t the hash can only be
    recalculated knowing the key.  This prevents the scenario of someone
    altering data and also changing the hash to match.
   </p><p>
    If the key is larger than the hash block size it will first be hashed and
    the result will be used as key.
   </p></div></div><div class="sect2" id="PGCRYPTO-PASSWORD-HASHING-FUNCS"><div class="titlepage"><div><div><h3 class="title">F.28.2. Password Hashing Functions <a href="#PGCRYPTO-PASSWORD-HASHING-FUNCS" class="id_link">#</a></h3></div