GPS scramble recorder

apps/gps-scramble/ChangeLog

@@ -0,0 +1 @@
+0.01: Initial app

apps/gps-scramble/README.md

@@ -0,0 +1,23 @@
+# GPS Scramble
+
+This app wraps the existing [GPS recorder] and "scrambles" the GPS recording so, if lost, a read of the GPS files on the watch won't give away your home, work or other locations.
+
+## Tech
+
+The scrambling works by shifting your GPS records so they start in the middle of the pacific ocean, making it very difficult for someone to attempt to guess where the GPS track originated. To restore your track, the recorder app can unscramble these coordinates when provided with the starting location for your track.
+
+The constraints on this design are:
+- Avoid needing to enter a password whenever the watch loads
+- Avoid storing true GPS coordinates (to prevent SWD reads)
+- Avoid heavy crypto
+- Avoid reliance on an external device, e.g. a phone
+
+## Discussion
+
+Initial discussion took place on the [espruino forum](https://forum.espruino.com/conversations/388489/).
+
+## Todo
+
+- [ ] Handle unscrambling a restart of GPS recording at a new location
+
+[GPS recorder]: https://github.com/espruino/BangleApps/blob/0eea248390f5245c8d5bceb3eb2e976fab193a45/apps/recorder/widget.js#L22-L58

apps/gps-scramble/metadata.json

@@ -0,0 +1,16 @@
+{
+  "id": "gps-scramble",
+  "name": "GPS Scrambler",
+  "shortName": "GPS Scramble",
+  "version": "0.01",
+  "description": "Scramble GPS to maintain privacy if your watch is lost",
+  "icon": "icon.png",
+  "tags": "tool,outdoors,gps",
+  "supports": ["BANGLEJS", "BANGLEJS2"],
+  "readme": "README.md",
+  "type": "recorder",
+  "storage": [
+    { "name": "gps-scramble.recorder.js", "url": "recorder.js" },
+    { "name": "gps-scramble.img", "url": "icon.js", "evaluate": true }
+  ]
+}

apps/gps-scramble/recorder.js

@@ -0,0 +1,31 @@
+(function (recorders) {
+    var __assign = Object.assign;
+    var pacific = { lat: -4.21, lon: -146.25 };
+    var gpsRecorder = recorders.gps;
+    if (!gpsRecorder)
+        return;
+    delete recorders.gps;
+    recorders.gpsScramble = function () {
+        var gps = gpsRecorder();
+        var offset;
+        return __assign(__assign({}, gps), { name: "GPS (scramble)", fields: gps.fields.concat("ScrambleStart"), getValues: function () {
+                var values = gps.getValues();
+                values.push(String(!offset));
+                if (!values[0].length) {
+                }
+                else if (offset) {
+                    values[0] = (Number(values[0]) + offset[0]).toFixed(6);
+                    values[1] = (Number(values[1]) + offset[1]).toFixed(6);
+                }
+                else {
+                    offset = [
+                        pacific.lat - Number(values[0]),
+                        pacific.lon - Number(values[1]),
+                    ];
+                    values[0] = String(pacific.lat);
+                    values[1] = String(pacific.lon);
+                }
+                return values;
+            } });
+    };
+});

apps/gps-scramble/recorder.ts

@@ -0,0 +1,45 @@
+((recorders: Recorders) => {
+	// @ts-ignore helper
+	const __assign = Object.assign;
+
+	const pacific = { lat: -4.21, lon: -146.25 };
+
+	// @ts-ignore index signature
+	const gpsRecorder = recorders.gps;
+	if (!gpsRecorder) return;
+
+	// @ts-ignore index signature
+	delete recorders.gps;
+
+	// @ts-ignore index signature
+	recorders.gpsScramble = () => {
+		const gps = gpsRecorder();
+		let offset: undefined | [number, number];
+
+		return {
+			...gps,
+			name: "GPS (scramble)",
+			fields: gps.fields.concat("ScrambleStart"),
+			getValues: () => {
+				const values = gps.getValues() as string[];
+				values.push(String(!offset));
+
+				if (!values[0]!.length) {
+					// no change
+				} else if (offset) {
+					values[0] = (Number(values[0]) + offset[0]).toFixed(6);
+					values[1] = (Number(values[1]) + offset[1]).toFixed(6);
+				} else {
+					offset = [
+						pacific.lat - Number(values[0]),
+						pacific.lon - Number(values[1]),
+					];
+					values[0] = String(pacific.lat);
+					values[1] = String(pacific.lon);
+				}
+
+				return values;
+			},
+		};
+	};
+})

apps/recorder/interface.html

@@ -160,15 +160,54 @@
 
 function downloadTrack(filename, callback) {
   Util.showModal("Downloading Track...");
+
+  const pacific = { lat: -4.21, lon: -146.25 };
+  const offset = {
+    lat: Number(document.getElementById("unscramble-lat").value),
+    lon: Number(document.getElementById("unscramble-lon").value),
+  };
+
   Util.readStorageFile(filename,data=>{
     Util.hideModal();
     var lines = data.trim().split("\n");
     var headers = lines.shift().split(",");
     var track = lines.map(l=>trackLineToObject(headers, l));
+
+    if (localStorage.getItem("recorder-unscramble-gps")=="true") {
+      for (const entry of track) {
+        if (entry.Latitude.length) {
+          entry.Latitude = Number(entry.Latitude) - pacific.lat + offset.lat;
+          entry.Longitude = Number(entry.Longitude) - pacific.lon + offset.lon;
+        }
+      }
+    }
+
     callback(track);
   });
 }
 
