区块链多方计算平台,区块链多方计算方法

区块链多方计算平台是一种基于区块链技术的新型计算模式，它支持多方计算，可以实现更有效的数据存储和处理。它基于分布式账本技术，可以保证数据的安全性和可信性，支持智能合约，可以实现自动化的数据处理和分析。

去中心化是区块链多方计算平台的核心理念，它是一种去中心化的计算模式，可以让多方参与者共同参与数据的存储、处理和分析，从而避免数据的中心化集中。可以说，去中心化是区块链多方计算平台的核心优势，它可以更好地保护数据的安全性和可信性，并且可以更有效地支持多方计算。

智能合约是区块链多方计算平台的重要组成部分，它是一种自动执行的代码，可以自动执行用户设定的规则。智能合约可以让多方参与者共同完成数据的处理和分析，并且可以有效地实现自动化的多方计算。智能合约可以实现自动化的交易，可以更有效地实现数据的存储和处理，从而更好地支持多方计算。

可信计算是区块链多方计算平台的重要特性，它可以保证数据的安全性和可信性。可信计算是基于分布式账本技术，它可以有效地保护数据的安全性和可信性，并且可以有效地支持多方计算。可信计算可以有效地防止数据的篡改和窃取，并且可以更有效地支持多方计算。

总之，区块链多方计算平台是一种基于区块链技术的新型计算模式，它支持多方计算，可以实现更有效的数据存储和处理，其特点是去中心化、智能合约和可信计算。它可以更好地保护数据的安全性和可信性，并且可以更有效地支持多方计算。
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『一』Blockchain core technology research goals

Key breakthroughs include security privacy protection, open cross-chain protocols, efficient on-chain and off-chain collaboration and secure smart contract mechanisms, etc. Blockchain application support technology.

1. Security and privacy protection technology. The focus is on achieving technological breakthroughs in secure multi-party computation, zero-knowledge proof, secure transmission, and homomorphic encryption.

2. Chain-to-chain interconnection technology. The focus is on making breakthroughs in cross-chain protocols, homogeneous/heterogeneous cross-chain architecture, security, scalability and performance.

3. On-chain and off-chain collaboration technology. The focus is on breakthroughs in technologies such as on-chain and off-chain data collaborative access control, efficient storage and management.

4. Secure smart contract technology. The focus is on breakthroughs in smart contract formal verification, security vulnerability risk assessment, and smart contract auditing.

5. Blockchain supervision technology. Focus on achieving technological breakthroughs and applications in blockchain penetrating supervision technology, dynamic monitoring technology, blockchain risk isolation and control, etc.

                                                                                                                                                                                                                                                         Secure multi-party computing is closely related to traditional cryptography, but it is not completely equivalent. The combination with the distributed technology blockchain can improve the security of data by encrypting information.

『三』What are the protection mechanisms of blockchain ledgers under the blockchain computing mode?

Consensus confirmation, multi-party storage, safe and trustworthy, and cannot be tampered with. The blockchain computing model uses the blockchain data structure to verify and store data, and uses the distributed node consensus algorithm to generate and update data. The guarantee mechanism of the blockchain account includes consensus confirmation, multi-party storage, security and reliability. Trustworthy, cannot be tampered with, and guarantees that the mechanism is a mechanism that provides material and spiritual conditions for management activities. It is divided according to functions. According to the function of the mechanism, it is divided into incentive mechanism, restriction mechanism and guarantee mechanism.

『四』Why is it said that the integration of blockchain and privacy computing is an inevitable trend

From a larger perspective, it is necessary to build comprehensive privacyThe protection and governance system not only needs to integrate multiple technologies such as blockchain, artificial intelligence, big data, and privacy computing, but also needs to combine many strategies such as laws, regulations, and regulatory governance.

In the digital society, everyone has a stronger demand for data production factors. Whether it is user services or business marketing, a large amount of data needs to be used, especially in the distributed collaboration business model. Everyone hopes that data can flow smoothly and the value of the data can be reasonably reflected. But contrary to this, data silos still exist and the extensive use of data still needs to be solved.

At the same time, legal compliance has become the general trend. Whether domestic or international, laws and regulations related to personal information protection and data security have been promulgated one after another, which have put forward more stringent requirements for personal information protection and data security. This means that the security of data must be ensured and the privacy rights of individuals must be respected; in the entire life cycle of data, comprehensive specifications must be implemented to achieve compliant circulation.

Being user-centered, exchanging data under the premise of security and privacy, and providing high-quality and compliant services are the trends in the construction of a digital society, which require more improvements in technology, business models, and governance systems. Innovation. Initiatives such as introducing private computing into distributed systems and developing compliant data exchanges all reflect this innovative spirit.

In the field of privacy computing, blockchain, federated learning and secure multi-party computing have become three key core technologies, and these three technologies have different focuses on each other and have many overlaps and connections.

Among them, from the perspective of blockchain, we can see that on the one hand, the data on the blockchain needs to be protected by privacy algorithms; on the other hand, the blockchain can also become a privacy computing The base and hub in collaboration: Use blockchain technology to record and trace data sets, algorithm models, and calculation processes in multi-party collaboration, evaluate and reach consensus on the final results, and continuously optimize collaboration efficiency.

In the past few years, when we explored application implementation in the blockchain field, we often used blockchain to build "distributed ledgers" for business scenarios. Compliant applications will perform KYC (Know Your Client) on users and merchants, and there are many questions that need to be answered through innovative solutions such as privacy computing.

For example, can identity information be disclosed to the entire consortium chain? At the time of the transaction, are the transaction amounts and relevant parties clearly disclosed? Can the assets owned by everyone be queried at will? Can people's business practices be misused without authorization?

For example, in the points card and coupon business in the consumption scenario, merchants usually do not want to expose their business conditions too much, such as how many users open cards, recharge, and daily turnover, etc. ;Individual users also do not wantOne’s own consumption behavior is publicly scrutinized.

