From 390fd66d978f981e3449b874ada90b8b07aba318 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bartosz=20Chy=C5=BCy?= <chyzybartosz@gmail.com>
Date: Sun, 7 Jun 2020 15:19:24 +0200
Subject: [PATCH] MessageStore

---
 .../Symmetric/ISymmetricEncryptionEngine.cs   | 13 +++++
 .../Pages/AuthorizationPage.xaml              |  4 +-
 .../SafeMessageStorage.csproj                 |  2 +-
 .../AuthorizationService.cs                   | 13 +++--
 .../AuthorizationServiceMOCK.cs               |  7 +--
 .../IAuthorizationService.cs                  |  8 +--
 .../IMessageStorageService.cs                 | 11 ++--
 .../SafeMessageStorageService.cs              | 51 +++++++++++++++++++
 .../ViewModels/AuthorizationPageViewModel.cs  |  2 +-
 .../ViewModels/SetPasswordPageViewModel.cs    |  2 +-
 10 files changed, 91 insertions(+), 22 deletions(-)
 create mode 100644 src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Encryption/Symmetric/ISymmetricEncryptionEngine.cs
 create mode 100644 src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Services/MessageStorageService/SafeMessageStorageService.cs

diff --git a/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Encryption/Symmetric/ISymmetricEncryptionEngine.cs b/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Encryption/Symmetric/ISymmetricEncryptionEngine.cs
new file mode 100644
index 0000000..b3fb700
--- /dev/null
+++ b/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Encryption/Symmetric/ISymmetricEncryptionEngine.cs
@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace SafeMessageStorage.Encryption.Symmetric
+{
+    public interface ISymmetricEncryptionEngine
+    {
+        string Encrypt(string content, string key);
+
+        string Decrypt(string cipher, string key);
+    }
+}
diff --git a/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Pages/AuthorizationPage.xaml b/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Pages/AuthorizationPage.xaml
index 6839fc5..ba7db68 100644
--- a/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Pages/AuthorizationPage.xaml
+++ b/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Pages/AuthorizationPage.xaml
@@ -5,7 +5,7 @@
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
              mc:Ignorable="d"
              x:Class="SafeMessageStorage.Pages.AuthorizationPage"
-             Title="Authorize">
+             Title="AuthorizeAsync">
     <ContentPage.Content>
         <StackLayout VerticalOptions="CenterAndExpand" Padding="40">
             <Label Text="Enter your security code"
@@ -14,7 +14,7 @@
             <Label x:Name="ErrorMessageLabel"
                    TextColor="#d22"
                    Margin="0,10" HorizontalOptions="Center"/>
-            <Button Text="Authorize" Command="{Binding AuthorizeCommand}"/>
+            <Button Text="AuthorizeAsync" Command="{Binding AuthorizeCommand}"/>
         </StackLayout>
     </ContentPage.Content>
 </ContentPage>
\ No newline at end of file
diff --git a/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage.csproj b/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage.csproj
index 992183c..ee655dd 100644
--- a/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage.csproj
+++ b/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage.csproj
@@ -6,12 +6,12 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="Newtonsoft.Json" Version="12.0.3" />
     <PackageReference Include="Xamarin.Forms" Version="4.6.0.847" />  
     <PackageReference Include="Xamarin.Essentials" Version="1.3.1" />
   </ItemGroup>
 
   <ItemGroup>
-    <Folder Include="Encryption\Symmetric\" />
     <Folder Include="Views\" />
   </ItemGroup>
 
diff --git a/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Services/AuthorizationService/AuthorizationService.cs b/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Services/AuthorizationService/AuthorizationService.cs
index 635bb5d..193a9f3 100644
--- a/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Services/AuthorizationService/AuthorizationService.cs
+++ b/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Services/AuthorizationService/AuthorizationService.cs
@@ -8,7 +8,7 @@ namespace SafeMessageStorage.Services.AuthorizationService
 {
     public class AuthorizationService : IAuthorizationService
     {
-        private readonly string _passwordKey = "passwordGUID";
+        private readonly string _passwordKey = "86d9ee32-c00e-4b18-bb1b-a4f7d9e23ec9";
         private readonly IHashProvider _hashProvider;
 
