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The consensus mechanism is one of the important elements of the blockchain and the core rule of the normal operation of the distributed ledger. It is mainly used to solve the trust problem between people and determine who is responsible for generating new blocks and maintaining the effective unification of the system in the blockchain system. Thus, it has become an everlasting research hot topic in blockchain.
This article starts with the concept and role of the consensus mechanism. First, it enables the reader to have a preliminary understanding of the consensus mechanism as a whole; then starting with the two armies and the Byzantine general problem, the evolution of the consensus mechanism is introduced in the order of the time when the consensus mechanism is proposed; Then, it briefly introduces the current mainstream consensus mechanism from three aspects of concept, working principle and representative project, and compares the advantages and disadvantages of the mainstream consensus mechanism; finally, it gives suggestions on how to choose a consensus mechanism for blockchain projects and pointed out the possibility of the future development of the consensus mechanism.
First, concept and function of the consensus mechanism
1.1 Concept: The core rules for the normal operation of distributed ledgers
1.2 Role: Solve the trust problem and decide the generation and maintenance of new blocks
1.2.1 Used to solve the trust problem between people
1.2.2 Used to decide who is responsible for generating new blocks and maintaining effective unity in the blockchain system
1.3 Mainstream model of consensus algorithm
Second, the origin of the consensus mechanism
2.1 The two armies and the Byzantine generals
2.1.1 The two armies problem
2.1.2 The Byzantine generals problem
2.2 Development history of consensus mechanism
2.2.1 Classification of consensus mechanism
2.2.2 Development frontier of consensus mechanism
Third, Common Consensus System
Fourth, Selection of consensus mechanism and summary of current situation
4.1 How to choose a consensus mechanism that suits you
4.1.1 Determine whether the final result is important
4.1.2 Determine how fast the application process needs to be
4.1.2 Determining the degree to which the application requires for decentralization
4.1.3 Determine whether the system can be terminated
4.1.4 Select a suitable consensus algorithm after weighing the advantages and disadvantages
4.2 Future development of consensus mechanism
Last lecture review: Chapter 1 Concept and Function of Consensus Mechanism plus Chapter 2 Origin of Consensus Mechanism
Chapter 3 Common Consensus Mechanisms (Part 1)
Figure 6 Summary of relatively mainstream consensus mechanisms
Source: Hasib Anwar, "Consensus Algorithms: The Root Of The Blockchain Technology"
The picture above shows 14 relatively mainstream consensus mechanisms summarized by a geek Hasib Anwar, including PoW (Proof of Work), PoS (Proof of Stake), DPoS (Delegated Proof of Stake), LPoS (Lease Proof of Stake), PoET ( Proof of Elapsed Time), PBFT (Practical Byzantine Fault Tolerance), SBFT (Simple Byzantine Fault Tolerance), DBFT (Delegated Byzantine Fault Tolerance), DAG (Directed Acyclic Graph), Proof-of-Activity (Proof of Activity), Proof-of- Importance (Proof of Importance), Proof-of-Capacity (Proof of Capacity), Proof-of-Burn ( Proof of Burn), Proof-of-Weight (Proof of Weight).
Next, we will mainly introduce and analyze the top ten consensus mechanisms of the current blockchain.
Work proof mechanism. That is, the proof of work means that it takes a certain amount of computer time to confirm the work.
Figure 7 PoW work proof principle
The PoW represented by Bitcoin uses the SHA-256 algorithm function, which is a 256-bit hash algorithm in the password hash function family:
Proof of work output = SHA256 (SHA256 (block header));
if (output of proof of work
New difficulty value = old difficulty value* (time spent by last 2016 blocks /20160 minutes)
Target value = maximum target value / difficulty value
The maximum target value is a fixed number. If the last 2016 blocks took less than 20160 minutes, then this coefficient will be small, and the target value will be adjusted bigger, if not, the target value will be adjusted smaller. Bitcoin mining difficulty and block generation speed will be inversely proportional to the appropriate adjustment of block generation speed.
-Representative applications: BTC, etc.
