s="p">(</span>
        <span class="nv">$key</span><span class="p">,</span>
        <span class="s1">&#39;sha512&#39;</span><span class="p">,</span>
        <span class="k">NULL</span><span class="p">,</span>
        <span class="k">NULL</span><span class="p">,</span>
        <span class="s1">&#39;authentication&#39;</span>
<span class="p">);</span>

<span class="c1">// $hmac_key is a pseudo-random key with a length of 64 bytes</span>
</pre></div>
</div>
</dd></dl>

</dd></dl>

</div>
</div>


          </d