Ethereum Byzantine excavation time

1.

blockchain includes public blockchain, joint (instry) blockchain and private blockchain. Public chain point-to-point e-cash system: bitcoin, smart contract and decentralized application platform: ethereum

blockchain is a new application mode of distributed data storage, point-to-point transmission, consensus mechanism, encryption algorithm and other computer technologies

blockchain is an important concept of bitcoin. In essence, it is a decentralized database. At the same time, as the underlying technology of bitcoin, it is a series of data blocks generated by using cryptographic methods. Each data block contains a batch of bitcoin network transaction information, Used to verify the validity of its information (anti-counterfeiting) and generate the next block

extended data

according to the different degree of blockchain network centralization, three kinds of blockchains under different application scenarios are differentiated:

1. The blockchain with the whole network open and without user authorization mechanism is called public chain

2. The authorized nodes are allowed to join the network, and the information can be viewed according to the authority. It is often used in the inter agency blockchain, which is called alliance chain or instry chain

3. All the nodes in the network are in the hands of one organization, which is called private chain

alliance chain and private chain are also called licensing chain, and public chain is called non licensing chain

blockchain features

1, decentralization. Blockchain technology does not rely on additional third-party management institutions or hardware facilities, and there is no central control. In addition to the self-contained blockchain itself, each node realizes information self verification, transmission and management through distributed accounting and storage. Decentralization is the most prominent and essential feature of blockchain

2. Openness. Blockchain technology is based on open source. In addition to the private information of all parties involved in the transaction is encrypted, the data of blockchain is open to everyone. Anyone can query blockchain data and develop related applications through the open interface, so the information of the whole system is highly transparent

3. Independence. Based on consensus specifications and Protocols (similar to various mathematical algorithms such as hash algorithm used by bitcoin), the whole blockchain system does not rely on other third parties, and all nodes can automatically and safely verify and exchange data in the system without any human intervention

4. Safety. As long as 51% of all data nodes cannot be controlled, the network data cannot be arbitrarily manipulated and modified, which makes the blockchain itself relatively safe and avoids subjective and artificial data changes

5. Anonymity. Unless there are legal requirements, technically speaking, the identity information of each block node does not need to be disclosed or verified, and the information can be transferred anonymously

2. What is "decentralization"

"decentralization" is translated from the English word decentralization, which is composed of the prefix de -, stem central and suffix ization. Among them, the stem central means "center", the suffix - ization means "... Hua", and the prefix de - has the meanings of leaving, removing, canceling and opposite. Therefore, it is very accurate to translate it into decentralization

what is the meaning of decentralization

vitalik buterin, founder of Ethereum, published the article "the meaning of decentralization" in February 2017, elaborating the meaning of decentralization. He thinks that we should distinguish the centralization and decentralization of computer software from three perspectives: architecture, governance and logic

Architecture centralization refers to the number of nodes that the system can tolerate and continue to run; Governance centralization refers to how many indivials and organizations are needed to control the system; Logic centralization refers to whether the interface and data presented by the system are like a single whole

blockchain is a unified account book of the whole network, so it is logically centralized, which is beyond doubt. From the perspective of architecture, blockchain is based on peer-to-peer network, so it is decentralized. From the perspective of governance, blockchain makes it difficult for a few people to control the whole system through consensus algorithm, so it is decentralized. The decentralization of architecture and governance brings three benefits to blockchain: fault tolerance, anti attack and anti collusion

five differences between blockchain and traditional distributed system

as a new kind of distributed system, blockchain is often mistakenly regarded as a distributed database or log system. In fact, there is a fundamental difference between blockchain and traditional distributed system, namely decentralization. Now let's look at the main differences between blockchain and traditional distributed systems:

(1) consistency algorithm: what blockchain needs to solve is the Byzantine general problem, that is, there are one or more fraulent nodes in the network, which may deliberately violate the protocol or transmit wrong data, Therefore, Byzantine fault-tolerant consensus algorithms, such as BFT, pow, POS, are often used in blockchain; The traditional distributed system only needs to consider the node failure and communication errors, and often uses consistency algorithms such as Paxos and raft, which can not resist the fraulent nodes

