For blockchain 30, the following statement is correct
"blockchain is equivalent to this account book, and the block is equivalent to a page of this account book. The information carried in the block is the transaction content recorded on this page. The blockchain is block by block, and each block is filled with transaction records and connected together to form a chain, which is called blockchain. "
take bitcoin as an example, there is a "power race" every ten minutes to compete for the right to charge. It's like saying that you have a lot of calculation power, just like your muscles are stronger and more capable of fighting. Everyone will convince you to keep this account, that is, the right to write a block (note that it is not the content in the block) to the general ledger of the blockchain. However, it should be noted that computing power can only determine the probability of winning the competition. For example, there are several lotteries in total, and those with more computing power can buy more to improve the winning probability. However, those who buy more may not win the lottery in the end.
blockchain is a data block chain guaranteed by such computing power. Starting from the first block, each block collects data according to certain rules, and then attaches a value to these data, so that the result of the formed data block after similar one-way function calculation falls into a certain range. By estimating the computing power of the whole network and the size of the control result range, the data blocks that meet the requirements can be found in a long enough time. This calculation result will be included by the next block, and the chain data structure formed in this way is called blockchain
each small ledger is called a block, and each different blockchain protocol (generating different cryptocurrency) will specify the size of each block (the initial bitcoin is 1m). The ledger constitutes a block, the block constitutes a chain list, and the block header contains the hash value of the previous block, which is the blockchain. In this way, no one can modify the content or exchange the order at will. If you do, it means you need to recalculate all the special numbers
regulations allow everyone in the world to build blocks. Every person who builds a new block (finds this special number - sha256 value has 30 zeros) can get a reward. For this part of people (miners) who build a new block:
1. There is no sender information, There is no need to sign
2. Each new block will add a new virtual (encrypted) currency to the whole currency
3. The process of building a new block is also called "mining": it requires a lot of work and can inject new currency into the whole economy
4. The work of mining is: receiving transaction information, building blocks, broadcasting blocks, Then get new money as a reward
for each miner, each block is like a small lottery, and everyone is trying to guess the number quickly until a lucky person finds a special number, so that there are many zeros at the beginning of the hash value of the whole block, and they can get a reward. I remember a Zhihu respondent gave an image analogy. Blockchain is like a king with a beautiful daughter (block). Many young people are looking forward to it. The king's method is to give a very difficult topic for all young people to calculate (learning to change their lives), Who can calculate quickly (or be lucky in the process of calculating the hash value) will be able to win the beauty
for users who want to use this system to collect and pay, they don't need to listen to all the transactions, but just listen to the blocks broadcast by the miners, and then update them to their saved blockchain
"block" can also be imagined as a box, There are some digital currencies and a small note in the block, on which the only transaction information generated in the past ten minutes is recorded, such as "small a transferred to small B100 yuan"; Of course, this piece of information must have been encrypted to ensure that only small a and small B (through the key in their hands) have the ability to interpret the real content
after this magical block was created, it was soon buried underground. Where is it buried? No one does not know that all computer nodes need to participate in digging three feet before it is possible to find (find an effective workload proof). Obviously, this is an event with huge workload and random results. However, for the computer node, once the block is g out from the ground, it will get the valuable digital currency in the block, as well as the tip paid by small a in the process of "small a transferred to small B100 yuan". At the same time, for this node, only he has the right to truly record the contents of the note, which is an honor, while other nodes can only use its , a without digital currency blessing. Of course, there are some other special things about this magical block.
the process of computer nodes digging out blocks from underground is called "mining". As I said just now, this is a huge workload, a lot of luck and a lot of profits. A node on zhangheng road in Pudong New Area of Shanghai, China, suddenly jumped out and said excitedly, "I've g the block! The little notes inside are all valid! The reward belongs to me! ". Although Zhang Heng Road node has got digital currency at the moment, for other computer nodes, because it also involves some other interests, they will not choose to believe what Zhang Heng Road node says by default; Based on the principle that strangers do not trust each other, they take the so-called block () g by Zhang Heng Road node, and start to check whether the small note information in the block is true and effective, etc. In the world of blockchain, nodes check the accuracy of the small note information, or indirectly or directly judge whether the node that successfully digs out the block is lying How to define the true and effective information of a small note will be explained later, but I won't go into details here. In the verification process, each node will directly express their identification (accurate) and attitude towards zhangheng road node through the following two behaviors: stop half or even 80% of the mining process; Add the block () g out by zhangheng road node to the end of its own blockchain. You can be a little confused: if you stop mining, you may have done 80% of the mining work. Then 80% of the previous work is in vain?! Then, what the hell is at the end of the blockchain? For the first puzzle. I want to say that what you said is right, but there is no way. The reality is so cruel. Even if 80% of the work is done, you have to give up. The 80% of the work can be regarded as useless, absolutely damaging the wealth and the masses. The second puzzle is, what is the ghost at the end of blockchain and blockchain? Here, it is not clear in advance, but you can simply imagine: blocks are generated and g out periodically, and a computer node may have executed "take blocks from others" n times in advance; The process of "checking the validity of small notes" must have stored n blocks on its own node, and these blocks will be arranged in a chain in order of time. Yes, this chain is what you always think of as the blockchain. If you still can't understand, it doesn't matter. There will be many opportunities for in-depth study later in the article
