README

A simple, customizable, and modern CAPTCHA generation library for PHP 8.2+. Generate text-based or mathematics-based CAPTCHAs with full control over appearance, fonts, colors, and distortion.

Ank (अंक) means "Number" in Hindi

Features

• 🎨 Two CAPTCHA Types: Text-based alphanumeric codes or simple math problems
• 🎭 Highly Customizable: Colors, fonts, size, quality, and text distortion
• 🔒 Secure: Uses cryptographically secure random number generation
• 🎯 One-Time Validation: CAPTCHA answers are automatically removed after validation
• 🖼️ 12 Beautiful Fonts: Hand-picked Google Fonts included
• 🚀 Modern PHP: Built with PHP 8.2+ features (enums, match expressions, strict types)
• 📦 Zero Dependencies: Only requires PHP with GD extension
• ✅ Well Tested: Comprehensive test suite with high code coverage

Installation

Install via Composer:

composer require vaibhavpandeyvpz/ank

Requirements

• PHP >= 8.2
• GD extension with FreeType support (for font rendering)

Quick Start

Basic Usage

<?php

use Ank\CaptchaGenerator;
use Ank\MathCaptchaGenerator;

// Create a text-based CAPTCHA generator
$captcha = new CaptchaGenerator();

// Generate and display the CAPTCHA image
header('Content-Type: image/jpeg');
echo $captcha->getCaptcha();

// Later, validate user input
if ($captcha->isValid($_POST['captcha_code'])) {
    // CAPTCHA is valid
    echo "Verification successful!";
} else {
    // CAPTCHA is invalid
    echo "Invalid CAPTCHA code.";
}

Mathematics CAPTCHA

<?php

use Ank\MathCaptchaGenerator;

// Create a math-based CAPTCHA generator
$captcha = new MathCaptchaGenerator();

// Generate and display the math problem
header('Content-Type: image/jpeg');
echo $captcha->getCaptcha();

// Validate the answer (user provides numeric answer)
if ($captcha->isValid($_POST['answer'])) {
    echo "Correct answer!";
}

Advanced Usage

Customizing Appearance

The CAPTCHA image can be fully customized using a fluent interface:

<?php

use Ank\CaptchaGenerator;
use Ank\Font;

$captcha = new CaptchaGenerator();

$image = $captcha->getCaptcha()
    ->setBackgroundColor('#000000')      // Black background
    ->setForegroundColor('#FFFFFF')      // White text
    ->setFont(Font::BANGERS)             // Use Bangers font
    ->setSize(300, 100)                  // 300x100 pixels
    ->setQuality(100)                     // Maximum JPEG quality
    ->setDistortion(15, 8);              // More distortion (angle, offset)

header('Content-Type: image/jpeg');
echo $image;

Configuring Text CAPTCHA Length

<?php

use Ank\CaptchaGenerator;

$captcha = new CaptchaGenerator();
$captcha->setLength(8);  // Generate 8-character codes

$image = $captcha->getCaptcha();

Using Custom Storage

By default, CAPTCHA answers are stored in $_SESSION. You can provide a custom storage array:

<?php

use Ank\CaptchaGenerator;

$customStorage = [];
$captcha = new CaptchaGenerator($customStorage);

// The CAPTCHA answer will be stored in $customStorage
$captcha->getCaptcha('my_captcha_id');

Multiple CAPTCHAs

You can generate multiple CAPTCHAs with different IDs:

<?php

use Ank\CaptchaGenerator;

$captcha = new CaptchaGenerator();

// Generate multiple CAPTCHAs
$image1 = $captcha->getCaptcha('login_form');
$image2 = $captcha->getCaptcha('registration_form');
$image3 = $captcha->getCaptcha('contact_form');

// Validate each independently
if ($captcha->isValid($_POST['login_captcha'], 'login_form')) {
    // Login form CAPTCHA is valid
}

Available Fonts

The library includes 12 fonts from Google Fonts:

use Ank\Font;

