get ready for preshared keys

TODO.md

@@ -4,6 +4,7 @@
 * when a text arrives, move that node info card to the bottom on the window - put the text to the left of the card.  with a small arrow/distance/shortname
 * all chat in the app defaults to group chat
 * show connection state on gui
+* make my android app show mesh state
 * when notified phone should download messages
 * at connect we might receive messages before finished downloading the nodeinfo.  In that case, process those messages later
 * investigate the Signal SMS message flow path, see if I could just make Mesh a third peer to signal & sms?
@@ -18,17 +19,16 @@
 * optionally turn off crypto in signal - preferably though see if there is a nice way to be a peer of signal/sms and now mesh.
 * change signal package ID - if distributing modified binary
 * good tips on which bands might be more free https://github.com/TheThingsNetwork/ttn/issues/119
-* make my android app show mesh state
 * use https://codelabs.developers.google.com/codelabs/jetpack-compose-basics/#4 to show service state
 * connect to bluetooth device automatically using minimum power, start looking at phone boot
 * fix BT device scanning
 * call crashlytics from exceptionReporter!!!  currently not logging failures caught there
 * if nessary restart entire BT adapter with this tip from Michael https://stackoverflow.com/questions/35103701/ble-android-onconnectionstatechange-not-being-called
 * show direction and distance on the nodeinfo cards
+* test with oldest android
 
 # Medium priority
 
-* test with oldest android
 * stop using a foreground service
 * change info() log strings to debug()
 * use platform theme (dark or light)
@@ -39,7 +39,7 @@ Don't leave device discoverable.  Don't let unpaired users do things with device
 
 # Low priority
 
-* make analytics optional
+** make analytics optional
 * also add a receiver that fires after a new update was installed from the play store
 
 # Done

app/src/main/proto/mesh.options

@@ -14,5 +14,8 @@
 # FIXME, something more like 200? And do fragmentation and reassembly (for larger payloads) at the Android layer, not the esp32 layer.
 *Data.payload max_size:100
 
+# 256 bit psk key
+*RadioConfig.psk max_size:32
+
 # MyMessage.name         max_size:40 
 # or fixed_length or fixed_count, or max_count

app/src/main/proto/mesh.proto

@@ -145,7 +145,6 @@ message MeshPacket {
 
 // Full settings (center freq, spread factor, pre-shared secret key etc...) needed to configure a radio
 message RadioConfig {
-    // FIXME
 
     // We should send our position this often (but only if it has changed significantly)
     uint32 position_broadcast_msec = 1;
@@ -157,11 +156,24 @@ message RadioConfig {
 
     float center_freq = 4;
 
-    uint32 bandwidth = 5;
+    enum ModemConfig {
+        // Note: these mappings must match ModemConfigChoice in the device code.
+        Bw125Cr45Sf128 = 0; ///< Bw = 125 kHz, Cr = 4/5, Sf = 128chips/symbol, CRC on. Default medium range
+        Bw500Cr45Sf128 = 1; ///< Bw = 500 kHz, Cr = 4/5, Sf = 128chips/symbol, CRC on. Fast+short range
+        Bw31_25Cr48Sf512 = 2; ///< Bw = 31.25 kHz, Cr = 4/8, Sf = 512chips/symbol, CRC on. Slow+long range
+        Bw125Cr48Sf4096 = 3; ///< Bw = 125 kHz, Cr = 4/8, Sf = 4096chips/symbol, CRC on. Slow+long range
+    }
 
-    int32 spread_factor = 6;
+    /// This value replaces bandwidth/spread_factor/coding_rate.  If you'd like to experiment with other options
+    /// add them to MeshRadio.cpp in the device code.
+    ModemConfig modem_config = 5;
+    // uint32 bandwidth = 5;
+    // int32 spread_factor = 6;
+    // int32 coding_rate = 7;
 
-    int32 coding_rate = 7;
+    /// A simple preshared key for now for crypto.  At first I'm using 256 bit (32 byte) block for the Speck crypto
+    /// but for beta we'll want something more carefully thought through.
+    bytes psk = 8;
 
     // If true, radio should not try to be smart about what packets to queue to the phone
     bool keep_all_packets = 100;
@@ -220,7 +232,6 @@ message MyNodeInfo {
     /// FIXME - add useful debugging state (queue depths etc)
 }
 
-
 // This message is never sent over the wire, but it is used for serializing DB state to flash in the device code
 // FIXME, since we write this each time we enter deep sleep (and have infinite flash) it would be better to use some sort of append only data
 // structure for the receive queue and use the preferences store for the other stuff
@@ -236,8 +247,6 @@ message DeviceState {
     repeated MeshPacket receive_queue = 4;
 }
 
-
-
 // packets from the radio to the phone will appear on the fromRadio characteristic.  It will support
 // READ and NOTIFY.  When a new packet arrives the device will notify?  possibly identify instead?
 // it will sit in that descriptor until consumed by the phone, at which point the next item in the FIFO