It looks like they are actually using keyed Skein and call it HMAC<p><a href="https:&#x2F;&#x2F;github.com&#x2F;pkcsecurity&#x2F;trabant&#x2F;blob&#x2F;master&#x2F;pkc_skein.c#L74" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;pkcsecurity&#x2F;trabant&#x2F;blob&#x2F;master&#x2F;pkc_skein...</a>