Allow import of private key, make it so key material isn't removed when navigating off the add a cert page (#64)

android/app/src/main/kotlin/net/defined/mobile_nebula/MainActivity.kt

@@ -49,6 +49,7 @@ class MainActivity: FlutterActivity() {
                 "nebula.parseCerts" -> nebulaParseCerts(call, result)
                 "nebula.generateKeyPair" -> nebulaGenerateKeyPair(result)
                 "nebula.renderConfig" -> nebulaRenderConfig(call, result)
+                "nebula.verifyCertAndKey" -> nebulaVerifyCertAndKey(call, result)
 
                 "listSites" -> listSites(result)
                 "deleteSite" -> deleteSite(call, result)
@@ -104,6 +105,25 @@ class MainActivity: FlutterActivity() {
         return result.success(yaml)
     }
 
+    private fun nebulaVerifyCertAndKey(call: MethodCall, result: MethodChannel.Result) {
+        val cert = call.argument<String>("cert")
+        if (cert == "") {
+            return result.error("required_argument", "cert is a required argument", null)
+        }
+
+        val key = call.argument<String>("key")
+        if (key == "") {
+            return result.error("required_argument", "key is a required argument", null)
+        }
+
+        return try {
+            val json = mobileNebula.MobileNebula.verifyCertAndKey(cert, key)
+            result.success(json)
+        } catch (err: Exception) {
+            result.error("unhandled_error", err.message, null)
+        }
+    }
+
     private fun listSites(result: MethodChannel.Result) {
         sites!!.refreshSites(activeSiteId)
         val sites = sites!!.getSites()

ios/Runner/AppDelegate.swift

@@ -34,6 +34,7 @@ func MissingArgumentError(message: String, details: Any?) -> FlutterError {
             case "nebula.parseCerts": return self.nebulaParseCerts(call: call, result: result)
             case "nebula.generateKeyPair": return self.nebulaGenerateKeyPair(result: result)
             case "nebula.renderConfig": return self.nebulaRenderConfig(call: call, result: result)
+            case "nebula.verifyCertAndKey": return self.nebulaVerifyCertAndKey(call: call, result: result)
                 
             case "listSites": return self.listSites(result: result)
             case "deleteSite": return self.deleteSite(call: call, result: result)
@@ -71,6 +72,21 @@ func MissingArgumentError(message: String, details: Any?) -> FlutterError {
         return result(json)
     }
     
+    func nebulaVerifyCertAndKey(call: FlutterMethodCall, result: FlutterResult) {
+        guard let args = call.arguments as? Dictionary<String, String> else { return result(NoArgumentsError()) }
+        guard let cert = args["cert"] else { return result(MissingArgumentError(message: "cert is a required argument")) }
+        guard let key = args["key"] else { return result(MissingArgumentError(message: "key is a required argument")) }
+        
+        var err: NSError?
+        var validd: ObjCBool = false
+        let valid = MobileNebulaVerifyCertAndKey(cert, key, &validd, &err)
+        if (err != nil) {  
+            return result(CallFailedError(message: "Error while verifying certificate and private key", details: err!.localizedDescription))
+        }
+        
+        return result(valid)
+    }
+    
     func nebulaGenerateKeyPair(result: FlutterResult) {
         var err: NSError?
         let kp = MobileNebulaGenerateKeyPair(&err)

lib/components/config/ConfigTextItem.dart

@@ -5,10 +5,11 @@ import 'package:flutter/material.dart';
 import 'package:mobile_nebula/components/SpecialTextField.dart';
 
 class ConfigTextItem extends StatelessWidget {
-  const ConfigTextItem({Key key, this.placeholder, this.controller}) : super(key: key);
+  const ConfigTextItem({Key key, this.placeholder, this.controller, this.style = const TextStyle(fontFamily: 'RobotoMono')}) : super(key: key);
 
   final String placeholder;
   final TextEditingController controller;
+  final TextStyle style;
 