         public AuthorizationService(IHashProvider hashProvider)
@@ -17,22 +17,27 @@ namespace SafeMessageStorage.Services.AuthorizationService
         }
 
         public bool IsAuthorized { get; private set; }
+
+        public string AuthorizedUserHash { get; private set; }
+
         public bool IsPasswordSet => Xamarin.Essentials.SecureStorage.GetAsync(_passwordKey).Result != null;
-        public async Task<bool> Authorize(string password)
+        public async Task<bool> AuthorizeAsync(string password)
         {
             var keyChainPassword = await Xamarin.Essentials.SecureStorage.GetAsync(_passwordKey);
             var result = keyChainPassword?.Equals(_hashProvider.GetHashString(password)) ?? false;
             IsAuthorized = result;
+            AuthorizedUserHash = IsAuthorized ? keyChainPassword : null;
             return result;
         }
 
-        public Task<bool> Deauthorize()
+        public Task<bool> DeauthorizeAsync()
         {
             IsAuthorized = false;
+            AuthorizedUserHash = null;
             return Task.FromResult(true);
         }
 
-        public async Task<bool> ChangePassword(string currentPassword, string newPassword)
+        public async Task<bool> ChangePasswordAsync(string currentPassword, string newPassword)
         {
             var keyChainPassword = await Xamarin.Essentials.SecureStorage.GetAsync(_passwordKey);
             var passwordMatch = keyChainPassword?.Equals(_hashProvider.GetHashString(currentPassword)) ?? true;
diff --git a/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Services/AuthorizationService/AuthorizationServiceMOCK.cs b/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Services/AuthorizationService/AuthorizationServiceMOCK.cs
index a0d3b63..f611fd2 100644
--- a/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Services/AuthorizationService/AuthorizationServiceMOCK.cs
+++ b/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Services/AuthorizationService/AuthorizationServiceMOCK.cs
@@ -8,18 +8,19 @@ namespace SafeMessageStorage.Services.AuthorizationService
     public class AuthorizationServiceMOCK : IAuthorizationService
     {
         public bool IsAuthorized => false;
+        public string AuthorizedUserHash => "kanapka";
         public bool IsPasswordSet => false;
-        public Task<bool> Authorize(string password)
+        public Task<bool> AuthorizeAsync(string password)
         {
             return Task.FromResult(false);
         }
 
-        public Task<bool> Deauthorize()
+        public Task<bool> DeauthorizeAsync()
         {
             throw new NotImplementedException();
         }
 
-        public Task<bool> ChangePassword(string currentPassword, string newPassword)
+        public Task<bool> ChangePasswordAsync(string currentPassword, string newPassword)
         {
             return Task.FromResult(true);
         }
diff --git a/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Services/AuthorizationService/IAuthorizationService.cs b/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Services/AuthorizationService/IAuthorizationService.cs
index c451ad3..c23332e 100644
--- a/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Services/AuthorizationService/IAuthorizationService.cs
+++ b/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Services/AuthorizationService/IAuthorizationService.cs
@@ -9,12 +9,14 @@ namespace SafeMessageStorage.Services.AuthorizationService
     {
         bool IsAuthorized { get; }
 
+        string AuthorizedUserHash { get; }
+
         bool IsPasswordSet { get; }
 
-        Task<bool> Authorize(string password);
+        Task<bool> AuthorizeAsync(string password);
 
-        Task<bool> Deauthorize();
+        Task<bool> DeauthorizeAsync();
 
-        Task<bool> ChangePassword(string currentPassword, string newPassword);
+        Task<bool> ChangePasswordAsync(string currentPassword, string newPassword);
     }
 }
diff --git a/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Services/MessageStorageService/IMessageStorageService.cs b/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Services/MessageStorageService/IMessageStorageService.cs
index e11f469..588a9b5 100644
--- a/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Services/MessageStorageService/IMessageStorageService.cs
+++ b/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Services/MessageStorageService/IMessageStorageService.cs
@@ -8,15 +8,12 @@ namespace SafeMessageStorage.Services.MessageStorageService
 {
     public interface IMessageStorageService
     {
-        Task<bool> IsStorageEmpty { get; }
-
-        Task<bool> SaveMessage(Message message);
-
-        Task<Message> ReadMessage();
-
-        Task<bool> DeleteMessage();
+        bool IsStorageEmpty { get; }
 
