AES VI

src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/App.xaml.cs

@@ -1,7 +1,9 @@
 using System;
 using SafeMessageStorage.Encryption.Hash.Providers;
+using SafeMessageStorage.Encryption.Symmetric;
 using SafeMessageStorage.Pages;
 using SafeMessageStorage.Services.AuthorizationService;
+using SafeMessageStorage.Services.MessageStorageService;
 using Xamarin.Forms;
 using Xamarin.Forms.Xaml;
 namespace SafeMessageStorage
@@ -12,7 +14,9 @@ namespace SafeMessageStorage
         public App()
         {
             InitializeComponent();
-            MainPage = new NavigationPage(new AuthorizationPage(new AuthorizationService(new Sha256HashProvider())));
+            var authorizationService = new AuthorizationService(new Sha256HashProvider());
+            var messageStorageService = new SafeMessageStorageService(authorizationService, new SymmetricEncryptionEngine());
+            MainPage = new NavigationPage(new AuthorizationPage(authorizationService,messageStorageService));
         }
 
         protected override void OnStart()

src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Encryption/Symmetric/SymmetricEncryptionEngine.cs

@@ -0,0 +1,65 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Security.Cryptography;
+using System.Text;
+
+namespace SafeMessageStorage.Encryption.Symmetric
+{
+    public class SymmetricEncryptionEngine : ISymmetricEncryptionEngine
+    {
+        public string Encrypt(string content, string key)
+        {
+            byte[] iv = new byte[16];
+            byte[] array;
+
+            using (Aes aes = Aes.Create())
+            {
+                aes.Key = Encoding.UTF8.GetBytes(key).Take(16).ToArray();
+                aes.IV = iv;
+
+                ICryptoTransform encryptor = aes.CreateEncryptor(aes.Key, aes.IV);
+
+                using (MemoryStream memoryStream = new MemoryStream())
+                {
+                    using (CryptoStream cryptoStream = new CryptoStream((Stream)memoryStream, encryptor, CryptoStreamMode.Write))
+                    {
+                        using (StreamWriter streamWriter = new StreamWriter((Stream)cryptoStream))
+                        {
+                            streamWriter.Write(content);
+                        }
+
+                        array = memoryStream.ToArray();
+                    }
+                }
+            }
+
+            return Convert.ToBase64String(array);
+        }
+
+        public string Decrypt(string cipher, string key)
+        {
+            byte[] iv = new byte[16];
+            byte[] buffer = Convert.FromBase64String(cipher);
+
+            using (Aes aes = Aes.Create())
+            {
+                aes.Key = Encoding.UTF8.GetBytes(key).Take(16).ToArray();
+                aes.IV = iv;
+                ICryptoTransform decryptor = aes.CreateDecryptor(aes.Key, aes.IV);
+
+                using (MemoryStream memoryStream = new MemoryStream(buffer))
+                {
+                    using (CryptoStream cryptoStream = new CryptoStream((Stream)memoryStream, decryptor, CryptoStreamMode.Read))
+                    {
+                        using (StreamReader streamReader = new StreamReader((Stream)cryptoStream))
+                        {
+                            return streamReader.ReadToEnd();
+                        }
+                    }
+                }
+            }
+        }
+    }
+}

src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Models/Message.cs

@@ -19,13 +19,13 @@ namespace SafeMessageStorage.Models
             
         }
 
-        public string Id { get; }
+        public string Id { get; set; }
 
-        public  string Title { get; }
+        public  string Title { get; set; }
 
-        public string Content { get;  }
+        public string Content { get; set; }
 
-        public DateTimeOffset TimeOfCreation { get; }
+        public DateTimeOffset TimeOfCreation { get; set; }
 
     }
 }

src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Pages/AddMessagePage.xaml.cs

@@ -13,20 +13,38 @@ namespace SafeMessageStorage.Pages
     [XamlCompilation(XamlCompilationOptions.Compile)]
     public partial class AddMessagePage : ContentPage
     {
-        //private IMessageStorageService _messageStorage;
+        private IMessageStorageService _messageStorage;
 
