Editor’s note: Authors of this article: Wang Qiulin (an early developer of blockchain technology, developed a variety of blockchain games, and worked in the research and development of a well-known Tokyo software company); Chongmu (blockchain developer technology ecology researcher, game man bull Founder, founder of dll.io), released with authorization.

Blockchain (Blockchain) is a distributed peer-to-peer network running on the Internet without a central control point. It uses a distributed collective operation method to implement a set of non-tamperable and trustworthy database technology solutions. It is characterized by decentralization storage, highly transparent information, and not easy to tamper with. To put it more simply, the blockchain is a "big public ledger" that uses computer programs to record all transaction information at the terminal nodes of the entire network.

secondary title

technology accumulation period

During this period, the core technologies involved in the blockchain were gradually proposed and improved. These technologies laid a solid foundation for the birth of the blockchain and also gave birth to the early seeds of encrypted digital currency.

In 1976, BaileyW.Diffie and MartinE.Hellman published the paper "New Directions in Cryptography". The thesis covers all new developments in cryptography in the next few decades, including asymmetric encryption, elliptic curve algorithm, hashing and other means, which has established the development direction of the entire cryptography so far, and also has a profound impact on blockchain technology and The birth of Bitcoin played a decisive role.

In the same year, Hayek published the last monograph on economics in his life: "The Denationalization of Currency". Spiritual guide.

In 1977, the famous RSA algorithm was born, and the three inventors won the Turing Award in 2002. The algorithm is written by taking advantage of the principle that it is difficult to factorize a large integer, but it is easy to verify that the factors form a large integer. If you want to crack RSA, you only need to be able to quickly decompose large integers. Obviously this is the easiest and fastest way to crack RSA. But it is extremely difficult to decompose a large integer (called NP-Hard problem in mathematics), which is why RSA can guarantee that it cannot be cracked. Currently, the RSA encryption scheme is mainly used in the online banking system.

In 1980, MerkleRalf formally proposed the Merkle-Tree data structure and the corresponding algorithm data structure. This structure is a tree that stores hash values. The leaves of the Merkle tree are data blocks (for example, files or collections of files). hash value. A non-leaf node is the hash of the concatenated strings of its corresponding child nodes. In the P2P network that was born later, Merkle Tree is used to ensure that the data blocks received from other nodes are not damaged and have not been replaced, and even check that other nodes will not deceive or publish false blocks. Blockchain systems such as Bitcoin and Ethereum also use this structure to verify data.

In 1982, Lamport proposed the Byzantine Generals Problem, which marked that the reliability theory and practice of distributed computing entered a substantive stage.

The problem can be briefly described as: generals communicate only through messengers and must agree on a common battle plan. However, one or more of them may be traitors trying to confuse others. The problem is to find an algorithm to ensure that the loyal generals reach an agreement.

Corresponding to specific computer problems, a reliable distributed computer system must be able to handle the failure of one or more nodes. Failed nodes may exhibit an often overlooked type of behavior—that is, send conflicting information to other nodes in the system. The problem of solving such failures is represented abstractly as the Byzantine generals problem

In the same year, David Chaum proposed the cryptographic payment system ECash. It can be seen that with the development of cryptography, people with keen eyes have begun to try to apply it to the fields related to currency and payment. It should be said that ECash is a cryptographic payment system. One of the earliest pioneers in the study of money.

In 1985, Koblitz and Miller independently proposed the famous Elliptic Curve Cryptography (ECC) algorithm, in which a pair of keys needs to be generated. One of the keys is called the private key and needs to be kept secret; the other key is called the public key and can be disclosed to others. The mathematical relationship between the private key and the public key is irreversible, that is, through a certain mathematical function, we can calculate the public key from the private key, but we cannot deduce the private key from the public key in reverse (or computationally it is not possible).

This asymmetric encryption algorithm has a useful property:If the data is encrypted with the public key, it can only be decrypted with the corresponding private key; if the data is encrypted with the private key, it can only be decrypted with the corresponding public key. Compared with the traditional RSA algorithm, ECC with strictly selected parameters has stronger security and is not easy to be attacked. As for Bitcoin and Ethereum, they both use the ECC algorithm to ensure the security of the currency.