// All available fonts
Font::ACME
Font::BANGERS
Font::BARRIO
Font::BREE_SERIF
Font::FRECKLE_FACE
Font::GOCHI_HAND
Font::LUCKIEST_GUY
Font::PANGOLIN
Font::RALEWAY
Font::RIGHTEOUS
Font::ROBOTO_SLAB
Font::SANSITA

// Get a random font
$randomFont = Font::random();

// Get all fonts
$allFonts = Font::all();

Color Formats

Colors can be specified in multiple formats:

$image->setBackgroundColor('#FFFFFF');  // 6-digit hex with #
$image->setBackgroundColor('FFFFFF');   // 6-digit hex without #
$image->setBackgroundColor('#FFF');     // 3-digit hex with #
$image->setBackgroundColor('FFF');        // 3-digit hex without #

API Reference

CaptchaGenerator

Text-based CAPTCHA generator.

Methods:

• getCaptcha(string $id = 'default'): CaptchaImageInterface - Generate a new CAPTCHA
• isValid(string $input, string $id = 'default'): bool - Validate user input
• setLength(int $length): static - Set the length of generated codes

MathCaptchaGenerator

Mathematics-based CAPTCHA generator.

Methods:

• getCaptcha(string $id = 'default'): CaptchaImageInterface - Generate a new math problem
• isValid(string $input, string $id = 'default'): bool - Validate the answer

CaptchaImage

CAPTCHA image object with customization methods.

Methods:

• getImage(): string - Generate and return JPEG image data
• setBackgroundColor(string $hex): static - Set background color
• setForegroundColor(string $hex): static - Set text color
• setFont(Font $font): static - Set font
• setSize(int $width, int $height): static - Set image dimensions
• setQuality(int $quality): static - Set JPEG quality (0-100)
• setDistortion(int $angle, int $offset): static - Set text distortion
• setText(string $text): static - Set the text to display

Error Handling

The library throws Ank\Exception\ImageGenerationException if image generation fails:

<?php

use Ank\CaptchaGenerator;
use Ank\Exception\ImageGenerationException;

try {
    $captcha = new CaptchaGenerator();
    $image = $captcha->getCaptcha();
    echo $image->getImage();
} catch (ImageGenerationException $e) {
    // Handle image generation failure
    error_log('CAPTCHA generation failed: ' . $e->getMessage());
    // Fallback or error page
}

Security Considerations

1. One-Time Use: CAPTCHA answers are automatically removed after validation to prevent replay attacks
2. Secure Random: Uses random_int() for cryptographically secure random number generation
3. Session Storage: By default uses PHP sessions, but you can provide custom storage
4. Case Sensitive: Text CAPTCHAs are case-sensitive by design

Examples

Complete Form Example

<?php
// captcha.php - Generate CAPTCHA image
session_start();

use Ank\CaptchaGenerator;

$captcha = new CaptchaGenerator();
header('Content-Type: image/jpeg');
echo $captcha->getCaptcha('form_captcha');

<?php
// form-handler.php - Validate form submission
session_start();

use Ank\CaptchaGenerator;

$captcha = new CaptchaGenerator();

if ($captcha->isValid($_POST['captcha'], 'form_captcha')) {
    // Process form
    echo "Form submitted successfully!";
} else {
    echo "Invalid CAPTCHA. Please try again.";
}

AJAX Example

<?php
// api/captcha.php
session_start();

use Ank\CaptchaGenerator;

$captcha = new CaptchaGenerator();
$image = $captcha->getCaptcha('ajax_captcha');

header('Content-Type: image/jpeg');
echo $image;

// client-side
fetch("/api/captcha.php")
    .then((response) => response.blob())
    .then((blob) => {
        const img = document.getElementById("captcha-image");
        img.src = URL.createObjectURL(blob);
    });

Testing

Run the test suite:

composer test

Or with PHPUnit directly:

vendor/bin/phpunit

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Fonts are hand-picked from Google Fonts and are used in accordance with their licenses.

Author

Vaibhav Pandey

• GitHub: @vaibhavpandeyvpz
• Email: contact@vaibhavpandey.com

Changelog

See GitHub Releases for the changelog.