Therefore, before the privacy issue can be completely solved, the approach we usually adopt is to introduce core authorities to participate in consensus and maintain the full ledger, while other participants are layered and sharded with different permissions. role participation. However, this increases the complexity of the system to a certain extent and affects the user experience. At the same time, it brings challenges to the scale and popularization of blockchain applications.

At present, blockchain is also commonly used in the field of government affairs, such as smart city management and various people's livelihood applications, to provide everyone with a good experience of "one-stop service", which requires multiple fields and multiple regions. , Multi-department collaboration. We can see that government affairs applications have wide coverage, many roles, and data have multiple levels of sensitivity and importance.

Blockchain can serve as a base for distributed collaboration, building a hub for data circulation through data directories, data lakes, etc., while introducing privacy computing and comprehensive governance rules to define the boundaries of data and make data While "not leaving the database", capabilities such as identity authentication, hidden query, and model construction can still be achieved.

From a larger perspective, building a comprehensive privacy protection and governance system requires not only the integration of blockchain, artificial intelligence, big data, privacy computing and other technologies, but also the integration of legal Regulations, regulatory governance and many other strategies.

Blockchain privacy protection has rich scenarios, numerous roles, diverse processes, and three-dimensional data. We can use the "double loop" mechanism for further analysis.

First of all, we start from the user side, respect the user's right to know and control the data, and leave important data to the user for management.

For example, among the "four elements" of identity verification, the user's identity credentials and contact information usually come from authoritative agencies such as governments and operators. When users have contact with a certain business scenario, they do not need Provide all plaintext information, and only need to selectively disclose some verifiable credentials to replace the plaintext.

Based on the distributed verification mechanism, multi-scenario verification can be realized to prove one's legal identity. At this time, even if the business provider does not obtain more plaintext data, it cannot refuse service. This fundamentally reduces or even eliminates the risk of leakage of users’ key privacy.

Secondly, on the business side, technologies such as federated learning and secure multi-party computing can still be used to process business data that has been authorized by users and collected in compliance with regulations.

Under the premise of users’ informed consent, collaborative computing with partners is realized on the B-side. Data does not leave the database and privacy is not leaked, but business operations such as risk control, marketing, and advertising are implemented. Matters of great value. Ultimately, the business results are improved, which not only brings benefits to the business side, but also provides users withProvide better services or returns in terms of equity. Its entire value system is closed-loop, compliant and sustainable.

For example, in the Internet of Things and blockchain, on the collection side, it is necessary to assign identities and identifiers to devices, and at the same time, the algorithm must be able to de-identify and prevent leakage; on the user side, it must not only provide personalized Services must also prevent unnecessary profiling. While verifying user identities and qualifications, they must not track user behavior for no reason. Ultimately, when providing high-quality services and securely storing user data, they must respect The user's wishes, including the requirement to log out.

Such a "dual cycle system" may not only technically require iterative reconstruction of devices, APPs, and backend services, but may also produce many innovations in its business model, operational governance concepts, etc. . The entire chain will be very long, and a lot of work needs to be done, covering a vast industrial chain such as chips, hardware, networks, software, and cloud platforms.

At present, there is no single technology that can “conquer the world” and meet the requirements of “full link” and “dual circulation”. Then we might as well break down the scenario a little more, list it more comprehensively, combine some technologies and solutions, and first solve the pain points in a certain scenario.

In fact, when we communicate with many industrial application developers, they prefer to focus on specific and urgent problems and get targeted and implementable solutions, such as hiding the amount when transferring money. , scores will not be disclosed when ranking, identity will not be revealed when voting, videos will not be leaked during the KYC process, etc.

Problems in specific scenarios can often be addressed in a targeted manner based on a certain algorithm or a combination of algorithms in privacy computing. We can work hard every day to solve scenario-based problems one after another, make up for things that may have been missed before, introduce new technologies and new ideas to foreseeable rigid needs, and implement them innovatively. In this way, the data security fence will be gradually raised bit by bit, and eventually the Great Wall of data security will be built.

In distributed collaboration, many scenarios are cross-institutional and cross-network. Whether it is blockchain or privacy computing, there will be requirements to interoperate with other partners and other platforms. We see that the relevant working groups of the Academy of Information and Communications Technology are discussing a number of interconnection specifications. The core framework is to achieve "node interoperability", "resource interoperability" and "algorithm interoperability".

Node interoperability requires basic elements such as networks and protocols to be interoperable. Resource interoperability emphasizes the release and storage, addressing and use of resources, and governance and auditing (including deletion of data, offline services, etc.). At this level, everyone implements a relatively consistent view and provides a common interface. The interoperability of algorithms is very detailed and scenario-based. Each algorithm has its own characteristics, and its cryptographic foundation, operation rules, and collaboration processes will be different, which in turn affects the management of resources.Management qualifications and the topology of the node network will put forward more requirements.

On the basis of interoperability, there are also requirements such as "self-consistency", "security", and "correctness", and with the development of the field, the "scalability" of continuously adding more functions is also very important. important. In the past, everyone may have worked hard to accumulate technology and experience. In the future, when implementing it, they need to pay more attention to interfaces and specifications, open their minds, communicate and build together, and seek consensus and win-win results through open source and open methods.

To summarize, here are some thoughts on the development of privacy computing:

Third, achieve standardization and popularization to promote the large-scale implementation of new technologies and new concepts. For example, relevant industry standards and evaluation systems are of great benefit to help practitioners clarify their development paths and meet industry requirements.

After so many years of blockchain development, apart from the technology itself, the most difficult thing is actually “how to explain clearly what a blockchain is”. It is hoped that in terms of popular science promotion, the emerging privacy computing will have more new ideas and achieve better results.

Looking back at the craze of blockchain and privacy computing, we see that industry and society are calling for data security and privacy protection, and the industry has already produced many available research results and has received certain recognition. Looking into the foreseeable future, we will be more open and pragmatic, focus on users and scenarios, and explore standardized, large-scale, and sustainable application paths.