+        Task<bool> SaveMessageAsync(Message message);
 
+        Task<Message> ReadMessageAsync();
 
+        Task<bool> DeleteMessageAsync();
     }
 }
diff --git a/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Services/MessageStorageService/SafeMessageStorageService.cs b/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Services/MessageStorageService/SafeMessageStorageService.cs
new file mode 100644
index 0000000..2703e8a
--- /dev/null
+++ b/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/Services/MessageStorageService/SafeMessageStorageService.cs
@@ -0,0 +1,51 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Threading.Tasks;
+using Newtonsoft.Json;
+using SafeMessageStorage.Encryption.Symmetric;
+using SafeMessageStorage.Models;
+using SafeMessageStorage.Services.AuthorizationService;
+
+namespace SafeMessageStorage.Services.MessageStorageService
+{
+    public class SafeMessageStorageService : IMessageStorageService
+    {
+        private IAuthorizationService _authorizationService;
+        private ISymmetricEncryptionEngine _encryptionEngine;
+        private readonly string _messageKey = "377f2486-d2c3-48a7-b821-45d7314479cd";
+
+        public bool IsStorageEmpty => Xamarin.Essentials.SecureStorage.GetAsync(_messageKey).Result != null;
+
+        public async Task<bool> SaveMessageAsync(Message message)
+        {
+            CheckIfAuthorized();
+            var encrypyedMessage = _encryptionEngine.Encrypt(JsonConvert.SerializeObject(message), _authorizationService.AuthorizedUserHash);
+            await Xamarin.Essentials.SecureStorage.SetAsync(_messageKey, encrypyedMessage);
+            return true;
+        }
+
+        public async Task<Message> ReadMessageAsync()
+        {
+            CheckIfAuthorized();
+            var encryptedMessage =await Xamarin.Essentials.SecureStorage.GetAsync(_messageKey);
+            if (encryptedMessage == null)
+                return null;
+
+            var decryptedMessage = _encryptionEngine.Decrypt(encryptedMessage, _authorizationService.AuthorizedUserHash);
+            return JsonConvert.DeserializeObject<Message>(decryptedMessage);
+        }
+
+        public async Task<bool> DeleteMessageAsync()
+        {
+            CheckIfAuthorized();
+            return Xamarin.Essentials.SecureStorage.Remove(_messageKey);
+        }
+
+        private void CheckIfAuthorized()
+        {
+            if(!_authorizationService.IsAuthorized)
+                throw new UnauthorizedAccessException();
+        }
+    }
+}
diff --git a/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/ViewModels/AuthorizationPageViewModel.cs b/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/ViewModels/AuthorizationPageViewModel.cs
index ad48825..ccb894c 100644
--- a/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/ViewModels/AuthorizationPageViewModel.cs
+++ b/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/ViewModels/AuthorizationPageViewModel.cs
@@ -42,7 +42,7 @@ namespace SafeMessageStorage.ViewModels
 
         private async Task Authorize(string code)
         {
-            if (await _authorizationService.Authorize(code))
+            if (await _authorizationService.AuthorizeAsync(code))
                 AuthorizationSucceeded?.Invoke(this, EventArgs.Empty);
             else
             {
diff --git a/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/ViewModels/SetPasswordPageViewModel.cs b/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/ViewModels/SetPasswordPageViewModel.cs
index 4cdcde2..7884be7 100644
--- a/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/ViewModels/SetPasswordPageViewModel.cs
+++ b/src/SafeMessageStorage/SafeMessageStorage/SafeMessageStorage/ViewModels/SetPasswordPageViewModel.cs
@@ -43,7 +43,7 @@ namespace SafeMessageStorage.ViewModels
             }
             else
             {
-               if(await _authorizationService.ChangePassword(null, password)) 
+               if(await _authorizationService.ChangePasswordAsync(null, password)) 
                    PasswordSetSucceeded?.Invoke(this,EventArgs.Empty);
             }
         }