more crypto

1 files changed, 34 insertions, 10 deletions

diff --git a/draft-schanzen-gns.xml b/draft-schanzen-gns.xml
index 0f7edb7..07ed475 100644
--- a/draft-schanzen-gns.xml
+++ b/draft-schanzen-gns.xml
@@ -108,30 +108,35 @@
           <t>
             Given a GNS record block a symmetric encryption scheme is used to
             en-/decrypt "BDATA". The keys are derived from the record label "l"
-            and the public key "P". Both "l" and "P" are implicity known by the
-            GNS resolver. The key material "K" is derived as follows:
+            and a public key "dG", where "d" is an ECDSA private key and "G"
+            is a EC generator. "d" and "dG" are derived from the public/private
+            key pair "x,P" of a GNS zone.
+            Both "l" and "P" are implicity known by the GNS resolver.
+            The key material "K" and initialization vector "IV"
+            are derived as follows:
           </t>
           <artwork name="" type="" align="left" alt=""><![CDATA[
             h := SHA512 (l,P)
             d := h*x mod n
-            K := HKDF (P,l)
+            K := HKDF (dG,l,"gns-aes-ctx-key")
+            IV := HKDF (dG,l,"gns-aes-ctx-iv")
             ]]></artwork>
           <t>
             "HKDF" is a hash-based key derivation function as defined in
             <xref target="RFC5869" />. For the XTR, we use HMAC-SHA512 and
-            HMAC-SHA256 in PRF as proposed in (paper). Using this HKDF, we
-            derive two symmetric 256-bit keys "Ka,Kt" from "K":
+            HMAC-SHA256 in PRF as proposed in (paper). We divide "K" into a
+            256-bit AES key "Kaes" and a 256-bit TWOFISH key "Ktwo".
           </t>
         <figure anchor="figure_hddf_keys">
           <artwork name="" type="" align="left" alt=""><![CDATA[
             0     8     16    24    32    40    48    56
             +-----+-----+-----+-----+-----+-----+-----+-----+
-            |                    AES KEY                    |
+            |                    AES KEY (Kaes)             |
             |                                               |
             |                                               |
             |                                               |
             +-----+-----+-----+-----+-----+-----+-----+-----+
-            |                  TWOFISH KEY                  |
+            |                  TWOFISH KEY (Ktwo)           |
             |                                               |
             |                                               |
             |                                               |
@@ -139,12 +144,31 @@
           ]]></artwork>
           <!--        <postamble>which is a very simple example.</postamble>-->
         </figure>
+        <t>
+          Similarly, we divide "IV" into a 128-bit initialization vector IVaes
+          and a 128-bit initialization vector IVtwo:
+        </t>
+        <figure anchor="figure_hddf_keys">
+          <artwork name="" type="" align="left" alt=""><![CDATA[
+            0     8     16    24    32    40    48    56
+            +-----+-----+-----+-----+-----+-----+-----+-----+
+            |                    AES IV (IVaes)             |
+            |                                               |
+            +-----+-----+-----+-----+-----+-----+-----+-----+
+            |                  TWOFISH IV (IVtwo)           |
+            |                                               |
+            +-----+-----+-----+-----+-----+-----+-----+-----+
+          ]]></artwork>
+          <!--        <postamble>which is a very simple example.</postamble>-->
+        </figure>
 
           <t>
-            The two symmetric keys are used for a AES+TWOFISH combined cipher:
+            The symmetric keys and IVs are used for a AES+TWOFISH combined
+            cipher. Both ciphers are used in CFB (ref) mode.
           </t>
           <artwork name="" type="" align="left" alt=""><![CDATA[
-            RDATA := TWOFISH256(Kt, AES256(Ka, BDATA))
+            RDATA := AES256(Kaes, IVaes, TWOFISH256(Ktwo, IVtwo, BDATA))
+            BDATA := TWOFISH256(Ktwo, IVtwo, AES256(Kaes, IVaes, RDATA))
             ]]></artwork>
 
         </section>
@@ -163,7 +187,7 @@
             |                                               |
             |                                               |
             +-----+-----+-----+-----+-----+-----+-----+-----+
-            |       RDATA SIZE      |          TYPE         |
+            |       DATA SIZE       |          TYPE         |
             +-----+-----+-----+-----+-----+-----+-----+-----+
             |           FLAGS       |        DATA           |
             +-----+-----+-----+-----+                       |