diff --git a/loc_chain_app/lib/pages/keygen.dart b/loc_chain_app/lib/pages/keygen.dart
index f36160e..c634f6c 100644
--- a/loc_chain_app/lib/pages/keygen.dart
+++ b/loc_chain_app/lib/pages/keygen.dart
@@ -1,54 +1,11 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter/widgets.dart';
+
 import 'package:fast_rsa/rsa.dart';
 import 'package:fast_rsa/model/bridge.pb.dart';
-import 'package:path_provider/path_provider.dart';
-
-import 'dart:io';
 
-class KeyFileManager {
-  static Future<String> get _localPath async {
-    final directory = await getApplicationDocumentsDirectory();
-    return directory.path;
-  }
-
-  static Future<File> get _pubKeyFile async {
-    final path = await _localPath;
-    return File('$path/rsa.pub');
-  }
-
-  static Future<File> get _privKeyFile async {
-    final path = await _localPath;
-    return File('$path/rsa');
-  }
-
-  static Future<KeyPair> readKeyPair() async {
-    try {
-      String privKey = await _privKeyFile.then(
-        (file) => file.readAsString(),
-      );
-      String pubKey = await _pubKeyFile.then(
-        (file) => file.readAsString(),
-      );
-
-      return KeyPair(
-        privateKey: privKey,
-        publicKey: pubKey,
-      );
-    } catch (e) {
-      print(e);
-      return KeyPair();
-    }
-  }
-
-  static Future<void> writeKeyPair(KeyPair pair) async {
-    final File privKeyFile = await _privKeyFile;
-    final File pubKeyFile = await _pubKeyFile;
-    pubKeyFile.writeAsString(pair.publicKey);
-    privKeyFile.writeAsString(pair.privateKey);
-  }
-}
+import 'package:loc_chain_app/util/keyfile_manager.dart';
 
 class KeygenPage extends StatefulWidget {
   KeygenPage({Key? key, required this.title}) : super(key: key);
diff --git a/loc_chain_app/lib/util/keyfile_manager.dart b/loc_chain_app/lib/util/keyfile_manager.dart
new file mode 100644
index 0000000..97c2136
--- /dev/null
+++ b/loc_chain_app/lib/util/keyfile_manager.dart
@@ -0,0 +1,46 @@
+import 'package:fast_rsa/model/bridge.pb.dart';
+import 'package:path_provider/path_provider.dart';
+import 'dart:io';
+
+class KeyFileManager {
+  static Future<String> get _localPath async {
+    final directory = await getApplicationDocumentsDirectory();
+    return directory.path;
+  }
+
+  static Future<File> get _pubKeyFile async {
+    final path = await _localPath;
+    return File('$path/rsa.pub');
+  }
+
+  static Future<File> get _privKeyFile async {
+    final path = await _localPath;
+    return File('$path/rsa');
+  }
+
+  static Future<KeyPair> readKeyPair() async {
+    try {
+      String privKey = await _privKeyFile.then(
+        (file) => file.readAsString(),
+      );
+      String pubKey = await _pubKeyFile.then(
+        (file) => file.readAsString(),
+      );
+
+      return KeyPair(
+        privateKey: privKey,
+        publicKey: pubKey,
+      );
+    } catch (e) {
+      print(e);
+      return KeyPair();
+    }
+  }
+
+  static Future<void> writeKeyPair(KeyPair pair) async {
+    final File privKeyFile = await _privKeyFile;
+    final File pubKeyFile = await _pubKeyFile;
+    pubKeyFile.writeAsString(pair.publicKey);
+    privKeyFile.writeAsString(pair.privateKey);
+  }
+}
diff --git a/loc_chain_app/lib/util/transaction.dart b/loc_chain_app/lib/util/transaction.dart
new file mode 100644
index 0000000..c8c1643
--- /dev/null
+++ b/loc_chain_app/lib/util/transaction.dart
@@ -0,0 +1,5 @@
+import 'package:flutter/services.dart';
+import 'package:fast_rsa/model/bridge.pb.dart';
+import 'package:fast_rsa/rsa.dart';
+
+class Transaction {}