『Wu』In-depth understanding of the consensus mechanism and algorithm principles of the blockchain

The so-called "consensus mechanism" is to complete transactions in a very short time through the voting of special nodes Verification and confirmation; for a transaction, if several nodes with unrelated interests can reach a consensus, we can think that the entire network can also reach a consensus on it. To put it more simply, if a Chinese Weibo influencer, a virtual currency player in the United States, an African student and a European traveler do not know each other, but they all agree that you are a good person, then it can basically be concluded that You're not a bad person.

In order for the entire blockchain network node to maintain the same data and ensure the fairness of each participant, all participants in the entire system must have a unified agreement, which is what we have here The consensus algorithm to be used. All Bitcoin nodes follow unified protocol specifications. The protocol specification (consensus algorithm) consists of relevant consensus rules, which can be divided into two major cores: proof of work and the longest chain mechanism. The ultimate expression of all rules (consensus) is the longest chain of Bitcoin. The purpose of the consensus algorithm is to ensure that Bitcoin continues to operate on the longest chain, thereby ensuring the consistency and reliability of the entire accounting system.

Users in the blockchain do not need to consider the credit of the other party when conducting transactions, do not need to trust the other party, and do not need a trusted intermediary or central agency.Transactions only need to be implemented based on the blockchain protocol. The premise for smooth transactions without the need for a trusted third-party intermediary is the consensus mechanism of the blockchain, that is, in a market environment of mutual understanding and trust, each node participating in the transaction considers its own interests and does not violate any regulations. Motives and behaviors of cheating, so each node will actively and consciously abide by the preset rules to judge the authenticity and reliability of each transaction, and write the record of passing inspection into the blockchain. The interests of each node are different, and logically there is no incentive for them to collude to deceive. This is especially obvious when some nodes in the network have public reputation. Blockchain technology uses a consensus algorithm based on mathematical principles to establish a "trust" network between nodes, and uses technical means to achieve an innovative credit network.

At present, the mainstream consensus algorithm mechanisms in the district industry include: workload proof mechanism, equity proof mechanism, share authorization proof mechanism and Pool verification pool.

The workload proof mechanism is the proof of workload, which is a requirement that must be met when generating a new transaction information (i.e. a new block) to be added to the blockchain. In a blockchain network built based on the proof-of-work mechanism, nodes compete for accounting rights by calculating the numerical solution of random hashing. The ability to obtain the correct numerical solution to generate blocks is a specific manifestation of the node's computing power. The proof-of-work mechanism has the advantage of being completely decentralized. In a blockchain with a proof-of-work mechanism as the consensus, nodes can enter and exit freely. The well-known Bitcoin network uses a proof-of-work mechanism to produce new currencies. However, since the application of the workload proof mechanism in the Bitcoin network has attracted most of the computing power of computers around the world, it is difficult for other blockchain applications that want to try to use this mechanism to obtain the same scale of computing power to maintain their own security. At the same time, mining based on the proof-of-work mechanism also causes a lot of waste of resources, and the period required to reach consensus is also long, so this mechanism is not suitable for commercial applications.

In 2012, a netizen with the pseudonym Sunny King launched Peercoin. This encrypted electronic currency uses a proof-of-work mechanism to issue new coins and a proof-of-stake mechanism to maintain network security. This is the role of the proof-of-stake mechanism in encrypted electronic currency. first application in . Rather than requiring the certifier to perform a certain amount of computational work, Proof of Stake simply requires the certifier to provide ownership of a certain amount of cryptocurrency. The way the proof-of-stake mechanism works is that when a new block is created, the miner needs to create a "coin rights" transaction, which sends a number of coins to the miners themselves according to a preset ratio. The proof-of-stake mechanism reduces the mining difficulty of nodes in equal proportions based on the proportion and time of tokens owned by each node based on the algorithm, thus speeding up the search for random numbers. This consensus mechanism can shorten the time required to reach consensus, but essentially still requires nodes in the network to perform mining operations. Therefore, the PoS mechanism does not fundamentallySolve the problem that the PoW mechanism is difficult to apply in the commercial field.

The share authorization certification mechanism is a new consensus mechanism to ensure network security. While trying to solve the problems of the traditional PoW mechanism and PoS mechanism, it can also offset the negative effects of centralization by implementing technological democracy.

The share authorization certification mechanism is similar to board voting. This mechanism has a built-in real-time shareholder voting system, just like the system is convening a never-ending shareholders' meeting at any time, where all shareholders vote. determine company decisions. The decentralization of the blockchain established based on the DPoS mechanism relies on a certain number of representatives rather than all users. In such a blockchain, all nodes vote to elect a certain number of node representatives, who act on behalf of all nodes to confirm blocks and maintain the orderly operation of the system. At the same time, all nodes in the blockchain have the power to remove and appoint representatives at any time. If necessary, all nodes can vote to disqualify the current node representatives and re-elect new representatives to achieve real-time democracy.

The share authorization certification mechanism can greatly reduce the number of nodes participating in verification and accounting, thereby achieving second-level consensus verification. However, this consensus mechanism still cannot perfectly solve the application problems of blockchain in business, because this consensus mechanism cannot get rid of its dependence on tokens, and the existence of tokens is not required in many commercial applications.

The Pool verification pool is based on traditional distributed consistency technology and is supplemented by a data verification mechanism. It is a consensus mechanism widely used in current blockchains.

The Pool verification pool can work without relying on tokens. Based on mature distributed consensus algorithms (Pasox, Raft), it can achieve second-level consensus verification, which is more suitable for multi-party participation. Polycentric business model. However, the Pool verification pool also has some shortcomings. For example, the degree of distribution that the consensus mechanism can achieve is not as good as the PoW mechanism.

Here we mainly explain some algorithm principles of the blockchain workload proof mechanism and the Bitcoin network. How to prove your workload? I hope everyone can have a basic understanding of the consensus algorithm.

The main feature of the proof-of-work system is that the client has to do a certain amount of difficult work to get a result, and the verifier can easily use the results to check whether the client has done the corresponding work. A core feature of this scheme is asymmetry: the work is modest for the requester and easy to verify for the verifier. It differs from CAPTCHAs, which are easier to solve by humans rather than easier to solve by computers.

