A PHP library for generating Captcha challenges using libgd.
- Easy expression captcha:
- Hard expression captcha:
- Easy string captcha:
- Hard string captcha (colored):
- GitHub: https://github.com/dangkyokhoang/PHP-Captcha-Generator.
- Packagist: https://packagist.org/packages/dkh/captcha-generator.
- GD Graphics Library (ext-gd).
You can easily get the library installed on your project by running this command.
composer require dkh/captcha-generator
ExpressionCaptchaexpression captcha requires users to do basic arithmetic operations (addition, subtraction, multiplication and division) to solve.StringCaptchastring captcha only requires users to recognize the characters in the string.
To create a captcha, use new *Captcha($size?, $level?).
// Default size: 3 and default difficulty level: 1
$expression_captcha = new ExpressionCaptcha();
$string_captcha = new StringCaptcha();
// Specific size and difficulty level
$size = 10;
$level = 2;
$another_expression_captcha = new ExpressionCaptcha($size, $level);To get captcha's solved value, call $captcha->solve() or *Captcha::solveString($string).
Store the solved value somewhere, e.g in a session variable, to later verify user's captcha input.
$_SESSION['captcha'] = $captcha->solve();
// Or in a way that is infrequent,
// use static method *Captcha::solveString()
$my_expression = '1+6:3-2*4';
$_SESSION['my_captcha'] = ExpressionCaptcha::solveString($my_expression);To verify user's captcha input, compare it with the captcha's previously solved value stored somewhere.
$user_captcha_input = $_POST['captcha'] ?? '';
$is_matched = $_SESSION['captcha'] === $user_captcha_input;To render captcha into image, call $captcha->render($options?), Captcha::renderString($string, $options?). Return value is a PNG image data string encoded with base64.
To dislay the captcha image, use data URL data:image/png;base64, or save the rendered image somewhere and return the image's path.
$base64_image = $captcha->render();
echo sprintf('<img src="data:image/png;base64,%s">', $base64_image);
// Or in a way like this:
$my_string = 'any will do?';
$image_path = 'captcha.png';
$base64_image_to_be_saved = Captcha::renderString($my_string);
file_put_contents(
$image_path,
base64_decode($base64_image_to_be_saved)
);
echo sprintf('<img src="/%s">', $image_path);
// Image rendered with some options
$another_base64_image = $captcha->render([
'height' => 50,
'fill' => [0, 0, 0, 30],
// The alpha channel is optional
'color' => [255, 255, 255]
]);
echo sprintf(
'<img src="data:image/png;base64,%s">',
$another_base64_image
);<?php
require_once 'vendor/autoload.php';
use Dkh\ExpressionCaptcha;
session_start();
// Verify user's captcha input
if (isset($_POST['captcha']) && isset($_SESSION['captcha'])) {
$is_matched = $_POST['captcha'] === $_SESSION['captcha'];
} else {
$is_matched = null;
}
$message = $is_matched !== null ?
($is_matched ? 'Captcha matched' : 'Captcha not matched') :
'Try solving the captcha';
// Create a captcha
$captcha = new ExpressionCaptcha();
// Store captcha's solved value
$_SESSION['captcha'] = $captcha->solve();
// Render the captcha into image
// The return value is a PNG image string encoded with base64
$base64_image = $captcha->render();
echo sprintf(
'<!DOCTYPE html>' .
'<html>' .
'<body>' .
'<form method="POST">' .
'<img src="data:image/png;base64,%s"><br>' .
'<input name="captcha" placeholder="Input captcha">' .
'<input type="submit" value="Submit"><br>' .
'</form>' .
'<div>Message: %s</div>' .
'</body>' .
'</html>',
$base64_image,
$message
);