In 1990, David Chaum created an untraceable cryptographic online payment system based on previous theories, which was later eCash, but eCash is not a decentralized system. And Leslie Lamport proposed Paxos, a consensus algorithm with high fault tolerance.

In 1991, Stuart Haber and W. Scott Stornetta proposed a protocol to use timestamps to ensure the security of digital files. This concept was later adopted by the Bitcoin blockchain system.

In 1992, Scott Vanstone et al. proposed the Elliptic Curve Digital Signature Algorithm (ECDSA). CDSA is a combination of ECC and DSA. The whole signing process is similar to DSA, the difference is that the algorithm adopted in the signature is ECC, and the final signed value is also divided into r and s. (DSA algorithm is the national standard digital signature algorithm of the United States, which can only digitally sign users, but not user data encryption and key exchange.)

In 1997, the HashCash method, which is the first generation of POW (Proof Of Work) algorithm, appeared. It was invented at that time and was mainly used for anti-spam. In various papers published subsequently, the specific algorithm design and implementation have completely covered the POW mechanism used by Bitcoin later.

Hashcash is based on the mathematical problem of factoring a large integer like RSA. I hope you do a lot of work, that is, pay the calculation cost of the CPU (this concept is very important, and this is also the key in Bitcoin), and get the correct result. , to access certain resources (such as sending spam to your mailbox).

What hashcash uses is not RSA, but a hashing process called hash. The algorithm used is called SHA (Secure Hash Algorithm). One characteristic of SHA is that only when the input data is exactly the same can the same hash value be obtained. Otherwise, even if the input data differs by only one punctuation mark, the stamps will be very different.

How HashCash works in email sending: For example, A wants to send email to B, and B requires A to add a string to the header of the email (this string is called a stamp, hashcash stamp), and requires the hash generated by this stamp The value must satisfy that the first 20 bits are all 0. So to get a hash value that satisfies the rules, A can only keep trying various random numbers as the suffix of the stamp (the rest of the stamp is used to record the relevant information of the mail, it is meaningful and cannot be changed at will), this is the so-called Paying the price of the CPU, this time is the cost of about one million calculations, and the execution time of a CPU is about a few seconds.

Bitcoin uses the HashCash method to prevent double-spending, which is the foundation of Bitcoin's operation and prevents forged transactions.

secondary title

Decentralization concrete implementation plan emerges

If the various researches before 1999 laid the theoretical foundation of the blockchain, then the development of p2p technology in the next ten years provided a specific implementation plan for the decentralized blockchain, thus complementing Bitcoin. The final piece of the puzzle.

In 1999, Napster, a pioneer of P2P network resource sharing, was founded by Shawn Fanning when he was studying at Northeastern University in the United States. It swept the United States through the service of sharing MP3. It has a server for storing the link location of mp3 files and providing retrieval, while the real mp3 files are stored on tens of thousands of personal computers, and the searched files are directly spread and shared among personal computers through P2P. The disadvantage of this method is that a server is required. In the era of fierce copyright disputes over mp3 files, Napster quickly became the target of public criticism and was forced to close down by many record companies for copyright infringement. And Napster ceased to exist when the servers were shut down.

On March 14, 2000, a message was published on the mailing list of the US underground hacker site Slashdot, saying that AOL's Nullsoft department had released an open source Napster clone software Gnutella. Gnutella has learned from Napster's failure and pushed the P2P concept one step further: it does not have a central directory server, but uses a distributed peer-to-peer network model. It is a server again, and all the data are placed on the personal computer. As long as the user installs the software, his computer will immediately become a server that can provide complete directory and file services, and will automatically search for other similar servers, thus forming a super server network composed of countless PCs. The Server and Client of the traditional network are redefined in front of it, so Gnutella is called the first true peer-to-peer network architecture.