-        public AddMessagePage(/*IMessageStorageService messageStorageService*/)
+        public AddMessagePage(IMessageStorageService messageStorageService)
         {
             InitializeComponent();
+            _messageStorage = messageStorageService;
         }
 
 
         private async void Button_OnClicked(object sender, EventArgs e)
         {
+            if (string.IsNullOrWhiteSpace(TitleEntry.Text))
+            {
+                await DisplayAlert("Message not valid", "Title cannot be empty", "ok");
+                return;
+            }
+            if (string.IsNullOrWhiteSpace(ContentEntry.Text))
+            {
+                await DisplayAlert("Message not valid", "Content cannot be empty", "ok");
+                return;
+            }
+
             var message = new Message(TitleEntry.Text,ContentEntry.Text);
-            //if(await _messageStorage.SaveMessageAsync(message))
+            if (await _messageStorage.SaveMessageAsync(message))
-                MessageAdded?.Invoke(this,message);
+            {
+                MessageAdded?.Invoke(this, message);
                 await Navigation.PopAsync();
+            }
+            else
+            {
+                await DisplayAlert("Failed", "Unable to add message, try again", "ok");
+            }
         }
 
         public event EventHandler<Message> MessageAdded;

src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Pages/AuthorizationPage.xaml.cs

@@ -4,6 +4,7 @@ using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using SafeMessageStorage.Services.AuthorizationService;
+using SafeMessageStorage.Services.MessageStorageService;
 using SafeMessageStorage.ViewModels;
 using Xamarin.Forms;
 using Xamarin.Forms.Xaml;
@@ -15,11 +16,13 @@ namespace SafeMessageStorage.Pages
     {
         private AuthorizationPageViewModel _viewModel => this.BindingContext as AuthorizationPageViewModel;
         private IAuthorizationService _authorizationService;
-        public AuthorizationPage(IAuthorizationService authorizationService)
+        private IMessageStorageService _messageStorage;
+        public AuthorizationPage(IAuthorizationService authorizationService, IMessageStorageService messageStorage)
         {
             InitializeComponent();
             BindingContext = new AuthorizationPageViewModel(authorizationService);
             _authorizationService = authorizationService;
+            _messageStorage = messageStorage;
 
             _viewModel.AuthorizationFailed += _viewModel_AuthorizationFailed;
             _viewModel.AuthorizationSucceeded += _viewModel_AuthorizationSucceeded;
@@ -38,7 +41,7 @@ namespace SafeMessageStorage.Pages
 
         private async void _viewModel_AuthorizationSucceeded(object sender, EventArgs e)
         {
-            await Navigation.PushAsync(new MessagesListPage());
+            await Navigation.PushAsync(new MessagesListPage(_messageStorage));
         }
 
         private async void _viewModel_AuthorizationFailed(object sender, string e)

src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Pages/MessageDetailPage.xaml.cs

@@ -4,6 +4,7 @@ using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using SafeMessageStorage.Models;
+using SafeMessageStorage.Services.MessageStorageService;
 using Xamarin.Forms;
 using Xamarin.Forms.Xaml;
 
@@ -13,12 +14,12 @@ namespace SafeMessageStorage.Pages
     public partial class MessageDetailPage : ContentPage
     {
         private string _messageId;
-
+        private IMessageStorageService _messageStorage;
-        public MessageDetailPage(Message message)
+        public MessageDetailPage(Message message, IMessageStorageService messageStorage)
         {
             InitializeComponent();
             _messageId = message.Id;
-
+            _messageStorage = messageStorage;
             Title = message.Title;
             MessageContent.Text = message.Content;
 
@@ -27,11 +28,10 @@ namespace SafeMessageStorage.Pages
 
         private async void DeleteMessage()
         {
-            MessageDeleted?.Invoke(this,_messageId);
+            if (await _messageStorage.DeleteMessageAsync(_messageId))
-            await Navigation.PopAsync();
+                await Navigation.PopAsync();
+            else
+                await DisplayAlert("Unable to delete messafe", "please try again", "ok");
         }
-
-        public event EventHandler<string> MessageDeleted;
-
     }
 }

src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Pages/MessagesListPage.xaml

@@ -4,7 +4,8 @@
              xmlns:d="http://xamarin.com/schemas/2014/forms/design"
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
              mc:Ignorable="d"
-             x:Class="SafeMessageStorage.Pages.MessagesListPage">
+             x:Class="SafeMessageStorage.Pages.MessagesListPage"
+             Title="Messages">
   <StackLayout>
       <ListView x:Name="MyListView"
                 ItemsSource="{Binding Messages}"

src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Pages/MessagesListPage.xaml.cs

