Blockchain is defined by cryptography

1. 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
blockchain is the underlying technology of bitcoin, like a database ledger, recording all transaction records. Because of its safety and convenience, this technology has graally attracted the attention of the banking and financial instry
in April 2018, a group of scholars from Oxford University announced the establishment of Woolf University, the world's first blockchain University
in a narrow sense, blockchain is a kind of chain data structure that combines data blocks in chronological order in a sequential way, and it can not be tampered with and forged by cryptography
broadly speaking, blockchain technology is a new distributed infrastructure and computing method, which uses blockchain data structure to verify and store data, uses distributed node consensus algorithm to generate and update data, uses cryptography to ensure the security of data transmission and access, and uses intelligent contract composed of automated script code to program and operate data.

2.

From the perspective of technology and architecture, I will tell you my understanding of blockchain in common language

what is blockchain? In a word, blockchain is a storage system. To be more specific, blockchain is a distributed storage system without an administrator and each node has all the data

What are the common storage systems like

first, how to ensure high availability

the common storage system usually uses "rendancy" to solve the problem of high availability. As shown in the figure above, if the data can be copied into several copies and rendant to multiple places, high availability can be guaranteed. The data in one place is hung, and there is data in other places. For example, the master-slave cluster of MySQL is the same principle, and the raid of disk is also the same principle

two points need to be emphasized in this place are: data rendancy often leads to consistency problems

1. For example, in the master-slave cluster of MySQL, there is actually a delay in reading and writing, which means there is a inconsistency in reading and writing in a short period of time. This is a side effect of data rendancy

The second point is that data rendancy often reces the efficiency of writing, because data synchronization also consumes resources. If you add two slave libraries, the write efficiency will be affected. The common storage system is to use rendancy to ensure the high availability of data

so the second question, ordinary storage system, can write more

the answer is yes, for example, take this graph as an example:

in fact, MySQL can do a master-slave synchronization of al masters, master-slave synchronization of al masters, two nodes can be written at the same time. If you want to do a multi room multi live data center, in fact, multi room multi live data synchronization. What we should emphasize here is that multi-point writing often leads to the consistency problem of writing conflicts. Take MySQL as an example, suppose that the attribute of a table is self incrementing ID, then the data in the database is 1234 now. If one of the nodes writes and inserts a piece of data, it may become 5, and then these 5 pieces of data are synchronized to another master node, Before synchronization, if another write node inserts a piece of data, a piece of data with self incrementing ID of 5 will be generated. Then, after the generation, synchronize to another node, and the synchronized data will conflict with the two local 5's after it arrives, which will lead to synchronization failure and write consistency conflict. This problem will occur in the case of multi-point writing

how to ensure consistency in multi-point writing

the reform "Swan class" gives you more technical work

3. The definition of Chongqing jinwowo analysis blockchain technology is as follows:
1. Blockchain is a distributed database (system) placed in a non secure environment
2. The blockchain uses cryptography to ensure that the existing data cannot be tampered with
3, the blockchain uses consensus algorithm to reach consensus on new data
the system with the above three properties is blockchain.

4. Blockchain encryption algorithm
asymmetric encryption algorithm is a function that converts the original plaintext file or data into a series of unreadable ciphertext codes by using an encryption key. The encryption process is irreversible. Only holding the corresponding decryption key can the encrypted information be decrypted into readable plaintext. Encryption enables private data to be transmitted through the public network under the condition of low risk, and protects the data from being stolen and read by the third party
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 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.

5. In essence, blockchain is a distributed database system with cryptography technology, multi-party participation, common maintenance and continuous growth, also known as distributed shared ledger. Each account page in the shared ledger is a block, and each block is full of transaction records. The blocks are connected closely, forming a chain structure; If you don't understand this area, I suggest you learn the basic knowledge from Xuan, Ling, network and company! At present, there are few people who really understand technology and business. Many people follow suit and learn. They are not clear about the definition of blockchain, so they start to attack the blockchain field. Some of them are learning technology, and some of them choose to invest in the blockchain market

6. Blockchain is an important concept of bitcoin. According to the 2014-2016 global bitcoin Development Research Report released by fire coin and Internet Finance Laboratory of Wukou School of finance of Tsinghua University and Sina Technology, blockchain is the underlying technology and infrastructure of bitcoin. In essence, it is a decentralized database, as well as the underlying technology of bitcoin. Blockchain is a series of data blocks generated by cryptography. Each data block contains the information of a bitcoin network transaction, which is used to verify the validity of the information (anti-counterfeiting) and generate the next block
in a narrow sense, blockchain is a kind of chain data structure that combines data blocks in chronological order in a sequential way, and it can not be tampered with and forged by cryptography. In a broad sense, blockchain technology is a new distributed infrastructure and computing paradigm, which uses blockchain data structure to verify and store data, uses distributed node consensus algorithm to generate and update data, uses cryptography to ensure the security of data transmission and access, and uses intelligent contract composed of automated script code to program and operate data
domestic blockchain application platforms include digital currency crowdfunding platform, asset custody system based on blockchain technology, which is jointly developed by coin Ying China, China Post and IBM.

