[Important] China's first original blockchain technology solution "Quantum Chain White Paper" is officially released (white paper download)

Rage Commentary : The Qtum open source community released the white paper "Quantum Chain White Paper - Value Transfer Protocol and Decentralized Application Platform", which mainly introduces how to achieve point-to-point value transfer through the Value Transfer Protocol in the Qtum system, and based on this protocol, how to build a decentralized application development platform (DAPP Platform) that supports multiple industries (finance, Internet of Things, supply chain, social games, etc.), and specific implementation plans.

Reporter: Amber Dingding

Recently, the Qtum open source community published a white paper titled "Quantum Chain White Paper - Value Transfer Protocol and Decentralized Application Platform". This white paper mainly explains in detail how to achieve point-to-point value transfer through the Value Transfer Protocol in the Qtum system, and how to build a decentralized application development platform (DAPP Platform) that supports multiple industries (finance, Internet of Things, supply chain, social games, etc.) based on this protocol, and the specific implementation plan. This white paper can find answers to many questions such as what the third blockchain ecosystem developed by the Qtum open source community is like and why the quantum chain was designed.

Follow the WeChat public account “区块链笔Blockchain” and the keyword “Qtum” to view and download the full text of this report.

The Qtum open source community has been committed to developing a third blockchain ecosystem beyond Bitcoin and Ethereum, and is committed to expanding the application and technical boundaries of blockchain technology so that ordinary Internet users can feel the value of blockchain technology. In the Qtum system, point-to-point value transfer can be achieved through the Value Transfer Protocol, and based on this protocol, a decentralized application development platform (DAPP Platform) that supports multiple industries (finance, Internet of Things, supply chain, social games, etc.) can be built.

Design intention and principles of applicability

Since the Bitcoin code was open sourced in 2009, many Altcoins and other blockchain projects have emerged in the community. Altcoin projects have become a test field for blockchain technology (except for some meaningless Altcoins), and have a certain reference significance for the development and maturity of blockchain technology (such as NameCoin, etc.). In addition, there are some projects that expand the boundaries of blockchain technology from different angles, such as ColorCoin Protocol, NXTCoin, Ripple and Stellar, BitShare, Dash, Maidsafe, Factom, etc. In addition, there is the Ethereum project, which is committed to becoming a general smart contract platform and decentralized application platform. The design goal is to create the first POS smart contract platform compatible with the BIP protocol, and through the introduction of Identity, Oracle and Data feeds, in terms of compliance, it meets the regulatory requirements of different industries.

The main problems currently faced by blockchain technology are:

There is a lack of new smart contract platforms. The existing smart contract platforms are mainly based on Proof of Stake, and the consensus mechanism of Proof of Stake is difficult to be deployed on a large scale by industry applications. The compatibility between different blockchain technologies, such as the Bitcoin ecosystem based on the UTXO model and the Ethereum ecosystem based on the Account model, is difficult to be compatible. The consensus mechanism itself lacks flexibility. Due to the differences in participants, the requirements for the consensus mechanism in the public chain and the alliance chain are different. There is a lack of consideration for industry compliance. For example, the identity and KYC parts required by the financial industry are difficult to guarantee in the existing blockchain system. The existing blockchain system is very closed. At present, the triggering conditions of most smart contracts mostly come from the blockchain system itself, and there are few triggering conditions from the outside world, lacking interaction with the real world.

The Qtum system is designed mainly to solve these problems.

Compared with the development of Internet technology, both blockchain technology itself and applications based on blockchain technology are in the early stages of development, and there are many directions worth exploring. Therefore, we hope to build an independent blockchain ecosystem in addition to Bitcoin and Ethereum, and to push the usability of the entire blockchain industry forward, which is also the original intention of the design. We will be committed to expanding the application and technical boundaries of blockchain technology, so that ordinary Internet users can feel the value of blockchain technology, and build a brand-new ecosystem for developers and users based on blockchain technology.

Its own applicability design principles will make development more practical and convenient, such as backward compatibility design, modular design that is conducive to software development and maintenance, a smart contract platform with a secure, reliable, highly available POS mechanism compatible with the UTXO model for different industries, and the principle of providing a complete API service for the Qtum system and providing wallet users with 2 or 3 different operation modes for ease of use.

