Achain is a decentralized public blockchain platform. Developers can use the Achain platform to release tokens, smart contracts and blockchain systems simply, quickly and securely. Achain is committed to creating a blockchain network system with global information exchange, value interconnection, and trust exchange. Achain's concept and technical mission is to build a blockchain world without barriers.

1. Project introduction

Achain's unique RDPOS distributed consensus mechanism realizes Turing's complete smart contract virtual machine with independent intellectual property rights. The transaction performance on the chain is as high as 1000TPS. It is a simple, fast and safe blockchain platform. Users Achain can be used to quickly deploy enterprise-level decentralized applications such as digital assets and smart contracts. ACT coins have the value of the Achain ecosystem. Token holders are able to participate in community activities such as creating and publishing smart contracts, accessing web services, voting proxies, and earning profits.

Project Features

Stability
Stability is a necessary condition for Achain to be usable. Blockchain has its own decentralized features, and decentralized networks are usually complex and full of uncertainties. Therefore, we abstract and simplify the blockchain with the help of modular design tools, and run smart contracts by building a modular virtual machine - Lua Virtual Machine (hereinafter referred to as LVM). This design can bring two benefits. One is to optimize the performance of LVM to directly improve the efficiency of contract execution and reduce the interference factors caused by system coupling; the other is to weaken the correlation between the blockchain network and the running status of smart contracts. The stability of the chain network can still be guaranteed.

Security
PoW has made great contributions to the security of the Bitcoin network, but due to the growing demand for mining and the difficulty of computing power, almost all rights are concentrated in the hands of miners and mining pools. Through professional cooperation, they have in fact become a highly centralized "central server". If more than 51% of the computing power is combined, it can theoretically control most Bitcoin transactions, such as the well-known DOS (Denial of Service) attack. In addition, the high power consumption is also criticized. Compared with the PoW model, the PoS model is still developing, and these development directions are mainly based on security and applications. The PoS model has great security advantages over the PoW model, but the premise is that enough holders are attracted to carry out PoS mining in order to give full play to the advantages of security. DPoS is an improvement of PoS, and Achain has innovated a more commercially applicable RDPoS consensus mechanism. In the case of the same security as DPoS, it can theoretically improve the block response and increase the stability and security of the network. In addition, Achain innovatively proposes an intelligent sandbox mechanism. Any contract released by anyone must first be trial-run in the smart sandbox. Achain will conduct a full-path automated test on it and continuously monitor its running status. If the health level deteriorates, or a loophole is found. The network will terminate it at its own judgment to avoid damage to the blockchain ecology caused by problematic contracts.

Scalability
Scalability is proposed to solve the problem of information islands where blockchains are incompatible with each other. First of all, we believe that upgrades and forks are one of the effective ways for network evolution. After forks, a main chain and several sub-chains are formed. The main chain and the sub-chain are completely equivalent from a technical point of view, but they are set with different identifications based on community consensus. Each sub-chain can be appropriately customized according to different business applications. By constructing VEP between sub-chains, its working method is similar to that of a gateway. The sub-chains can exchange information and exchange value through VEP. Through such collaboration, a multi-application blockchain ecosystem can be formed. Not only that, non-blockchain online data will also be included in the Achain ecosystem, supplemented by smart contracts, which can respond to events in the real world.

Ease of use
Achain achieves ease of use in two ways. One is to provide a Blockchain as a Service platform (Blockchain as a Service, referred to as BaaS) to lower the threshold for enterprises and individuals to use. Through network forking, data customization, smart contract release and upgrade, asset transaction monitoring, etc., supplemented by visualization functions, blockchain applications become easy to use. The second is that Achain provides multi-language support, from Lua, C++ to Java, so that developers on different platforms can develop easily.

Application scenario

Supply chain finance
Supply chain finance is a financial service in which financial institutions (usually banks) manage the capital flow and logistics of upstream and downstream small and medium-sized enterprises around the core enterprise, and control the risk to the lowest level by integrating information. It is One of the industries that has developed rapidly in recent years. Due to the high cost of establishing credit, financial institutions have to act cautiously based on risk control, and often miss some high-quality projects. Achain can help enterprises and financial institutions reconstruct their credit systems and establish more efficient supply chain finance.