@@ -4,6 +4,7 @@ using System.ComponentModel;
 using System.Linq;
 using System.Threading.Tasks;
 using SafeMessageStorage.Models;
+using SafeMessageStorage.Services.MessageStorageService;
 using Xamarin.Forms;
 using Xamarin.Forms.Xaml;
 
@@ -12,27 +13,37 @@ namespace SafeMessageStorage.Pages
     [XamlCompilation(XamlCompilationOptions.Compile)]
     public partial class MessagesListPage : ContentPage
     {
+        private IMessageStorageService _messageStorage;
+        private bool _initialized;
         public ObservableCollection<Message> Messages { get; set; }
         
-        public MessagesListPage()
+        public MessagesListPage(IMessageStorageService messageStorage)
         {
             InitializeComponent();
-            Messages = new ObservableCollection<Message>()
+            _messageStorage = messageStorage;
-            {
+            Messages = new ObservableCollection<Message>();
-                new Message("Siemano","jakas wiadomosc"),
-                new Message("Kanapka","elo")
-            };
 
             BindingContext = this;
         }
 
+        protected override async void OnAppearing()
+        {
+            base.OnAppearing();
+            Messages.Clear();
+            var messages = await _messageStorage.ReadMessagesAsync();
+            foreach (var message in messages)
+            {
+                Messages.Add(message);
+            }
+        }
+
         async void Handle_ItemTapped(object sender, ItemTappedEventArgs e)
         {
             if (e.Item == null)
                 return;
             var message = ((ListView) sender).SelectedItem as Message;
-            var detailPage = new MessageDetailPage(message);
+            var detailPage = new MessageDetailPage(message, _messageStorage);
-            detailPage.MessageDeleted += (sender, messageId) => OnMessageDeleted(messageId);
+            //detailPage.MessageDeleted += (sender, messageId) => OnMessageDeleted(messageId);
             await Navigation.PushAsync(detailPage);
 
             ////Deselect Item
@@ -41,17 +52,10 @@ namespace SafeMessageStorage.Pages
 
         private async void Button_OnClicked(object sender, EventArgs e)
         {
-            var addMessagePage = new AddMessagePage();
+            var addMessagePage = new AddMessagePage(_messageStorage);
-            addMessagePage.MessageAdded+= (o, message) => Dispatcher.BeginInvokeOnMainThread(()=>Messages.Add(message));
+            //addMessagePage.MessageAdded+= (o, message) => Dispatcher.BeginInvokeOnMainThread(()=>Messages.Add(message));
 
             await Navigation.PushAsync(addMessagePage);
         }
-
-
-        private void OnMessageDeleted(string messageId)
-        {
-            var toRemove = Messages.FirstOrDefault(m => m.Id == messageId);
-            Messages.Remove(toRemove);
-        }
     }
 }

src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Services/MessageStorageService/SafeMessageStorageService.cs

@@ -16,6 +16,12 @@ namespace SafeMessageStorage.Services.MessageStorageService
         private ISymmetricEncryptionEngine _encryptionEngine;
         private readonly string _messagesKey = "377f2486-d2c3-48a7-b821-45d7314479cd";
 
+        public SafeMessageStorageService(IAuthorizationService authorizationService, ISymmetricEncryptionEngine encryptionEngine)
+        {
+            _authorizationService = authorizationService;
+            _encryptionEngine = encryptionEngine;
+        }
+
         public bool IsStorageEmpty => Xamarin.Essentials.SecureStorage.GetAsync(_messagesKey).Result != null;
 
         public async Task<bool> SaveMessageAsync(Message message)
@@ -34,10 +40,10 @@ namespace SafeMessageStorage.Services.MessageStorageService
             CheckIfAuthorized();
             var encryptedMessage =await Xamarin.Essentials.SecureStorage.GetAsync(_messagesKey);
             if (encryptedMessage == null)
-                return null;
+                return new List<Message>();
 
             var decryptedMessage = _encryptionEngine.Decrypt(encryptedMessage, _authorizationService.AuthorizedUserHash);
-            return JsonConvert.DeserializeObject<List<Message>>(decryptedMessage);
+            return JsonConvert.DeserializeObject<List<Message>>(decryptedMessage).Where(x=>x.Id!=null);
         }
 
         public async Task<bool> DeleteMessageAsync(string messageId)