The figure below shows the workload proof process.

For example, given a basic character creation "hello, world!", the workload requirement we give is that you can add an integer value called nonce (random number) after this character creation, and after the change (add nonce) is subjected to SHA-256 operation. If the result (expressed in hexadecimal form) starts with "0000", the verification is passed. In order to achieve this proof-of-work goal, it is necessary to continuously increment the nonce value and perform a SHA-256 hash operation on the resulting character creation. According to this rule, it takes 4251 operations to find the hash with leading 4 zeros.

Through this example, we have a preliminary understanding of the proof-of-work mechanism. Some people may think that if proof of work is just such a process, then it is enough to remember that the nonce is 4521 so that the calculation can pass verification. Of course not, this is just an example.

Next we simply change the input to "Hello, World! + integer value". The integer value ranges from 1 to 1000, which means that the input is turned into an array of 1 to 1000: Hello, World !1;Hello,World!2;...;Hello,World!1000. Then perform the above proof of work on each input in the array in turn - find the hash with leading 4 zeros.

Due to the pseudo-random nature of the hash value, it is easy to calculate based on the relevant knowledge of probability theory. It is expected that it will take 2 to the 16th power of attempts to obtain a hash hash with four leading zeros. List. If you count the actual results of the 1,000 calculations just performed, you will find that the average number of calculations is 66,958, which is very close to 2 to the 16th power (65,536). In this example, the number of calculations expected by mathematics is actually the required "workload". Repeating the workload proof multiple times will be a probability event that conforms to statistical laws.

The actual number of calculations used to count the input characters and obtain the corresponding target result is as follows:

For any node in the Bitcoin network, if you want to generate a new block To join the blockchain, you must solve this puzzle of the Bitcoin network. The key elements of this question are the proof-of-work function, block and difficulty value. The workload proof function is the calculation method of this question, the block is the input data of this question, and the difficulty value determines the amount of calculation required to understand this question.

The proof-of-work function used in the Bitcoin network is the SHA-256 mentioned above. Blocks are actually generated in the proof-of-work process. Kuangong constantly constructs block data and checks whether each calculated result meets the required workload, thereby determining whether the block meets the network difficulty. The block header is the Bitcoin workloadInput data for the proof function.

The difficulty value is an important reference indicator for miners to mine. It determines how many hash operations it takes for miners to generate a legal block. The Bitcoin network generates a block approximately every 10 minutes. If the generation of new blocks basically maintains this speed under different network computing power conditions, the difficulty value must be adjusted according to changes in the computing power of the entire network. The general principle is to ensure that the network always generates a new block in 10 minutes, regardless of the mining power.

The adjustment of the difficulty value occurs independently and automatically in each complete node. Every 2016 blocks, all nodes will automatically adjust the difficulty value according to a unified format. This formula is based on the time spent in the latest 2016 blocks and the expected time (assuming a withdrawal is generated every 10 minutes, the expected time is 20160 minutes) and adjusted according to the ratio of actual duration to expected duration. That is, if blocks are generated faster than 10 minutes, increase the difficulty value; anyway, decrease the difficulty value. The formula is expressed as follows:

New difficulty value = old difficulty value * (20160 minutes/time spent in the past 2016 blocks).

Proof of work requires a target value. The calculation formula of the target value (Target) of Bitcoin's proof of work is as follows:

Target value = maximum target value/difficulty value, where the maximum target value is a constant value

The size of the target value is inversely proportional to the difficulty value. To achieve the Bitcoin workload proof, the block hash value calculated in the mine must be less than the target value.

We can also simply understand the process of Bitcoin workload as performing SHA-256 hash operation by constantly changing the block header (that is, trying different nonce values) and using it as input. Find a process that has a hash value in a specific format (that is, requires a certain number of leading 0s), and the more leading 0s required, the more difficult it becomes.

The steps of Bitcoin’s proof-of-work puzzle can be roughly summarized as follows:

The process can be represented by the following figure:

Bitcoin’s proof of work is the main work we commonly call “mining”. Understanding the workload proof mechanism will lay the foundation for us to further understand the consensus mechanism of the Bitcoin blockchain.

『Lu』 How is the development of Tencent Blockchain? What are the scenarios where blockchain concept stocks have been implemented? Is it a new outlet for getting rich?

In the field of blockchain, Tencent Blockchain The speed of chain development is relatively fast. As early as 2015, Tencent’s blockchain team has begun to pay attention to blockchain technology.It has also conducted independent research and development. As of December 31, 2019, the number of Tencent blockchain-related invention patent applications in China reached 990, ranking first among Chinese applicants. After several years of R&D and exploration, Tencent Blockchain has achieved good results in both the development of underlying technology and the construction of industrial ecology.

The development history of Tencent’s blockchain:

There are no technical problems, it’s just a question of whether to do it or not. ”

When asked what technical difficulties he encountered, Cai Yige, the head of Tencent Blockchain, answered this way. After thinking about it, he added that for theories such as secure multi-party computation and zero-knowledge proof, Technologies that have made breakthroughs in the past have not yet been engineered, which is an industry-wide problem.

For Tencent Blockchain, the bigger problem seems to be to find more scenarios. "Blockchain "Chain + supply chain finance" is a scenario that Tencent is promoting this year.

At the end of last year, the supply chain financial service platform Xingbei Cloud Chain was released, and its underlying blockchain technology is supported by Tencent Blockchain. In addition, Tencent also invested in Lianyirong, which was Tencent’s only strategic investment in supply chain finance.

Now that it has been almost a year, how is this scene and Tencent’s blockchain progressing?

Today, after the establishment meeting of the Blockchain Policy and Legal Research Group and the press conference of the "Blockchain and Supply Chain Finance White Paper", Odaily Planet Daily interviewed Cai Yige, General Manager of Tencent's Blockchain Business, and Lianyirong Company General Manager Ji Kun.

