Problem comparing hex values

[molive]

I've only recently started working with PHP, but I've been stuck on this problem for hours now and searched everywhere for a solution with no success. Hopefully, someone here can help.

I'm writing a password verification function to verify the user's password with a SSHA hash from a database. Most of this code is taken from php.net

function asc2hex($temp) { 
   $len = strlen($temp);
   $data = '';
   for ($i=0; $i<$len; $i++) $data.=sprintf("%02x",ord(substr($temp,$i,1)));
   return $data;
}

function validatePassword($password, $hash) {
  if ((!isset($password)) || (!isset($hash)) || ($password=="") || ($hash=="")) {
    return false;
  }
  // Verify SSHA hash
  $ohash = base64_decode(substr($hash, 6));
  $osalt = substr($ohash, 20);
  $o_hex = asc2hex(substr($ohash, 0, 20));
  $n_hex = sha1($password . $osalt);

echo 'o_hex (HEX) - "'.$o_hex.'"<br />';
echo 'n_hex (HEX) - "'.$n_hex.'"<br />';
echo '<br />';

  if ($o_hex === $n_hex) {
    return "true";
  }
  else {
    return "false";
  }
}

The problem is, validatePassword always returns true!

For example:

$userpass = "qbrtxpse";

if (validatePassword($userpass,"{SSHA}xXhNJfxymPwDTydUApoFBHuiQ7VqcFFL")) {
  echo 'User authorized<br />';
}
else {
  echo 'No user with those credentials found<br />';
}

This always results in 'User authorized', even though the echo's inside validatePassword show that $o_hex and $n_hex aren't the same.

I've tried converting $n_hex to ascii and comparing them that way, and I've tried strcmp($o_hex, $n_hex), but the result is always true!

Please help! What am I doing wrong?