Proof of stake. That is, a mechanism for reaching consensus based on the holding currency. The longer the currency is held, the greater the probability of getting a reward.
PoS implementation algorithm formula: hash(block_header) =
Among them, coinage means coin age, which means that the older the coin age, the easier it is to get answers. The calculation of the coin age is obtained by multiplying the coins owned by the miner by the remaining usage time of each coin, which also means that the more coins you have, the easier it is to get answers. In this way, pos solves the problem of wasting resources in pow, and miners cannot own 51% coins from the entire network, so it also solves the problem of 51% attacks.
-Representative applications: ETH, etc.
Delegated proof of stake. That is, currency holding investors select super nodes by voting to operate the entire network , similar to the people's congress system.
The DPOS algorithm is divided into two parts. Elect a group of block producers and schedule production.
Election: Only permanent nodes with the right to be elected can be elected, and ultimately only the top N witnesses can be elected. These N individuals must obtain more than 50% of the votes to be successfully elected. In addition, this list will be re-elected at regular intervals.
Scheduled production: Under normal circumstances, block producers take turns to generate a block every 3 seconds. Assuming that no producer misses his order, then the chain they produce is bound to be the longest chain. When a witness produces a block, a block needs to be generated every 2s. If the specified time is exceeded, the current witness will lose the right to produce and the right will be transferred to the next witness. Then the witness is not only unpaid, but also may lose his identity.
-Representative applications: EOS, etc.
Delayed proof of work. A new-generation consensus mechanism based on PoB and DPoS. Miners use their own computing power, through the hash algorithm, and finally prove their work, get the corresponding wood, wood is not tradable. After the wood has accumulated to a certain amount, you can go to the burning site to burn the wood. This can achieve a balance between computing power and mining rights.
In the DPoW-based blockchain, miners are no longer rewarded tokens, but "wood" that can be burned, burning wood. Miners use their own computing power, through the hash algorithm, and finally prove their work, get the corresponding wood, wood is not tradable. After the wood has accumulated to a certain amount, you can go to the burning site to burn the wood. Through a set of algorithms, people who burn more wood or BP or a group of BP can obtain the right to generate blocks in the next event segment, and get rewards (tokens) after successful block generation. Since more than one person may burn wood in a time period, the probability of producing blocks in the next time period is determined by the amount of wood burned by oneself. The more it is burned, the higher the probability of obtaining block rights in the next period.
Two node types: notary node and normal node.
The 64 notary nodes are elected by the stakeholders of the dPoW blockchain, and the notarized confirmed blocks can be added from the dPoW blockchain to the attached PoW blockchain. Once a block is added, the hash value of the block will be added to the Bitcoin transaction signed by 33 notary nodes, and a hash will be created to the dPow block record of the Bitcoin blockchain. This record has been notarized by most notary nodes in the network. In order to avoid wars on mining between notary nodes, and thereby reduce the efficiency of the network, Komodo designed a mining method that uses a polling mechanism. This method has two operating modes. In the "No Notary" (No Notary) mode, all network nodes can participate in mining, which is similar to the traditional PoW consensus mechanism. In the "Notaries Active" mode, network notaries use a significantly reduced network difficulty rate to mine. In the "Notary Public Activation" mode, each notary public is allowed to mine a block with its current difficulty, while other notary public nodes must use 10 times the difficulty of mining, and all normal nodes use 100 times the difficulty of the notary public node.
Figure 8 DPoW operation process without a notary node
-Representative applications: CelesOS, Komodo, etc.
CelesOS Research Institute丨DPoW consensus mechanism-combustible mining and voting
Practical Byzantine fault tolerance algorithm. That is, the complexity of the algorithm is reduced from exponential to polynomial level, making the Byzantine fault-tolerant algorithm feasible in practical system applications.
Figure 9 PBFT algorithm principle
First, the client sends a request to the master node to call the service operation, and then the master node broadcasts other copies of the request. All copies execute the request and send the result back to the client. The client needs to wait for f+1 different replica nodes to return the same result as the final result of the entire operation.
