What are the advantages and disadvantages of using image-based CAPTCHA systems in PHP?

Issue: Image-based CAPTCHA systems are commonly used to prevent automated bots from submitting forms on websites. While they are effective in deterring bots, they can also be difficult for users to solve, especially those with visual impairments. Implementing an image-based CAPTCHA system in PHP requires generating random images, storing them securely, and validating user input. 

// Generate a random image for CAPTCHA
$randomString = md5(rand());
$image = imagecreate(200, 50);
$background = imagecolorallocate($image, 255, 255, 255);
$textColor = imagecolorallocate($image, 0, 0, 0);
imagestring($image, 5, 50, 20, $randomString, $textColor);
header('Content-type: image/png');
imagepng($image);
imagedestroy($image);

Keywords

image-based CAPTCHA advantages disadvantages PHP security

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