(2) central controller: there is no central controller in the blockchain network, and no node can control or coordinate the generation of ledger data. All nodes coordinate through consensus algorithm to generate consistent ledger. However, the traditional publishing system is often controlled by one organization, which uniformly dispatches all nodes to participate in the calculation

(3) rule making: the rule of blockchain is consensus protocol, also known as consensus mechanism, and consensus algorithm is a part of it. Consensus mechanism is generally designed and developed by a person or a team, and the corresponding proceres are developed for the community to use. This seems to be the same as the traditional distributed system, but the change and upgrading of the consensus mechanism of the blockchain requires the community to have a consensus on it. If no consensus can be reached, anyone can implement hard bifurcation and build another community and chain. This is the decentralization process of consensus mechanism.

3. When it comes to money, mining is indispensable. In Ethereum network, if you want to get Ethereum, you also need to mine it. When it comes to mining, there must be a consensus mechanism
do you remember what the consensus mechanism of bitcoin is? The consensus mechanism of bitcoin is pow. To put it simply, the more work you do, the higher the amount of computation you pay, the more likely you will be the first to find the correct hash value, and the more likely you will be rewarded with bitcoin
however, there are some defects in the pow of bitcoin, that is, it is too slow to process transactions, and miners need to constantly collide hash values through calculation, which is costly and inefficient. Friends who are interested in blockchain knowledge should see such a saying:
in order to make up for the deficiency of bitcoin, Ethereum has proposed a new consensus mechanism, called POS (this is the abbreviation of English, which means "proof of equity", also translated into "proof of equity")
POS simply means the same as its literal meaning: equity, equity. The more currency you hold, the more equity you have, the higher your equity
Ethereum's POS means that the more money you hold, the longer you hold it, the less difficult it will be to calculate and the easier it will be to mine
in the initial setting of Ethereum, Ethereum hopes to build a relatively stable system by using POW in the early stage, then graally adopt POW + POS, and finally completely transition to POS. So, it's true that the consensus mechanism of Ethereum is POS, but POS is only a plan or goal at the beginning of Ethereum's release. At present, Ethereum has not yet transitioned to POS, and the consensus mechanism adopted by Ethereum is still pow, that is, the pow of bitcoin, but it is slightly different from the pow of bitcoin
the amount of information here is a bit large,
the first information point is that the consensus mechanism currently adopted by Ethereum is also pow, but it is slightly different from the pow of bitcoin. So, what's the difference between the pow of Ethereum and bitcoin: in short, the mining difficulty of Ethereum can be adjusted, but the mining difficulty of bitcoin can't be adjusted. Just like our college entrance examination, because the teaching situation and the number of students in different provinces are not the same, so the college entrance examination is divided into national papers and provincial independent proposition
Ethereum said that I am in favor of the topic by region. Bitcoin said: No, it must be the same volume in the whole country. The difficulty is the same for everyone
the popular explanation is that bitcoin uses computer computing power to do a lot of hash collisions, enumerate various possibilities to find a correct hash value. The Ethereum system has a special formula to calculate the difficulty of each block. If a block is verified faster than the previous block, Ethereum protocol will increase the difficulty of the block. By adjusting the block difficulty, the time needed to verify the block can be adjusted
according to the Ethereum protocol, the dynamic adjustment method of difficulty is to make the time interval of creating new blocks in the whole network 15 seconds, and the network uses 15 seconds to create blockchain. In this way, because the time is too fast, the synchronization of the system is greatly improved, and it is difficult for malicious participants to launch 51% (that is, more than half) of the computing power to modify historical data in such a short time
the second information point is: in the initial setting of Ethereum, we hope to achieve the transition from POW to
POS through phased upgrade
dating back to 2014, at the beginning of Ethereum's launch, the team announced that the launch of the project would be divided into four stages, namely, Froniter, homestead, metropolis and serenity. In the first three stages, the consensus mechanism adopts pow (workload proof mechanism), and in the fourth stage, it switches to POS (equity proof mechanism)
on July 30, 2015, the first phase "frontier" of Ethereum was officially released. This phase is only suitable for developers. Developers can write smart contracts and decentralized application DAPP on Ethereum network, and miners begin to enter Ethereum network to maintain network security and get Ethereum coins. The leading-edge version is similar to the beta version, proving whether the Ethereum network is reliable or not
on March 14, 2016, Ethereum entered the second stage of "homeland". In this stage, Ethereum provides the wallet function, so that ordinary users can easily experience and use Ethereum. There is no obvious technology improvement in other aspects, but it shows that Ethereum network can run smoothly
in September 2017, Ethereum has reached the third stage of "metropolis"“ "Metropolis" is composed of Byzantine and Constantinople. The goal of this stage is to introce the hybrid chain mode of POW and POS, so as to prepare for the smooth transition from POW to POS. This is the latest popular "Ethereum Constantinople upgrade". In the Constantinople upgrade, Ethereum will make some changes to the underlying protocols and algorithms to lay a good foundation for the implementation of POW and
POS
how much reward will Ethereum get for mining? Miners who win the block creation competition will get the following income:
1. Static reward, 5 ethereums
2. The fuel cost in the block, i.e. gas, we talked about in the last issue
3. As a part of the block, it includes the extra reward of "Uncle block". Uncle is uncle of uncle, and each uncle block can get 1 / 32 of the mining reward as a reward, that is, 5 times 1 / 32, which is equal to 0.15625 ethereums. Here, let's briefly explain the concept of "TERT block". The concept of "TERT block" was proposed by Ethereum. Why should we introce the concept of TERT block? This also starts with bitcoin. In the bitcoin protocol, the longest chain is considered absolutely correct. If a block is not part of the longest chain, it is called a "orphan block". An isolated block is a block, which is also legal, but it may be found later, or the network transmission is slower, and it does not become part of the longest chain. In bitcoin, the solitude is meaningless and will be discarded later, and the miners who find the solitude will not receive mining related rewards
however, Ethereum does not think that isolated blocks are worthless, and Ethereum system will give rewards to miners who find isolated blocks. In Ethereum, isolated blocks are called "Uncle blocks", which can contribute to the security of the main chain. Ethereum's ten second block interval is too fast, which will rece the security. By encouraging the use of tertiary blocks, the main chain can obtain more security guarantees (because the isolated block itself is legal). Moreover, paying the tertiary block can also stimulate the miners to actively mine and actively use tertiary blocks. Therefore, Ethereum thinks that it is valuable.