Two qualifications: 1. All nodes must be deterministic. That is to say, the results of the operation must be the same under the same conditions and parameters. 2. All nodes must start from the same status. Under these two limited qualifications, even if there are failed replica nodes, the PBFT algorithm agrees on the total order of execution of all non-failed replica nodes, thereby ensuring security.
-Representative applications: Tendermint Consensus, etc.
Next Lecture: Chapter 3 Common Consensus Mechanisms (Part 2) + Chapter 4 Consensus Mechanism Selection and Status Summary
As the first DPOW financial blockchain operating system, CelesOS adopts consensus mechanism 3.0 to break through the "impossible triangle", which can provide high TPS while also allowing for decentralization. Committed to creating a financial blockchain operating system that embraces supervision, providing services for financial institutions and the development of applications on the supervision chain, and formulating a role and consensus ecological supervision layer agreement for supervision.
The CelesOS team is dedicated to building a bridge between blockchain and regulatory agencies/financial industry. We believe that only blockchain technology that cooperates with regulators will have a real future. We believe in and contribute to achieving this goal.
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Before this thing called the Web was born, there was an era when the Internet was invented in the 1970s, at the peak of the Cold War between the United States and the Soviet Union. The United States had a central computer controlling its nuclear weapons. A single attack may paralyze the computer system, making it impossible for them to fight back. Therefore, the US government has established a decentralized system that allows many computers to be distributed throughout the country. If an attack occurs, the defense system will continue to operate to ensure that the two countries can destroy each other. For the Internet, this history is dark, but this is also the origin of decentralized thinking. Then, in 1990, Tim Berners-Lee created the Web. The Web is one of the earliest applications on the Internet. It enables people to obtain information more efficiently. However, it is a relatively specialized tool, mainly used by researchers and students. But then it soon changed. With the popularization of software tools, the Web has gradually entered the eyes of ordinary people.
Browsers like Microsoft Internet Explorer brought the web to the public's perspective five years later. Everyone can start surfing the Internet. Although the web design was very bad at that time, the connection method was dial-up Internet access. It took a long time to download a photo, not to mention downloading a video. This is what the web prototype looks like
The beginning of the Web is decentralized to some extent, it is driven by the most common computers. There is a photo of Tim‘s computer with a sticker that says Do Not Shut Down, because this computer provides the Internet with power.
The beginning of the Web was open source, which means anyone can freely build on this basis, which enables the establishment and development of enterprises like Google and Amazon.
The web is initially read-only, people just read data from the network, and do not perform input operations on the network.
All this changed around 2005. Youtube, Facebook, Twitter, and other new websites brought the current Web world, also known as the classical Internet.
This is the first time anyone can publish content online without the need to understand any computer technology that is too professional. Facebook, YouTube and Twitter are all ways for people to create their own web, which directly determines the result of today's large-scale popularization of the web.
Since then, people have begun to see problems with these new websites. Although they make our online life more convenient, they slowly build walled gardens on the open web. We started to deviate from the Web of most early vision. At the same time, computers that used to power the web have gradually evolved into centralized data centers that provide computing power on these platforms. Later, the development of smartphones has accelerated this phenomenon. We access the web through various portable devices to obtain and transmit a large amount of information. Unfortunately, quoting Tony Aube's previous evaluation of today's network, today's Web has collapsed. Now it is like a giant baby. It is already aging before it has experienced sufficient growth. Over the past decade, Internet-based services have tended to be centralized. As the network matures, we gradually tend to rely on a few companies. Google provides the fastest and most convenient search service, gaining 74% control of search traffic. Facebook built the largest social network and gained control of the online identity of 2.2 billion people. Although most people feel that they are enjoying various free Internet services, in fact, free things are often the most expensive. All these services are based on the possession and utilization of the most precious resources of the Internet, and that is data.