According to two disclosures, in less than a year of operation, the micro-enterprise chain platform has approximately tens of billions of transactions on the chain, with 12 banks connected and more than 70 Enterprises participate, involving industries such as energy, automobiles, and manufacturing. The current penetration supplier level is about level 1 and level 2, which can reduce the interest rate by 2-8 points compared with traditional bank loans.

Micro-enterprises The chain platform is Tencent's key case in supply chain finance. Tencent mainly provides the underlying technical infrastructure, including the underlying self-developed alliance chain, real-time clearing and account transfer capabilities; Lianyirong is mainly responsible for integrating resources and promoting the platform.

Supply chain finance is the leading scenario of blockchain, but in fact the real implementation is still very slow, which makes people doubt the substantial changes it brings. The two do not deny that this business is in a very early stage At this stage, it will take some time to promote companies to join, but they all believe that "after joining the blockchain, supply chain finance will actually change very much."

What Odaily Planet Daily wants to know more is, With the addition of supply chain finance after blockchain, will companies and financial institutions be more willing to join in? And can this reduce the balance of small and medium-sized enterprise loans and increase the number of companies that receive loans?

"( The biggest difficulty in supply chain finance lies in the participation of financial institutions, because only they can provide funds. "Ji Kun believes that the addition of blockchain can enhance banks' willingness to enter supply chain finance.

In his view, the traditional banks of the four major banks are quite keen on the layout of blockchain. He saidIt shows that supply chain finance itself is decentralized and the authenticity of underlying assets is very difficult to check. It is not mainstream in traditional financial institutions, and there was no way to achieve penetration before. Therefore, banks can only obtain the data of first-tier suppliers, but Those most in need of financing may be second- and third-tier suppliers. Now blockchain + supply chain finance has changed the credibility of multi-level data circulation, strong credit cannot be split, and the synchronization efficiency of information, making it difficult for small, medium and micro enterprises in the supply chain to obtain loans from financial institutions in the past. Can get a loan. Banks have always wanted to do business with second- and third-tier suppliers. By joining the blockchain, institutions can better control their own data.

As for promoting enterprise use, Ji Kun said that it will take a certain amount of time for many enterprises to accept it. However, because the blockchain of supply chain finance mainly replaces the role of the original commercial paper, the circulation of the commercial paper itself There are some pain points, such as fraud, so they are relatively easy to accept.

When Odaily Planet Daily asked about how to ensure the authenticity of on-chain information, Cai Yige said that different information can be cross-verified, but he also believed that this was indeed a problem, using blocks The chain does not guarantee the authenticity of the information on the chain. Therefore, the first step of the micro enterprise chain's assets is actually accounts receivable, and it is true to use invoices to protect the underlying assets. As the business systems of small and medium-sized enterprises become electronic, they will go deeper in the future.

He also added that blockchain can also improve the efficiency of information synchronization. "I think it is the control of information. It turns out that in a centralized situation, even if you have information, it can be tampered with."

After talking about the focus of Tencent Blockchain this year, everyone naturally wants to know the future plan of. However, Cai Yige’s answer was the same as at the beginning: “We can’t talk about plans. We will continue to think about the scenarios in which blockchain can exert value.”

About this development:

First, you must choose the right scene and be sure to find experts in this industry.

Second, it must be in line with the nature of technology and have commercial value.

Third, it must meet the needs of future development.

Fourth, the architecture must truly solve the problem and be fully integrated with other technologies.

The concept of blockchain should be a new trend. Specifically, make more use of Internet searches to increase knowledge. Internet search results-Tencent Blockchain Development will be put for you.

『撒』 Alipay has launched a technology that makes "data available and invisible", called Ant Blockchain Morse Computing

In the new era of business intelligence, a broad consensus has been formed: Data is the most basic means of production, and the use of data by various industries and enterprises has also entered a mature stage. In the foreseeable future, the depth and breadth of data utilization will be further upgraded, entering the stage of cross-institutional and cross-industry data sharing, integration, and innovation, thereby opening up the magnificent picture of the Big Data 2.0 era: data connectivity covering government, commercial institutions, and individual departments. Sharing, based on industry chain data opening up and vertical and horizontal trunk lines of peer data cooperation, can be used in finance, marketing, public services, medical,scientific research and many other fields. Richer and multi-dimensional data resources create a multiplier effect, breed greater data value, open the door to business innovation, and thus bring more inclusive benefits and convenience to users.

Although there is a strong demand and willingness for data cooperation between institutions, in the specific cooperation process, due to obstacles such as business value, data security, privacy protection, and infrastructure, it is very difficult to implement data cooperation. In fact, Countless "data islands" have been formed. In the process of data cooperation and sharing, we mainly face the following problems:

Ant Blockchain Moss Secure Computing Platform aims at the above-mentioned pain points of data security trust, personal privacy protection and insufficient data infrastructure, adhering to the " Based on the principles of "data is available and invisible" and "moving computing to the data end", we use cutting-edge technologies such as blockchain, cryptography, privacy protection, secure multi-party computing, and trusted computing to build a secure, privacy-protecting, efficient, universal, and lightweight It provides a large-scale and decentralized data cooperation infrastructure to open up data islands, help institutions achieve safe, convenient and compliant data cooperation, and bring more convenience and benefits to users.

The Ant Blockchain Moss secure computing platform provides a new secure and privacy-protecting data cooperation method, which can pass passwords without leaking local data and keeping the original data out of the domain. Learning algorithms, distributed execution of predetermined logical operations and obtaining expected results, thereby completing data cooperation efficiently and safely. At present, Ant Moss has been widely used in joint financial risk control, rapid insurance claims settlement, people's livelihood and government affairs, multi-party joint marketing, multi-party joint scientific research, cross-border data cooperation and other fields.

