Academician of blockchain University of Electronic Science and t
blockchain includes public blockchain, joint (instry) blockchain and private blockchain. Public chain point-to-point e-cash system: bitcoin, smart contract and decentralized application platform: Ethereum
blockchain is a new application mode of distributed data storage, point-to-point transmission, consensus mechanism, encryption algorithm and other computer technologies
blockchain is an important concept of bitcoin. In essence, it is a decentralized database. At the same time, as the underlying technology of bitcoin, it is a series of data blocks generated by using cryptographic methods. Each data block contains a batch of bitcoin network transaction information, Used to verify the validity of its information (anti-counterfeiting) and generate the next block
extended data
according to the different degree of blockchain network centralization, three kinds of blockchains under different application scenarios are differentiated:
1. The blockchain with the whole network open and without user authorization mechanism is called public chain
2. The authorized nodes are allowed to join the network, and the information can be viewed according to the authority. It is often used in the inter agency blockchain, which is called alliance chain or instry chain
3. All the nodes in the network are in the hands of one organization, which is called private chain
alliance chain and private chain are also called licensing chain, and public chain is called non licensing chain
blockchain features
1, 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
2. 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
3. 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
4. Safety. As long as 51% of all data nodes cannot be controlled, the network data cannot be arbitrarily manipulated and modified, which makes the blockchain itself relatively safe and avoids subjective and artificial data changes
5. Anonymity. Unless there are legal requirements, technically speaking, the identity information of each block node does not need to be disclosed or verified, and the information can be transferred anonymously
digital economy and blockchain Technology: he is one of the earliest scholars engaged in blockchain technology in China. He has proposed and developed such theoretical methods as smart contract engineering (SCE), legal code technology, verification as a service (VAAs), etc. in the fields of combination of digital economy and blockchain, planning and consulting of digital economic Park, digital governance of blockchain, and so on Blockchain scalability, Multi Chain interconnection and blockchain formal verification technology have in-depth research and patent achievements. He presided over the research and development of Beihang blockchain series procts, including various forms of blockchain systems with independent intellectual property rights, browsers, monitors, deployment tools and blockchain big data management system (opendata)
distributed parallel computing and network: he has been engaged in cluster computing system, high-performance computing, aerospace electronic bus, and integrated network information technology research in complex computing environment for a long time. He proposed and studied the theory of reconfigurable multi cluster computing based on wolf pack and applied it to practice, and developed several application software systems
formal design and verification methods: in close cooperation with irit and INRIA, we have established a Sino French joint research laboratory for formal methods, studied model driven formal design and verification methods, proposed a number of innovative extension technologies based on AADL and synchronous language signal, and developed a number of model transformation, model validation and verification methods Verification and automatic code generation tools
in recent years, he has published more than 60 papers on SCI / EI retrieval in important academic journals at home and abroad, edited new technologies of network computing (416 pages, published by Science Press in 2001), and cooperatively completed the national authoritative textbook introction to distributed computing system (490 pages, published by Tsinghua University Press in 2014), which won the first prize of 2016 textbook, It has been adopted by more than ten key universities. He has successively presided over and participated in a number of National Natural Science Fund, national key R & D projects, 863 major projects, Junkou 863 project, National Nuclear high-tech foundation project, aerospace fund, and a number of important engineering projects in aerospace field. He won more than 30 national invention patents and soft works, won the five-year achievement award of aviation fund in 2015, and won the second-class innovation achievement award of Instry University Research Institute in 2018.
(1) distributed ledger, that is, transaction bookkeeping is completed by multiple nodes distributed in different places, and each node records complete accounts, so they can participate in monitoring the legitimacy of transactions, At the same time, they can testify together
different from traditional distributed storage, the uniqueness of distributed storage of blockchain is mainly reflected in two aspects: one is that each node of blockchain stores complete data according to block chain structure, while traditional distributed storage generally stores data in multiple copies according to certain rules. Second, the storage of each node in the blockchain is independent and has the same status, which relies on the consensus mechanism to ensure the consistency of storage, while the traditional distributed storage generally synchronizes data from the central node to other backup nodes[ 8]
no single node can record the account data separately, so as to avoid the possibility that a single bookkeeper is controlled or bribed to record false accounts. In theory, unless all the nodes are destroyed, the accounts will not be lost, so as to ensure the security of the account data
(2) asymmetric encryption and authorization technology, the transaction information stored on the blockchain is public, but the account identity information is highly encrypted, which can only be accessed under the authorization of the data owner, thus ensuring the data security and personal privacy
(3) consensus mechanism is how to reach a consensus among all accounting nodes to determine the validity of a record, which is not only a means of identification, but also a means of preventing tampering. Blockchain proposes four different consensus mechanisms, which are suitable for different application scenarios and achieve a balance between efficiency and security
the consensus mechanism of blockchain has the characteristics of "the minority is subordinate to the majority" and "everyone is equal", in which "the minority is subordinate to the majority" does not completely refer to the number of nodes, but also can be the computing power, the number of shares or other characteristics that can be compared by computers“ "Everyone is equal" means that when the nodes meet the conditions, all nodes have the right to put forward the consensus results first, and then directly recognized by other nodes, and finally may become the final consensus results. Taking bitcoin as an example, the workload proof is adopted. Only when more than 51% of the accounting nodes in the whole network are controlled can a nonexistent record be forged. When there are enough nodes in the blockchain, this is basically impossible, thus eliminating the possibility of fraud.
(4) smart contract, which is based on these trusted and tamperable data, can automatically execute some pre-defined rules and terms. Take insurance as an example. If everyone's information (including medical information and risk occurrence information) is true and reliable, it is easy to carry out automatic claim settlement in some standardized insurance procts
and then apply for Yudian terminal security system
and then use the Tencent Yudian to kill the virus
it's just that the requirements for applying for a license are much higher than before, and the difficulty is also increased, so some applicants can't meet the examination requirements, so they may tell you that they can't apply, but this is not the case
in addition, in other European countries, there are very few content licenses specifically for digital currency, many of which are related to traditional financial licenses, because there are also many projects involving payment business.