feat: Add NostrKeyValidAttribute for validating Nostr Key format

This commit adds a new file `NostrKeyValidAttribute.cs` which contains an attribute class for validating the Nostr Key format. The validation logic is implemented in the `IsValid` method of this class. This change also includes modifications to the `User` model to add properties for storing public and private keys, and updates to the `LoginViewModel` to validate the account key using this new attribute.

Additionally, there are changes made to localization files, database service, and view models related to user authentication.

src/NuSocial/Core/Validation/NostrKeyValidAttribute.cs

@@ -0,0 +1,76 @@
+using Microsoft.Extensions.Localization;
+using Nostr.Client.Keys;
+using NuSocial.Localization;
+using System.ComponentModel.DataAnnotations;
+
+namespace NuSocial.Core.Validation
+{
+    /// <summary>
+    /// Attribute class for validating Nostr Key format.
+    /// </summary>
+    public sealed class NostrKeyValidAttribute : ValidationAttribute
+    {
+        /// <inheritdoc/>
+        protected override ValidationResult IsValid(object? value, ValidationContext validationContext)
+        {
+            if (validationContext is null)
+            {
+                throw new ArgumentNullException(nameof(validationContext));
+            }
+
+            var instance = validationContext.ObjectInstance;
+            var loc = (IStringLocalizer<NuSocialResource>?)instance.GetType().GetProperty("L")?.GetValue(instance);
+            var invalidMessage = loc?["InvalidNostrKey"] ?? "Invalid Key";
+
+            if (value is string valueString && !string.IsNullOrEmpty(valueString))
+            {
+                bool isValid = false;
+
+                if (valueString.StartsWith("npub", StringComparison.OrdinalIgnoreCase))
+                {
+                    try
+                    {
+                        _ = NostrPublicKey.FromBech32(valueString);
+                        isValid = true;
+                    }
+                    catch (ArgumentException) { }
+                }
+                else if (valueString.StartsWith("nsec", StringComparison.OrdinalIgnoreCase))
+                {
+                    try
+                    {
+                        _ = NostrPrivateKey.FromBech32(valueString);
+                        isValid = true;
+                    }
+                    catch (ArgumentException) { }
+                }
+                else
+                {
+                    try
+                    {
+                        _ = NostrPublicKey.FromHex(valueString);
+                        isValid = true;
+                    }
+                    catch (ArgumentException) { }
+
+                    if (!isValid)
+                    {
+                        try
+                        {
+                            _ = NostrPrivateKey.FromHex(valueString);
+                            isValid = true;
+                        }
+                        catch (ArgumentException) { }
+                    }
+                }
+
+                if (!isValid)
+                {
+                    return new(invalidMessage);
+                }
+            }
+
+            return ValidationResult.Success!;
+        }
+    }
+}

src/NuSocial/Localization/NuSocial/en.json

@@ -15,6 +15,7 @@
     "AboutPlaceholder": "Add something interesting about you ..",
     "AccountId": "Account ID",
     "AccountKeyPlaceholder": "nsec1...",
-    "NuSocial": "NuSocial"
+    "NuSocial": "NuSocial",
+    "TapToRegenerate": "Tap to regenerate"
   }
 }

src/NuSocial/Models/User.cs

@@ -1,19 +1,41 @@
-namespace NuSocial.Models;
+using Nostr.Client.Keys;
+using SQLite;
+
+namespace NuSocial.Models;
 
 public class User
 {
+    [Ignore]
+    public NostrPublicKey? PublicKey { get; set; }
+
+    [Ignore]
+    public NostrPrivateKey? PrivateKey { get; set; }
+
+    public string PublicKeyString
+    {
+        get => PublicKey?.Bech32 ?? string.Empty;
+        set => PublicKey = NostrPublicKey.FromBech32(value);
+    }
 
