[tor-commits] [obfsproxy/master] Fix ticket handshake spec.

[asn at torproject.org]

commit 39aa6ffabe29ae305fbb1c36e78a9abb154e0894
Author: Philipp Winter <phw at torproject.org>
Date:   Sat Mar 8 17:40:35 2014 +0100

    Fix ticket handshake spec.
    
    The first message makes use of the HMAC key which is derived from the master
    key.  It does not use the master key itself.
---
 doc/scramblesuit/scramblesuit-spec.txt |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/doc/scramblesuit/scramblesuit-spec.txt b/doc/scramblesuit/scramblesuit-spec.txt
index 208b264..f928845 100644
--- a/doc/scramblesuit/scramblesuit-spec.txt
+++ b/doc/scramblesuit/scramblesuit-spec.txt
@@ -114,12 +114,14 @@
     uniformly chosen from {0..1388} bytes.  After the padding, a 16-byte mark M
     is appended which is defined as:
 
-      M = HMAC-SHA256-128(k_t, T)
+      M = HMAC-SHA256-128(k_sh, T)
 
     The mark is used to easily locate the MAC which is the last part of the
-    handshake.  The MAC is defined as:
+    handshake.  k_sh is the 256-bit HMAC key which is used by the client to
+    authenticate outgoing data.  It is derived from k_t (which is embedded in
+    the ticket) as described in Section 2.3.  The MAC is defined as:
 
-      MAC = HMAC-SHA256-128(k_t, T | P | E)
+      MAC = HMAC-SHA256-128(k_sh, T | P | E)
 
     The variable E is a string representation of the current Unix epoch divided
     by 3600.  It represents the amount of hours which have passed since the