Random Confirm Code Generator

confirm_code.php

<?
 
class confirm_code
{
    protected static function generate_random_bytes($length=16){
        if(function_exists('openssl_random_pseudo_bytes')) {
            $rnd = openssl_random_pseudo_bytes($length, $strong);
            if ($strong === TRUE)
                return $rnd;
        }
        $rand = '';
        // Unix/Linux platform?
        $fp = @fopen('/dev/urandom','rb');
        if ($fp === FALSE)
          throw new Exception("No method for generating random bytes");
        $rand .= @fread($fp,$length);
        @fclose($fp);
        return $rand;
    }
 
    
    public static function create($length=6)
    {
        $keyspace = '0123456789';
        $entropy  = self::generate_random_bytes($length);
        $entropy   = str_split($entropy);
        $callback = function($str) {
                return ord($str);
            };
        $entropy_list = array_map($callback, $entropy);
        $confirm_code = "";
        foreach ($entropy_list as $value)
            $confirm_code .= $keyspace[($value % 10)];
        return $confirm_code;
    }
}

// test
/*
for ($i=0; $i < 10; $i++)
{
    printf("\n%s", confirm_code::create());
}
*/