[lsd0001] branch master updated: remove twofish

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martin-schanzenbach pushed a commit to branch master
in repository lsd0001.

The following commit(s) were added to refs/heads/master by this push:
     new 34709ff  remove twofish
34709ff is described below

commit 34709ff00d670ac2ed286e2e8237a22f72d0acd0
Author: Martin Schanzenbach <mschanzenbach@posteo.de>
AuthorDate: Wed Sep 23 17:43:53 2020 +0200

    remove twofish
---
 draft-schanzen-gns.xml | 66 ++++++++++++++------------------------------------
 1 file changed, 18 insertions(+), 48 deletions(-)

diff --git a/draft-schanzen-gns.xml b/draft-schanzen-gns.xml
index 3339e15..96fb1b2 100644
--- a/draft-schanzen-gns.xml
+++ b/draft-schanzen-gns.xml
@@ -1042,43 +1042,27 @@ q := SHA512 (HDKD-Public(zk, label))
        <artwork name="" type="" align="left" alt=""><![CDATA[
 PRK_k := HKDF-Extract ("gns-aes-ctx-key", zk)
 PRK_iv := HKDF-Extract ("gns-aes-ctx-iv", zk)
-K := HKDF-Expand (PRK_k, label, 512 / 8);
-NONCES := HKDF-Expand (PRK_iv, label, 32 / 8)
+K := HKDF-Expand (PRK_k, label, 256 / 8);
+NONCE := HKDF-Expand (PRK_iv, label, 32 / 8)
 IV := EXPIRATION
 ]]></artwork>
        <t>
          HKDF is a hash-based key derivation function as defined in
          <xref target="RFC5869" />. Specifically, HMAC-SHA512 is used for the
          extraction phase and HMAC-SHA256 for the expansion phase.
-         The output keying material is 64 octets (512 bit) for the symmetric
-         keys and 16 octets (128 bit) for the nonces.
-         We divide the resulting keying material "K" into a 256 bit AES
-         <xref target="RFC3826" /> key
-         and a 256-bit TWOFISH <xref target="TWOFISH" /> key:
+         The output keying material is 32 octets (256 bit) for the symmetric
+         key and 4 octets (32 bit) for the nonce.
+         The symmetric key "K" is a 256 bit AES <xref target="RFC3826" /> key:
        </t>
-       <figure anchor="figure_hkdf_keys">
-         <artwork name="" type="" align="left" alt=""><![CDATA[
-0     8     16    24    32    40    48    56
-+-----+-----+-----+-----+-----+-----+-----+-----+
-|                    AES KEY                    |
-|                                               |
-|                                               |
-|                                               |
-+-----+-----+-----+-----+-----+-----+-----+-----+
-|                  TWOFISH KEY                  |
-|                                               |
-|                                               |
-|                                               |
-+-----+-----+-----+-----+-----+-----+-----+-----+
-           ]]></artwork>
-         <!--        <postamble>which is a very simple example.</postamble>-->
-       </figure>
        <t>
-         The NONCES are divided into two 32 bit NONCE values. Each is combined
-         with a 64 bit  initialization vecor and a counter as defined in
-         <xref target="RFC3686" /> into a 128 bit COUNTERBLOCK.
-         The initialization vector is the expiration time of the resource
-         record block:
+         The nonce is combined with a 64 bit initialization vector and a
+         32 bit block counter as defined in <xref target="RFC3686" />.
+         The block counter begins with the value of one,i and it is incremented
+         to generate subsequent portions of the key stream.
+         The block counter is a 32-bit integer value in network byte order.
+         The initialization vector is the expiration time of the
+         resource record block in network byte order.
+         The resulting COUNTER wire format is as follows:
        </t>
        <figure anchor="figure_hkdf_ivs">
          <artwork name="" type="" align="left" alt=""><![CDATA[
@@ -1089,22 +1073,19 @@ IV := EXPIRATION
 |       EXPIRATION      |
 |                       |
 +-----+-----+-----+-----+
-|        COUNTER        |
+|      BLOCK COUNTER    |
 +-----+-----+-----+-----+
            ]]></artwork>
          <!--        <postamble>which is a very simple example.</postamble>-->
        </figure>
 
        <t>
-         The keys and counter blocks are used for a CTR-AES-256 and
-         CTR-TWOFISH-256 chained symmetric cipher. Both ciphers are used in
-         counter mode (CTR) as defined in <xref target="MODES" />.
+         The key and counter block are used for the AES cipher in counter mode
+         as defined in <xref target="MODES" /> (CTR-AES-256):
        </t>
        <artwork name="" type="" align="left" alt=""><![CDATA[
-RDATA := AES(K[0:31], COUNTERBLOCK,
-             TWOFISH(K[32:63], COUNTERBLOCK, BDATA))
-BDATA := TWOFISH(K[32:63], COUNTERBLOCK,
-                 AES(K[0:31], COUNTERBLOCK, RDATA))
+RDATA := CTR-AES256(K, COUNTER, BDATA)
+BDATA := CTR-AES256(K, COUNTER, RDATA)
          ]]></artwork>
        <t>
          In order to ensure ciphertext indistinguishability, care must be
@@ -2114,17 +2095,6 @@ ee83f0cc79c4c5ea
        &RFC8032;
        &RFC8126;
 
-       <reference anchor="TWOFISH">
-         <front>
-           <title>
-             The Twofish Encryptions Algorithm: A 128-Bit Block Cipher, 1st 
Edition
-           </title>
-           <author initials="B." surname="Schneier" fullname="B. Schneier">
-             <organization/>
-           </author>
-           <date year="1999" month="March"/>
-         </front>
-       </reference>
        <reference anchor="GNS" 
target="https://doi.org/10.1007/978-3-319-12280-9_9";>
          <front>
            <title>A Censorship-Resistant, Privacy-Enhancing and Fully 
Decentralized Name System</title>

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