Specific implementation plan of Quantum Chain

Through the mobile DAPP development strategy, the technical advantages of blockchain are brought to users in different industries and ordinary Internet users. Qtum's public chain system focuses on the practical application of smart contracts, and will provide a compliant and open blockchain technology test field for traditional Internet companies (finance, Internet of Things, etc.) through the perfect design of Oracle and identity.

Qtum will make a series of innovations in blockchain technology and concepts, including different consensus protocols for public chains and consortium chains, UTXO-based smart contract models, the concept and implementation of simple blockchain contracts, the design of smart contract ledgers, the design and implementation of Oracle and Data Feed, etc.

As for the consensus mechanism of the quantum chain, the consensus mechanism in the quantum chain is designed to be modular and can be plugged in and out like a plug-in. It can be applied to different application scenarios of public and private chains. In the selection of Qtum's consensus mechanism, according to the principles of technical reliability and decentralization, we finally selected the consensus mechanism based on Proof of Stake as the basic consensus mechanism of the public chain.

In the alliance chain based on Qtum, we use a consensus mechanism that combines Proof of Time and Raft protocols to provide services to industry customers. This involves identity recognition and trusted networks, and more importantly, the periodic random selection of accounting nodes in a restricted group. We will combine the Proof of Time and Raft protocols proposed by Qtum for the alliance chain system to design the corresponding consensus protocol, and the main design goal is the block time: 250 milliseconds confirmation time 750 milliseconds - 3 seconds to meet the characteristics of scalability and low latency.

New changes in Gas, identity, and privacy

The Gas mechanism will change. The concept of Gas in the EVM system will be removed in the Qtum system. The contract itself and the contract calling the contract will set their own corresponding fees, which need to include the cost of the entire transaction process (including recursive calls). In order to prevent P2P spam, a small fee will be charged for each transaction. In addition to this fee, the accounting nodes and the network will choose the number of opcodes they can execute at a certain rate.

Regarding the contract ledger and its readability, in the Qtum system, in addition to the traceable Transaction Ledger based on the UTXO model, a Contract Ledger for the contract content will be built to facilitate everyone's audit and reading of smart contracts. In addition, a Contract Ledger will be built to store all Qtum plaintext readable contract content, bringing more transparency, readability, and auditability.

Innovation in identity recognition and privacy protection. The Qtum system will manage users on the Qtum platform through smart contracts. The Qtum system will provide an optional identity recognition module. Identity is a prerequisite for the blockchain system to connect to the financial system. In the Qtum system, we will distinguish between identity customers and non-identity customers. Developers will develop the corresponding identity smart contract code and open source the code to third parties. Through the introduction of third-party credit reporting agencies, customers verified by the Identity smart contract will have more priority in the Qtum system. For example, in the financial service-oriented DAPP in the Qtum system, customers verified by Identity will be given more permissions. Regarding privacy (i.e. privacy protection), because the Qtum system is compatible with the UTXO model, ZeroCoin is an encrypted transmission protocol based on the UTXO model. Currently, Zcash is in public beta. We will provide more privacy protection for smart contracts and transactions in the Qtum system through integration with the Zcash protocol.

Practical applications based on quantum chain

In the actual application of Quantum Chain, we will start from three aspects, namely decentralized applications, support for multiple industries, and mobile terminals (Go Mobile). First, decentralized applications. Through the introduction of mobile terminal strategies, different DAPP ideas will be productized so that ordinary Internet users can truly feel the value brought by blockchain technology. DAPP applications for different industries can bring blockchain technology to more users and industries. For example, decentralized social networking, decentralized storage and decentralized domain name services, decentralized computing services, etc., through the introduction of incentive mechanisms, will make deeper use of the concept of shared economy and change the existing APP market and business model.

Secondly, in the Qtum system, the consensus mechanism based on the integration of Proof of Time and Raft protocol can meet the requirements of blockchain speed and capacity in the trusted network. Through the introduction of simple contracts based on blockchain technology and Oracle and Data Feeds, more offline factors can also be introduced. Through the design of Identity and Privacy, it can meet the regulatory requirements of the financial industry. In addition, it can support the application needs of multiple industries: such as finance, Internet of Things, supply chain, social and games, charity, digital assets and equity, etc. In addition, based on Qtum's smart contracts and simple contracts, through Turing's complete programming language, it can support more complex business logic and will support more industries.

In addition, we will work with third-party developers to provide users with mobile services, including: mobile wallets, mobile Dapp applications, mobile smart contract applications and other services.