PHP random alphanumeric string generation

random_alphanumeric_string.php

<?php
class RandomStringGenerator
{
    const DEFAULT_ALPHABET = 'abcdefghijklmnopqrstuvwxyz0123456789';

    /**
     * Generates a random string of requested length and from given alphabet.
     *
     * @param int    $stringLength
     * @param string $alphabet
     *
     * @return string
     */
    public function generate(int $stringLength, string $alphabet = self::DEFAULT_ALPHABET)
    {
        $len = strlen($alphabet);

        if ($stringLength > $len) {
            $multiplier = (int)ceil($stringLength / $len);
            $alphabet   = str_repeat($alphabet, $multiplier);
        }
        return substr(str_shuffle($alphabet), 0, $len);
    }
    
    /**
     * Smaller alpabet, but more cryptographically random [a-f0-9] (hexadecimal)
     */
    function generate1($stringLength)
    {
        return mb_substr(bin2hex(random_bytes($stringLength)), 0, $stringLength);
    }
}