   @override
   Widget build(BuildContext context) {
@@ -19,7 +20,7 @@ class ConfigTextItem extends StatelessWidget {
             minLines: 3,
             maxLines: 10,
             placeholder: placeholder,
-            style: TextStyle(fontFamily: 'RobotoMono'),
+            style: style,
             controller: controller));
   }
 }

lib/screens/siteConfig/AddCertificateScreen.dart

@@ -24,69 +24,54 @@ class CertificateResult {
 }
 
 class AddCertificateScreen extends StatefulWidget {
-  const AddCertificateScreen({Key key, this.onSave, this.onReplace}) : super(key: key);
+  const AddCertificateScreen({Key key, this.onSave, this.onReplace, this.pubKey, this.privKey}) : super(key: key);
 
   // onSave will pop a new CertificateDetailsScreen
   final ValueChanged<CertificateResult> onSave;
   // onReplace will return the CertificateResult, assuming the previous screen is a CertificateDetailsScreen
   final ValueChanged<CertificateResult> onReplace;
 
+  final String pubKey;
+  final String privKey;
+
   @override
   _AddCertificateScreenState createState() => _AddCertificateScreenState();
 }
 
 class _AddCertificateScreenState extends State<AddCertificateScreen> {
   String pubKey;
-  String privKey;
+  bool showKey = false;
 
   String inputType = 'paste';
 
+  final keyController = TextEditingController();
   final pasteController = TextEditingController();
   static const platform = MethodChannel('net.defined.mobileNebula/NebulaVpnService');
 
   @override
   void initState() {
-    _generateKeys();
+    pubKey = widget.pubKey;
+    keyController.text = widget.privKey;
     super.initState();
   }
 
   @override
   void dispose() {
     pasteController.dispose();
+    keyController.dispose();
     super.dispose();
   }
 
   @override
   Widget build(BuildContext context) {
-    if (pubKey == null) {
-      return Center(
-        child: PlatformCircularProgressIndicator(cupertino: (_, __) {
-          return CupertinoProgressIndicatorData(radius: 500);
-        }),
-      );
-    }
-
     List<Widget> items = [];
     items.addAll(_buildShare());
+    items.add(_buildKey());
     items.addAll(_buildLoadCert());
 
     return SimplePage(title: 'Certificate', child: Column(children: items));
   }
 
-  _generateKeys() async {
-    try {
-      var kp = await platform.invokeMethod("nebula.generateKeyPair");
-      Map<String, dynamic> keyPair = jsonDecode(kp);
-
-      setState(() {
-        pubKey = keyPair['PublicKey'];
-        privKey = keyPair['PrivateKey'];
-      });
-    } on PlatformException catch (err) {
-      Utils.popError(context, 'Failed to generate key pair', err.details ?? err.message);
-    }
-  }
-
   List<Widget> _buildShare() {
     return [
       ConfigSection(
@@ -136,6 +121,33 @@ class _AddCertificateScreenState extends State<AddCertificateScreen> {
     return items;
   }
 
+  Widget _buildKey() {
+    if (!showKey) {
+      return Padding(
+          padding: EdgeInsets.only(top: 20, bottom: 10, left: 10, right: 10),
+          child: SizedBox(
+              width: double.infinity,
+              child: PlatformElevatedButton(
+                  child: Text('Show/Import Private Key'),
+                  color: CupertinoColors.secondaryLabel.resolveFrom(context),
+                  onPressed: () => Utils.confirmDelete(context, 'Show/Import Private Key?', () {
+                    setState(() {
+                      showKey = true;
+                    });
+                  }, deleteLabel: 'Yes'))));
+    }
+
+    return ConfigSection(
+      label: 'Import a private key generated on another device',
+      children: [
+        ConfigTextItem(
+          controller: keyController,
+          style: TextStyle(fontFamily: 'RobotoMono', fontSize: 14)
+        ),
+      ],
+    );
+  }
+
   List<Widget> _addPaste() {
     return [
       ConfigSection(
@@ -201,7 +213,7 @@ class _AddCertificateScreenState extends State<AddCertificateScreen> {
   _addCertEntry(String rawCert) async {
     // Allow for app store review testing cert to override the generated key
     if (rawCert.trim() == _testCert) {
-      privKey = _testKey;
+      keyController.text = _testKey;
     }
 