As early as when the network was first launched, it had no native way to deliver value. People are very cautious about using bank cards online. The best way to make money online is to provide free services and make money through advertising. In such a way that let individual users have been using the free service, and later to make more accurate advertising push, advertising services company gave birth to birth, they open the default web advertising business, while at the same time there are a variety of ad blocker After being born, advertising service providers will also use freely collected user information and network behavior information to conduct user analysis and push advertisements through improved inducement operations. Sometimes he does not hesitate to use false news and other means. The network environment has gradually become dirty, and the cost of obtaining effective information has been gradually increased by advertising.
The problem of advertising is only one of the manifestations of data occupation and utilization by centralized organizations. Many more serious problems are gradually revealed and gradually paid attention to, including user data loss, personal data leakage, user behavior data is monitored, and data over-censorship Problems, etc. Every day, every day is not performed in every corner of the world. The entire network world urgently needs a re-upgrade to solve the increasingly serious problem of centralized data.
Next Generation Internet (NGI)
The classical Internet was gradually formed after people discovered changes in the Web, as the ideas of the classical Internet spread, inevitable problems have arisen, what will Web3.0 look like. At that time, people had a lot of conjectures. People guessed that Web3.0 would be an artificial intelligence web or a virtual reality web. Although we think these are exciting technologies, we don't think they will redefine the web.
Last year, there was a large conference called NGI Summit. In the conference, just like the discussion of Web 2.0, the clear information obtained through the discussion of a large number of engineers and researchers is: NGI is to return to the decentralized network
In fact, with the emergence of these problems in today's Internet world, a series of seemingly unrelated technologies are also developing on the edge of the technology industry, such as cryptocurrency, blockchain, and distributed storage. NGI is more like a synonym for a better vision of the Internet in the future.
NGI is different from the previous generation of internet transformation. The core of NGI is not speeding, performance, or convenience. The actual on many NGI applications compared with today's applications, but also very slow, not convenient.
NGI is about ownership and control. It matters who controls the technology and our daily applications, and who owns the data and files generated on the network. It is breaking the momentum that has shaped the network for nearly a decade: the balance between convenience and ownership. We are used to this motivation and take everything for granted: using the network means being monitored, and using the social network means that we give personal data to the platform. How could there be other ways? But NGI refused to accept that it believed that people could benefit from the Internet, but there was no need to hand over data control to a few companies. The power is not above the iron law of the universe, it's just a product of the circumstances of technology, we are in the process to make a choice. NGI is a movement, which aims to build a different technology to make better choices. NGI is not trying to replace the network but to change the underlying architecture while keeping things we like—reform, not revolution. NGI is a set of technologies aimed at reconstructing Internet control rights. These include financial projects (crypto currencies), basic communication technologies (end-to-end encrypted information transfer), mass consumer scenarios (open social networks, p2p markets), and key Internet data file infrastructure (decentralized DNS and distributed storage). NGI should include any technology that is conducive to changing Internet centralization and allowing users to gain control of digital life. Currently, there are many solutions for decentralized computing power, but decentralized storage capacity is still not strong and perfect. Because only if it implements the calculation decentralized and storage decentralized, to truly achieve NGI vision of truly decentralized applications and services, and for user data to truly returned to the user by the user's control.
What should decentralized applications and services look like
In the NGI network, we should be able to create products and services that are not controlled by any company, but these products and services can still reach the level of centralized companies. Just like Bitcoin, these products are decentralized, although the degree of decentralization necessary for any product and the benefits it may bring will be very different.
For example, what might a decentralized video sharing platform look like, it would be similar to YouTube that allows users to share video content, comments, thumbs up, and so on. The platform encourages users to contribute through the built-in incentive mechanism. Users can not only “like” the video, but they can also make a small payment or charge a certain fee for the content creator through the copyright distribution control of the network protocol, without having to consider twists way to perform fan monetization. Even if it only costs a few cents for each like, it is still better than traditional centralized video platforms, because, on these platforms, the creator ’s revenue per million views is only a few thousand dollars, On the decentralized platform, there is no middleman's fee, users can directly use peer-to-peer transactions.
