What are common pitfalls when using PHP to generate random images for captchas?

Common pitfalls when using PHP to generate random images for captchas include not properly seeding the random number generator, resulting in predictable or non-random images, and not properly handling image generation errors, leading to broken or missing captchas. To solve these issues, make sure to seed the random number generator with a unique value each time the captcha is generated and implement error handling to gracefully handle any issues that may arise during image generation. 

// Seed the random number generator with a unique value
mt_srand(microtime(true) * 100000 + memory_get_usage(true));

// Generate a random image for captcha
$image = imagecreatetruecolor(200, 50);

// Handle any errors that may occur during image generation
if(!$image) {
    die('Error generating captcha image');
}

// Rest of the captcha generation code goes here

Keywords

image generation captcha randomization security vulnerabilities PHP functions

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