Take credit business as an example. The first is the prevention and control of long-term lending. Data shows that for every additional institution a loan applicant applies to, the probability of default increases by 20%. However, the central bank’s credit reporting coverage is currently limited, and more than 400 million natural persons lack credit reporting records; various credit institutions have spent time and money accumulating user credit data and are unwilling to share it with competitors; even if credit institutions are willing to share data, There are also many obstacles such as data security, user privacy, and compliance. With the help of Ant Moss, multiple financial institutions can establish a risk control data alliance based on multi-party secure computing technology, and share blacklists, credit applications, credit records and other data in a confidential manner without leaking the original data of each institution, and distributed encryption calculations can obtain statistics. result. Secondly, under the premise of user authorization, financial institutions can use Antmos to obtain massive multi-dimensional data from cross-industry governments, operators, e-commerce, independent data service providers, etc., to improve the accuracy of credit assessment models, thereby increasing the acceptance rate, Reduce bad debt rate. Combined with blockchain technology, Antmos also provides functions such as certificate storage, authorization, and billing for data service calls, improving the data alliance's commercial operations, cooperative management, supervision, and auditing capabilities.

Let’s take insurance claims as an example. Commercial insurance participants must collect relevant forms, medical receipts, medical records and other information after medical treatment, and then submit or upload them to the insuranceThe company's claims platform requires compensation only after passing the review. The entire claims process is long, inefficient, and has the potential for fraudulent claims. Many insurance companies hope to directly connect with hospital data and establish a fast compensation channel. However, hospitals are concerned about medical data security and patient privacy leaks, and are reluctant to directly open sensitive medical data. With the help of Ant Moss, secure computing nodes can be deployed in a distributed manner in the hospital domain and insurance company claims service domain, and the insurance company can remotely deploy the claim settlement model and adjustment rules on the computing nodes in the hospital domain. After the patient initiates a claim for medical treatment, the hospital-side secure computing node automatically uses the original medical treatment and prescription data of the claim applicant to perform local encrypted calculations to obtain the claim settlement result, and only outputs whether compensation and the amount of compensation are paid to the insurance company. In this way, a closed loop of business and data can be formed while protecting the security of medical data and personal privacy, greatly improving the efficiency and accuracy of claims settlement, and solving the pain point of "difficult medical treatment and more difficult claims settlement". The data summary and judgment results involved in the entire claims process can be encrypted and stored in the blockchain to facilitate subsequent profit sharing, auditing, and supervision.

Finally, take the field of government affairs as an example. With the help of Antmos, efficient and secure data sharing can also be achieved between departments and between government departments and the public. When building big data platforms in various places, there is no need to move all data from industrial and commercial, taxation, civil affairs and other departments to the platform. Instead, computing models or rules only need to be deployed in the data domains of each department, and encrypted calculations can be performed in real time according to business requests. Called in real time. The data demand department can quickly adjust and optimize calculation strategies and rules, and can feed back the calculation results to the original data department to provide improvement suggestions for data collection and sorting, thereby consolidating the data foundation for people's livelihood and government affairs, and realizing "multiple data" conveniently and securely. Don’t run around, people don’t have to run errands.”

Ant Moss relies on the Ant Financial Technology platform and combines blockchain technology to make complex privacy protection and cryptography algorithms transparent and productized, providing secure publishing, security models, security statistics, and secure queries. , security scripts and other core functions. Ant Moss products have the following features and advantages:

•Data security: The underlying detailed data and original data of all parties involved in data cooperation do not leave the computing node, and all calculations are performed in a ciphertext state. , the querying party can only obtain the results of query and calculation.

•Transparent and trustworthy: Designed according to the open source idea, it ensures the security of computing and enhances mutual trust by disclosing algorithms. It has applied for more than 50 patents related to multi-party secure computing algorithms. In addition, Antmos has obtained security and privacy protection certifications from many domestic and foreign authoritative organizations such as the Ministry of Public Security, the National Information Technology Research Center and Trust Arc, and participated in the formulation of national security computing standards by the China Academy of Information and Communications Technology.

•Privacy protection: To ensure minimal data utilization, all calculations are performed on encrypted or desensitized data, and allThe output is minimized, ensuring the security of personal privacy data to the greatest extent.

•Decentralized architecture: Using a completely decentralized architecture, data calculation and interaction are completed independently between multiple computing nodes. There is no central control node, which reduces trust costs and has stronger disaster tolerance. and anti-attack capabilities.

•Blockchain verification audit: Use blockchain technology to carry out certificate storage, authorization, billing, etc. of data service calls to ensure that data calculation and utilization are legal and compliant; provide verification of calculation data and processes Verification auditing, data monitoring and other functions ensure the authenticity and credibility of the calculation process, data authenticity and data quality.

Ant Moss looks forward to more partners joining in, achieving its own business growth through secure and compliant data cooperation, and providing secure data cooperation solutions with more industry attributes.

Product official website address: https://tech.antfin.com/procts/MORSE (Welcome to apply for trial)

Contact information: [email protected]

< p>『8』 Modern cryptography in blockchain

1983 - Blind signature described by David Chaum
1997 - HashCash invented by Adam Back (an example of a proof-of-work system)
2001 - Ron Rivest, Adi Shamir and Yael Tauman proposed ring signatures to the crypto community
2004 - Patrick P. Tsang and Victor K. proposed using a ring signature system for voting and electronic cash;
2008 - Bitcoin White Paper published by Satoshi Nakamoto
2011 - Analysis of Anonymity in the Bitcoin System, Fergal Reid and Martin Harrigan
2012 - Destination Address Bitcoin Anonymity (Disposable Addresses in CryptoNote).

Secure multi-party computation originated from Yao Qizhi’s millionaire problem in 1982. Later Oded Goldreich had a more detailed and systematic discussion.

The Yao Millionaire problem was first raised by Professor Yao Qizhi, a Chinese computer scientist and Turing Award winner. The problem is formulated as follows: Two millionaires, Alice and Bob, want to know who of them is richer, but neither of them wants the other to know any information about their wealth. This problem has some practical applications: Suppose Alice wants to buy some goods from Bob, but the maximum amount she is willing to pay is x dollars;The lowest selling price Bob hopes is y yuan. Both Alice and Bob really want to know which is bigger, x or y. If x>y, they can all start bargaining; if z
This scheme is used to compare two numbers to determine which one is larger. Alice knows an integer i; Bob knows an integer j. Alice and B0b want to know whether i>=j or j>i, but neither wants the other party to know their own numbers. For simplicity, assume that the range of j and i is [1, 100]. Bob has a public key Eb and a private key Db.