On September 6, 2000, Jed McCaleb and Sam Yagan invented the EDonkey2000 network in San Francisco, USA. It consists of two parts, the client and the server, and can work on various operating platforms such as windows and linux. eDeonkey divides network nodes into server layer and client layer, and blocks files to improve download speed. It allows everyone to run the server side, the file index server is not centralized, but private to each person, spread all over the world, and then these servers are connected. Since selfish people mostly only want to "acquire" rather than "share" when using P2P software, eDonkey introduces a mandatory sharing mechanism, that is, introduces a social model between clients, that is, a credit system to encourage people exchange shared files with each other.

The most popular p2p client programs under the eDonkey network are eDonkey2000 and emule. Emule is the successor of eDonkey, but it is better. It uses DHT to build the underlying network topology. It is a very popular P2P file sharing software.

In April 2001, Bram Cohen, a student at Buffalo University, designed and released the BitTorrent protocol, and released the first usable version in July. The BitTorrent protocol is a P2P file transfer protocol based on the TCP/IP protocol, and is at the application layer of the TCP/IP structure. The BitTorrent protocol itself also includes many specific content agreements and extension agreements, and is constantly expanding.

According to the BitTorrent protocol, the file publisher will generate and provide a .torrent file according to the file to be released, that is, the seed file, also referred to as "seed". A .torrent file is essentially a text file, which contains two parts: tracker information and file information. Tracker information is mainly the address of the Tracker server used in BT download and the settings for the Tracker server. The file information is generated based on the calculation of the target file, and the calculation result is encoded according to the B encoding rule in the BitTorrent protocol. Its main principle is that it is necessary to virtually divide the downloaded file into blocks of equal size, and the block size must be an integer power of 2k (because it is a virtual block, each block file is not generated on the hard disk), and each block Index information and Hash verification code are written into the seed file (.torrent). So, the torrent file (.torrent) is the "index" of the downloaded file. When downloading, the BitTorrent client first parses the .torrent file to get the Tracker address, and then connects to the Tracker server. The Tracker server responds to the downloader's request and provides the downloader with the IPs of other downloaders (including the publisher). The downloader then connects to other downloaders. According to the .torrent file, the two inform the other party of the blocks they already have, and then exchange the data that the other party does not have. At this time, other servers are not required to participate, and the data traffic on a single line is dispersed, thus reducing the burden on the server.

Every time the downloader gets a block, he needs to calculate the Hash verification code of the downloaded block and compare it with the .torrent file. If they are the same, it means that the block is correct. If they are not the same, they need to re-download the block. This regulation is to solve the problem of the accuracy of the downloaded content.

In the same year of 2001, NSA released SHA-256, SHA-384, and SHA-512 respectively. These algorithms are collectively referred to as SHA-2. In 2008, SHA-224 was added. Since SHA-1 is not very secure, the current versions of SHA-2 have become mainstream. These include SHA-256, the hashing algorithm that Bitcoin eventually adopted.

SHA-256 is a hash function. For messages of any length, SHA256 will generate a 256-bit long hash value, called a message digest. This summary is equivalent to an array of 32 bytes in length, usually represented by a hexadecimal string of length 64.

In 2002, Napster officially went bankrupt in 2002 after shutting down its service due to a court ruling in 2001.

In 2003, Handschuh and Gilbert used Chabaud-joux attack to obtain a partial collision of SHA-256 in theory, and proved that SHA-256 can resist Chabaud-joux attack. The existing methods of attacking the Hash function include birthday attack, rainbow table attack, differential attack and so on. The Hash function used for message uniqueness and data integrity verification, its security depends on the properties of the function itself and the resistance against collisions. The algorithm structure characteristics of the Hash function and the length of the Hash value are the main factors that determine the collision performance of the function. The longer the Hash value, the more resistant it is to birthday attacks. SHA-256 has a 256-bit Hash value, and MD5 and SHA-1 have 128 and 160-bit Hash values ​​respectively. Therefore, SHA-256 is more resistant to birthday attacks than MD5 and SHA-1. Through the analysis of Chabaud-Joux attacking SHA-256, a partial collision of SHA-256 is found, and its complexity is 2^66, but an overall collision of SHA-256 cannot be found, so the SHA-256 algorithm can also resist the existing Some differential attacks. It can be seen that in terms of resisting birthday attacks and known differential attacks, the SHA-256 algorithm is more secure than the widely used MD5 and SHA-1.

