OWASP PureCaptcha project aims to help developers use easy-to-user independent CAPTCHAs in their project with zero hassle. Traditionally, using CAPTCHAs required making accounts in a third party provider and using rigorous APIs, or installing many libraries and then using text rendering and image modification libraries to render a CAPTCHA image.
PureCaptcha on the other hand, aims to do all of the above in one step. It includes very simple code to render a few ASCII characters into bitmap images, and code to modify, scale, rotate and distort simple bitmap images. It then outputs the CAPTCHA as a simple monochrome BMP image (which has a very small size).
It also provides example usages for CAPTCHAs. It is of utmost importance to properly use CAPTCHAs, otherwise side-channel and logical attacks would be viable on the system.
Read more about OWASP PureCaptcha at https://www.owasp.org/index.php/OWASP_PureCaptcha
##Usage##
Basic usage
Use the following script as the source of the captcha image.
require_once "purecaptcha.php";
$pureCaptcha = new PureCaptcha();
$captcha = $pureCaptcha->show();
Store $captcha in the session and compare it user input later.
Complete API
captcha : The text to be displayed in captcha length : The length of the captcha text
spacing : The spacing between two characters in the captcha
degree : The degree of rotation of captcha text in clockwise direcion
scaleX : Amount to be scaled in x direction
scaleY : Amount to be scaled in y direction
noisePercent : The noise percentage
// Getters and setters are provided for each
$pureCaptcha->setCaptcha("M2H7");
$captha = $pureCaptcha->getCaptcha();