Technical means of digital currency offline payment

3. Blockchain + digital currency opens "different" payment methods
with the continuous development and progress of society, great changes have taken place in our lifestyle, such as mobile payment and online shopping, which have brought great convenience to our life. Since the birth of online shopping, online payment has become a part of our life
online shopping is convenient, but it is also through the middle of a "invisible" process of payment, such as we bought something on the Internet, first pick out what you love, then you have to pay the problem:
now most people use Alipay is the way of payment, then first Alipay will receive payment request. Then it initiates the protocol to the network, saves the information to the database, and forwards the request to the bank. When the Alipay account shows that the dection is successful, it will have to be connected to the bank through the Internet. Then the buyer will confirm receipt after receiving the goods, so that the buyer will dect the money before transferring to the seller's account. Not only is the transaction process too cumbersome and complex, it is clear that the transaction between the two parties has to go through a series of links. More importantly, once the intermediate payment link collapses, the whole transaction will stop, and the subsequent operation is really troublesome

in fact, the popular explanation is that when I want to buy something, I give the money to the middleman and ask him to help the seller. If the middleman makes any mistakes, it may lead to the situation that the money can not be recovered and the goods can not be obtained
is there any way to simplify the transaction process and improve the transaction efficiency? Yes, the current hot blockchain technology and digital currency payment can better solve the above problems:

blockchain has become one of the hot topics in the past two years. Blockchain can replace the existence of these third-party services:
first, blockchain can not be tampered with. Every transaction will be distributed to each block for record keeping, Then use cryptography to verify, any malicious damage or record deletion will be found, so the whole process of shopping will be seen. Blockchain strengthens the trust, traceability and transparency in the transaction, making our transaction faster and more convenient<

the second is the unique payment characteristics of digital currency:
the decentralization of digital currency can eliminate the intervention of the third party, and there is no need to worry about the problems of the third party, resulting in the whole transaction payment process can not continue
the point-to-point transmission of digital currency saves the time link in the whole payment process and realizes fast payment, so that both parties can receive money quickly and save time
openness and transparency of digital currency: except for cash transactions, all transactions based on online payment are just a series of numbers, and all transactions of digital currency are open and transparent. You can check the transaction records of all payments, which can ensure the security of the overall commodity payment
and like China's booming WeChat, Alipay and other payment platforms, cross-border payment has been realized, but there is a problem that fees will be more expensive than domestic payments, and the settlement cycle will be longer than domestic. In general, efficiency will be slow, time is long, and hand renewal is expensive. Digital money will make traditional transactions "no longer traditional". That will also make cross-border payment more efficient: digital currency is not subject to the "constraints" of any country or bank. Based on blockchain technology, it can just bypass this centralized system with low handling charges, and its point-to-point transmission transaction characteristics can effectively improve the current problems of long-time and high cost of cross-border payment

the times have been developing, and the way of life is constantly improving. Online shopping and payment are born from our development, with both advantages and disadvantages. Then we will try our best to push everything in a better direction
digital currency is on the rise. Although the current digital currency is not perfect, many countries have begun to use digital currency as a payment method. Due to the various characteristics of digital currency, bitcoin, Ethernet, Las Y2, QTP (wechat ID: yingbivc), ASEC and other digital currencies are being actively used. They can not only simplify the traditional online payment transaction process, but also circulate payment around the world and rece exchange rate issues such as handling charges. Don't just look at digital currency with one eye. Maybe in the near future, it will open the era of digital currency full payment!

4. In fact, the technical systems corresponding to various digital currencies are quite different
moreover, the development of digital currency is still immature.

5. Well, this is the answer given by my teacher

A: filter some common database operation keywords,
select, insert, update, delete, and, * etc., or filter the content through the system function addslashes
register in PHP configuration file_ globals=off; Set to off state. (the function will close the registered global variables); If receiving the value of post form, use$_ POST[' user'], If it is set to on, the value will be received by $user.
when writing SQL statements, try not to omit small quotation marks (the one above tab) and single quotation marks.
improve the skills of database naming, and name some important fields according to the characteristics of the program, so that they are not easy to be guessed.
encapsulate common methods to avoid directly exposing SQL statements.
Open PHP safe mode_ Mode = on
Open magic_ quotes_ GPC is used to prevent SQL injection. It is turned off by default. When it is turned on, it automatically converts the SQL query statement submitted by the user to & quot&# 39;& quot; Convert to & quot&# 92;&# 39;& quot;
control the output of error message, close the error message prompt, and write the error message to the system log
preprocess with mysqli or PDO

6. A machining center of about one meter is a relatively large one. This kind of machining center is generally equipped with imported systems, such as FANUC, Siemens, Mitsubishi, etc. the specific price is more than 30 Wan. Different manufacturers also have a certain impact on the price. Shenyang machine tool factory and Dalian machine tool factory are better domestic machining centers, We should choose the machining center according to your actual situation. If you want to buy in Northwest China, we suggest you look for Dongyue machine tool. They all sell the first-line well-known brands in China. They are the general agent of many first-line brands in Northwest China, and the price is relatively favorable. The 850 in our factory was bought from them last year. I hope it can help you

7.

There are also many differences between the promotion of digital currency and wechat payment. It does not have an Internet giant like Tencent, nor does it have an investment ecosystem under Tencent. Digital currency mostly cooperates with local governments. At present, digital currency prefers the offline scheme. In the three rounds of pilot projects in Shenzhen, the red packets of digital currency are only used offline, while in the pilot projects in Beijing, the red packets of digital currency are only used offline, It is also limited to offline use. At present, only Suzhou's online payment scheme has made a breakthrough. In Suzhou's digital currency pilot project, Jingdong digital currency has become the first technology company to cooperate with all six major banks, and is the pilot consumer scheme of digital currency e-commerce platform

Exploring online payment scheme is also one of the directions of the next digital currency pilot project

although digital currency has been connected to various business schemes, they are all third-party schemes rather than proprietary business schemes if digital currency wants to break the third-party payment barriers and offline & lt; Code card & quot; For digital currency, acquiring new users is not the current challenge. How to retain users is a difficult problem in promotion. A Shenzhen citizen who won the red envelope of digital currency told time, After using the red envelope of digital currency for offline consumption, the related apps are unloaded, and no other available solutions have been found. Therefore, the biggest challenge faced by digital currency is how to achieve user retention and breakthrough in the environment of a few technology companies dominating the micro payment market, This is how to build a self operating ecosystem for the government and how to cultivate the use habits of market users