In 2005, the website of eDonkey2000 network company was shut down, but the eDonkey network is still operating normally.

In the same year of 2005, Wang Xiaoyun and others officially announced the MD5 and SHA-1 collision algorithms. By February 2005, according to Professor Wang Xiaoyun's research report, they had developed a series of new technologies for searching SHA-1 collisions. Their analysis shows that SHA-1 collisions can be found in less than 2^69 hash operations. For the complete 80-round SHA-1 attack, this is the first time a collision has been found in less than the theoretical limit of 2^80 Hash operations. According to their estimates, for SHA-1 cut down to 70 rounds it is possible to find "real collisions" with today's supercomputers. Their research methods can be naturally applied to the deciphering analysis of SHA-0 and SHA-1 with reduced number of rounds. On March 6, 2005, Arjen Lenstra, Wang Xiaoyun, and Benne de Weger announced that they constructed a pair of X.509 certificates based on the MD5 Hash function, which produced the same signature.

In the same year of 2005, Hal Finney proposed a reusable proof of work mechanism (Reusable Proofs of Work, RPOW), combining B-money and the Hashcash algorithm proposed by Adam Back to create a cryptocurrency. This system regards hashcash as a POW token and generates an RSA-signed token during the exchange, which is called Reusable Proofs of Work (RPOW) tokens. RPOW can be transferred from one person to another, and at each transfer step Generate a new RPOW token, so each RPOW token can only be used once.

secondary title

Blockchain 1.0 Era Begins

August 18, 2008 Domain"bitcoin.org"be registered.

In November 2008, Satoshi Nakamoto published the paper "BTC: A Peer-to-Peer Electronic Cash System" and proposed the data structure of BlockChain. A decentralized electronic trading system can be established on a trustless basis.

It enables online payments to be directly initiated by one party and paid to another without going through any financial institution. This solution enables the cash system to operate in a peer-to-peer environment and prevents the double spending problem. The network timestamps all transactions by hashing them into an ever-extending chain of hash-based proof-of-work as transaction records, unless Complete all proof-of-work again, and the formed transaction records will not be changed. The longest chain will not only serve as proof of the observed sequence of events, but also be seen as coming from the largest pool of CPU computing power. As long as the majority of CPU computing power is not planning to cooperate to attack the entire network, then honest nodes will generate the longest chain that outpaces attackers. The system itself requires very little infrastructure. Information is spread across the network on a best-effort basis, and nodes can leave and rejoin the network at any time, taking the longest proof-of-work chain as proof of transactions that occurred while the node was offline.

On January 3, 2009, the btc network was officially launched, and the version of the open source client was released. The founder of Bitcoin, Satoshi Nakamoto, made the first block "Genesis Block" in the Bitcoin world. Satoshi Nakamoto left an unchangeable sentence in the genesis block: "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks The brink of a bailout) was the moment when Britain's chancellor of the exchequer, Darling, was forced to consider a second attempt to bail out the banking crisis. This sentence was the headline of the day's front-page article in The Times. The first to receive a bitcoin transfer The man was Hal Finney who invented RPOW. He downloaded the bitcoin client on the day it went live and received 10 bitcoins from Satoshi Nakamoto.

In September 2010, Slush, the first mining farm, invented the cooperative mining method of multiple nodes, which became the beginning of the bitcoin mining industry. You know, before May 2010, 10,000 bitcoins were only worth $25. If calculated according to this price, all bitcoins (21 million) would be worth $50,000. in any sense. Therefore, the decision to establish a mining pool means that someone believes that Bitcoin will become a virtual currency that can be exchanged with real-world currencies in the future and has unlimited room for growth. This is undoubtedly a vision.

On April 27, 2011, the official version 0.3.21 with historical records was launched, which supports a lot of new features, including UPNP with satoshi as the unit, etc., and the btc system has gradually matured.