4. How to use the three technical indicators to understand the rise and fall of bitcoin

coincola coying Cola
Global innovative digital asset trading platform
how to use the three technical indicators to understand the rise and fall of bitcoin
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4 minutes
recently, "bitcoin broke through $8000" has been on the hot search. For a while, bitcoin rose, reborn rose sharply, and Ethereum led the rise... A week later, this big play dominated by bitcoin didn't seem to come to an end, and the trading volume was once pushed up to 100 billion US dollars

in the investment world, "madness" and "fear" coexist. Today's "madness" stems from last year's long-term "fear". However, this time, coincola Cola Research Institute tracks and analyzes the technical indicators behind the rising market, and deconstructs the "passion" of the market with the "rationality" of data< (1) mining and bitcoin price

start with the relationship between mining and bitcoin. The core technology of bitcoin is "blockchain", which is connected by blocks. Each block corresponds to a bill. All transaction information and transfer records of bitcoin are recorded on the blockchain. Every other point in time, the bitcoin system will generate a random code on the system node. Due to distributed accounting, all computers on the Internet can search for the code. Whoever finds the code will generate a block and then get bitcoin. This process is mining. Calculating this random code requires a lot of GPU operations, so miners need to use mining machines with massive graphics cards to make profits

1. Bitcoin computing power: starting to pick up

remarks: June 2018-may 2019 bitcoin hash value

data source: bitcoin visual, coincola Research Institute

the above figure shows the bitcoin hash value. The hash value of the bitcoin network represents the computing power of the blockchain. The growth of computing power means that miners increase mining investment or increase the number of miners. Since the second half of 2018, the hash value has recovered from falling back to picking up, from 32eh / s at the end of the year to 50eh / s now, and the recent growth trend is remarkable. The continuous growth of bitcoin hash value (representing computing power) indicates that the market is optimistic about the future of bitcoin

