mebjas / purecaptcha

OWASp PureCaptcha project

PureCaptcha

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();