From 8e2a30647b9f8dd683b25f39278a09968effcde2 Mon Sep 17 00:00:00 2001
From: Zachary Atkins <atkins12@llnl.gov>
Date: Sat, 10 Apr 2021 15:26:38 -0500
Subject: [PATCH 1/2] added cached keypair to manager

---
 loc_chain_app/lib/util/keyfile_manager.dart | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/loc_chain_app/lib/util/keyfile_manager.dart b/loc_chain_app/lib/util/keyfile_manager.dart
index 97c2136..85bb962 100644
--- a/loc_chain_app/lib/util/keyfile_manager.dart
+++ b/loc_chain_app/lib/util/keyfile_manager.dart
@@ -3,6 +3,8 @@ import 'package:path_provider/path_provider.dart';
 import 'dart:io';
 
 class KeyFileManager {
+  static KeyPair keyPair = KeyPair();
+
   static Future<String> get _localPath async {
     final directory = await getApplicationDocumentsDirectory();
     return directory.path;
@@ -19,6 +21,9 @@ class KeyFileManager {
   }
 
   static Future<KeyPair> readKeyPair() async {
+    if (keyPair.hasPublicKey() && keyPair.hasPrivateKey()) {
+      return keyPair;
+    }
     try {
       String privKey = await _privKeyFile.then(
         (file) => file.readAsString(),
@@ -26,11 +31,11 @@ class KeyFileManager {
       String pubKey = await _pubKeyFile.then(
         (file) => file.readAsString(),
       );
-
-      return KeyPair(
+      keyPair = KeyPair(
         privateKey: privKey,
         publicKey: pubKey,
       );
+      return keyPair;
     } catch (e) {
       print(e);
       return KeyPair();
@@ -38,9 +43,10 @@ class KeyFileManager {
   }
 
   static Future<void> writeKeyPair(KeyPair pair) async {
+    keyPair = pair;
     final File privKeyFile = await _privKeyFile;
     final File pubKeyFile = await _pubKeyFile;
-    pubKeyFile.writeAsString(pair.publicKey);
-    privKeyFile.writeAsString(pair.privateKey);
+    pubKeyFile.writeAsString(keyPair.publicKey);
+    privKeyFile.writeAsString(keyPair.privateKey);
   }
 }

From a7c7133d4f685fec6b9270dec067ec80d09e2769 Mon Sep 17 00:00:00 2001
From: Zachary Atkins <atkins12@llnl.gov>
Date: Sat, 10 Apr 2021 15:26:51 -0500
Subject: [PATCH 2/2] implemented hashing

---
 loc_chain_app/lib/util/transaction_manager.dart | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/loc_chain_app/lib/util/transaction_manager.dart b/loc_chain_app/lib/util/transaction_manager.dart
index 9bfee07..659fc0a 100644
--- a/loc_chain_app/lib/util/transaction_manager.dart
+++ b/loc_chain_app/lib/util/transaction_manager.dart
@@ -3,15 +3,25 @@ import 'package:shared_preferences/shared_preferences.dart';
 import 'package:sqflite/sqflite.dart';
 import 'package:fast_rsa/rsa.dart';
 
+import 'package:loc_chain_app/util/keyfile_manager.dart';
+
 import 'dart:io';
 
 class Transaction {
-  Transaction({required this.otherUserID}) {
+  Transaction({required this.hash}) {
     SharedPreferences.getInstance().then((s) => _id = s.getString('id') ?? '0');
   }
   late final String _id;
-  final String otherUserID;
-  static Hash? makeTransactionHash() {}
+  final String hash;
+  static Future<String> makeTransactionHash(String otherUserId) async {
+    String id = await SharedPreferences.getInstance()
+        .then((s) => s.getString('id') ?? '');
+    bool idLess = id.compareTo(otherUserId) < 0;
+    var lesser = idLess ? id : otherUserId;
+    var greater = idLess ? otherUserId : id;
+    return RSA.signPKCS1v15("$lesser-$greater", Hash.HASH_SHA256,
+        KeyFileManager.keyPair.privateKey);
+  }
 }
 
 class TransactionsDBManager {