In October 2011, Litecoin was born. Litecoin is inspired by Bitcoin (BTC) and has the same technical realization principle. The creation and transfer of Litecoin is based on an open source encryption protocol, which is not managed by any central authority. Compared with Litecoin, which aims to improve Bitcoin, Litecoin has three significant differences. First, the Litecoin network can process one block every 2.5 minutes (rather than 10 minutes), thus providing faster transaction confirmation. Second, the Litecoin network is expected to produce 84 million Litecoins, which is four times the amount of currency issued by the Bitcoin network. Third, Litecoin uses the scrypt encryption algorithm first proposed by Colin Percival in its workload proof algorithm instead of the SHA-256 used by Bitcoin, which makes it easier to mine Litecoin on ordinary computers compared to Bitcoin. for easy. Each Litecoin is divided into 100,000,000 smaller units, defined by eight decimal places.

In August 2012, Sunny King released Peercoin (also known as PPCoin, PPC, Peercoin). The biggest innovation of PPC is that its mining method mixes PoW workload proof and PoS equity proof. PPC is also the first encrypted digital currency that adopts PoS consensus. The PoS mining method only needs ordinary computers and clients to process transactions and maintain network security, achieving the purpose of energy saving and security.

• PPC uses the SHA256 algorithm, which is improved and optimized on the basis of BTC. The biggest contribution of PPC is that in order to prevent deflation, it created an original POS interest system with a fixed inflation rate of 1%, and its "mining" process is more energy-efficient and efficient. There is no upper limit on the supply of PPC. As of September 2014, the total amount was around 21 million, and the total amount is expected to be around 25 million by 2020.

• PoS, that is, Proof of Stake, translated as proof of rights and interests. Regardless of PoW or PoS, it can be understood as the question of "who is qualified to write the blockchain". PoW proves that it is qualified to write the blockchain through computing power, while PoS proves that it is qualified to write the blockchain through the currency age it owns.

• In the early stage of PPC, PoW mining was used to mine and distribute currency to ensure fairness. In the later stage, the PoS mechanism is adopted to ensure network security, that is, it is more difficult to own 51% of the currency, so as to prevent 51% attacks. The core concept of PoS is currency age, which is the time for holding currency. For example, if you have 10 coins and hold them for 90 days, you will have a coin age of 900 coin days. In addition, the use of coins means the destruction of the coin age. In PoS, there is a special transaction called interest currency, that is, the holder can consume the coin age to obtain interest, and at the same time get the priority to generate blocks for the network and PoS minting coins.

In September 2012, the founders of Rippllepay, Ryan Fugger, Jed McCaleb and Chris Larsen jointly established openCoin, and developed the Ripple protocol, which is an open-source, distributed payment protocol. It makes payments between merchants and customers and even developers virtually free and instant without chargebacks, and it supports any currency - including dollars, yen, euros, and even bitcoin.

In January 2013, OpenCoin launched XRP, also known as Ripple currency or Ripple currency. It is a virtual currency based on the Ripple protocol, with two main functions: 1. Preventing malicious attacks 2. Bridge currency. Like Bitcoin, the Ripple system is built on a cryptographically signed public blockchain, so there is no need for an initial trust gateway or gateway design. Ripple coins can be sent directly from user to user with no gateway or counterparty risk, which is how all currencies on the Ripple network (including USD) are used.

Due to the open source nature of the Ripple protocol, malicious attackers can create a large number of "junk accounts" and cause network paralysis. In order to avoid this situation, Ripple Labs requires each Ripple account to have at least 20 XRP. Every time a transaction is made, there will be Four hundred-thousandths of XRP are destroyed. This fee is almost negligible for normal traders, but for malicious attackers (manufacturing a large number of false accounts and transaction information), the destroyed XRP will increase geometrically, and the cost will be huge. This is designed to contain this malicious attack.

In March 2013, Bitcoin released version 0.8, which is the most important version in the history of Bitcoin. It has improved the internal management of the Bitcoin node itself, the optimization of network communication, and introduced Leveldb, a new index mechanism and Query mode, and Bloomfilter mode to reduce the transmission volume of SPV nodes and other features. It was after this point in time that Bitcoin really supported large-scale transactions on the entire network, becoming the electronic cash envisioned by Satoshi Nakamoto, and truly exerting global influence

Things are not always so smooth. In the most important version 0.8, Bitcoin introduced a big bug, so a hard fork appeared in Bitcoin shortly after the release of this version, causing the entire Bitcoin to fall back to the old Version 0.7, this also led to a sharp drop in the price of Bitcoin.

