From db527b6759115065f1f0fc8dbfbc402e237a68eb Mon Sep 17 00:00:00 2001
From: Mark Qvist <mark@unsigned.io>
Date: Thu, 20 May 2021 16:56:08 +0200
Subject: [PATCH] Optimised announces to 151 bytes

---
 RNS/Destination.py            |  5 +----
 RNS/Identity.py               | 12 ++++++------
 RNS/Packet.py                 |  1 +
 docs/source/understanding.rst |  4 ++--
 4 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/RNS/Destination.py b/RNS/Destination.py
index f788e48..f4798ad 100755
--- a/RNS/Destination.py
+++ b/RNS/Destination.py
@@ -156,10 +156,7 @@ class Destination:
 
         signature = self.identity.sign(signed_data)
 
-        # TODO: Check if this could be optimised by only
-        # carrying the hash in the destination field, not
-        # also redundantly inside the signed blob as here
-        announce_data = self.hash+self.identity.get_public_key()+random_hash+signature
+        announce_data = self.identity.get_public_key()+random_hash+signature
 
         if app_data != None:
             announce_data += app_data
diff --git a/RNS/Identity.py b/RNS/Identity.py
index 489105d..2bd697d 100644
--- a/RNS/Identity.py
+++ b/RNS/Identity.py
@@ -149,16 +149,16 @@ class Identity:
         if packet.packet_type == RNS.Packet.ANNOUNCE:
             RNS.log("Validating announce from "+RNS.prettyhexrep(packet.destination_hash), RNS.LOG_DEBUG)
             destination_hash = packet.destination_hash
-            public_key = packet.data[10:Identity.KEYSIZE//8+10]
-            random_hash = packet.data[Identity.KEYSIZE//8+10:Identity.KEYSIZE//8+20]
-            signature = packet.data[Identity.KEYSIZE//8+20:Identity.KEYSIZE//8+20+Identity.KEYSIZE//8]
+            public_key = packet.data[:Identity.KEYSIZE//8]
+            random_hash = packet.data[Identity.KEYSIZE//8:Identity.KEYSIZE//8+10]
+            signature = packet.data[Identity.KEYSIZE//8+10:Identity.KEYSIZE//8+10+Identity.KEYSIZE//8]
             app_data = b""
-            if len(packet.data) > Identity.KEYSIZE//8+20+Identity.KEYSIZE//8:
-                app_data = packet.data[Identity.KEYSIZE//8+20+Identity.KEYSIZE//8:]
+            if len(packet.data) > Identity.KEYSIZE//8+10+Identity.KEYSIZE//8:
+                app_data = packet.data[Identity.KEYSIZE//8+10+Identity.KEYSIZE//8:]
 
             signed_data = destination_hash+public_key+random_hash+app_data
 
-            if not len(packet.data) > Identity.KEYSIZE//8+20+Identity.KEYSIZE//8:
+            if not len(packet.data) > Identity.KEYSIZE//8+10+Identity.KEYSIZE//8:
                 app_data = None
 
             announced_identity = Identity(create_keys=False)
diff --git a/RNS/Packet.py b/RNS/Packet.py
index 25917e9..8ee68a3 100755
--- a/RNS/Packet.py
+++ b/RNS/Packet.py
@@ -186,6 +186,7 @@ class Packet:
         self.packed = True
         self.update_hash()
 
+
     def unpack(self):
         self.flags = self.raw[0]
         self.hops  = self.raw[1]
diff --git a/docs/source/understanding.rst b/docs/source/understanding.rst
index a34371b..7190eea 100644
--- a/docs/source/understanding.rst
+++ b/docs/source/understanding.rst
@@ -672,8 +672,8 @@ Binary Packet Format
      wire size including all fields.
 
      - Path Request    :    33  bytes
-     - Announce        :    323 bytes
-     - Link Request    :    141 bytes
+     - Announce        :    151 bytes
+     - Link Request    :    182 bytes
      - Link Proof      :    205 bytes
      - Link RTT packet :    86  bytes
      - Link keepalive  :    14  bytes
\ No newline at end of file