blue-twilight/app/Helpers/MiscHelper.php

<?php

namespace App\Helpers;

class MiscHelper
{
    public static function gravatarUrl($emailAddress, $size = 48, $default = 'identicon')
    {
        $hash = md5(strtolower(trim($emailAddress)));
        return sprintf('https://www.gravatar.com/avatar/%s?s=%d&d=%s', $hash, $size, $default);
    }

    public static function randomString($length = 10)
    {
        $seed = 'abcdefghijklmnopqrstuvwxyz01234567890';
        $string = '';

        while (strlen($string) < $length)
        {
            $string .= substr($seed, rand(0, strlen($seed) - 1), 1);
        }

        return $string;
    }
}