2. Mining difficulty: stepped up

remarks: bitcoin difficulty from June 2018 to may 2019

data source: bitcoin visual, coincola Research Institute

the figure above shows bitcoin difficulty. Since 2019, the difficulty of bitcoin mining has increased in a step-by-step manner, from the low 5T to the current 7T. It can be seen that the rapid rise of bitcoin in this round has reced mining costs and increased market entry personnel. The increasing difficulty of mining means that there are profit opportunities in cryptocurrency market, and the market is generally optimistic< (2) the number of active addresses and transactions on the chain are important indicators reflecting the activity of cryptocurrency, which are highly correlated with the price of cryptocurrency

1. The number of active addresses on the bitcoin chain: a straight line rise

remarks: the number of active addresses on the bitcoin chain from June 2018 to may 2019

data source: coinmetrics, coincola Research Institute

active addresses refer to the addresses where transactions have taken place every day, that is, how many independent addresses conct transfer transactions on the chain every day. Since 2019, the number of active addresses on the bitcoin chain has been rising, especially in recent years. From 540.60143k in January to 832.592k now. It shows that the rapid growth of active users of cryptocurrency is a very positive signal for the market

2. The number of transactions on the bitcoin chain: continued to rise

remarks: the number of transactions on the bitcoin chain from June 2018 to may 2019

data source: bitinfo charts, coincola Research Institute

since 2019, the number of transactions on the bitcoin chain has continued to rise, from 235k in early 2019 to 374k now. Moreover, since April and may, after two rounds of sharp rise in the price of bitcoin, the number of transactions on the chain has remained at a high level, even showing signs of a short-term surge< (3) lightning network and bitcoin price

in essence, lightning network adds a layer to the basic layer of bitcoin blockchain in order to make the transaction fast and cheap. With the existence of lightning network, users can remit money to each other at any time and pay very little. Lightning network represents not only the technical level of bitcoin, but also the important basis of bitcoin value

1. Lightning network nodes: rapid growth

remarks: bitcoin lightning network nodes from January 2018 to may 2019

data source: bitinfo charts, coincola Research Institute

the test version of lightning network started on the bitcoin main network on March 15, 2018. The number of lightning network nodes was only 64 at the beginning of 2018 and increased to 2329 at the end of 2018. Since 2019, the number of lightning network nodes has increased rapidly, and now it has reached 4289. In less than half a year, the number of nodes has doubled. The continuous expansion of nodes indicates the continuous upgrading and development of bitcoin lightning network technology, which is an important indicator of bitcoin price

2. Lightning network capacity: speed up

remarks: bitcoin lightning network capacity from January 2018 to may 2019

data source: bitcoin visual, coincola Research Institute

the data above shows that as of May 15, 2019, bitcoin lightning network capacity has increased to 1039 BTC, equivalent to 833usd, while at the beginning of 2019, it is only 504btc, Lightning network capacity doubled, and the growth rate accelerated. This means that the expansion of bitcoin has been well solved in lightning network technology, which will help keep the payment channel active and effectively support the functional application of bitcoin

the performance of mining, chain trading and lightning network is closely related to the price of bitcoin. On the one hand, the rise of bitcoin price acts as a catalyst to stimulate its performance in mining, chain and lightning network; On the other hand, mining, chain trading and lightning network are the important cornerstone of bitcoin price trend and the important basis of bitcoin price expectation<

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5.

One of the characteristics of blockchain projects (especially public chains) is open source. Through open source code, to improve the credibility of the project, so that more people can participate. But the open source code also makes it easier for attackers to attack blockchain system. In the past two years, there have been a number of hacker attacks. Recently, the anonymous currency verge (xvg) was attacked again. The attacker locked a vulnerability in the xvg code, which allowed malicious miners to add false timestamps on the block, and then quickly dig out new blocks. In a few hours, the attacker obtained nearly $1.75 million worth of digital currency. Although the subsequent attack was successfully stopped, no one can guarantee whether the attacker will attack again in the future

of course, blockchain developers can also take some measures

one is to use professional code audit services,

the other is to understand the security coding specifications and take preventive measures