The research on Secure Multi-Party Computation is mainly aimed at the problem of how to safely calculate an agreed function without a trusted third party. Secure multi-party computation is used in electronic elections, electronic It plays an important role in scenarios such as voting, electronic auctions, secret sharing, and threshold signatures.

Homomorphic Encryption is an Open Problem proposed in the cryptography community a long time ago. As early as 1978, Ron Rivest, Leonard Adleman, and Michael L. Dertouzos proposed this concept in the context of banking [RAD78]. Yes, you read that right, Ron Rivest and Leonard Adleman are R and A respectively in the famous RSA algorithm.

What is homomorphic encryption? Craig Gentry, who proposed the first construction of Fully Homomorphic Encryption [Gen09], gave the best intuitive definition: A way to delegate processing of your data, without giving away access to it.
< br /> What does this mean? General encryption schemes focus on data storage security. That is, I want to send an encrypted thing to other people, or I want to store something on a computer or other server. I want to encrypt the data before sending or storing it. Without the key, it is impossible for the user to obtain any information about the original data from the encrypted result. Only users with the key can correctly decrypt and obtain the original content. We noticed that during this process, users cannot do any operations on the encryption results, they can only store and transmit them. Any operation on the encryption result will result in incorrect decryption or even decryption failure.

The most interesting thing about the homomorphic encryption scheme is that it focuses on data processing security. Homomorphic encryption provides a function for processing encrypted data. That is, others can process the encrypted data, but the processing will not reveal any of the original content. At the same time, the user who has the key decrypts the processed data and gets exactly the processed result.

A bit abstract? Let’s take a real-life example. A user named Alice bought a large piece of gold, and she wanted workers to make it into a necklace. But workers may steal gold during the building process. After all, even one gram of gold is worth a lot of money... So is there a way for workers to process the gold nuggets (delegate processing of your data), but Not getting any gold (without giving away access to it)? Of course there is a way, Alice can do this: Alice locks the gold in a sealed box, and this box is equipped with a glove. Workers can wear this glove to handle the gold inside the box. But the box was locked, so not only could the workers not get to the gold nuggets, but they also couldn't get to any gold that fell out during handling. After processing is completed. Alice took the box back, opened the lock, and got the gold.

The correspondence here is: Box: Encryption algorithm Lock on the box: User key Put the gold nugget in the box and lock it with a lock: Encrypt the data using a homomorphic encryption scheme : Apply the homomorphic feature to directly process the encryption result under the condition that the data cannot be obtained. Unlock: Decrypt the result and directly obtain the processed result. Where can homomorphic encryption be used? Hasn’t the concept of cloud computing been mentioned in recent years? Homomorphic encryption is almost tailor-made for cloud computing! Let's consider the following scenario: a user wants to process a piece of data, but his computer's computing power is weak. This user can use the concept of cloud computing and let the cloud help him process and get the results. But if the data is handed over directly to the cloud, security cannot be guaranteed! Therefore, he can use homomorphic encryption, and then let the cloud process the encrypted data directly and return the processing results to him. In this way: the user pays the cloud service provider and gets the processing results; the cloud service provider earns the fee and correctly processes the data without knowing the user's data;

Aggregated signature by Boneh et al. proposed to improve the efficiency of signature and verification mainly by aggregating multiple signatures into one signature. To sign data of multiple users, aggregate signatures can greatly reduce the complexity of signature calculations. CL is the aggregate signature.

There are two participants in the zero-knowledge proof process, one is called the prover and the other is called the verifier. The prover holds a secret and wants the tester toThe witness believes that he holds the secret, but does not want to reveal the secret to the verifier.

Both parties follow an agreement and through a series of interactions, the verifier will eventually draw a clear conclusion that the prover does or does not know the secret.

For the example of Bitcoin, whether a transfer transaction is legal or not actually only needs to prove three things:

The money sent belongs to the person who sent the transaction
Send The amount sent by the sender is equal to the amount received by the receiver
The sender's money was indeed destroyed
During the entire proof process, the miners do not actually care about the specific amount of money spent, who the sender is, and the recipient Who exactly is it? Miners only care about whether the system's money is conserved.

zcash uses this idea to implement private transactions.

The three properties of zero-knowledge proof correspond to:

(1) Completeness. If both the prover and the verifier are honest, follow every step of the proof process, and perform correct calculations, then the proof must be successful and the verifier must be able to accept the prover.
(2) Rationality. No one can impersonate the prover and make this proof successful.
(3) Zero knowledge. After the proof process is completed, the verifier only obtains the information that "the prover possesses this knowledge", but does not obtain any information about the knowledge itself.

There are only ring members, no managers, and no cooperation between ring members is required. The signer can sign independently by using his own private key and the public keys of other members in the set, without the need for other members. With the help of people, other members of the set may not be aware that they are included.
Ring signatures can be used as a way to reveal secrets, for example, a ring signature can be used to provide an anonymous signature from a "senior White House official" without revealing which official signed the message. Ring signatures are suitable for this application because the anonymity of a ring signature cannot be revoked and because the group used for the ring signature can be created on the fly.

1) Key generation. Generate a key pair (public key PKi, private key SKi)
2) signature for each member in the ring. The signer uses his own private key and the public keys of any n ring members to generate a signature a
for message m
3) Signature verification. The signer verifies whether the signature is signed by a member of the ring based on the ring signature and message m. If valid, receive it; if invalid, discard it.

General process of group signature

Blind SignatureBlind signature for short - is a digital signature method in which the message content is invisible to the signer before the message content is signed. In 1982, David Chaum first proposed the concept of blind signature. Because of its blindness, blind signature can effectively protect the specific content of the signed message, so it is widely used in fields such as e-commerce and electronic elections.

Analogy example: To sign a document is to put a piece of carbon paper in the envelope. When the signer signs the envelope, his signature is signed on the document through the carbon paper.

