Unique key generation

strtolower(substr(crypt(time()), 0, 7));

strtolower(substr(crypt(uniqid(rand(), true)), 0, 7));

$this->password = '';

for($i=0; $i<10; $i++)
{
    if($i%2 == 0)
        $this->password .= chr(rand(65,90));
    if($i%3 == 0)
        $this->password .= chr(rand(97,122));
    if($i%4 == 0)
        $this->password .= chr(rand(48,57));
}

$ukey = dechex(time()) . crypt( time() . md5(microtime() + mt_rand(0, 100000)) );

function GetUniqueValue()
{
   static $counter = 0; //initalized only 1st time function is called
   return strtr(microtime(), array('.' => '', ' ' => '')) . $counter++;
}