Start updating and improving reclaimID protocol.HEADmaster

1 files changed, 78 insertions, 52 deletions

diff --git a/draft-schanzen-reclaimid.xml b/draft-schanzen-reclaimid.xml
index 4776d46..3698e5b 100644
--- a/draft-schanzen-reclaimid.xml
+++ b/draft-schanzen-reclaimid.xml
@@ -247,67 +247,59 @@
         issued by a user for an identity to a relying party.
         The Ticket may then be used by the relying party to retrieve the
         shared attributes from the name system.
-        The record wire format of a Ticket is as follows:
       </t>
-       <figure anchor="figure_ticket">
-         <artwork name="" type="" align="left" alt=""><![CDATA[
+      <t>
+        A ticket is a GNS name that points to information pertaining to
+        the authorization given to the relying party.
+        The ticket has the format:
+      </t>
+      <figure>
+        <artwork type="abnf"><![CDATA[
+ticket = "TID.IDENTITY.zkey"
+TID = *gnslabel
+IDENTITY = *gnslabel
+]]>
+        </artwork>
+      </figure>
+       <t>
+         The TID essentially serves as a shared secret between user and
+         relying party. knowledge of the IDENTITY key and the TID allows
+         the relying party to iteratively query attribute data in GNS.
+         The record set under the TID label contains references to the shared attributes as
+         well as any credential presentations which attest attribute values.
+         The record set also includes the AUDIENCE key.
+       </t>
+       <section anchor="rp_rr" numbered="true" toc="default">
+        <name>Relying party reference</name>
+       <t>
+         A RP resource record is stored in GNS under records
+         of type "RECLAIM_RP". An RP reference
+         is stored in GNS under the TID.
+         The record format of a RECLAIM_RP is as follows:
+       </t>
+         <figure anchor="figure_gnsrp">
+           <artwork name="" type="" align="left" alt=""><![CDATA[
 0     8     16    24    32    40    48    56
 +-----+-----+-----+-----+-----+-----+-----+-----+
-|      IDENTITY TYPE    |       IDENTITY        |
-+-----------------------+                       |
-|                       +-----------------------|
-|                       |    AUDIENCE TYPE      |
-+-----+-----+-----+-----+-----+-----+-----+-----+
-|                    AUDIENCE                   |
-|                                               |
-|                                               |
-|                                               |
-+-----+-----+-----+-----+-----+-----+-----+-----+
-|                      TID                      |
+|                 AUDIENCE KEY                  |
 |                                               |
 |                                               |
 |                                               |
 +-----+-----+-----+-----+-----+-----+-----+-----+
              ]]></artwork>
            <!--        <postamble>which is a very simple example.</postamble>-->
-       </figure>
-       <t>
-         where:
-       </t>
-       <dl>
-         <dt>IDENTITY TYPE</dt>
-         <dd>
-           Is the 32 bit identity type as defined in GANA for GNS
-           identity zone types (e.g. PKEY).
-         </dd>
-         <dt>IDENTITY</dt>
-         <dd>
-           Is the 256 bit identity public zone key of the user.
-         </dd>
-         <dt>AUDIENCE TYPE</dt>
-         <dd>
-           Is the 32 bit audience type as defined in GANA for GNS
-           identity zone types (e.g. PKEY).
-         </dd>
-         <dt>AUDIENCE</dt>
-         <dd>
-           Is the 256 bit audience public zone key of the relying party.
-         </dd>
-         <dt>TID</dt>
-         <dd>
-           Is a 256 bit ticket identifier.
-         </dd>
-       </dl>
-       <t>
-         The TID essentially serves as a shared secret between user and
-         relying party. knowledge of the IDENTITY key and the TID allows
-         the relying party to iteratively query attribute data in GNS.
-         Tickets are stored as RECLAIM_TICKET records under a label derived
-         from the TID by applying a Base64-encoding. In addition to the ticket,
-         the record set also contains references to the shared attributes as
-         well as any credential presentations which attest attribute values.
-      </t>
-      <section anchor="attrrefs" numbered="true" toc="default">
+         </figure>
+         <t>
+           where:
+         </t>
+         <dl>
+           <dt>AUDIENCE KEY</dt>
+           <dd>
+             Is the audience zone key.
+           </dd>
+         </dl>
+      </section>
+       <section anchor="attrrefs" numbered="true" toc="default">
         <name>Attribute References</name>
        <t>
          An attribute reference is stored in GNS under records
@@ -440,6 +432,40 @@
 
    <section anchor="security" numbered="true" toc="default">
      <name>Security Considerations</name>
+    <section anchor="tickets_generation" numbered="true" toc="default">
+      <name>Ticket generation</name>
+      <t>
+        The TID in a Ticket <bcp14>SHOULD</bcp14> have at least 256 bits of entropy.
+        The TID could be generated by simply sampling 32 bytes of random data and
+        encoding it using a suitable text encoding compatible with GNS labels such as
+        Base64.
+      </t>
+      <t>
+        The TID <bcp14>MAY</bcp14> be derived using more sophisticated means in order to
+        be able to relax security requirements on the exchange or storage of authorization metadata.
+        One option is to derive the TID using ephemeral Diffie-Hellman.
+        The user would first create an ephemeral key pair and calculate the TID in order to
+        populate the GNS resource records:
+      </t>
+      <artwork name="" type="" align="left" alt=""><![CDATA[
+CreateTid(AUDIENCE_PK):
+  x := rand() 
+  ETK := X25519 (x, AUDIENCE_PK)
+  dhs := X25519 (x, G)
+  TID := Base64 (SHA-512 (dhs))
+  return (TID,ETK)
+  ]]></artwork>
+      <t> 
+        This allows to the user to only transfer the ETK which can in turn be
+        used by the relying party to calculate the ticket identifier (TID)
+        using its private key:
+      </t>
+       <artwork name="" type="" align="left" alt=""><![CDATA[
+CalculateTid(AUDIENCE_SK,ETK):
+  dhs := X25519 (AUDIENCE_SK, G)
+  return TID := Base64 (SHA-512 (dhs))
+  ]]></artwork>
+   </section>
    </section>
    <section anchor="gana" numbered="true" toc="default">
        <name>GANA Considerations</name>