     try {
@@ -217,12 +229,20 @@ class _AddCertificateScreenState extends State<AddCertificateScreen> {
           return Utils.popError(context, 'Certificate was invalid', tryCertInfo.validity.reason);
         }
 
-        //TODO: test that the pubkey we generated equals the pub key in the cert
+        var certMatch = await platform.invokeMethod(
+            "nebula.verifyCertAndKey",
+            <String, String>{"cert": rawCert, "key": keyController.text}
+        );
+        if (!certMatch) {
+          // The method above will throw if there is a mismatch, this is just here in case we introduce a bug in the future
+          return Utils.popError(context, 'Error loading certificate content',
+              'The provided certificates public key is not compatible with the private key.');
+        }
 
         // If we are replacing we just return the results now
         if (widget.onReplace != null) {
           Navigator.pop(context);
-          widget.onReplace(CertificateResult(certInfo: tryCertInfo, key: privKey));
+          widget.onReplace(CertificateResult(certInfo: tryCertInfo, key: keyController.text));
           return;
         }
 
@@ -232,7 +252,7 @@ class _AddCertificateScreenState extends State<AddCertificateScreen> {
               certInfo: tryCertInfo,
               onSave: () {
                 Navigator.pop(context);
-                widget.onSave(CertificateResult(certInfo: tryCertInfo, key: privKey));
+                widget.onSave(CertificateResult(certInfo: tryCertInfo, key: keyController.text));
               });
         });
       }

lib/screens/siteConfig/CertificateDetailsScreen.dart

@@ -10,7 +10,7 @@ import 'package:mobile_nebula/services/utils.dart';
 
 /// Displays the details of a CertificateInfo object. Respects incomplete objects (missing validity or rawCert)
 class CertificateDetailsScreen extends StatefulWidget {
-  const CertificateDetailsScreen({Key key, this.certInfo, this.onDelete, this.onSave, this.onReplace})
+  const CertificateDetailsScreen({Key key, this.certInfo, this.onDelete, this.onSave, this.onReplace, this.pubKey, this.privKey})
       : super(key: key);
 
   final CertificateInfo certInfo;
@@ -24,6 +24,9 @@ class CertificateDetailsScreen extends StatefulWidget {
   // onReplace is used to install a new certificate over top of the old one
   final ValueChanged<CertificateResult> onReplace;
 
+  final String pubKey;
+  final String privKey;
+
   @override
   _CertificateDetailsScreenState createState() => _CertificateDetailsScreenState();
 }
@@ -164,7 +167,7 @@ class _CertificateDetailsScreenState extends State<CertificateDetailsScreen> {
                       // Slam the page back to the top
                       controller.animateTo(0,
                           duration: const Duration(milliseconds: 10), curve: Curves.linearToEaseOut);
-                    });
+                    }, pubKey: widget.pubKey, privKey: widget.privKey, );
                   });
                 })));
   }

lib/screens/siteConfig/SiteConfigScreen.dart

@@ -3,6 +3,8 @@ import 'dart:convert';
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import 'package:flutter_platform_widgets/flutter_platform_widgets.dart' as fpw;
 import 'package:mobile_nebula/components/FormPage.dart';
 import 'package:mobile_nebula/components/PlatformTextFormField.dart';
 import 'package:mobile_nebula/components/config/ConfigPageItem.dart';
@@ -36,11 +38,16 @@ class _SiteConfigScreenState extends State<SiteConfigScreen> {
   bool newSite = false;
   bool debug = false;
   Site site;
+  String pubKey;
+  String privKey;
 
