0.26

git-svn-id: file:///home/ksmith/gitmigration/svn/xmpp/trunk@2737 4b5297f7-1745-476d-ba37-a9c6900126ab

xep-0167.xml

@@ -28,6 +28,12 @@
   &seanegan;
   &robmcqueen;
   &diana;
+  <revision>
+    <version>0.26</version>
+    <date>2009-02-16</date>
+    <initials>psa</initials>
+    <remark><p>Clarified service discovery features; added support for zrtp-hash in the signalling channel.</p></remark>
+  </revision>
   <revision>
     <version>0.25</version>
     <date>2008-12-19</date>
@@ -504,7 +510,7 @@ delivery-method=inline; configuration=somebase16string;
 
 <section1 topic='Negotiation of SRTP' anchor='srtp'>
   <p>&rfc3711; defines the Secure Real-time Transport Protocol, and &rfc4568; defines the SDP "crypto" attribute for signalling and negotiating the use of SRTP in the context of offer-answer protocols such as SIP. To enable the use of SRTP and gatewaying to non-XMPP technologies that make use of the "crypto" SDP attribute, we define a corresponding &lt;crypto/&gt; element qualified by the 'urn:xmpp:jingle:apps:rtp:1' namespace.</p>
-  <p>If the initiator wishes to use SRTP, the session-initiate stanza MUST include an &lt;encryption/&gt; element, which MUST contain at least one &lt;crypto/&gt; element and MAY include multiple instances of the &lt;crypto/&gt; element. The &lt;encryption/&gt; element MUST be a child of the &lt;description/&gt; element. If the initiator requires the session to be encrypted, the &lt;encryption/&gt; element MUST include a 'required' attribute whose logical value is TRUE and whose lexical value is "true" or "1" &BOOLEANNOTE;, where this attribute defaults to a logical value of FALSE (i.e., a lexical value of "false" or "0").</p>
+  <p>If the initiator wishes to use SRTP, the session-initiate stanza shall include an &lt;encryption/&gt; element, which MUST contain at least one &lt;crypto/&gt; element and MAY include multiple instances of the &lt;crypto/&gt; element. The &lt;encryption/&gt; element MUST be a child of the &lt;description/&gt; element. If the initiator requires the session to be encrypted, the &lt;encryption/&gt; element MUST include a 'required' attribute whose logical value is TRUE and whose lexical value is "true" or "1" &BOOLEANNOTE;, where this attribute defaults to a logical value of FALSE (i.e., a lexical value of "false" or "0").</p>
   <p>The &lt;crypto/&gt; element is defined as empty (i.e., not containing any child elements); the XML attributes of the &lt;crypto/&gt; element are as follows:</p>
   <ul>
     <li>crypto-suite -- this maps to the SDP "crypto-suite" parameter and has the same semantics (i.e., it is an identifier that describes the encryption and authentication algorithms).</li>
@@ -581,6 +587,27 @@ delivery-method=inline; configuration=somebase16string;
   ]]></example>
 </section1>
 
+<section1 topic='Negotiation of ZRTP' anchor='zrtp'>
+  <p>An alternative approach to end-to-end encryption of RTP traffic is provided by &zrtp;. Although negotiation of ZRTP mainly occurs in the media channel rather than the signalling channel, the ZRTP specification defines one SDP attribute called "zrtp-hash" (this communicates the ZRTP version supported as well as a hash of the Hello message).</p>
+  <p>The SDP format is shown below.</p>
+  <code>
+a=zrtp-hash:zrtp-version zrtp-hash-value
+  </code>
+  <p>An example follows.</p>
+  <code>
+a=zrtp-hash:1.10 fe30efd02423cb054e50efd0248742ac7a52c8f91bc2df881ae642c371ba46df
+  </code>
+  <p>This SDP attribute has been translated into Jingle as a &lt;zrtp-hash/&gt; element, as shown below.</p>
+  <code><![CDATA[
+<zrtp-hash version='zrtp-version'>zrtp-hash-value</zrtp-hash>
+  ]]></code>
+  <p>An example follows.</p>
+  <code><![CDATA[
+<zrtp-hash version='1.10'>fe30efd02423cb054e50efd0248742ac7a52c8f91bc2df881ae642c371ba46df</zrtp-hash>
+  ]]></code>
+  <p>Therefore, if the initiator wishes to use ZRTP, the session-initiate stanza shall include an &lt;encryption/&gt; element, which MUST contain one and only one &lt;zrtp-hash/&gt; element. Note: The &lt;encryption/&gt; element MUST include only 1+ &lt;crypto/&gt; elements (for SRTP) or 1 &lt;zrtp-hash/&gt; element (for ZRTP), but not both.</p>
+</section1>
+
 <section1 topic='Informational Messages' anchor='info'>
   <section2 topic='Format' anchor='info-format'>
     <p>Informational messages can be sent by either party within the context of Jingle to communicate the status of a Jingle RTP session, device, or principal. The informational message MUST be an IQ-set containing a &JINGLE; element of type "session-info", where the informational message is a payload  element qualified by the 'urn:xmpp:jingle:apps:rtp:info:1' namespace; the following payload elements are defined: <note>A &lt;trying/&gt; element (equivalent to the SIP 100 Trying response code) is not necessary, since each session-level action is acknowledged via XMPP IQ semantics.</note></p>
@@ -692,7 +719,12 @@ delivery-method=inline; configuration=somebase16string;
 </section1>
 
