What's the use of verification code to understand the answer?

① In the peak of online ticket purchase at the end of the year, the 12306 graphic verification code system of China Railway Customer Service Center made many ticket buyers "spit": distinguish oranges from oranges with low image quality; Some photos of squid, octopus and stars are really difficult to distinguish, which makes people ask, what is the use of such a complicated verification code system?

To answer this question, we must first understand what a verification code is.

③ The verification code is actually a Web automatic program. It has a scientific name-"automatic Turing test to distinguish between computer and human", which is a test in which the machine asks the operator questions to identify whether the operator is a human or a machine. At present, this test can be mainly divided into four categories:

4 graphic verification code: also known as mainstream verification code, it only provides static pictures at first, which is easy to be recognized by some software; Later, it became a dynamic verification code picture, and it is difficult for the recognizer to identify which layer is the real verification code picture. The anti-spam injection of this captcha can almost reach 100%, which is a very effective captcha innovation mode. At the same time, there can be hundreds of animation effects, so it can also increase the aesthetic effect of website pages. The verification code of China Railway Customer Service Center belongs to this type.

⑤ SMS verification code: Verify the authenticity of the user by sending a verification code to the mobile phone. Large websites, especially shopping websites, provide this function, which can ensure the safety of shopping more accurately and safely.

⑥ Mobile phone voice verification code: The verification code can realize automatic voice broadcast, and can also send short messages to users' mobile phones to ensure foolproof. If there is a dial-up failure, the system can automatically replay it to ensure that no one is missed, which fundamentally solves the problem that website users cannot receive the verification code.

⑦ Video verification code: It is a rookie in the verification code. This verification code composed of random numbers, letters and Chinese is dynamically embedded in MP4 and other videos, which increases the difficulty of cracking. The combination of letters and numbers, the shape and size of the font, the speed, the display effect and the dynamic changes of the trajectory in the video verification code increase the difficulty of malicious screen capture cracking, and its security is much higher than that of ordinary verification codes. Moreover, this verification code will not make users feel bored, and at the same time reduce the difficulty of user identification and make it easier for users to identify. However, at present, this verification code has not been popularized because of its high technical difficulty.

Today, everyone understands what a verification code is and the main types of verification codes. Let's introduce its functions.

Pet-name ruby verification code is mainly used to intercept unreasonable intrusion. For example, if you want to enter a page, you must pass the verification. At this time, the operator must input numbers and letters in turn, or sometimes add text images (such as 12306 graphic verification) from internet documents that cannot be recognized by the computer but can be recognized by the naked eye; Only when the operator passes the verification can the web page be opened smoothly, otherwise it will not work. Its use principle is the same in preventing malicious password cracking, forum flooding and ticket brushing.

Take 12306 verification code as an example. The greatest significance of its existence is to distinguish between people operating on the page and automation software, so as to effectively prevent scalpers from vicious hoarding of tickets. And its "evolutionary history" is actually a history of constantly "fighting wits" with scalpers and ticketing software: from simple numbers, letters, addition and subtraction at the beginning, to flashing twisted letters, twisted letters with interference lines, and then to the current graphic verification.

With the development of computer technology, the design of verification code becomes more and more complicated, and programmers and crackers are engaged in a seemingly endless "seesaw battle". But in any case, verification code is still an indispensable guarantee system for websites to fight against malicious hackers. Just like the graphic verification code of China Railway Customer Service Center 12306, it will continue to be used until it is replaced by another brand-new and better anti-hacking software.

(From Window of Knowledge No.3 20 16)

22. The purpose of this paper is to adopt this sequence. (2 points)

23. Which interpretation method is mainly used in paragraphs ④ to ⑦? What's the role? (3 points)

24. Can the word "mainstream" in paragraph (4) be replaced by "main" and why? (3 points)

Graphic verification code: also known as mainstream verification code.

25. One of the following statements is () (2 points).

A. 12306 graphic verification code is "spit out" because it can only prevent garbage injection.

B. SMS verification code can't solve the vicious scalper hoarding goods because of too few functions.

C. Video verification code has not been popularized at present, because the technical difficulty of this verification code is too great.

D. the verification code will become more and more complicated.

26. In the information age, it is believed that there will be more advanced verification codes in the future, but at the same time, hackers and malicious crackers will try their best to crack them. How to treat this phenomenon? (3 points)

Reference answer:

22. verification code; Logic. (2 points)

23. Classification (1 min); The types and characteristics of verification codes are clearly explained, which makes the article clearer and more convincing. (2 points) (**3 points)

24. "Mainstream" can't be replaced by "main" (1), because "mainstream" refers to the commonly used graphic verification code at present, while "main" means the most important, which is inconsistent with the facts. (2 points) (**3 points)

25.C (2 points)

26. Verification code is still an indispensable safeguard system for websites to resist malicious operations by hackers. The behavior of hackers and malicious crackers will only promote the improvement of captcha technology and accelerate the research of captcha. (If meaningful, 3 points)