Blockchain is related to cryptography

1. blockchain technology uses mathematical methods to achieve distributed accounting and solve the trust problem, so as to complete the decentralization, which will bring far-reaching influence in many fields such as communication, finance, Internet of things, government management and so on
blockchain refers to the technical solution of collective maintenance of a reliable database through centralization and distrust in the past, and it is a technical way for the whole people to participate in bookkeeping. Previous bookkeeping methods were all centralized and needed centralized intermediary, whether it was traditional government, financial institutions, notarization institutions or emerging e-commerce platform and online payment platform
in economic hypothesis, information is sufficient. In fact, it is precisely because of insufficient information that there are very large intermediaries. The existence of intermediaries increases the transaction cost and raises the transaction threshold. In essence, blockchain technology is a large-scale collaboration tool. It makes direct value transfer possible by using pure technology for the first time, and continues the trend of Internet decentralization and disintermediation. Disintermediated blockchain technology will greatly subvert the information intermediary instry
blockchain technology is the basic technology for building bitcoin data structure and encrypted transmission of transaction information, which realizes the issue and transaction of bitcoin. The core of blockchain technology is that all the current participating nodes jointly maintain the transaction and database, so that the transaction is based on the principle of cryptography rather than trust, so that any agreed parties can directly carry out payment transactions without the participation of a third party
technically, a block is a data structure for recording transactions, reflecting the capital flow of a transaction. In the system, the transaction blocks are connected to form a main chain, and all the nodes participating in the calculation record the main chain or part of the main chain
a block contains the following three parts: transaction information, hash formed by the previous block and random number. Transaction information is the task data carried by the block, including the private keys of both parties, the number of transactions, the digital signature of electronic currency, etc; The hash hash formed by the previous block is used to connect the blocks and realize the sequence of past transactions; Random number is the core of the transaction. All nodes compete to calculate the answer of the random number. The node that gets the answer the fastest generates a new block and broadcasts it to all nodes for updating, so as to complete a transaction.

2.

Although the blockchain technology is still in the early stage of development, the corresponding talents are in short supply

Computer (software engineering, information and computing science, information technology, information security, etc.)

2, mathematics related majors

3, economics related majors

4, cryptography

at present, various well-known institutions around the world are competing to launch blockchain teaching courses, Some universities have even set up corresponding completion certificates for blockchain courses

3. If you are interested in blockchain technology, you can learn the knowledge of cryptography at the beginning, and learn how to strengthen contracts other than trust through numbers. This is the most basic principle of blockchain. Then you can look at the programming books, understand the basic code, and do simple programming. After that, you can download some common blockchains, Study its code arrangement, see how it adds contracts, and make simple modifications to build its own smart contracts. Of course, if you are only affected by the recent price and hype and decide to join the instry, I suggest you learn more about the Bulls who hype it, listen to their opinions, and learn how others reap!

4. It is not said that blockchain is good, but proved by facts. China Merchants Bank, Minsheng Bank, Ping An Bank, ant financial services, Wanda and other domestic giants have begun to pay attention to blockchain technology. It seems that the digital currency planned by the central bank will also use blockchain technology. Some large international enterprises or institutions have also paid attention to blockchain technology long ago. Of course, the most famous examples of blockchain technology are Ethereum, bitcoin and decent.

5. The encryption of jinwowo blockchain can ensure that the privacy of data sources can be better protected when big data is called, so as to eliminate the bad phenomenon of reselling data.

6. Blockchain technology involves a wide range of disciplines and contents, including network communication, data storage, data encryption, consensus mechanism, security mechanism, cryptography and other related contents. Only by comprehensively mastering these knowledge can we better master the blockchain technology. In addition, the most important thing for learning blockchain technology is to use blockchain in practice, and the real purpose of learning technology is to develop applications that are helpful to life and proction. Xuanling technology has been committed to the development of blockchain technology related applications, and has an experienced development team. If you have relevant intention, you can contact the official website.

7. There are many basic definitions of blockchain. Here, I will analyze the opinions of different schools, and use a more understandable explanation:
blockchain English Name: blockchain, also known as block chain, is a kind of chain data structure that combines data blocks in chronological order, It is a distributed account book that can not be tampered with and forged by means of cryptography
blockchain is essentially a distributed database, which is a series of data blocks generated by using cryptographic methods. Each data block contains the information of a network transaction, which is used to verify the validity of its information (anti-counterfeiting) and generate the next block
2. Working principle
the core potential of blockchain lies in the characteristics of distributed database and how to help transparency, security and efficiency
in the past, institutions used a central database to support transaction processes and calculations. The control of the database is in the hands of its owner, who manages the access and update rights to the database, which limits the transparency and scalability, and makes it difficult for outsiders to ensure that the data records are not manipulated
at the same time, e to technical limitations, distributed database is basically impossible to achieve. But with the development of software, communication and encryption technology, it is possible to build a distributed database across organizations. Blockchain has graally emerged
3. Core idea
the basic idea of blockchain is to establish a network-based public ledger (data block), each block contains the information of a network transaction. All the participating users in the network work together to keep accounts and check accounts. All the data are open and transparent, and can be used to verify the effectiveness of the information. In this way, the authenticity and non tamperability of information can be guaranteed at the technical level without the central server as the trust intermediary.

8.

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

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