 <section1 topic='Determining Support' anchor='support'>
-  <p>If an entity supports Jingle RTP session, it MUST advertise that fact by returning a feature of "urn:xmpp:jingle:apps:rtp:1" &VNOTE; in response to &xep0030; information requests.</p>
+  <p>To advertise its support for Jingle RTP Sessions and specific media types for RTP, when replying to &xep0030; information requests an entity MUST return the following features:</p>
+  <ul>
+    <li>URNs for any version of this protocol that the entity supports -- e.g., "urn:xmpp:jingle:apps:rtp:1" for this version and "urn:xmpp:jingle:apps:rtp:0" for the previous version &VNOTE;</li>
+    <li>URNs for all of the media types that the entity supports -- e.g., "urn:xmpp:jingle:apps:rtp:audio" for RTP audio and "urn:xmpp:jingle:apps:rtp:video" for RTP video</li>
+  </ul>
+  <p>An example follows.</p>
   <example caption="Service discovery information request"><![CDATA[
 <iq from='romeo@montague.lit/orchard'
     id='disco1'
@@ -708,7 +740,10 @@ delivery-method=inline; configuration=somebase16string;
     type='result'>
   <query xmlns='http://jabber.org/protocol/disco#info'>
     <feature var='urn:xmpp:jingle:0'/>
+    <feature var='urn:xmpp:jingle:apps:rtp:0'/>
     <feature var='urn:xmpp:jingle:apps:rtp:1'/>
+    <feature var='urn:xmpp:jingle:apps:rtp:audio'/>
+    <feature var='urn:xmpp:jingle:apps:rtp:video'/>
   </query>
 </iq>
   ]]></example>
@@ -1827,12 +1862,16 @@ Romeo                         Juliet
   </xs:complexType>
 
   <xs:complexType name='encryptionElementType'>
-    <xs:sequence>
+    <xs:choice>
       <xs:element name='crypto' 
                   type='cryptoElementType'
                   minOccurs='0' 
                   maxOccurs='unbounded'/>
-    </xs:sequence>
+      <xs:element name='zrtp-hash' 
+                  type='zrtpElementType'
+                  minOccurs='0' 
+                  maxOccurs='1'/>
+    </xs:choice>
   </xs:complexType>
 
   <xs:complexType name='payloadElementType'>
@@ -1859,6 +1898,14 @@ Romeo                         Juliet
     </xs:simpleContent>
   </xs:complexType>
 
+  <xs:complexType name='zrtpElementType'>
+    <xs:simpleContent>
+      <xs:extension base='xs:string'>
+        <xs:attribute name='version' type='xs:string' use='required'/>
+      </xs:extension>
+    </xs:simpleContent>
+  </xs:complexType>
+
   <xs:simpleType name='empty'>
     <xs:restriction base='xs:string'>
       <xs:enumeration value=''/>
@@ -1936,6 +1983,6 @@ Romeo                         Juliet
   </section2>
 </section1>
 <section1 topic='Acknowledgements' anchor='ack'>
-  <p>Thanks to Milton Chen, Paul Chitescu, Olivier Cr&#234;te, Tim Julien, Steffen Larsen, Jeff Muller, Mike Ruprecht, Justin Uberti, and Paul Witty for their feedback.</p>
+  <p>Thanks to Milton Chen, Paul Chitescu, Olivier Cr&#234;te, Tim Julien, Steffen Larsen, Jeff Muller, Mike Ruprecht, Sjoerd Simons, Justin Uberti, and Paul Witty for their feedback.</p>
 </section1>
 </xep>