Sign plaintext packets in licensed mode (#10969)

* feat: sign licensed plaintext packets

Preserve and publish identity keys in licensed mode so existing XEdDSA signatures can authenticate plaintext traffic. Sign licensed broadcasts and direct messages when they fit, while keeping PKI encryption disabled and normal routing behavior unchanged.

* fix(security): persist licensed channel sanitation

* fix(security): close licensed migration lifecycle gaps

* fix(security): address licensed signing review feedback

* test: restore signing globals from Unity teardown

* fix(baseui): allow confirmed ham region selection

* fix(baseui): guard region picker validation

* style: trunk fmt

---------

Co-authored-by: Ben Meadors <benmmeadors@gmail.com>
Co-authored-by: Austin <vidplace7@gmail.com>

src/modules/AdminModule.cpp

@@ -11,6 +11,7 @@
 #include "gps/RTC.h"
 #include "input/InputBroker.h"
 #include "meshUtils.h"
+#include <ErriezCRC32.h>
 #include <FSCommon.h>
 #include <Throttle.h>
 #include <ctype.h> // for better whitespace handling
@@ -70,6 +71,17 @@
 AdminModule *adminModule;
 bool hasOpenEditTransaction;
 
+#if !(MESHTASTIC_EXCLUDE_PKI_KEYGEN || MESHTASTIC_EXCLUDE_PKI)
+static bool licensedIdentityWillMigrate()
+{
+    if (config.security.private_key.size != 32 || config.security.public_key.size != 32)
+        return true;
+    if (nodeDB->checkLowEntropyPublicKey(config.security.public_key))
+        return true;
+    return crc32Buffer(config.security.public_key.bytes, config.security.public_key.size) != nodeDB->getNodeNum();
+}
+#endif
+
 /// A special reserved string to indicate strings we can not share with external nodes.  We will use this 'reserved' word instead.
 /// Also, to make setting work correctly, if someone tries to set a string to this reserved value we assume they don't really want
 /// a change.
@@ -765,6 +777,8 @@ void AdminModule::handleGetModuleConfigResponse(const meshtastic_MeshPacket &mp,
 void AdminModule::handleSetOwner(const meshtastic_User &o)
 {
     int changed = 0;
+    bool identityUpdated = false;
+    bool channelsSanitized = false;
 
     if (*o.long_name) {
         // Apps built against the older 39-byte limit may send longer names; clamp
@@ -783,15 +797,28 @@ void AdminModule::handleSetOwner(const meshtastic_User &o)
         owner.short_name[sizeof(owner.short_name) - 1] = '\0';
         sanitizeUtf8(owner.short_name, sizeof(owner.short_name));
     }
-    snprintf(owner.id, sizeof(owner.id), "!%08x", nodeDB->getNodeNum());
-
     if (owner.is_licensed != o.is_licensed) {
         changed = 1;
+#if !(MESHTASTIC_EXCLUDE_PKI_KEYGEN || MESHTASTIC_EXCLUDE_PKI)
+        const bool identityWillMigrate =
+            o.is_licensed && config.lora.region != meshtastic_Config_LoRaConfig_RegionCode_UNSET && licensedIdentityWillMigrate();
+        if (identityWillMigrate)
+            sendWarning(licensedIdentityMigrationMessage);
+#endif
         owner.is_licensed = o.is_licensed;
         if (channels.ensureLicensedOperation()) {
             warnLicensedMode();
+            channelsSanitized = true;
         }
+#if !(MESHTASTIC_EXCLUDE_PKI_KEYGEN || MESHTASTIC_EXCLUDE_PKI)
+        if (owner.is_licensed && config.lora.region != meshtastic_Config_LoRaConfig_RegionCode_UNSET) {
+            identityUpdated = nodeDB->generateCryptoKeyPair();
+            if (identityWillMigrate)
+                nodeDB->licensedIdentityMigrationPending = false;
+        }
+#endif
     }
+    snprintf(owner.id, sizeof(owner.id), "!%08x", nodeDB->getNodeNum());
     if (owner.has_is_unmessagable != o.has_is_unmessagable ||
         (o.has_is_unmessagable && owner.is_unmessagable != o.is_unmessagable)) {
         changed = 1;
@@ -801,7 +828,8 @@ void AdminModule::handleSetOwner(const meshtastic_User &o)
 
     if (changed) { // If nothing really changed, don't broadcast on the network or write to flash
         service->reloadOwner(!hasOpenEditTransaction);
-        saveChanges(SEGMENT_DEVICESTATE | SEGMENT_NODEDATABASE);
+        saveChanges(SEGMENT_DEVICESTATE | SEGMENT_NODEDATABASE | (identityUpdated ? SEGMENT_CONFIG : 0) |
+                    (channelsSanitized ? SEGMENT_CHANNELS : 0));
     }
 }
 
