In the fields of programming and cybersecurity, CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) is a technology used to verify that the user is a human and not a machine. It is usually presented to the user in the form of an image or text and requires the user to provide the correct response to pass verification.
The purpose of CAPTCHAs is to prevent malicious attacks or abuse of the system by automated programs such as malware or bots. CAPTCHAs effectively differentiate between human users and automated programs by requiring users to perform tasks that are relatively simple but difficult for machines.
Common types of verification codes include:
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Image CAPTCHA: Image CAPTCHA requires the user to identify and select an object or feature in a specific image. For example, a user may need to select an image from a set of images that contains a specific object, such as a car, a traffic light, or an animal.
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Text CAPTCHA: Text CAPTCHA requires the user to correctly identify or enter the displayed text. This might involve identifying distorted letters, numbers or words, or solving some text-based puzzles or questions.
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Voice CAPTCHA: Voice CAPTCHA requires the user to listen and correctly identify or answer randomly generated characters or numbers played through a voice.
Here is an example of simple image captcha generation code written in Python:
from PIL import Image, ImageDraw, ImageFont
import random
# 生成随机字母