+  static const platform = MethodChannel('net.defined.mobileNebula/NebulaVpnService');
   final nameController = TextEditingController();
 
   @override
   void initState() {
+    //NOTE: this is slightly wasteful since a keypair will be generated every time this page is opened
+    _generateKeys();
     if (widget.site == null) {
       newSite = true;
       site = Site();
@@ -54,6 +61,14 @@ class _SiteConfigScreenState extends State<SiteConfigScreen> {
 
   @override
   Widget build(BuildContext context) {
+    if (pubKey == null) {
+      return Center(
+        child: fpw.PlatformCircularProgressIndicator(cupertino: (_, __) {
+          return fpw.CupertinoProgressIndicatorData(radius: 50);
+        }),
+      );
+    }
+
     return FormPage(
         title: newSite ? 'New Site' : 'Edit Site',
         changed: changed,
@@ -139,6 +154,8 @@ class _SiteConfigScreenState extends State<SiteConfigScreen> {
               if (site.certInfo != null) {
                 return CertificateDetailsScreen(
                     certInfo: site.certInfo,
+                    pubKey: pubKey,
+                    privKey: privKey,
                     onReplace: (result) {
                       setState(() {
                         changed = true;
@@ -148,7 +165,7 @@ class _SiteConfigScreenState extends State<SiteConfigScreen> {
                     });
               }
 
-              return AddCertificateScreen(onSave: (result) {
+              return AddCertificateScreen(pubKey: pubKey, privKey: privKey, onSave: (result) {
                 setState(() {
                   changed = true;
                   site.certInfo = result.certInfo;
@@ -243,4 +260,18 @@ class _SiteConfigScreenState extends State<SiteConfigScreen> {
       ],
     );
   }
+
+  _generateKeys() async {
+    try {
+      var kp = await platform.invokeMethod("nebula.generateKeyPair");
+      Map<String, dynamic> keyPair = jsonDecode(kp);
+
+      setState(() {
+        pubKey = keyPair['PublicKey'];
+        privKey = keyPair['PrivateKey'];
+      });
+    } on PlatformException catch (err) {
+      Utils.popError(context, 'Failed to generate key pair', err.details ?? err.message);
+    }
+  }
 }

lib/services/utils.dart

@@ -83,7 +83,11 @@ class Utils {
 
   static Widget trailingSaveWidget(BuildContext context, Function onPressed) {
     return CupertinoButton(
-        child: Text('Save', style: TextStyle(fontWeight: FontWeight.bold)),
+        child: Text('Save', style: TextStyle(
+            fontWeight: FontWeight.bold,
+            //TODO: For some reason on android if inherit is the default of true the text color here turns to the background color
+            inherit: Platform.isIOS ? true : false
+        )),
         padding: Platform.isAndroid ? null : EdgeInsets.zero,
         onPressed: () => onPressed());
   }

nebula/mobileNebula.go

@@ -250,6 +250,20 @@ func x25519Keypair() ([]byte, []byte, error) {
 	return pubkey[:], privkey[:], nil
 }
 
-//func VerifyCertAndKey(cert string, key string) (string, error) {
+func VerifyCertAndKey(rawCert string, pemPrivateKey string) (bool, error) {
-//
+	rawKey, _, err := cert.UnmarshalX25519PrivateKey([]byte(pemPrivateKey))
-//}
+	if err != nil {
+		return false, fmt.Errorf("error while unmarshaling private key: %s", err)
+	}
+
+	nebulaCert, _, err := cert.UnmarshalNebulaCertificateFromPEM([]byte(rawCert))
+	if err != nil {
+		return false, fmt.Errorf("error while unmarshaling cert: %s", err)
+	}
+
+	if err = nebulaCert.VerifyPrivateKey(rawKey); err != nil {
+		return false, err
+	}
+
+	return true, nil
+}