Guosheng Blockchain: What is the dual offline payment of digital currency?
Editor's Note: This article comes fromJishi Communication (ID: SJJ_Telecom)Editor's Note: This article comes from
Jishi Communication (ID: SJJ_Telecom)
Jishi Communication (ID: SJJ_Telecom)
, Author: Song Jiaji, reproduced by Odaily with authorization.
We previously explained some of the positioning and functions of the central bank’s digital currency through a series of in-depth reports. Recently, Mu Changchun, director of the central bank’s digital currency research institute, also mentioned that DCEP needs to support “dual offline” payments in the future. Many investors are interested in the interesting detail of dual offline payments. Digital currency is a general direction in the future, and a very important technical practice of this solution is to replace cash. In the absence of the Internet, users cannot use WeChat Pay or Alipay to pay online, but they can still pay customers in cash without the Internet, which is an important aspect of ensuring the Cash function. So how does digital currency realize dual offline payment?
The topic of dual offline payment has been mentioned a lot recently. We have discussed with the new Cape technology management team in the industry who do dual offline payment. Their business is more in the campus scene. The campus cafeteria uses dual Offline technology, so we will discuss the development history of dual offline, recent solutions, how to deal with high concurrency, how to achieve it when the network is not good, and related security issues.
Summary of core ideas
1. Dual offline payment application scenarios and principles
The dual offline payment core refers to a process of completing business when both the medium and the receiving terminal are offline, the most typical ones are payment business and identity verification. For the payment business, it completes the closed-loop transaction process through the deferred payment request after the transaction is completed. The core is a technical solution that realizes fast verification and payment.
Its business mechanism has two core points. One is that there are two features in the business mechanism, including authentication and payment; the other is that there is a trust mechanism between the terminal and the medium. There are three dimensions in terms of transaction security mechanisms: (1) one is the amount of risk control, which is the amount of transactions after dual offline; (2) the second is that there will be a mechanism for advance payment and recovery; (3) the third is Credit system. In fact, in the dual offline scenario, code and face are essentially a process of enjoy first, pay later, and solve the problem of user experience. The applicable scenario is: a large number of people quickly complete verification or small payment scenarios in a short period of time. When the network is not smooth or the information environment is abnormal, it is also required to ensure the success rate of the transaction, otherwise it may cause group incidents. Typical occasions Such as: public transportation, consumption in campus canteens; take campus canteens as an example: class ends at 12 o’clock, and tens of thousands of people finish their meals within an hour. If dual offline transactions are not supported, either mass incidents will be triggered, or the school will allow students to eat for free , the school pays the bill; the dual offline feature of the campus scene is that the campus core identity must be a campus identity, which is the difference between a closed environment and an open environment (such as a bus); the core identity requires the identity of a student or a teacher to consume, which is specific to a specific scene Strategy.
At present, there are two implementation paths that are being launched, and there are two future technical directions. At present, the dual offline verification and payment of cards, codes and faces has been realized, which is mainly a contract bookkeeping plus the operator's funds. route.
There are two more routes above the bottom line of funds. One is the credit line that the school allows students to grant credit, which is controlled when they leave school; the other is the funding path based on marketing strategies.
One of the technical directions currently being researched is IoT edge computing. Enhance risk control capabilities through edge computing; in addition to transaction behavior (limits, limit scenarios, overdraft risk control quotas, etc.), based on the Internet of Things, through the same venue transaction location, the edge computing gateway completes the write-off machine risk control balance, increasing the effect of dual offline risk control);
2. The future development direction of dual offline:
Q&A:
(1) Edge computing plus the application of blockchain technology. Because the future development direction of campus payment is bound to improve user experience, this model can solve the problem of campus account management. In terms of blockchain technology research, we are currently researching the technology paths with and without coins. The scene with coins in the closed environment of the campus is mainly the wallet points of the card, and the scene without coins is mainly the super ledger. Credit resume, employment terms.
(2) Digital currency. This is also our next research direction. This area mainly follows the national standards and regulations for application innovation. In the era of IC cards, it follows the PBOC specifications. In the future, the country will also issue some specifications for digital currency to solve the acquisition transactions in closed-loop scenarios. question. With the support of policies and the scenario of school permission, we will continue to study the user experience of dual offline payment, and use continuous iteration of technology to study industry norms. At present, we have no real production and application of digital currency, and innovation needs to be based on the central bank's management regulations.
For the application of dual offline campus payment scenarios, cards and NFC are the earliest, and the electronic wallet transaction mechanism has become the standard configuration of banks. With the development of mobile payment and face payment, students no longer carry cards and cash. Face payment has gradually become the mainstream. At present, the network environment of the school will still fail, so in the closed campus scene, the network and The face must be able to adapt to the dual offline requirements like a card, so as to avoid group incidents caused by network or system congestion during peak hours, or the situation of free orders. The transaction mechanism of the two parties uses the two-way authentication of the terminal, the upload calculation process of the delayed record, and the mechanism of the risk control amount of the credit, and has a series of security measures.
Q: When we use dual offline, for example, I only recharge 100 yuan, but it may be because there is no real-time settlement in the offline state. I spent 110 at the time, so after the settlement, it may be a chase for me, right? ?
A: Yes. The NFC card has an electronic wallet, which does not exist in this situation, but if you want to code and face, this situation may exist. Here are some risk control mechanisms and qualifications for risk control quotas. According to your personal consumption situation and the remaining balance of your balance, there will be some risk control technology risk control quota controls, and offline transaction quotas will be controlled. In addition, there will be some transaction control on the terminal side, which will reduce the transaction risk after offline.