With the core enterprise as the endorsement, Achain will establish a blockchain platform for warehousing, logistics, digital bills and corporate credit. It can realize the information of goods, warehousing, logistics and accounts receivable jointly witnessed by upstream and downstream enterprises and financial institutions in the supply chain. The issuance, confirmation, circulation, splitting, and acceptance of digital bills are triggered by the contracts of each participant in the supply chain. The triggering conditions can be based on changes in the data status in warehousing, logistics blockchain, and core enterprise databases. The triggering rules are based on The contract of the participating parties is written, and the behaviors of complying with or violating the rules will be recorded in the credit blockchain and cannot be tampered with.

Achain utilizes technical advantages such as BaaS and smart sandbox, and enterprises can achieve rapid deployment. Establish unused blockchain networks through fast bifurcation at low cost, use VEP to establish connection protocols, and implement event-driven by integrating data. All participants can jointly verify the authenticity of the data, so as to ensure the smooth transfer of funds in the supply chain and improve the efficiency of collaboration.

Product traceability
The retail industry is naturally characterized by fragmented transaction data, diversified transaction nodes, and complex transaction networks. When people buy goods through online malls or offline supermarkets, the packaging will be marked with origin information, production date, and manufacturer. But it is difficult for us to judge the authenticity of this information. Due to the large profit margins of counterfeiting, high-value products such as diamonds, leather bags, skin care products, etc. are more likely to be counterfeit. Counterfeiting not only damages the interests of consumers, but also damages the reputation and brand image of businesses. The society also has to consume funds and manpower to exercise legal supervision and legal sanctions. For commodity traceability, there are currently several pain points: first, commodity traceability not only needs to be traced back to the production link, but also needs to be traced to the circulation link. This will inevitably increase the joint endorsement of more subjects, and the difficulty of cross-organizational collaboration can be imagined; second, the systems used by both manufacturers and logistics providers must be centralized, and there is a problem of isolated information islands; third, there are centralized systems The risk of an individual doing evil.

Aiming at the above three pain points, Achain proposes a corresponding solution - blockchain + Internet of Things. With the help of the Internet of Things, data in production and logistics can be collected in real time through smart devices, and connected to Achain through VEP to store in the traceability network. The unique data storage structure and distributed ledger technology of the blockchain ensure that the data on the chain cannot be tampered with. At the same time, asymmetric encryption and relative anonymity can ensure that the core information of the enterprise is not leaked. When consumers need to inquire about commodity information, they can trace all the information of the commodity as long as they know the commodity code and production batch.

Technical Overview
Implementation of Contract and LVM
Traditional smart contracts are limited to the input and output of data on the chain, which can only support some simple application scenarios. For this reason, Achain redefines the smart contract. In addition to on-chain data, it also allows on-chain and off-chain data to interact, and supports event responses to changes in the state of on-chain and off-chain data. Most commercial applications in the real world are very complex, and this complexity is reflected in data structures and logic rules. In order to achieve the above goals, Achain has made two preparations in the top-level design. One is to abstract potential applications, extract general requirements, and design API interfaces and data structures in advance. The second is to choose a Turing-complete language to approximate the rules in the real physical world as much as possible.

Consensus Mechanism
Due to the distributed nature, the blockchain needs a consensus mechanism to function properly. Currently widely used consensus algorithms mainly include: Proof of Work (PoW: Proof of Work), Proof of Stake (PoS: Proof of Stake), Practical Byzantine Fault Tolerance Algorithm (PBFT: Practical Byzantine Fault Tolerance), Delegated Proof of Equity (DPoS: Delegated Proof of Stake). From the consideration of safety and practicality, Achain chooses DPoS, and improves the RDPoS consensus mechanism based on it.

RDPoS not only inherits the advantages of DPoS - it does not need to consume additional computing power to realize the distribution of rights and interests after block production, it can also dynamically determine the execution results of smart contracts by agents or all nodes according to the transaction status of the network .

