From 7c8c479b969ba631712ce98c39b111f06aba1d1e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20G=C3=B6ttgens?= <tgoettgens@gmail.com>
Date: Wed, 19 Oct 2022 15:39:06 +0200
Subject: [PATCH] wire in OEM.proto keystore

---
 src/graphics/Screen.cpp |  7 -------
 src/mesh/Channels.cpp   | 24 ++++++++++++++++--------
 src/mesh/NodeDB.cpp     |  6 ++++++
 src/mesh/NodeDB.h       |  1 +
 4 files changed, 23 insertions(+), 15 deletions(-)

diff --git a/src/graphics/Screen.cpp b/src/graphics/Screen.cpp
index 601b83f9c..0f6c96f0f 100644
--- a/src/graphics/Screen.cpp
+++ b/src/graphics/Screen.cpp
@@ -84,10 +84,6 @@ static char ourId[5];
 // GeoCoord object for the screen
 GeoCoord geoCoord;
 
-// OEM Config File
-static const char *oemConfigFile = "/oem/oem.proto";
-OEMStore oemStore;
-
 #ifdef SHOW_REDRAWS
 static bool heartbeat = false;
 #endif
@@ -928,9 +924,6 @@ void Screen::setup()
     dispdev.setDetected(screen_model);
 #endif
 
-    // Load OEM config from Proto file if existent
-    loadProto(oemConfigFile, OEMStore_size, sizeof(oemConfigFile), OEMStore_fields, &oemStore);
-
     // Initialising the UI will init the display too.
     ui.init();
 
diff --git a/src/mesh/Channels.cpp b/src/mesh/Channels.cpp
index a87d66b14..200184720 100644
--- a/src/mesh/Channels.cpp
+++ b/src/mesh/Channels.cpp
@@ -62,13 +62,6 @@ Channel &Channels::fixupChannel(ChannelIndex chIndex)
         // Convert the old string "Default" to our new short representation
         if (strcmp(channelSettings.name, "Default") == 0)
             *channelSettings.name = '\0';
-
-        /* Convert any old usage of the defaultpsk into our new short representation.
-        if (channelSettings.psk.size == sizeof(defaultpsk) &&
-            memcmp(channelSettings.psk.bytes, defaultpsk, sizeof(defaultpsk)) == 0) {
-            *channelSettings.psk.bytes = 1;
-            channelSettings.psk.size = 1;
-        } */
     }
 
     hashes[chIndex] = generateHash(chIndex);
@@ -124,7 +117,22 @@ CryptoKey Channels::getKey(ChannelIndex chIndex)
             DEBUG_MSG("Expanding short PSK #%d\n", pskIndex);
             if (pskIndex == 0)
                 k.length = 0; // Turn off encryption
-            else {
+            else if (oemStore.oem_aes_key.size > 1) {
+                // Use the OEM key
+                DEBUG_MSG("Using OEM Key with %d bytes\n", oemStore.oem_aes_key.size);
+                memcpy(k.bytes, oemStore.oem_aes_key.bytes , oemStore.oem_aes_key.size);
+                k.length = oemStore.oem_aes_key.size;
+                // Bump up the last byte of PSK as needed
+                uint8_t *last = k.bytes + oemStore.oem_aes_key.size - 1;
+                *last = *last + pskIndex - 1; // index of 1 means no change vs defaultPSK
+                if (k.length < 16) {
+                    DEBUG_MSG("Warning: OEM provided a too short AES128 key - padding\n");
+                    k.length = 16;
+                } else if (k.length < 32 && k.length != 16) {
+                    DEBUG_MSG("Warning: OEM provided a too short AES256 key - padding\n");
+                    k.length = 32;
+                }
+            } else {
                 memcpy(k.bytes, defaultpsk, sizeof(defaultpsk));
                 k.length = sizeof(defaultpsk);
                 // Bump up the last byte of PSK as needed
diff --git a/src/mesh/NodeDB.cpp b/src/mesh/NodeDB.cpp
index 92115d127..319bb096b 100644
--- a/src/mesh/NodeDB.cpp
+++ b/src/mesh/NodeDB.cpp
@@ -38,6 +38,7 @@ MyNodeInfo &myNodeInfo = devicestate.my_node;
 LocalConfig config;
 LocalModuleConfig moduleConfig;
 ChannelFile channelFile;
+OEMStore oemStore;
 
 /** The current change # for radio settings.  Starts at 0 on boot and any time the radio settings
  * might have changed is incremented.  Allows others to detect they might now be on a new channel.
@@ -354,6 +355,8 @@ static const char *prefFileName = "/prefs/db.proto";
 static const char *configFileName = "/prefs/config.proto";
 static const char *moduleConfigFileName = "/prefs/module.proto";
 static const char *channelFileName = "/prefs/channels.proto";
+static const char *oemConfigFile = "/oem/oem.proto";
+
 
 /** Load a protobuf from a file, return true for success */
 bool loadProto(const char *filename, size_t protoSize, size_t objSize, const pb_msgdesc_t *fields, void *dest_struct)
@@ -433,6 +436,9 @@ void NodeDB::loadFromDisk()
             DEBUG_MSG("Loaded saved channelFile version %d\n", channelFile.version);
         }
     }
+
+    if (loadProto(oemConfigFile, OEMStore_size, sizeof(OEMStore), OEMStore_fields, &oemStore))
+        DEBUG_MSG("Loaded OEMStore\n");
 }
 
 /** Save a protobuf from a file, return true for success */
diff --git a/src/mesh/NodeDB.h b/src/mesh/NodeDB.h
index 574d6fe54..6b9744565 100644
--- a/src/mesh/NodeDB.h
+++ b/src/mesh/NodeDB.h
@@ -26,6 +26,7 @@ extern ChannelFile channelFile;
 extern MyNodeInfo &myNodeInfo;
 extern LocalConfig config;
 extern LocalModuleConfig moduleConfig;
+extern OEMStore oemStore;
 extern User &owner;
 
 /// Given a node, return how many seconds in the past (vs now) that we last heard from it