+    public string PrivateKeyString
+    {
+        get => PrivateKey?.Bech32 ?? string.Empty;
+        set => PrivateKey = NostrPrivateKey.FromBech32(value);
+    }
+
+    public bool IsReadOnly => PublicKey != null && PrivateKey == null;
 }
 
 public class AuthenticateResult
 {
-
+    public NostrKeyPair KeyPair { get; set; }
 }
 
 public class AuthenticateRequest
 {
 
 }
+
 public class UserConfiguration
 {
 

src/NuSocial/NuSocial.csproj

@@ -85,6 +85,11 @@
 		<framework>Flyout</framework>
 	</PropertyGroup>
 
+	<PropertyGroup Condition="'$(TargetFramework)'=='net7.0-ios'">
+	  <CodesignKey>Apple Development: Created via API (45692F9U2L)</CodesignKey>
+	  <CodesignProvision>VS: WildCard Development</CodesignProvision>
+	</PropertyGroup>
+
 	<ItemGroup>
 		<Content Remove="C:\Users\byter\.nuget\packages\secp256k1.native\0.1.24-alpha\build\netstandard1.0\..\..\runtimes\win-x64\native\secp256k1.dll" />
 	</ItemGroup>

src/NuSocial/Services/LocalStorage.cs

@@ -15,9 +15,9 @@ public interface IDatabase
     {
         Task DeleteAllDataAsync();
 
-        //Task<ObservableCollection<DataElement>> GetDataElementsAsync();
+        Task<ObservableCollection<User>> GetUsersAsync();
 
-        //Task UpdateDataElementsAsync(ObservableCollection<DataElement> dataElements);
+        Task UpdateUsersAsync(ObservableCollection<User> users);
     }
 
     /// <summary>
@@ -135,10 +135,10 @@ public async ValueTask DisposeAsync()
             GC.SuppressFinalize(this);
         }
 
-        ///// <summary>
-        ///// Gets data elements from the database.
-        ///// </summary>
-        //public Task<ObservableCollection<DataElement>> GetDataElementsAsync() => GetItemsAsync<DataElement>();
+        /// <summary>
+        /// Gets data elements from the database.
+        /// </summary>
+        public Task<ObservableCollection<User>> GetUsersAsync() => GetItemsAsync<User>();
 
         public async Task<ObservableCollection<T>> GetItemsAsync<T>(Action? reset = null) where T : class, new()
         {
@@ -155,10 +155,10 @@ public async ValueTask DisposeAsync()
             }
         }
 
-        ///// <summary>
-        ///// Updates data elements in the database.
-        ///// </summary>
-        //public Task UpdateDataElementsAsync(ObservableCollection<DataElement> dataElements) => UpdateIfPossible(dataElements);
+        /// <summary>
+        /// Updates data elements in the database.
+        /// </summary>
+        public Task UpdateUsersAsync(ObservableCollection<User> users) => UpdateIfPossible(users);
 
         protected virtual async Task DisposeAsync(bool disposing)
         {

src/NuSocial/ViewModels/LoginViewModel.cs

@@ -1,24 +1,60 @@
-using NuSocial.Core.ViewModel;
+using CommunityToolkit.Mvvm.Messaging;
+using Nostr.Client.Keys;
+using NuSocial.Core.Validation;
+using NuSocial.Core.ViewModel;
+using NuSocial.Messages;
+using System.ComponentModel.DataAnnotations;
 using Volo.Abp.DependencyInjection;
 
 namespace NuSocial.ViewModels;
 
 public partial class LoginViewModel : BaseFormModel, ITransientDependency
 {
+    private readonly IDatabase _db;
+
+    [Required]
     [ObservableProperty]
     [NotifyPropertyChangedFor(nameof(IsAccountKeyValid))]
+    [NostrKeyValid]
     private string _accountKey = string.Empty;
 
-    public LoginViewModel(IDialogService dialogService, INavigationService navigationService) : base(dialogService, navigationService)
+    public LoginViewModel(IDialogService dialogService, INavigationService navigationService, IDatabase db) : base(dialogService, navigationService)
     {
         Title = L["Login"];
+        _db = db;
     }
 
     public bool IsAccountKeyValid => !string.IsNullOrEmpty(AccountKey);
 