In July 2013, Sunny King founded Primecoin (codenamed XPM, also known as Primecoin), which is a digital currency based on Bitcoin. It uses a unique "scientific calculation proof" mechanism to replace Bitcoin. The "Hash Workload Proof" mechanism uses calculations to discover a prime number chain composed of a large number of prime numbers, and prime number coins are used as rewards for miners who discover prime numbers during the mining process. In the two months since its release in July 2013, the prime number discovered by PrimeCoin is 16 times larger than the largest known prime number based on the two-way double-chain algorithm, breaking the world record and becoming the largest known prime number. This unique mining calculation method is very powerful. For fields outside the cryptocurrency community, finding prime numbers (as opposed to SHA-256-based currencies) has an almost altruistic practical value.

In August 2013, Germany officially recognized Bitcoin, and Nasdaq completed transactions through its own blockchain platform. Although the People's Bank of China denied the status of Bitcoin, it was the only one in the world that immediately announced to be its own Cryptocurrency/digital currency bank.

At the end of 2013, Vitalik Buterin, the founder of Ethereum, released the first white paper of Ethereum and started the project. Ethereum (Ethereum, whose token is referred to as ETH) is committed to implementing a global decentralized and non-ownership digital technology computer to execute peer-to-peer smart contracts. Ethereum can be regarded as a distributed computer: the blockchain is the ROM of the computer, the smart contract is the program, and the miners of Ethereum are responsible for the calculation and act as the CPU. The smart contract will consume gas when it is executed. The amount of gas is determined by the amount of data that executes the code. The price of gas (xx gas/eth) is constantly changing according to the load of the eth network and the game between users. Because it supports smart contracts, the emergence of Eth is regarded as the arrival of the blockchain 2.0 era.

In February 2014, Daniel Larimer (BM) released Bitshares (also known as BTS, bit shares). The definition of Bitshares is "a point-to-point polymorphic digital asset exchange". Maintain the normal operation of the exchange. BitShares uses an architecture similar to the Bitcoin blockchain. In the Bitcoin blockchain architecture, the writing of each transaction data must come from the previous transaction data, and almost simultaneously generate a new output to be used as the writing of future transaction data.

Features of BTS include:

• 1. DPoS is adopted, and the PoW consensus algorithm is abandoned. Voted "representatives" replace miners in PoW;

• 2. Provide customized asset services according to user needs, such as using the Bitcoin blockchain to issue your own digital currency, and use the issuer as an endorsement;

• 3. Issue anchor assets, such as bitUSD and bitGold, using BTS three times the asset value as guarantee;

• 4. All transactions in BitShares are based on on-chain transactions, and all pending orders are placed on the blockchain, eliminating false transactions.

The BitShares community first proposed the DPoS (Delegated Proof of Stake) mechanism and introduced the concept of witnesses. DPoS is an improved version of Proof of Stake (PoS). The consensus process no longer requires all participating nodes to verify, but entrusts some representatives to conduct it, which greatly improves the consensus efficiency.

In April 2014, Dr. Gavin Wood, who collaborated with Vitalik, published the Ethereum Yellow Paper, which can be regarded as the technical bible of Ethereum, which standardized and explained important technologies such as the virtual machine (EVM) used by Ethereum to execute smart contracts. . According to the specific instructions in the yellow paper, the Ethereum client has been implemented in 7 programming languages ​​(C++, Go, Python, Java, JavaScript, Haskell, Rust), making the software more optimized in general.

In May 2014, Juan Benet launched the Interplanetary File System (IPFS for short). PFS is essentially a content-addressable, versioned, point-to-point hypermedia distributed storage and transmission protocol. The goal is to supplement or even replace the past 20 years. The Hypertext Media Transfer Protocol (HTTP) that I use, I hope to build a faster, safer, and freer Internet era. IPFS has at least eight layers of sub-protocol stacks, from top to bottom are identity, network, routing, exchange, objects, files, naming, and applications. Each protocol stack performs its own duties and cooperates with each other.