The core rules governing decentralized services are defined by open-source agreements. Users use the client of their choice to interact with the protocol. In other words, there will be various apps, but all are connected to the same video network. These clients can provide different functions, but all comply with the same sharing protocol, similar to email clients using the same initial standards. Developers do not need to apply for a license from any centralized organization. They can build their products without worrying about API access being blocked on a certain day. Because no company can turn it off. These are all benefits that a decentralized network has not yet fully recognized. Of course, the products and services created by centralized companies will still be used, but it will only prompt these companies to reduce the control of data and gradually return control to users. Early Internet companies promise " do not BE Evil" For Web3.0 who will have to ensure that the " CAN ' t BE Evil ".
What does it mean for users to control data?
Today, most user data are controlled by a centralized company, whether it is identity data, stored file data, or user behavior data.
In NGI, users will have maximum control over their data. First of all, users can completely use their own identities, rather than the identities provided by third parties, which limits the opportunities for various centralized providers to obtain user identity data. For example, one day you are not satisfied with the service of a chat app and want to switch to other social platforms, then all these data should be able to be taken directly by the user and migrated. You don't even need any help from any intermediate agency. Secondly, based on the construction of a decentralized storage network protocol, when you use social media, video media, rental housing, car rental, and other services, there will be no centralized data storage center to deposit your data and sell it. The reason why these companies collect user data is that these data have great value. In the NGI network, users will get the value of these data. If users want to sell their data, they will directly receive revenue instead of centralized companies. As people try to reform the ownership mechanism of data assets, the production and cooperation relations of the entire network will change substantially.
Currently, even with the existence of IPFS, a distributed storage protocol that has been developed for several years, the problem of decentralization of data has not been solved, and real commercial purposes cannot be achieved. Most Dapps are currently only decentralized services. So, when distributed storage can run on a large scale and stable, it may be when NGI can enter the public eye. It is also positive that DSP Lab (Distributed Storage Protocol Lab ) reasons for coming, it is the next generation of internet-based facilities will be file-based data encryption, distribution, storage, sharing some of the columns of the new generation of Internet paradigm to support from NGI Required distributed storage protocol.
Although NGI still has a lot of uncertainties, it also faces many problems that need to be solved. But NGI is still the most anticipated future. Blockchain technology is not an end in itself. They only have value if they solve the problem. NGI allows us to face and solve this problem again: The Internet has become too centralized, and it needs to be open.
NGI will not stop developing because of a certain technology development bottleneck or technical bottleneck. We can use the knowledge system used in the past years to continue to build these better and newer system versions.
NGI is not nothingness, nor utopia, nor can it escape from reality. The current internet also has various human problems. Politics, rights, and control have not disappeared due to the invention of the Internet. What can be determined in NGI is that it contains a design that restricts rights and controls. We have a second chance to build the Internet, but we may not have a third time, so let us take advantage of it and look forward to its arrival.
⟳ f-droid.org from Wed, 26 Feb 2020 20:21:50 GMT updated on Sun, 01 Mar 2020 05:23:29 GMT contains 2962 apps.Added (870)
In the Pentagon war game, young people born between the mid-1990s and early 2010s use cyber attacks to steal money and convert it to bitcoin, documents published by investigative news site The The war nickel calculator will only show you what the silver in your wartime nickels is worth (intrinsic value), and will not indicate any numismatic (collector) or base metal value. Use the war nickel calculator to compute how much the silver in your war nickels is worth, or to set a max bid on a war nickel auction based on its silver content Bitcoin is up on the news of the US air strike on Iran. Credit: ADVFN. This is a very interesting chart because it shows the global professionals reacting to the news much faster than the private Find out what your expected return is depending on your hash rate and electricity cost. Find out if it's profitable to mine Bitcoin, Ethereum, Litecoin, DASH or Monero. Do you think you've got what it takes to join the tough world of cryptocurrency mining? Accurate Bitcoin mining calculator trusted by millions of cryptocurrency miners. Updated in 2020, the newest version of the Bitcoin profit calculator makes it simple and easy to quickly calculate mining profitability for your Bitcoin mining hardware.
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