ideal state of many projects is similar to the bitcoin organization, but the actual situation is between the completely decentralized organization and the traditional company
when we discuss the fourth feature of blockchain, which is decentralized self-organization, we are actually going out of the code world, involving human organization and collaboration. Now, various discussions and practical explorations have also revealed the significance of blockchain beyond technology: it may serve as an infrastructure to support human proction organization and collaborative change. This is another example of the complete isomorphism between blockchain and Internet. Internet is not only a technology, it has changed people's organization and collaboration
in general, Ethereum has brought blockchain into a new stage. When discussing Ethereum, if we want to summarize two key words, they are smart contract and token; If I can only say one, I will choose "Tong Zheng". I would rather look for its meaning from the history of the Internet and repeat the previous analogy: as a token of value, its role is similar to HTML. With HTML, what kind of website to build depends entirely on our imagination
features:
1. Decentralization
in current system design or application development, central server is considered to realize all information exchange and data storage. But in the blockchain, through the construction of distributed architecture and open source protocol, all participants participate in data recording and verification, and then send them to each node through distributed propagation. Even if some nodes are attacked or damaged, the integrity and information update of the whole database will not be affected, which means that each participating node is "self-centered"
2, to trust
in traditional Internet mode, it is through the trusted central node (such as the housing registration system) or the third party channel (such as Alipay) to carry out the matching verification and trust accumulation, so it can not achieve the center of value transfer.
3. Timestamp
blocks are generated by packaging all the information (including data and code) generated in a certain period of time. The index information of the previous block is included in the page capital of each next block, and the chain is formed by end-to-end connection. Therefore, the addition of block (Complete History) and chain (complete verification) forms a time stamp (which can trace the complete history). It stores all the historical data in the system, provides retrieval and search functions for each data, and can trace the origin and verify each data by means of blockchain structure<
4. Asymmetric encryption
blockchain is an asymmetric encryption algorithm through the mathematical consensus mechanism, that is, a "key pair" is used in the process of encryption and decryption, and the two keys in the "key pair" have the characteristics of asymmetry: first, only the other key can be decrypted after one key is encrypted; Second, after one of the keys is public, other people can't work out another key according to the public key.