When code and face support dual offline transactions, there must first be a process of signing an electronic agreement in advance and activating the withholding, and then the second step is to delay the online payment. If the balance is insufficient, there are two modes before the settlement point: (1) one is that the school will have an allowed credit line; (2) one is if there is operator intervention, such as Alipay and Perfect Data Union, They will first advance to the school and merchants, and then he will pursue the payment through guidance channels or three-party channels.
If the payment cannot be recovered, there are two ways: (1) One way is that the school will cooperate with the management and control of leaving school, and when he leaves school, he will have to pay off the funds; (2) If this cannot be done , that will enter the tripartite credit system.
Because our group is college students, generally we believe that college students will not do this out of malicious intent, which is extremely rare.
Q: If the mobile wallet is NFC, because it belongs to this kind of open state, will there be behaviors such as malicious scratching among the crowd, which will lead to money being stolen, and are there any measures to avoid it?
A: The campus scene has its particularity, because the transaction distance between the card and POS should be 0 to 10 cm according to the norms, and the school scene is generally set at 5 cm. If you do not report the loss after the card is lost, you can directly take the POS machine close to the person. It is basically impossible to brush around 5 centimeters. If it really happened, it can be traced back, because only the PSAM card issued by the platform can be used in the POS machine, so everything must be traced back. Within a certain range, we also have mechanisms such as the consumption limit of the day. If the card is lost, there is no way;
Q: In the dual offline payment scenario, can the transfer of these funds be uploaded to the chain in real time, or will the data and fund transfer information be uploaded to the chain only after settlement?
A: There are two stages of blockchain exploration now: (1) The first stage we explore is to use blockchain to do our bookkeeping, the core is to solve the unforgeable traceability of commercial accounts; (2) the second stage The second stage may extend to a scenario similar to the issuance of credits in a closed environment on campus.
The biggest difference is actually who is the leading party, the scope and main uses of blockchain recognition, and the second we emphasize that we have to wait for some norms at the national policy level and some consensus at the industry level to be implemented before we will be in the blockchain industry. The production environment landed.
Q: Let’s discuss one more thing about the central bank’s digital currency. For example, two mobile phones can complete the transfer and DCEP payment with one touch. This dual offline technology, according to your understanding, what are the technical approaches and some problems? Pay attention?
A: You are talking about touch, because Huawei has been pushing the NFC technology path at the beginning of this year. Mobile phone touches should basically be based on technologies similar to near-field payment.
Q: We also saw a picture circulated on the Internet before, that is, a DCEP wallet was developed in the ICBC APP. If his DCEP account is inside the mobile banking APP, does it still need the Internet to use it? If the mobile phone is offline, can DCEP still use dual offline in the mobile banking APP?
A: He may have a mechanism, which may store the unique value of the token in the mobile phone and exchange this unique value with each other. There may be a mechanism to do dual offline.
Q: Does the double offline always exist, such as the problem of post-settling diagonal and double spending?
A: In theory, it exists, but in practice it is very rare, and the probability is extremely small. The offline time of the terminal is limited, and it will not be allowed to be used for a certain period of time when it is offline in the middle. The transaction limit and the number of transactions on your terminal with the same code or the same face will be limited. Similarly, if you want to open the code on your mobile APP, this code is also time-sensitive, and there will be multiple security mechanisms. NFC is more secure than QR codes. It's inside the security chip.
Q: NFC is easy to be called by devices that can be recognized around, and it can be stolen without unlocking the phone. Can this constitute a security risk?
A: It can recognize it, but it cannot deduct the money without the key. If someone wants to steal the amount in your NFC, it must have a corresponding authentication terminal. Even if you swipe, you can trace it and audit it.
Q: As for the issue of student files that you mentioned just now, human resources now have to use the data of Xuexin.com. It should be a centralized platform of the Ministry of Education. There is actually no problem in using it now. Why should it be used in Want to use the blockchain to register? Will there be any difference in reading information from the original centralized Xuexin.com?
A: It mainly solves the credible, traceable, non-tamperable, and non-forgeable data, and solves the problem of trust crisis, because there are now fake resumes.
Blockchain is one of the technical paths, and the application of blockchain will lead to the innovation of the business model of the talent service industry. For example, the establishment of blockchain public chain infrastructure based on talent data will give individuals, school employment offices, enterprises, education bureaus, Xuexin.com, etc. more independent on-chain models, which will significantly reduce cross-checking of information in the industry , Certification costs.
Q: Regarding the question of traceability, if it is a QR code, can it also be traceable? In addition, how does the QR code realize dual offline payment when it is offline?
A: It is a little different, there is no electronic wallet for code and face. The account QR code (campus code) issued by the on-campus payment system can be traced. When offline, the terminal can directly decode the unique identification ID on-campus for deduction transaction processing. In the later stage, the account will be written off after going online. The amount of dual offline payment is controlled by the risk control amount, the limit of the terminal offline transaction mechanism, the limit plus the time and frequency of generated codes and other mechanisms.
Q: For example, my mobile phone is in arrears today and cannot access the Internet. Can I still open the QR code for dual offline?
A: Yes for a period of time. The main reason here is that the code has a security mechanism, which is a mechanism of double digital certificates. For mobile phone users, it is a certificate login mode based on personal passwords. It caches the public key of the personal token platform certificate, and it needs to be updated regularly to form an effective QR code. However, if your token exceeds a certain If the time is too long, there is no way to generate a QR code, and it cannot be used again.
Q: In fact, the generation of the QR code has something to do with this terminal?
