<?php
  function rand_pass($min = 6, $max = 6)
  {
    $min = (int) $min;
    $max = (int) $max;

    $pass = sha1(rand(100, 1000) . time());
    $pass = strtolower(base64_encode($pass));
    $pass = str_replace(array('=', '+'), NULL, $pass);

    return substr($pass, 0, rand($min, $max));
  }