go into the more microcosmic world of the block and have a look at what the little note really is, how it came into being and its mission all its life: when initiating a transaction, the initiator will receive a little note, and he needs to write the transaction record, such as "stealing transfer to a piece of RMB 340" on the paper. It's amazing that when it's finished, on the back of the note, the transaction record will be automatically formatted to at least contain the two important fields of "input value" and "output value"“ Input value is used to record the effective source of digital currency, and output value is used to record the object to which digital currency is sent. The newly created note is immediately marked as an "unconfirmed" note. Small pieces of paper that are successfully g out of the ground and eventually connected to the blockchain are initially marked as "valid.". If the valid slip is used as the input value of other transactions, the valid slip will soon be marked as invalid. Due to various reasons, the block is disconnected and discarded from the chain, and the small notes once marked as "valid" in the block will be re marked as "unconfirmed". There is no concept of account balance in the blockchain. The digital asset you really own is actually a piece of transaction information; Get the balance in your digital wallet by simple addition and subtraction. The above 1, 2 and 3 are just the knowledge points forced to you at the beginning. Some of the descriptions may be a bit confusing, which makes you feel confused. Only by understanding the whole blockchain can you have a more comprehensive understanding of the mystery
block capacity. Bitcoin specifies that the block capacity is 1m when it is created, or in the source code. The reason why it was originally designed as 1m is, on the one hand, to prevent DoS attacks. On the other hand, when Zhongben Cong created the blockchain, the capacity was 32m. However, he changed the block capacity to 1m through a humble commit like "clear up". In order to prevent the volume of the blockchain from growing too fast, he added some mystery to the problem of block capacity. The capacity of 1m means that the maximum number of transactions processed by bitcoin is about 2400 (the size of 486882 block 1034.39 is very close)
to put it bluntly, blockchain is a small book for distributed bookkeeping, a tool for bookkeeping, and based on cryptography and cryptography technology, once data transactions are recorded in the book of blockchain, data can not be tampered with and denied. The Internet is the transmission of value, and the blockchain is the transmission of trust. Under the premise of blockchain technology as a credit endorsement, each node in the blockchain changes from a single center to a unified multi center with multi-party participation, which can achieve transaction transmission without the participation of a third party organization and improve the efficiency
bitcoin is a typical blockchain system, which can be studied carefully
1. Application of blockchain technology in the banking instry the biggest feature of blockchain technology is decentralization, which will rece a lot of costs for the banking instry. The development of digital currency will make it possible for banks to realize real-time digital transactions. For example, in bill transaction, bank bill transaction always relies on the third party to realize the transfer of valuable documents. Even in electronic bill transaction,
also needs to be authenticated through the information of central bank ECDs system. The blockchain technology can realize the point-to-point value transmission, which no longer needs centralized system control. This not only speeds up the bill transmission speed, but also reces the mistakes caused by human factors. The rection of process will naturally rece the demand of the bank for personnel and save the labor cost of the bank
2, the application of blockchain technology in the insurance instry
blockchain technology also has incomparable advantages in the insurance instry. From the perspective of data management, the application of blockchain technology can effectively improve the risk management and control ability of insurance companies, including the risk supervision of insurance companies and the risk management of policyholders
the application of blockchain technology in the insurance instry can strengthen the internal risk supervision of insurance companies. Blockchain technology can record the daily operation process of insurance company on the node, realize the in-process control of the company's capital flow, investment situation, compensation amount and other business, and improve the company's risk management and control ability
3. Application of blockchain technology in the securities instry
4, blockchain technology and financial infrastructure
blockchain technology is a decentralized mechanism for value exchange, which will lead to earth shaking changes in the existing financial infrastructure characterized by centralization
5. Application of blockchain technology in supply chain, It has become an effective guarantee for enterprise bank's loan credit, financing credit and transaction credit
want to know more about WeChat official account: block chain three
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
what is a blockchain? How does it work
bitcoin has become the trend of modern Internet, followed by blockchain. It is said that blockchain technology will lead to fundamental changes in Internet operation, enterprise operation and everything else
but what is blockchain? Most of us don't know much about blockchain. If you want to understand blockchain, you can read this article carefully
what is a blockchain? In the simplest terms, blockchain is a distributed ledger
to understand what this means, let's first look at its opposite: a centralized ledger. Because blockchain technology starts from finance, we will also use the bank as an example
the following is the process of our bank debit card transaction:
you can buy goods by swiping your card in the store
the merchant sends the bill to your bank to get the agreed amount
your bank will verify whether you are likely to authorize the purchase
banks remit money to businesses
finally, the bank records this information in its ledger
there are a lot of technologies involved here, but basically that's it. The last step is important - the bank keeps track of all transactions made by the customer. This ledger goes all the way back to the first transaction the bank made
