added initial RSA keypair generation

loc_chain_app/lib/widgets/navbar.dart

@@ -0,0 +1,50 @@
+import 'package:flutter/material.dart';
+import 'package:loc_chain_app/pages/home.dart';
+import 'package:loc_chain_app/pages/keygen.dart';
+
+class NavBarWidget extends StatefulWidget {
+  NavBarWidget({Key key}) : super(key: key);
+
+  @override
+  _NavBarWidgetState createState() => _NavBarWidgetState();
+}
+
+class _NavBarWidgetState extends State<NavBarWidget> {
+  int _selectedIndex = 0;
+  StatefulWidget _selectedWidget;
+  static List<Widget> pages = <Widget>[
+    HomePage(
+      title: 'Home',
+    ),
+    KeygenPage(
+      title: 'RSA Configuration',
+    ),
+  ];
+  void _onItemTapped(int index) => setState(() {
+        _selectedIndex = index;
+        _selectedWidget = pages[_selectedIndex];
+      });
+
+  @override
+  Widget build(context) => Scaffold(
+        body: _selectedWidget,
+        bottomNavigationBar: BottomNavigationBar(
+          items: const <BottomNavigationBarItem>[
+            BottomNavigationBarItem(
+              icon: Icon(Icons.home_rounded),
+              label: 'Home',
+              backgroundColor: Colors.cyan,
+            ),
+            BottomNavigationBarItem(
+              icon: Icon(Icons.lock_rounded),
+              label: 'RSA Configuration',
+              backgroundColor: Colors.cyan,
+            ),
+          ],
+          currentIndex: _selectedIndex,
+          selectedItemColor: Colors.lightBlueAccent,
+          unselectedItemColor: Colors.lightBlue[200],
+          onTap: _onItemTapped,
+        ),
+      );
+}