Starting in June 2014, Ethereum conducted a 42-day pre-sale of ether, netting 31,591 bitcoins, worth $18,439,086 at the time, in exchange for approximately 60,102,216 ethers. Proceeds from the sale were first used to pay off mounting legal debts, reward developers for their months of hard work, and fund continued development of ethereum. After the successful pre-sale of Ethereum, the development of Ethereum has become formalized under the management of the non-profit organization ETH DEV, which manages the development of Ethereum according to the contract of Ethereum Suisse - Vitalik Buterin, Gavin Wood and Jeffrey Wilcke as the three directors of the organization .

At the end of 2014 and continuing until the first half of 2015, Ethereum underwent a security review. Ethereum hired a number of third-party software security firms to conduct end-to-end reviews of all key components of the protocol (Ethereum VM, network, proof-of-work). The review found many security issues, and after the issues were raised and tested again, it resulted in a more secure platform.

In 2015, after The Economist published the cover article "Blockchain Technology Reshaping the World", blockchain technology set off a frenzy of financial technology in the world. The world's major financial institutions and banks are vying to study blockchain technology. Billions of dollars were invested in blockchain-related businesses in 2016 alone.

In June 2015, BitShares released version 2.0 and introduced graphene technology for the first time. The Graphene Toolkit is developed by Cryptonomex Inc., and provides authorization for the Graphene Toolkit to the BitShares blockchain. The terms of this agreement give BitShares unlimited access to the Graphene toolset and its derivatives. Graphene technology is designed to handle 100,000 transactions per second without any optimization pressure. Some of the essential features include keeping everything in memory, avoiding synchronization primitives (locks, atomic operations), and minimizing unnecessary computations. Use IDs instead of hashes.

At the end of July 2015, after nearly two rigorous tests, the official Ethereum network was released, which also marked the official operation of the Ethereum blockchain. The release of Ethereum is divided into four stages, namely Frontier (frontier), Homestead (homestead), Metropolis (metropolis) and Serenity (tranquility). In the first three stages, the Ethereum consensus algorithm adopts the workload proof mechanism (POW), In the fourth stage, it will switch to the proof-of-stake mechanism (POS).

On July 30, 2015, the Ethereum Frontier network was launched, and developers began to write smart contracts and decentralized applications to be deployed on the Ethereum real-time network. Additionally, miners started joining the Ethereum network to help secure the Ethereum blockchain and earn ether from mining blocks. Although the release of Frontier was the first milestone of the Ethereum project, and developers only tried to use it as a beta version, it turned out to be more useful and reliable than anyone expected, and developers immediately started building solutions to improve Ethereum. workshop ecosystem.

On March 14, 2016 (Pi Day), Ethereum launched the Homestead phase. Compared with the Frontier stage, the Homestead stage has no obvious technical milestones. It just shows that the Ethereum network has been running smoothly and is no longer an insecure and unreliable network. At this stage, Ethereum provides a wallet with a graphical interface, and the ease of use has been greatly improved. Ethereum is no longer exclusive to developers, and ordinary users can also experience and use Ethereum conveniently.

In October 2016, the Zerocoin Electric Coin Company with Zooko Wilcox as the founder and CEO released Zcash (ZEC for short, also known as Zerocoin). Zcash is the first blockchain system to use zero-knowledge proofs, which provide complete payment confidentiality while still being able to maintain a decentralized network using a public blockchain. Like Bitcoin, the total amount of Zcash tokens (ZEC) is also 21 million. The difference is that Zcash transactions automatically hide the sender, receiver and amount of all transactions on the blockchain. Only those who have the view key can see the contents of the transaction. Users have full control, and they can choose to provide their viewing keys to others. There are two types of ZCash wallet funds: transparent funds and private funds. Transparent funds are similar to Bitcoin funds; private funds enhance privacy, transactions involving private funds are kept confidential, and transactions between transparent funds and transparent funds are publicly available. of.