the ledger is kept, maintained and supervised by the bank. You can read it in your online bank account, but you can't change it. The bank is in full control. If it decides to make a change, there's nothing you can do
it is crucial that if hackers can access the bank's ledger, it may lead to many problems. They can change the account balance to make it look like some transaction never happened, and so on
that's why distributed ledger is so cool
blockchain network visualization
if the bank operates on a distributed ledger, each member of the bank will have a of the ledger. Whenever any member of the bank makes a purchase, they will tell all other members of the bank
each member validates the transaction and adds it to the ledger (the added record is called a "block"). This has some important benefits because there are no centralized permissions to manipulate records. Hacker access to one ledger won't be a big problem because other ledgers can easily verify it
on the other hand, it requires a lot of work. In short, the second system is blockchain (at least in the financial scenario)
as mentioned above, blockchain is a decentralized transaction list. If I send Xiaoming two bitcoins, I will send a message to everyone in the network, saying "I am sending Xiaoming two bitcoins", and they will record the transaction<
bitcoin and blockchain
let's take bitcoin as an example to illustrate
bitcoin transaction
but the transaction must be verified. This is where blockchain technology has become a bit more complex. Each bitcoin wallet (which we will complete in one second) has a public and private key
you use your private key to send transaction requests to other members of the network and confirm that you have cryptocurrency in your account. If they do, they allow transactions to register on the ledger
the mechanism of public / private key system is very complex, but it comes down to that every transaction is verifiable and secure< However, the computing cost of the whole system is very high. Everyone who updates the ledger needs a lot of authority to validate transactions and modify the ledger. This is where mining comes in. People who verify and modify use their own computing resources, and each time they get a small transaction fee
and they're using a lot of electricity to do it
in this way, each transaction will be verified and added to the ledger, and the person who performs the verification and modification will be paid. This is a reasonable system
at the same time, it is also very safe. To change a single block, you have to change each subsequent block. After all this is done, validation will fail because other copies of the chain will show someone tampered with one
how to define blockchain is a difficult problem
although the mechanism behind blockchain technology is not always intuitive, it seems that it is not too difficult to explain what blockchain is. But what we're describing here is the traditional definition
we can use this special type of blockchain for a wide range of applications;, Such as cryptocurrency, sharing medical information, sending security messages and so on. But more blockchain like technologies are being developed for other uses
for example, companies may use internal blockchains to manage problem tracking in software. Each block in the chain may represent a problem, and users can publish updates to the network. But is this a blockchain? In this case, the ledger is not public, it is only visible within the company
some people will say that this is not a blockchain
other blockchain like technologies are not encrypted. Are they still blockchain? What if it's centrally managed but uses other blockchain features? What defines the lowest level of blockchain technology? There is no consensus on these issues
what is a blockchain wallet
we usually hear people talk about bitcoin wallets, Ethernet wallets and other cryptocurrency specific wallets. But wallet technology can be used in any system that uses blockchain
a wallet is the software or hardware that "saves" your cryptocurrency. But it doesn't really have anything, it's just a place to store public and private keys. This information allows you to access the currency shown in the public ledger
the wallet is the only record of the key. So if you lose it, you will no longer be able to access your cryptocurrency
in the future of blockchain, how will it change our lives
one important thing about blockchain is that it is a public resource and no one really owns it because everyone owns it
blockchain is more than science fiction. We don't need to understand the mechanism behind this technology, but you need to understand that it may completely change our lives in the next 20 years
that sounds bold, but remember, 20 years ago, we were browsing the Internet on Netscape, using the most advanced Motorola flip phone, and buying our first DVD player. At that time, if we imagined that the computer could be held in our hands, and that we could buy a car, pay for money and watch movies on it, it would be considered a fantasy
although the impact of blockchain may not be as obvious as the Internet or as tangible as mobile phones, blockchain will effectively solve many troubles in daily life. For example, intermediary entrapment, transaction delay and so on. In our present life, middlemen can be seen everywhere. We take it for granted that they are a part of our life. If one day, these intermediaries no longer exist, you will find that the world will become a different one
imagine that by 2040, blockchain may become a mature and widely used technology. One day, you can't do without blockchain, just as you can't do without the Internet now, you will be surprised that this decentralized accounting technology has become a part of your lifestyle<
first praise
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centralized credit creation mode
blockchain puts forward a variety of different consensus mechanisms to help users effectively form bottom-up decisions and participate in major decisions
according to the white paper of bitcoin, nodes always think that the longest chain is the right blockchain and will continue to extend on it. All miners are mining on the longest chain, which is concive to the uniqueness of blockchain ledger. If the bitcoin transaction transferred to you is not recorded on the longest chain, you may face property losses
what is the "longest blockchain"? Because the miners all over the world are mining at the same time, it is possible that two miners can work out the correct answer at the same time, then the blockchain will form a fork, and the remaining miners may continue to mine on any fork, extending the blockchain
therefore, we usually require that after the bitcoin transfer is packaged, we need to go through the confirmation of six blocks to ensure that the miners will not go back to the other branch to excavate, then the real transfer is successful.