The so-called blind signature is to first put the concealed document into an envelope, and the process of removing the blind factor is to open the envelope. When the document is in an envelope, no one can read it. Signing a document is done by placing a piece of carbon paper in the envelope. When the signer signs the envelope, his or her signature is transferred to the document through the carbon paper.

Generally speaking, a good blind signature should have the following properties:

Unforgeable. No one can generate a valid blind signature in his name except the signer himself. This is the most basic property.
Non-repudiation. Once a signer signs a message, he cannot deny his signature on the message.
Blindness. Although the signer signs a message, he cannot obtain the specific content of the message.
Untraceability. Once the signature of a message is made public, the signer cannot be sure when he or she signed the message.
Blind signatures that meet the above properties are considered safe. These four properties are not only the standards we should follow when designing blind signatures, but also the basis for us to judge the performance of blind signatures.

In addition, the operability and implementation efficiency of the solution are also important

factors that we must consider when designing blind signatures. The operability and implementation speed of a blind signature depend on the following aspects:

1. The length of the key;
2. The length of the blind signature;
3. Blind Signature algorithm and verification algorithm.
Specific steps of blind signature
1. The recipient first blindly transforms the data to be signed, and sends the transformed blind data to the signer.
2. After being signed by the signer, it will be sent to the recipient.
3. The receiver performs a blinding transformation on the signature, and the result is the signer's blind signature of the original data.
4. This meets the condition ①. To satisfy condition ②, the signer must not be able to associate the blind signature with the blind data when he sees it afterwards. This is usually achieved by relying on some kind of protocol.

『玖』 What is the relationship between blockchain and big data storage?

The relationship between blockchain and big data storageAs follows:
1. Data security: Blockchain allows data to flow with real confidence
With its trustworthiness, security and non-tamperability, blockchain allows more data to be liberated. Let’s use a typical case to illustrate how blockchain promotes the generation of gene sequencing big data. Blockchain sequencing can use private keys to limit access rights, thereby circumventing legal restrictions on individuals' access to genetic data, and utilize distributed computing resources to complete sequencing services at low cost. The security of blockchain makes sequencing an industrialized solution, enabling global-scale sequencing, thus promoting the massive growth of data.
2. Data openness and sharing: Blockchain ensures data privacy
The government holds a large amount of high-density and high-value data, such as medical data, population data, etc. The openness of government data is a general trend and will have an immeasurable impetus to the development of the entire economy and society. However, the main difficulty and challenge in data openness is how to open data while protecting personal privacy. Blockchain-based data desensitization technology can ensure data privacy and provides a solution for data openness under privacy protection. Data desensitization technology mainly uses encryption algorithms such as hashing. For example, the Enigma system based on blockchain technology can calculate data without accessing the original data, which can protect the privacy of data and eliminate information security issues in data sharing. For example, company employees can safely open access to their salary information and jointly calculate the average salary within the group. Each participant is informed of his relative position within the group but not of the compensation of other members.
Data HASH desensitization processing diagram
3. Data storage: Blockchain is an immutable, full-historical, strongly endorsed database storage technology
Blockchain technology, through the network All nodes in the network participate in calculations and mutually verify the authenticity of their information to reach a consensus across the entire network. It can be said that blockchain technology is a specific database technology. So far, our big data is still in a very basic stage. Trusted blockchain data based on the consensus of the entire network is non-tamperable and full of history, which also enables the quality of the data to gain unprecedented strong trust endorsement. It also brings the development of database into a new era.
4. Data analysis: Blockchain ensures data security
Data analysis is the core of realizing data value. When conducting data analysis, how to effectively protect personal privacy and prevent core data leakage has become the primary consideration. For example, with the popularization of fingerprint data analysis applications and genetic data detection and analysis methods, more and more people are worried that once personal health data is leaked, it may lead to serious consequences. Blockchain technology can prevent such situations through multi-signature private keys, encryption technology, and secure multi-party computing technology. When the data is hashed and placed on the blockchain, digital signature technology is used to allow only authorized people to access the data. The private key ensures data privacy and can be sharedTo authorized research institutions. The data is uniformly stored on the decentralized blockchain, and data analysis can be performed without accessing the original data. This can not only protect the privacy of the data, but also safely provide it to global scientific research institutions and doctors for sharing. The basic health database will bring great convenience to solve sudden and difficult diseases in the future.
5. Data circulation: Blockchain protects data-related rights and interests
For individuals or institutions’ valuable data assets, blockchain can be used to register them, and transaction records are recognized and transparent by the entire network. , traceable, clarifying the source, ownership, use rights and circulation path of big data assets, which is of great value to data asset transactions.
On the one hand, blockchain can eliminate the threat of intermediaries copying data and help establish a trustworthy data asset trading environment. Data is a very special commodity, which is essentially different from ordinary commodities. It mainly has characteristics such as unclear ownership and "it is owned after seeing it and copying it". This also determines that the transaction method using traditional commodity intermediaries cannot meet the needs of data. Share, exchange and trade. Because the intermediary center has the conditions and ability to copy and save all the data flowing through it, this is extremely unfair to the data producers. This threat cannot be eliminated by relying on promises alone, and the existence of this threat has also become a huge obstacle to the flow of data. Based on decentralized blockchain, it can eliminate the threat of data copying by intermediary centers and protect the legitimate rights and interests of data owners.
On the other hand, blockchain provides a traceable path and can effectively solve the problem of data verification. The blockchain jointly participates in the calculation and recording of data through multiple nodes participating in calculations in the network, and mutually verifies the validity of their information. It can not only prevent information counterfeiting, but also provide a traceable path. By stringing together the transaction information of each block, a complete list of transaction details is formed. The ins and outs of each transaction are very clear and transparent. In addition, when people have questions about the "value" of a certain block, they can easily review historical transaction records to determine whether the value is correct, and identify whether the value has been tampered with or recorded incorrectly.
Everything is guaranteed on the blockchain, and big data will naturally become more active.
The tokens of crowdfunding projects on the Biying China platform are all developed based on blockchain technology, and relevant information will be recorded on the blockchain.