+function scrambleInit() {
+  document.getElementById("settings-unscramble-gps").addEventListener("change", event => {
+    var unscramble = event.target.checked;
+    localStorage.setItem("recorder-unscramble-gps", unscramble);
+
+    document.getElementById("unscramble-cfg").classList.toggle("d-hide", !unscramble);
+  });
+
+  if (localStorage.getItem("recorder-unscramble-gps")=="true")
+    document.getElementById("settings-unscramble-gps").click(); // trigger listener
+
+  const bind = (el, storeKey) => {
+    el.value = localStorage.getItem(storeKey);
+    el.addEventListener("change", event => {
+      localStorage.setItem(storeKey, event.target.value);
+    });
+  };
+
+  bind(document.getElementById("unscramble-lat"), "recorder-unscramble-gps-lat");
+  bind(document.getElementById("unscramble-lon"), "recorder-unscramble-gps-lon");
+}
+
 function getTrackList() {
   Util.showModal("Loading Track List...");
   domTracks.innerHTML = "";
@@ -264,13 +303,29 @@ <h2>Settings</h2>
             <input type="checkbox" id="settings-allow-no-gps" ${(localStorage.getItem("recorder-allow-no-gps")=="true")?"checked":""}>
             <i class="form-icon"></i> Include GPX/KML entries even when there's no GPS info
           </label>
+          <div>
+            <label class="form-switch">
+              <input type="checkbox" id="settings-unscramble-gps">
+              <i class="form-icon"></i> Unscramble/re-originate GPS
+            </label>
+
+            <div id="unscramble-cfg" class="d-hide">
+              <label class="form-label" for="unscramble-lat">Starting Latitude</label>
+              <input type="number" id="unscramble-lat" class="form-input" step="any">
+
+              <label class="form-label" for="unscramble-lon">Starting Longitude</label>
+              <input type="number" id="unscramble-lon" class="form-input" step="any">
+            </div>
+          </div>
         </div>
         </div>`;
         domTracks.innerHTML = html;
         document.getElementById("settings-allow-no-gps").addEventListener("change",event=>{
           var allowNoGPS = event.target.checked;
           localStorage.setItem("recorder-allow-no-gps", allowNoGPS);
         });
+        scrambleInit();
+
         Util.hideModal();
         var buttons = domTracks.querySelectorAll("button");
         for (var i=0;i<buttons.length;i++) {

bin/sanitycheck.js

@@ -81,7 +81,7 @@ const APP_KEYS = [
 const STORAGE_KEYS = ['name', 'url', 'content', 'evaluate', 'noOverwite', 'supports', 'noOverwrite'];
 const DATA_KEYS = ['name', 'wildcard', 'storageFile', 'url', 'content', 'evaluate'];
 const SUPPORTS_DEVICES = ["BANGLEJS","BANGLEJS2"]; // device IDs allowed for 'supports'
-const METADATA_TYPES = ["app","clock","widget","bootloader","RAM","launch","scheduler","notify","locale","settings","waypoints","textinput","module","clkinfo"]; // values allowed for "type" field
+const METADATA_TYPES = ["app","clock","widget","bootloader","RAM","launch","scheduler","notify","locale","settings","waypoints","textinput","module","clkinfo","recorder"]; // values allowed for "type" field
 const FORBIDDEN_FILE_NAME_CHARS = /[,;]/; // used as separators in appid.info
 const VALID_DUPLICATES = [ '.tfmodel', '.tfnames' ];
 const GRANDFATHERED_ICONS = ["s7clk",  "snek", "astral", "alpinenav", "slomoclock", "arrow", "pebble", "rebble"];

typescript/types/main.d.ts

@@ -10255,6 +10255,11 @@ interface StringConstructor {
    * @url http://www.espruino.com/Reference#l_String_String
    */
   new(...str: any[]): any;
+
+  /**
+   * Converts the given argument to a string
+   */
+  (s: any): string;
 }
 
 interface String {
@@ -10589,6 +10594,11 @@ interface NumberConstructor {
    * @url http://www.espruino.com/Reference#l_Number_Number
    */
   new(...value: any[]): any;
+
+  /**
+   * Converts the given argument to a number
+   */
+  (value: any): number;
 }
 
 interface Number {