How to calculate blockchain

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.

Seeing some answers to the debate on the definition of blockchain, I suddenly realize that my answer to this explanation principle has always been directed at bitcoin. There is no specific and unique answer in the instry between the definition of blockchain. Here I first summarize the characteristics of "blockchain" according to the papers I read:

1; Hash chain & quot There are several nodes participating in the system operation (distributed)

3. Reach a consensus on the consistency of basic data (consensus agreement / algorithm) through a certain protocol or algorithm

since bitcoin is currently one of the most typical and influential applications of blockchain, it will be much easier to understand how bitcoin uses blockchain before understanding other forms of blockchain applications

3. I'd like to know about blockchain. It's said that blockchain can create ten times the value of the Internet, so I'd like to ask you to use blockchain to create 1 million value for me. Anyway, it's just a small amount of money for blockchain.

4.

blockchain is a decentralized distributed ledger database . The advantage of this distributed ledger is that buyers and sellers can trade directly without any intermediary. Everyone has a backup, even if you lose this, it will not be affected

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blockchain application field

1, financial field

blockchain has potential huge application value in international exchange, letter of credit, equity registration, stock exchange and other financial fields. The application of blockchain technology in the financial instry can save the third-party intermediary link and realize the point-to-point direct docking, so as to greatly rece the cost and quickly complete the transaction payment

2. The Internet of things and logistics

blockchain can also be naturally combined in the field of Internet of things and logistics. Through blockchain, we can rece logistics costs, trace the proction and delivery process of goods, and improve the efficiency of supply chain management. This field is considered as a promising application direction of blockchain

3. The data stored on the public welfare field

blockchain is highly reliable and tamperable, which is naturally suitable for social public welfare scenarios. The relevant information in the public welfare process, such as donation project, collection details, fund flow, recipient feedback, etc., can be stored on the blockchain, and can be made transparent and public, which is convenient for social supervision

4. In the field of insurance

in terms of insurance claims, insurance institutions are responsible for fund collection, investment and claims settlement, and often have higher management and operation costs. Through the application of smart contract, there is no need for the applicant to apply or the insurance company to approve. As long as the claim conditions are triggered, the automatic claim settlement of the policy can be realized

5.

Share from DTV: how does the blockchain of DTV make profits in the end:

1. Build a blockchain ecosystem

Why do start-ups join in blockchain public chain projects one after another? Because it's a great opportunity. Any enterprise has the opportunity to create an ecosystem that subverts the existing pattern with its own ideas and operations. In this system, the currency designated by the ecosystem owner will circulate

because start-ups hold a certain amount of money and reserve some money for enterprises to dig, and the total amount of money is fixed, the faster the flow speed of the ecosystem is, the greater the demand for money is. More transactions chase less money, and the currency is bound to appreciate, but this idea is based on the fact that the currency is irreplaceable

now many research groups are developing cross chain technology to connect blockchains in different fields, so as to achieve the free circulation of money flow and data flow, and finally go to the exchange

in this case, the impact of a chain of money shortage on the ecosystem may not be as simple as the classical monetary theory, and the money price is likely not to follow the simple relationship between supply and demand. Designers need to think about this from a macroeconomic perspective

this is also the most attractive part of blockchain project: everyone is likely to establish new rules in this new field and become the manager of Qu centralized system. By then, the owners of the blockchain will have the ability to control the economy of the whole field - selling or inhaling digital currency will have a huge impact on the instry

2. Providing services for enterprises

providing services for enterprises is the main profit model of blockchain projects at the present stage, and cloud storage security skeptics are likely to turn to traceable and tamper proof blockchain service providers to seek maximum data security

for example, a blockchain start-up operating a data sharing platform, its main business includes providing data storage and data transaction services for customers, thus charging service fees and handling charges

there are many domestic start-up companies operating such businesses, such as cloud nest, border intelligence, magic chain technology, etc. Each company has excellent technology, but to make a profit, it may have to work hard on the operation

today, Tencent cloud's tbaas has joined this field and can provide services covering finance, supply chain, Internet of things, medical and other fields. It is believed that the competition and expansion of customers will become more difficult in the future

3. Smart contract participates in profit making

smart contract is like a contract that can be executed automatically. The validity of the contract is judged and enforced by machines instead of people. Its essence is still a piece of code, but the traceability and non tampering characteristics of blockchain can ensure that this piece of code runs automatically under the non trust mechanism. Blockchain is the precondition of smart contract operation

in practice, there are many opportunities for profit making through smart contracts, and smart contracts can solve these problems in a non black box way

in the running process of the program, the smart contract performs audit, classification information and other operations, which eliminates the interference of middlemen, and the record will not be artificially damaged, and the font on the file will not be blurred for a long time

but to some extent, the operators of smart contracts themselves become middlemen, and they automatically collect and pay audit fees through smart contracts. This kind of special intermediary service saves a lot of costs for customers, and its essence is realized by improving efficiency

4. Operation of special service driven system

many enterprises have their own exclusive fields in building blockchain community. Take the neurogenomics project led by geneticist church as an example. After enjoying the gene sequencing service provided by neurola, consumers can not pay in the form of legal money, but have to exchange legal money into the token issued by neurola

as more people exchange legal money for this token, nebula will successfully build a blockchain platform with gene data as the core, and after that, it will better carry out precision medical services

generally speaking, this mode relies on the actual technology, makes profits from offline services at the beginning of the project, and converts the legal money in the income into token in the process of making profits. With the progress of the project, the platform can carry out more precision medical services with the help of the data obtained from the start mode, and its profit methods have become diversified, but the whole process will not be separated from the entity

in the whole process of enterprise operation, token is mainly used as incentive, and token appreciation is not a problem that geneticists should consider

The original purpose of project 1CO is to crowdfunding in the market through pre-sale service. In 2013, the early 1CO company appeared in the financial field, and then quickly detonated the entire digital money market, resulting in the rise of speculation

however, this storm came and went quickly. From 2013 to 2014 alone, many projects died in the speculation or were directly judged as fraud

according to Engadget data, 45.6% of the 902 crowdfunding based digital currencies have failed in 2017

Even so, there are still many survivors. These enterprises (including those that build the ecosystem) attach great importance to the role of token, and the appreciation of token will be calculated as part of the profits

In essence, it is similar to an enterprise operating both financial assets (token) and operating assets (service) to manage operating assets to make financial assets profitable. However, if the proportion of "financial assets" is too large, the risk will come uninvited

The foundation of sharing economy is to monitor the available resources and corresponding demands in real time and make adjustments to maximize the utilization of resources. For unicorns like airbnb, they have a mature management mode and stable cash flow. They try blockchain because blockchain technology can bring more transparent, more efficient and fairer systems

this kind of enterprises use blockchain in the way of private chain or alliance chain. They don't need token to participate in circulation, and the nodes don't exist anonymously. They are interested in blockchain technology itself

with the blessing of blockchain technology, the manual input of ID information issued by the government will be transformed into the safe storage and verification of ID issued by the government. Customers and landlords can completely rely on the evaluation content. At the same time, the comments can be traced back to avoid the possibility of negative comments being deleted and the participation of the Navy

the profit model of airbnb and Tencent

6. Bitcontinent itself is a hardware manufacturer, selling mining machine is his main business, profiteering
then he built a mine pool, and many people bought mining machines in his custody

he can continuously earn money from the mine pool

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

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