7.

As an emerging technology, blockchain has attracted more and more attention. It is a new application of traditional technology in the Internet era, including distributed data storage technology, consensus mechanism and cryptography. With the establishment of various blockchain research alliances, more and more funds and personnel support related research. Hash algorithm, zero knowledge proof, ring signature and other cryptographic algorithms used in blockchain:

hash algorithm

as the basic technology of blockchain, the essence of hash function is to map a set of data of any length (limited) to a set of defined length data stream. If this function satisfies the following conditions:

(1) the calculation of hash value for any group of data is very simple

(2) it is difficult to find two different data with the same hash value

hash functions satisfying the above two properties are also called encrypted hash functions. In case of no contradiction, hash functions usually refer to encrypted hash functions. For the hash function, finding such that is called a collision. The current popular hash functions are MD5, SHA1, Sha2, Sha3

bitcoin uses sha256, and most blockchain systems use sha256 algorithm. So here's sha256< Step 1: additional filling bits. The length of the message is congruent with that of 448 mod512 (length = 448 mod512). The number of bits to be filled ranges from 1 to 512. The highest bit of the filled bit string is 1, and the rest bits are 0

Step2: additional length value. The bit length of the initial message (before filling) represented by 64 bit is appended to the result of step 1 (the low byte takes precedence)

Step3: initialize cache. A 256 bit cache is used to store the intermediate and final results of the hash function

Step 4: process 512 bit (16 word) packet sequence. The algorithm uses six basic logic functions and consists of 64 steps of iterative operation. Each step takes the 256 bit cache value as the input, and then updates the cache content. Each step uses a 32-bit constant KT and a 32-bit wt. Where WT is the packet after the packet, t = 1,2,..., 16

step5: after all 512 bit packets are processed, the output of the last packet of sha256 algorithm is 256 bit packet< In 2001, Rivest, Shamir and TauMan proposed ring signature for the first time. It is a simplified group signature, only ring members have no manager, and it does not need the cooperation between ring members. In the ring signature scheme, the signer first selects a temporary signer set, which includes signers. Then the signer can generate the signature independently by using his private key and the public key of others in the signature set without the help of others. Members of the signer collection may not know that they are included in it

ring signature scheme consists of the following parts:

(1) key generation. A key pair (public key PKI, private key ski) is generated for each member of the ring

(2) signature. The signer uses his private key and the public keys of any n ring members (including himself) to generate the signature a for the message M

(3) signature verification. According to the ring signature and message M, the verifier verifies whether the signature is signed by the member in the ring. If it is valid, it will be received, otherwise it will be discarded

ring signature satisfies the following properties:

(1) unconditional anonymity: the attacker can not determine which member of the ring generated the signature, even if the private key of the ring member is obtained, the probability is not more than 1 / n

(2) Correctness: the signature must be verifiable by all others

(3) unforgeability: other members of the ring can't forge the real signer's signature, and even if an external attacker obtains a valid ring signature, he can't forge a signature for message M

(1) anonymity. The verifier can verify that the signature is signed by a member of the group, but can't know which member it is, so that the signer can be anonymous< (2) traceability. In group signature, the existence of group administrator ensures the traceability of signature. The group administrator can revoke the signature and expose the real signer. The ring signature itself cannot reveal the signer unless the signer wants to expose or add additional information to the signature. A verifiable ring signature scheme is proposed. In this scheme, the real signer wants the verifier to know his identity. At this time, the real signer can confirm his identity by disclosing his secret information< (3) management system. Group signature is managed by group administrator, ring signature does not need to be managed, signer can only select a set of possible signers, obtain its public key, and then publish the set, all members are equal

the Xueshuo innovation blockchain Technology Workstation of Lianqiao ecation online is the only approved "blockchain Technology Specialty" pilot workstation of "smart learning workshop 2020 Xueshuo innovation workstation" launched by the school planning, construction and development center of the Ministry of ecation of China. Based on providing diversified growth paths for students, the professional station promotes the reform of the training mode of the combination of professional degree research, proction, learning and research, and constructs the applied and compound talent training system< br />