From dba5df7bac0a986dfc4ee46ed80aef110b55bd5c Mon Sep 17 00:00:00 2001
From: zzz <zzz@i2pmail.org>
Date: Wed, 28 Jul 2021 11:16:45 -0400
Subject: [PATCH] Prop. 157 updates
---
i2p2www/spec/proposals/157-new-tbm.rst | 22 +++++-----------------
1 file changed, 5 insertions(+), 17 deletions(-)
diff --git a/i2p2www/spec/proposals/157-new-tbm.rst b/i2p2www/spec/proposals/157-new-tbm.rst
index 35e296244..6764242af 100644
--- a/i2p2www/spec/proposals/157-new-tbm.rst
+++ b/i2p2www/spec/proposals/157-new-tbm.rst
@@ -5,7 +5,7 @@ Smaller Tunnel Build Messages
:author: zzz, orignal
:created: 2020-10-09
:thread: http://zzz.i2p/topics/2957
- :lastupdated: 2021-07-13
+ :lastupdated: 2021-07-28
:status: Open
:target: 0.9.51
@@ -534,20 +534,6 @@ Implementation Notes
Issues
======
-- HKDF details
-- Layer encryption changes?
-
- Should we do additional hiding from the paired OBEP or IBGW? Garlic?
-- For an IB build, the build message could be garlic encrypted to the IBGW,
- but then it would be larger.
-- We could do this for IB now for existing build messages if desired,
- but it's more expensive for ElGamal.
-- Is it worth it, or does the size of the message (much larger than
- typical database lookup, but maybe not database store) plus the
- delivery instructions make it obvious anyway?
-- For an OB build, the build reply message would have to be garlic encrypted
- by the OBEP to the originator, but that would not be anonymous.
- Is there another way? probably not.
Migration
@@ -683,8 +669,10 @@ Current build record cleartext size before unused padding: 193
Removal of full router hash and HKDF generation of keys/IVs would free up plenty of room for future options.
If everything is HKDF, required cleartext space is about 58 bytes (without any options).
-OTBRM is much smaller because there's one small plaintext record and one less encrypted record.
-
+The garlic-wrapped OTBRM will be slightly smaller than the garlic-wrapped STBM,
+because the delivery instructions are LOCAL not ROUTER,
+there's no DATETIME block included, and
+it uses an 8-byte tag rather than the 32-byte ephemeral key for a full 'N' message.
--
GitLab