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authorStef Walter <stefw@collabora.co.uk>2011-02-27 09:22:15 +0100
committerStef Walter <stefw@collabora.co.uk>2011-02-27 09:22:15 +0100
commit8f5374ca1b25c412b3c157f0a199e55ecde8be7e (patch)
tree817eaa6a38e37f156e83904cceb9f5c0c1db0d12
parent21aadb7dac9ae95a7c6bae12d4e404d98ca4a553 (diff)
downloadxdg-specs-8f5374ca1b25c412b3c157f0a199e55ecde8be7e.tar.xz
Specify the dh-ietf1024-sha256-aes128-cbc-pkcs7 algorithm suite.
This uses HKDF-SHA256 to digest the DH key into something usable by AES. The previous algorithm suite that this replaces just truncated the DH key which is cryptographically broken.
-rw-r--r--secret-service/specification.xml57
1 files changed, 54 insertions, 3 deletions
diff --git a/secret-service/specification.xml b/secret-service/specification.xml
index 9a9c81b..a6a1b76 100644
--- a/secret-service/specification.xml
+++ b/secret-service/specification.xml
@@ -308,7 +308,7 @@
</section>
<section>
- <title>Algorithm: dh-ietf1024-aes128-cbc-pkcs7</title>
+ <title>Algorithm: dh-ietf1024-sha256-aes128-cbc-pkcs7</title>
<segmentedlist>
<?dbhtml list-presentation="list"?>
@@ -321,13 +321,22 @@
<classname>Secret</classname> parameter</link></segtitle>
<seglistitem>
<!-- TODO: literal? -->
- <seg><emphasis>dh-ietf1024-aes128-cbc-pkcs7</emphasis></seg>
+ <seg><emphasis>dh-ietf1024-sha256-aes128-cbc-pkcs7</emphasis></seg>
<seg>Client DH pub key as an array of bytes</seg>
<seg>Service DH pub key as an array of bytes</seg>
<seg>16 byte AES initialization vector</seg>
</seglistitem>
</segmentedlist>
+ <para>DH key agreement <citation>rfc2631</citation> is used to create a secret key
+ using 1024 bit parameters of the standard IETF 'Second Oakley Group'
+ <citation>rfc2409</citation>. The secret key is then digested into a 128-bit key
+ appropriate for AES. This is done using HKDF <citation>rfc5869</citation> with NULL
+ salt and empty info, using the SHA-2 256 hash algorithm
+ <citation>fips-180-3.2008</citation>. The secrets are encrypted using AES
+ <citation>fips-197.2001</citation> in cipher block chaining mode with pkcs7 style
+ padding <citation>rfc2315</citation>.</para>
+
<para>The public keys are transferred as an array of bytes representing an
unsigned integer of arbitrary size, most-significant byte first (e.g., the
integer 32768 is represented as the 2-byte string 0x80 0x00)</para>
@@ -459,7 +468,7 @@
<part xml:id="ref-dbus-api">
<title>D-Bus API Reference</title>
- <chapter xml:id='object-paths'>
+ <chapter xml:id='object-paths'>
<title>Object Paths</title>
<para>The various DBus object paths used with the Secret Service API are designed to be human
@@ -502,4 +511,46 @@
<xi:include href="xml/annotation-glossary.xml" xmlns:xi="http://www.w3.org/2001/XInclude">
<xi:fallback/>
</xi:include>
+
+ <bibliography>
+ <title>References</title>
+
+ <bibliomixed>
+ <abbrev>rfc2315</abbrev>
+ IETF <ulink url="http://www.ietf.org/rfc/rfc2315.txt">RFC 2315</ulink>:
+ PKCS #7: Cryptographic Message Syntax Version 1.5
+ </bibliomixed>
+
+ <bibliomixed>
+ <abbrev>rfc2409</abbrev>
+ IETF <ulink url="http://www.ietf.org/rfc/rfc2409.txt">RFC 2409</ulink>:
+ The Internet Key Exchange (IKE)
+ </bibliomixed>
+
+ <bibliomixed>
+ <abbrev>rfc2631</abbrev>
+ IETF <ulink url="http://www.ietf.org/rfc/rfc2631.txt">RFC 2631</ulink>:
+ Diffie-Hellman Key Agreement Method
+ </bibliomixed>
+
+ <bibliomixed>
+ <abbrev>rfc5869</abbrev>
+ IETF <ulink url="http://www.ietf.org/rfc/rfc5869.txt">RFC 5869</ulink>:
+ HMAC-based Extract-and-Expand Key Derivation Function (HKDF)
+ </bibliomixed>
+
+ <bibliomixed>
+ <abbrev>fips-180-3.2008</abbrev>
+ NIST <ulink url="http://csrc.nist.gov/publications/fips/fips180-3/fips180-3_final.pdf">FIPS PUB 180-3</ulink>:
+ Secure Hash Standard (SHS), October 2008
+ </bibliomixed>
+
+ <bibliomixed>
+ <abbrev>fips-197.2001</abbrev>
+ NIST <ulink url="http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf">FIPS PUB 197</ulink>:
+ Advanced Encryption Standard (AES), November 2001
+ </bibliomixed>
+
+ </bibliography>
+
</book>