the security of cryptographic algorithm

with the development of quantum computer, it will bring a major security threat to the current cryptosystem. Blockchain mainly relies on elliptic curve public key encryption algorithm to generate digital signature for secure transactions. Currently, the most commonly used ECDSA, RSA, DSA, etc. can not withstand quantum attacks in theory, and there will be greater risks. More and more researchers begin to pay attention to cryptographic algorithms that can resist quantum attacks

of course, in addition to changing the algorithm, there is another way to improve the security:

refer to bitcoin's treatment of public key address to rece the potential risk of public key disclosure. As users, especially bitcoin users, the balance after each transaction is stored in a new address to ensure that the public key of the address where bitcoin funds are stored is not leaked

security of consensus mechanism

the current consensus mechanisms include proof of work (POW), proof of stake (POS), delegated proof of stake (dpos), practical Byzantine fault tolerance (pbft), etc

POW faces 51% attack. Because POW depends on computing power, when the attacker has the advantage of computing power, the probability of finding a new block will be greater than that of other nodes. At this time, the attacker has the ability to cancel the existing transaction. It should be noted that even in this case, the attacker can only modify his own transaction, but not the transaction of other users (the attacker does not have the private key of other users)

in POS, attackers can attack successfully only when they hold more than 51% token, which is more difficult than 51% computing power in pow

in pbft, when the malicious nodes are less than 1 / 3 of the total nodes, the system is secure. Generally speaking, any consensus mechanism has its own conditions. As an attacker, we also need to consider that once the attack is successful, the value of the system will return to zero. At this time, the attacker does not get any other valuable return except destruction

for the designers of blockchain projects, they should understand the advantages and disadvantages of each consensus mechanism, so as to select an appropriate consensus mechanism or design a new consensus mechanism according to the needs of the scene

security of smart contract

smart contract has the advantages of low operation cost and low risk of human intervention, but if there are problems in the design of smart contract, it may bring greater losses. In June 2016, the Dao, the most popular funding project of Ethereum, was attacked. The hacker obtained more than 3.5 million Ethereum coins, which later led to the bifurcation of Ethereum into Eth and etc

there are two aspects of the proposed measures:

one is to audit the security of smart contract, and the other is to follow the principle of smart contract security development

the security development principles of smart contract are: to be prepared for possible errors, to ensure that the code can correctly handle the bugs and vulnerabilities; Release smart contracts carefully, do well in function test and security test, and fully consider the boundary; Keep smart contracts simple; Pay attention to the threat intelligence of blockchain and check and update in time; Be clear about the characteristics of blockchain, such as calling external contracts carefully

security of digital wallet

there are three main security risks in digital wallet: first, design defects. At the end of 2014, a user lost hundreds of digital assets e to a serious random number problem (repeated r value). Second, the digital wallet contains malicious code. Third, the loss of assets caused by the loss or damage of computers and mobile phones

there are four main countermeasures:

one is to ensure the randomness of the private key

The second is to check the hash value before installing the software to ensure that the digital wallet software has not been tampered with

The third is to use cold wallet

The fourth is to back up the private key

6. EOS's vision is to become a public chain that can run a large number of commercial applications, and its core feature is "commercial"
in order to ensure decentralization and security, current public chain projects such as bitcoin and Ethereum have certain limitations in block scalability. Although the introction of Ethereum's smart contract has greatly enriched the application of blockchain, it also reces the threshold of issuing coins, making Ethereum's network very congested. Many existing public chains have the problems of slow network transfer speed, high cost, low concurrency or poor stability, which can not support the operation of real large-scale commercial applications
according to the white paper of EOS, EOS adopts the graphene block chain architecture, and the bft-dpos consensus mechanism reces the number of verification nodes, but makes the scalability of EOS significantly enhanced, and can support fast transaction processing speed. At present, bitcoin system can transfer about 7 times per second, while Ethereum can transfer 15 times per second; In contrast, EOS's white paper says it is expected to reach a million level TPS in the future
in addition, EOS provides a good development environment for users and developers. The transaction on EOS network does not need to charge service charge, which improves the user experience and makes it easier to attract users; EOS provides developers with a friendly underlying mole, which can support a variety of programming languages and rece the difficulty of DAPP development. Developers can focus more on the function implementation of the developed application.