@@ -1004,7 +1032,7 @@ void AdminModule::handleSetConfig(const meshtastic_Config &c, bool fromOthers)
                 // If we're setting region for the first time, init the region and regenerate the keys
                 if (isRegionUnset && validatedLora.region > meshtastic_Config_LoRaConfig_RegionCode_UNSET) {
 #if !(MESHTASTIC_EXCLUDE_PKI_KEYGEN || MESHTASTIC_EXCLUDE_PKI)
-                    if (crypto) {
+                    if (crypto && !owner.is_licensed) {
                         crypto->ensurePkiKeys(config.security, owner);
                     }
 #endif
@@ -1017,6 +1045,17 @@ void AdminModule::handleSetConfig(const meshtastic_Config &c, bool fromOthers)
                 }
                 // Ensure initRegion() uses the newly validated region
                 config.lora.region = validatedLora.region;
+#if !(MESHTASTIC_EXCLUDE_PKI_KEYGEN || MESHTASTIC_EXCLUDE_PKI)
+                if (owner.is_licensed && isRegionUnset && validatedLora.region > meshtastic_Config_LoRaConfig_RegionCode_UNSET) {
+                    const bool identityWillMigrate = licensedIdentityWillMigrate();
+                    if (identityWillMigrate)
+                        sendWarning(licensedIdentityMigrationMessage);
+                    nodeDB->generateCryptoKeyPair();
+                    changes |= SEGMENT_DEVICESTATE | SEGMENT_NODEDATABASE;
+                    if (identityWillMigrate)
+                        nodeDB->licensedIdentityMigrationPending = false;
+                }
+#endif
                 initRegion();
                 if (getEffectiveDutyCycle() < 100) {
                     validatedLora.ignore_mqtt = true; // Ignore MQTT by default if region has a duty cycle limit
@@ -1025,7 +1064,7 @@ void AdminModule::handleSetConfig(const meshtastic_Config &c, bool fromOthers)
                     //  Default root is in use, so subscribe to the appropriate MQTT topic for this region
                     snprintf(moduleConfig.mqtt.root, sizeof(moduleConfig.mqtt.root), "%s/%s", default_mqtt_root, myRegion->name);
                 }
-                changes = SEGMENT_CONFIG | SEGMENT_MODULECONFIG;
+                changes |= SEGMENT_CONFIG | SEGMENT_MODULECONFIG;
             } else {
                 //  Region validation has failed, so just copy all of the old config over the new config
                 validatedLora = oldLoraConfig;
@@ -1838,6 +1877,9 @@ void AdminModule::reboot(int32_t seconds)
 
 void AdminModule::saveChanges(int saveWhat, bool shouldReboot)
 {
+#ifdef PIO_UNIT_TESTING
+    lastSaveWhatForTest = saveWhat;
+#endif
     if (!hasOpenEditTransaction) {
         LOG_INFO("Save changes to disk");
         service->reloadConfig(saveWhat); // Calls saveToDisk among other things
@@ -1891,6 +1933,17 @@ void AdminModule::handleSetHamMode(const meshtastic_HamParameters &p)
     config.device.rebroadcast_mode = meshtastic_Config_DeviceConfig_RebroadcastMode_LOCAL_ONLY;
     // Remove PSK of primary channel for plaintext amateur usage
 
+#if !(MESHTASTIC_EXCLUDE_PKI_KEYGEN || MESHTASTIC_EXCLUDE_PKI)
+    if (config.lora.region != meshtastic_Config_LoRaConfig_RegionCode_UNSET) {
+        const bool identityWillMigrate = licensedIdentityWillMigrate();
+        if (identityWillMigrate)
+            sendWarning(licensedIdentityMigrationMessage);
+        nodeDB->generateCryptoKeyPair();
+        if (identityWillMigrate)
+            nodeDB->licensedIdentityMigrationPending = false;
+    }
+#endif
+
     if (channels.ensureLicensedOperation()) {
         warnLicensedMode();
     }

src/modules/AdminModule.h

@@ -40,6 +40,9 @@ class AdminModule : public ProtobufModule<meshtastic_AdminMessage>, public Obser
 
   private:
     bool hasOpenEditTransaction = false;
+#ifdef PIO_UNIT_TESTING
+    int lastSaveWhatForTest = 0;
+#endif
 
     uint8_t session_passkey[8] = {0};
     uint32_t session_time = 0;        // millis() when the current session passkey was issued
@@ -155,9 +158,12 @@ class AdminModule : public ProtobufModule<meshtastic_AdminMessage>, public Obser
 static constexpr const char *licensedModeMessage =
     "Licensed mode activated, removing admin channel and encryption from all channels";
 
+static constexpr const char *licensedIdentityMigrationMessage =
+    "Licensed signing requires an identity key; this node identity will change after key generation";
+
 static constexpr const char *publicChannelPrecisionMessage =
     "Precise position is not allowed on a public (open / known-key) channel; reduced to coarse precision";
 
 extern AdminModule *adminModule;
 
-void disableBluetooth();
+void disableBluetooth();

src/modules/NodeInfoModule.cpp

@@ -169,14 +169,8 @@ meshtastic_MeshPacket *NodeInfoModule::allocReply()
         ignoreRequest = true;
         return NULL;
     } else {
-        ignoreRequest = false;     // Don't ignore requests anymore
-        meshtastic_User u = owner; // deliberate copy: the licensed strip below must not clobber the global owner state
-
-        // Strip the public key if the user is licensed
-        if (u.is_licensed && u.public_key.size > 0) {
-            memset(u.public_key.bytes, 0, sizeof(u.public_key.bytes));
-            u.public_key.size = 0;
-        }
+        ignoreRequest = false; // Don't ignore requests anymore
+        meshtastic_User u = owner;
 
         // FIXME: Clear the user.id field since it should be derived from node number on the receiving end
         // u.id[0] = '\0';