As a public chain, Achain cannot form community consensus without the support of economic means——Token. Holding Token can not only obtain basic blockchain services such as contract release and network fork, but also participate in voting and become an agent node to provide services and obtain Token rewards. Achain named this Token ACT, and each ACT holder is called a stakeholder, and the corresponding voting weight is allocated according to the number of ACT holdings. Proxy nodes are elected by stakeholder voting. The top 99 agents with the most votes take turns to verify the transaction in turn, and the order is jointly determined by all agent nodes, and it is guaranteed that it cannot be tampered with. Agents can earn benefits if they work normally, and they will be punished if they work abnormally or do not work.

Account model
In the blockchain network, the account address is a scheme designed for safe exchange, and the account, public key, and private key generation process have the following relationship: private key—>public key—> Account address, all three of them use Secure Hash Algorithm (SHA for short), which can ensure sufficient security. A hash is a distillation of information, usually the output is much smaller than the input and has a fixed length. With current technical means, a hash with strong encryption must be irreversible. That is, the user's private key information cannot be deduced through the user's account address.

Achain uses the Account model instead of Bitcoin's UTXO model (Unspent Transaction Output). Although the design of UTXO is very ingenious, it supports multiple transactions in parallel, and the protection of account privacy is relatively good. However, Bitcoin's account design is specific to transactions, and it is very difficult to implement smart contracts based on UTXO. The smart contracts in the Achain ecosystem often require conditions and states to trigger asset transactions, so Achain finally chose the Account model.

Forked Network
Achain proposes a suitable forked network based on two considerations. One is to maintain robust vitality, and the other is to meet different application scenarios. First of all, the blockchain network is a community formed by many participants according to certain consensus. The split in the consensus makes the hard fork happen, and this kind of fork is sometimes good and sometimes bad. Through people's screening and elimination, a batch of valuable blockchain networks will eventually be left, which is very consistent with the law of continuous self-evolution of species and environments in the self-organizing world.

Achain will serve as the starting point of the entire forked network, which can also be called the main chain. The main chain can fork into parallel sub-chains, and the sub-chains can also continue to fork, and all chains have equal status. When a fork occurs, VEP will record and broadcast the registration information of this sub-chain, such as genesis block information, sub-chain ID, seed node, digital assets, service identification number, etc. If the fork continues to occur, these registration information will be updated by VEP again and synchronized to the entire network. When interaction between chains is required, a connection can be established in the form of service discovery through registration information, and information interaction and value exchange can be realized under the VEP framework. VEP is similar to the DNS service of the Internet, responsible for registering information, updating information, and providing access services.

Value Exchange Protocol (Value Exchange Protocol)
VEP is a standard protocol for connections between different blockchain networks. The VEP sets out guidelines for how to collaborate. It registers the registration information of each chain and provides services to the chains in the trusted list for query and connection requests. VEP supports two application scenarios: cross-chain node interaction and cross-chain contract invocation. The former utilizes the state changes of data stored in nodes or external data to indirectly allow contracts to interact and may generate new information. For example: Failure to repay the loan due in accordance with the contract will affect personal credit. Loan records can be stored in blockchain A, while credit data can be stored in blockchain B, and personally identifiable information may come from an external public database. The latter is mutual calls between contracts. The simplest example is the Token swap of two chains and keeping the total value unchanged.

Event-driven
Relying on VEP, Achain can realize information interaction and value exchange between chains, and even integrate IOT (Internet of Things), AI (Artificial Intelligence), enterprise or public Non-blockchain data sources such as service databases are also included in the ecology to achieve real-time event-driven (Event-Driven).

Two. Comment

Achain is a public blockchain platform. Developers are able to issue tokens, smart contracts, create applications and blockchain systems. Originated in 2015, the mainnet was launched in July 2017. Achain is committed to establishing a global blockchain information exchange and value transaction network. Achain was initially developed by the Singapore-based non-profit organization Achain Foundation, which is co-built and co-maintained by fan communities around the world.

Related Links:

https://www.achain.com/

http://www.qukuaiwang.com.cn/szhb/2352.html###

https://www.okex.com/cn/project/98/