CAPTCHA is abbreviated as “Completely Automated Public Turing test to tell Computers and Humans Apart”. CAPTCHA is basically a program that can tell whether its user is a human or a computer. They are colorful images with distorted text at the bottom of Web registration forms in many web application development websites. CAPTCHA are used by many websites to avoid abuse from “bots,” or automated programs or Scripts generally written to generate spam. These distorted images can be read only by humans and not computer generated programs, and hence bots cannot navigate sites protected by CAPTCHA. Some kinds of bots are harmful when attacked a web site.
Security and accessibility are the two main issues that a CAPTCHA must satisfy. The former issue of security is completely satisfied by providing a great protection from bots. The latter issue is on the verge of big challenge, because CAPTCHA is based on the picture vision which could be hard to the normal users and impossible physically disabled users.
CAPTCHA fools the bots by asking questions only human can answer it. It generates an image which incorporates distorted letters and different pictures with different letters in different shapes are generated. Finally it requests the user to enter the letters shown in the picture. In which case bots cannot not recognize each letter alone. After the user submits the answer CAPTCHA authenticates the answer.
How to Create CAPTCHA
Using programming languages like PHP and ASP and through web development India, CAPTCHA can be programmed. The code should satisfy three main functions. First, the code should generate a random picture with diverse properties. Then it should validate the answer given by the user. Finally it should make these pictures secure. To make the code more reliable you can ” Rotate the text randomly, add random spaces in between characters, use a TTF fonts and change the font randomly every time, use a random text and image size every time, use more advanced text distortion and colors, move the lines randomly, store the password in a random cookie”.
Importance of CAPTCHA
1. Using CAPTCHA you can protect your website or blogs from comment spams, as bloggers receive more than 100 spam comments each day. You can seek help of web development companies to implement this.
2. It is essential that mainly free services should be protected with a CAPTCHA in order to prevent abuse by automated programs.
3. CAPTCHA also avoids dictionary attacks. These are the type of attacks under which an automatically generated scripts or computer program tries random passwords on login forms in case on unsuccessful login.
4. It helps search engines to prevent crawling the spam contents that may be harmful for keeping database safe or sensitive data of being exploited.