Blockchain technology appeared earlier in 2008
1. Germination stage: the real germination stage of blockchain was from 2007 to 2009. In 2008, a Japanese American with the pseudonym of Nakamoto first expounded a new fantasy report on electronic money in the form of a synonym on the cryptography discussion group, and bitcoin came out. As early as 2007, Nakamoto began to explore a series of new technologies to create a new currency. On October 31, 2008, bitcoin white paper was released, and on January 3, 2009, bitcoin system officially began to operate
the main technologies supporting bitcoin system include hash function, distributed ledger, blockchain and asymmetric encryption; It can be seen that these technologies build the initial version of the blockchain, and it can also be said that the blockchain is the underlying technology of bitcoin. During the three years from 2007 to 2009, bitcoin was an experimental stage in which a very small number of people participated, and the real commercial activities had not really started
2. "Geek" niche stage: here, "geek" refers to people who are crazy about Internet technology and take technological innovation as fashion and life. On February 6, 2010, the first exchange of bitcoin appeared. On May 22 of the same year, someone bought two hamburgers with 10000 bitcoins. On July 17 of the same year, the exchange Mt. GOx was established, marking the official inflow of bitcoin into the market. Nevertheless, the only people who can really understand and enter the market to participate in bitcoin trading are geeks who are keen on Internet technology. They discuss bitcoin technology on the forum, mine for bitcoin on their own computers, and then buy and sell bitcoin on Mt. GOx. Now these geeks have become billionaires
3. Market brewing stage: the price of bitcoin was $13 at the beginning of 2013, but on March 18 of the same year, the government of Cyprus closed the bank and stock market e to the financial crisis, which made the price of bitcoin soar, and the highest price rose to $266 in April. On August 20 of the same year, the German government confirmed the currency status of bitcoin. On October 14, China network announced the opening of bitcoin payment channel. In November, the US Senate hearing also confirmed the legitimacy of bitcoin. On November 19, the price of bitcoin rose to US $1242, forming a new high. Nevertheless, the foundation for blockchain to enter the mainstream social economy is not yet available, and the soaring price of bitcoin is only e to over optimistic expectations. The containment of China's banking system, the collapse of Mt. GOx and other events made the price of bitcoin continue to fall. At the beginning of 2015, the price of bitcoin has dropped below $200. From 2013 to the beginning of 2015, the public began to understand bitcoin and blockchain
4. The mainstream period of blockchain: on June 23, 2016, the United Kingdom left the European Union, the fifth nuclear test of North Korea in September, Trump's election in November and other events, the uncertainty of the world's mainstream economy led to the recovery of bitcoin with the function of risk aversion. The market demand was large, and the increase of trading volume made the price of bitcoin soar from $400 in 2016 to $20000 in 2017, The wealth effect of bitcoin and the transaction overflow caused by network congestion of bitcoin have led to the outbreak of other series of virtual currencies, as well as a variety of blockchain applications, resulting in the emergence of a large number of blockchain assets that are 100 times, even 1000 times and 10000 times, which has aroused the crazy pursuit of the world, Subsequently, the Chicago Mercantile Exchange launched bitcoin futures trading, marking that bitcoin has officially entered the mainstream investment proct series, and bitcoin and blockchain have entered the global attention
5. Instry landing stage: after the market frenzy in 2017, the virtual currency and blockchain have been adjusted in terms of market, supervision, cognition, etc. in 2018, returning to rationality. In 2017, many blockchain projects that follow the blockchain technology will graally die out with the cooling of the market, and the projects with real blockchain applications will be initially implemented. 2018 is not only the first year of the blockchain, but also a gold rush period for the blockchain. After the waves wash away the sand, what remains is relatively good gold
from the perspective of the history of blockchain development, blockchain technology is not yet mature and is currently in the growth period. The specific practical application of blockchain is only used in the financial field. It still needs a long way to go to apply blockchain from other instries. However, we should grasp the trend of blockchain and actively learn from the new field of blockchain.
"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
from cable TV companies to retail enterprises, all walks of life are trying their best to keep their most precious property: monopoly. The traditional view is: "if you control the entrance and channel, then consumers have little choice."
however, we see that companies like Netflix and Amazon break the old pattern and provide more choices for our lives. Similarly, in the field of digital currency and finance, some of the largest financial institutions are facing serious challenges
it is expected that decentralized business and demand will rise in 2019, which will provide more opportunities for successful blockchain companies. At the same time, but this opportunity also means risk. If, as in 2018, the founders or entrepreneurs of blockchain companies make too many promises, and the projects are suspected of exaggeration, they may lose their reputation and first mover advantage< For decades, the world's largest financial institutions have controlled most of the financial systems of the global economy
however, blockchain companies have begun to gain fair competition opportunities through access to banking services and real-time payment. In 2019, the blockchain instry will enter the field of securities, loans and other derivative financial procts in addition to financial payment. Companies like securitize *, Dharma, dydx, compound finance and the ocean are committed to building decentralized finance
in the past few years, mobile application companies such as rap, gojek and paytm have been expanding their business, with payment, investment, remittance, loan and insurance procts emerging. As many Asian economies move from cash to the digital economy, they are rapidly attracting users of new banks
Asian regulators have provided clearer guidelines for blockchain and digital currency projects because they believe that blockchain is a catalyst for economic growth and may become a sunrise instry in the future
in addition, more than 80% of digital currency trading volume comes from Asia, so digital currency investors are eager to establish reliable infrastructure. If Grab, Gojek and Paytm can benefit from digital money investors, they will begin to support the block chain more, providing awesome experience for payment, loans and other derivatives.
back to the original heart
in the past few years, the digital currency instry has deviated from its original financial vision, which is well illustrated in Nakamoto's bitcoin white paper. Just like the prosperity and depression of the Internet, almost all imaginable real cases, such as the logistics chain of tracking the freshness of flowers, are attracting people's attention with the hot word of blockchain
however, just like the early Internet, real landing cases must match the development stage of technology
Netflix, for example, could not successfully stream TV programs in 2000, when less than 1% of people used broadband. In the past few years, it has become more and more obvious that payment is a real case of massive application of blockchain
in 2019, blockchain companies will develop rapidly in decentralized financial applications (such as loans and insurance procts) based on the smart contract platform
I always find that the best application landing occurs in specific market segments. As long as blockchain companies can focus on procts that solve specific problems, we will see more competitive and innovative blockchain companies
and that's a good thing for the instry as a whole.
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
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< Advantages:
1) the algorithm is simple and easy to implement
2) there is no need to exchange additional information between nodes to reach a consensus
3) it takes a lot of cost to destroy the system< Disadvantages:
1) waste of energy
2) it is difficult to shorten the block confirmation time
3) the new blockchain must find a different hash algorithm, otherwise it will face bitcoin attack
4) it is easy to generate bifurcation and needs to wait for multiple confirmations
5) there is no finality, and checkpoint mechanism is needed to make up for it.
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
as shown in the figure above, the bottom is data, and the top can write data. A space to store data, a software to manage data, provide an interface to write data, this is the storage system. For example, MySQL is the most common storage system
What are the problems of ordinary storage system? There are at least two common problems
the first is the problem of non high availability. There is a dangerous place for data. In technical terms, data is not highly available
The second problem is that there is only one write point. In technical terms, it is a single point of control
How do ordinary storage systems usually solve these two problems
in fact, MySQL can do a master-slave synchronization of al master, master-slave synchronization of al master, 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
(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
time treaty chain aims to realize the global block identity traffic ecology of (public chain + alliance chain + private chain) * side chain in the digital world.