php crypt problem

I am trying to store passwords in an encrypted format but it does not seem to be working correcty. Here is the php code I am using.

function encryptMe($input, $salt){
    $output = crypt($input,$salt);
return $output;
}

function getSalt(){
   //set number of repititions
   $reps="5000";

   $salt = substr(str_replace('+', '.', base64_开发者_如何学Goencode(
            pack('N4', mt_rand(), mt_rand(), mt_rand(), mt_rand())
            )), 0, 16);
   $salt = "$6$"."rounds=".$reps."$".$salt;     
   return $salt;    
}

I have the following statement also in my code.

$input['password'] = $_POST['password'];
$salt = getSalt();
$input['password'] = encryptMe($input['password'],$salt);

I have ran this multiple time with different salt but the same password and keep getting the same hash. Changeing the salt does not seem to have any effect and I cant figure out what is wrong. Can someone look at this code and help me?

Also is there any way to veryify that this is using SHA512?

That is because crypt() returns only a few first characters, so the inputs, even are different, still may return the same string since only the last characters changed.

Alternative way is using hash() for SHA-256. Somebody shared you a very interesting link in your post already.

Edit

This is how vBulletin encrypts passwords. Don't know if they're still using this method.

$password_hash = md5(md5($password_text) . $user_salt);
// $user_salt is a random three character string stored 
// in the user table as 'salt'.