Create Captcha Using PHP



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Many of the students from technical background, especially, of Computer science & Engineering, deal with numerous projects, considering their importance while job hunting and to enhance one's skills. Some of them may enjoy with their own projects while some feel them as hectic. But whatever, if we have proper knowledge, then nothing can stop us!
Hey, don't take it the easy way. Just because the source code is in your hands. The code is to be correctly connected to the database and implanted into the IDEs.

Here are a few details of the project CREATING CAPTCHA. This is to guide you how to initiate, design and run along with this project. All the best..



Abstract

CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) image is a way to prevent from bot attacks to our website's forms. BOT attacks are performed by computer programs themselves to communicate with other targeted programs. Other than common sense, a "human" sense is required to differentiate between a human and a bot.



Project details


A good way to avoid automatic form submissions when creating a web form is to add some kind of verification. One of the best ways is to use an image verification, called also captcha. CAPTCHA dynamically creates an image with a random string displayed on it, mostly unclear. Then visitor is asked to type that string in a text field and once the form is submitted it checks if the string on the image matches the one inputted by the user. Because there is no easy way to read a text from an image (image recognition), CAPTCHA helps us to know whether the form is from a human or a BOT.
So, this is one of the good ways to protect your web forms from spammers. CAPTCHAs can prevent bot-generated spam by requiring that the (unrecognized) sender pass a CAPTCHA test before the email message is delivered.
For automatically generating the CAPTCHA, we would suggest using a session variable where you store the string generated and displayed on the dynamically generated image.
Segmentation, or the ability to separate one letter from another is also made difficult in CAPTCHAs, as characters are crowded together with no white space in between. While used mostly for security reasons, CAPTCHAs also serve as a benchmark task for artificial intelligence technologies. "Any program that passes the tests generated by a CAPTCHA can be used to solve a hard unsolved AI problem"

Basic requirements:

Hardware Requirements:
 1. PC with Pentium IV processor.
 2. 512 MB RAM or above.
 3. 40 GB Hard Disk or above.

Software Requirements:
 1. Operating system : Windows XP (or latest).
 2. Front end : php, html
 3. Platform : php html
 4. Integrated development environment(IDE): Dream weaver or any text editors
 5. Back end : MY SQL SERVER