PHP salter

_salt()

function _salt($string, $len=null)
{
 return (!empty($len)) ?
         hash('sha512', str_pad($string, (strlen($string) + $len),
                             substr(hash('sha512', $string),
                                    round((float)strlen($string)/3, 0,
                                          PHP_ROUND_HALF_UP),
                                          ($len - strlen($string))),
                             STR_PAD_BOTH)) :
         hash('sha512', substr($string,
                               round((float)strlen($string)/3, 0,
                                     PHP_ROUND_HALF_UP), 16));
}

Uses unique string and length of desired output as arguments.

If string argument is lower then desired output length, the string gets hashed, padded with a divisible return of another hash of the string argument or it will return the hashed portion of the original string argument as a 16 character salt.