Add hash-used element

xep-0300.xml

@@ -24,6 +24,12 @@
   &mwild;
   &ksmith;
   &tobias;
+  <revision>
+    <version>0.5.2</version>
+    <date>2017-08-21</date>
+    <initials>ps</initials>
+    <remark><p>Add hash-used element</p></remark>
+  </revision>
   <revision>
     <version>0.5.1</version>
     <date>2017-03-17</date>
@@ -93,6 +99,8 @@
   <p>An XMPP protocol can include more than one instance of the &lt;hash/&gt; element, as long as each one has a different value for the 'algo' attribute:</p>
   <code><![CDATA[<hash xmlns='urn:xmpp:hashes:2' algo='sha-1'>2AfMGH8O7UNPTvUVAM9aK13mpCY=</hash>
 <hash xmlns='urn:xmpp:hashes:2' algo='sha-256'>2XarmwTlNxDAMkvymloX3S5+VbylNrJt/l5QyPa+YoU=</hash>]]></code>
+  <p>In certain scenarios it makes sense to communicate the hash algorithm that is used prior to the calculation of the hash value.</p>
+  <code><![CDATA[<hash-used xmlns='urn:xmpp:hashes:2' algo='sha-256'/>]]></code>
   <p>The value of the 'algo' attribute MUST be one of the values from the &ianahashes; maintained by &IANA;, or one of the values
   defined in the following table.</p>
   <table caption='Additional Hash Function Textual Names'>
@@ -393,6 +401,14 @@
     </xs:complexType>
   </xs:element>
 
+  <xs:element name='hash-used'>
+    <xs:complexType>
+      <xs:extension base='empty'>
+        <xs:attribute name='algo' type='xs:NCName' use='required'/>
+      </xs:extension>
+    </xs:complexType>
+  </xs:element>
+
 </xs:schema>
 ]]></code>
 </section1>