In June 2017, the EOS project led by BM (Daniel Larimer) started crowdfunding. The crowdfunding is carried out in the form of ERC-20 tokens deployed on the ETH network. Known as Blockchain 3.0, EOS is a blockchain architecture platform similar to the operating system, which aims to realize the performance expansion of distributed applications. EOS provides accounts, authentication, databases, asynchronous communication, and program scheduling on hundreds of CPUs or clusters. The technology's final form is a blockchain architecture that allows users to quickly and easily deploy decentralized applications. The blockchain can support millions of transactions per second, while ordinary users do not need to pay for usage. EOS uses graphene and DPoS technology to greatly increase the throughput of the system. According to the plan, EOS is expected to reach a transaction volume of one million transactions per second.

On July 21, 2017, the Bitcoin bifurcation scheme BIP91 has been supported by the computing power of the entire network, and it was unanimously agreed to upgrade the Segregated Witness first, and upgrade the block size of the underlying blockchain to 2M within the next 6 months. However, a "spoiler" appeared - ViaBTC, a mining pool owned by the mining giant Bitcoin Continental, prepared a hard fork system to launch "Bitcoin Cash" (Bitcoin Cash, also known as BCC) based on the original Bitcoin chain. ). Bitcoin Cash has modified the code of Bitcoin to support large blocks (increase the block size to 8M), does not include the SegWit function, and is a blockchain asset generated by the BitcoinABC scheme.

The previous life of Bitcoin Cash is Bitcoin. Before the fork, the data stored in the blockchain and the software it runs are compatible with all Bitcoin nodes. After the fork, it starts to execute new codes. Pack large blocks to form a new chain.

At 20:20 on August 1, 2017, bitcoin cash mining began,

Autumn 2017: EOS established a minimum viable test network, including P2P network code, Genesis import test, etc.

In November 2017, Bitcoin Cash changed its abbreviation from BCC to BCH

In January 2018, Sunny King, the blockchain expert who invented PeerCoin and PrimeCoin, announced that the new project "Virtual Economy Era (VEE)" (https://vee.tech) is under development , and he served as the chief designer of the project. Sunny King stated that "VEE aims to bring a next-generation platform for blockchain applications", and the definition listed on its official website is "The Fifth Generation of Bitcoin". VEE hopes to directly cross the "3.0 stage" and combine the latest scientific and technological achievements in cryptography, virtual machines and other fields to develop a new generation of blockchain bottom layer that allows users to actually feel technological changes. VEE will help various industries establish scalable decentralized databases, provide large capacity beyond the storage limit of traditional databases, and instant cloud computing services. VEE has chosen four programming languages ​​and redesigned the system with a layered and modular approach to adapt to the development of decentralized network applications. On the one hand, if an error occurs in an individual link, it can be resolved independently without affecting the entire network; on the other hand, the performance will be greatly improved. Specifically, the TPS (transactions per second) of the Bitcoin blockchain is on the order of single digits, Ethereum is in the ten digits, and the average TPS of VisaNet is 2,000, with a maximum of 56,000. VEE benchmarked against VisaNet, and raised TPS to four digits in the initial version.

In addition, in terms of the architecture design of the blockchain, VEE has improved the communication mechanism between different chains and supports cross-chain transactions. The bottom layer will carry at least a thousand main chains and side chains. Other technical teams can develop applications more flexibly and conveniently through the API provided by VEE to improve the performance of the private chain.

April 17, 2018: EOS released the Chinese version of the EOS.IO technical white paper v2, which will realize the horizontal and vertical expansion of decentralized applications.

In June 2018, EOS ended its crowdfunding mainnet and went online.

In September 2018, Sunny King announced that it will introduce a new consensus mechanism "Super Node PoS" in VEE ("supernode proof-of-stake"referred to as "SPoS"). SPoS runs on special hardware. King explained that SPoS is somewhat similar to DPoS, but will simplify the development and maintenance of blockchains. SPoS can run smoothly on optimized hardware. This special hardware is similar to the ASIC mining machine in PoW, but unlike the ASIC mining machine in PoW, this special hardware does not consume so much power. This system seems to be more centralized in design, but King has also designed a mechanism to ensure the security of the network, ensuring that each supernode (supernode) has equal power, and preventing a node from being too powerful.