     [RelayCommand(CanExecute = nameof(IsNotBusy))]
     private Task LoginAsync()
     {
-        return SetBusyAsync(() => { return Task.CompletedTask; });
+        return SetBusyAsync(() =>
+        {
+            return ValidateAsync(async (isValid) =>
+            {
+                if (isValid)
+                {
+                    if (AccountKey.StartsWith("npub", StringComparison.OrdinalIgnoreCase))
+                    {
+                        var pubKey = NostrPublicKey.FromBech32(AccountKey);
+
+                        var user = new User() { PublicKey = pubKey };
+                        await _db.UpdateUsersAsync(new ObservableCollection<User> { user });
+                        await Navigation.NavigateTo("//main", user);
+                    }
+                    else
+                    {
+                        var privKey = NostrPrivateKey.FromBech32(AccountKey);
+                        var pubKeyEc = privKey.Ec.CreateXOnlyPubKey();
+                        var pubKey = NostrPublicKey.FromEc(pubKeyEc);
+
+                        var user = new User() { PublicKey = pubKey, PrivateKey = privKey };
+                        await _db.UpdateUsersAsync(new ObservableCollection<User> { user });
+                        await Navigation.NavigateTo("//main", user);
+                    }
+                }
+            }, async () => await ShowErrorsCommand.ExecuteAsync(null));
+        });
     }
 }

src/NuSocial/ViewModels/MainViewModel.cs

@@ -1,11 +1,35 @@
-using NuSocial.Core.ViewModel;
+using CommunityToolkit.Mvvm.Messaging;
+using NuSocial.Core.ViewModel;
+using NuSocial.Messages;
 using Volo.Abp.DependencyInjection;
 
 namespace NuSocial.ViewModels;
 
 public partial class MainViewModel : BaseViewModel, ITransientDependency
 {
+    [ObservableProperty]
+    private User? _user;
+
     public MainViewModel(IDialogService dialogService, INavigationService navigationService) : base(dialogService, navigationService)
     {
     }
+
+    public override Task OnFirstAppear()
+    {
+        WeakReferenceMessenger.Default.Send<ResetNavMessage>(new());
+        return Task.CompletedTask;
+    }
+
+    public override Task OnParameterSet()
+    {
+        return SetBusyAsync(() =>
+        {
+            if (NavigationParameter is User user)
+            {
+                User = user;
+            }
+
+            return Task.CompletedTask;
+        });
+    }
 }

src/NuSocial/ViewModels/RegisterViewModel.cs

@@ -1,4 +1,5 @@
 using CommunityToolkit.Mvvm.Messaging;
+using Nostr.Client.Keys;
 using NuSocial.Core.ViewModel;
 using NuSocial.Messages;
 using System.ComponentModel.DataAnnotations;
@@ -24,14 +25,27 @@ public RegisterViewModel(IDialogService dialogService, INavigationService naviga
     private string? _about;
 
     [ObservableProperty]
-    private string _accountId = "123";
+    private string _publicKey = string.Empty;
+
+    [ObservableProperty]
+    private string _privateKey = string.Empty;
 
     public override Task OnFirstAppear()
     {
+        GenerateKeyPair();
+
         WeakReferenceMessenger.Default.Send<ResetNavMessage>(new("//start"));
         return Task.CompletedTask;
     }
 
+    private void GenerateKeyPair()
+    {
+        var keyPair = NostrKeyPair.GenerateNew();
+
+        PublicKey = keyPair.PublicKey.Bech32;
+        PrivateKey = keyPair.PrivateKey.Bech32;
+    }
+
     [RelayCommand(CanExecute = nameof(IsNotBusy))]
     private Task CreateAsync()
     {
@@ -44,4 +58,14 @@ private Task CreateAsync()
             }, async () => await ShowErrorsCommand.ExecuteAsync(null));
         });
     }
+
+    [RelayCommand(CanExecute = nameof(IsNotBusy))]
+    private Task RegenerateAsync()
+    {
+        return SetBusyAsync(() =>
+        {
+            GenerateKeyPair();
+            return Task.CompletedTask;
+        });
+    }
 }

src/NuSocial/Views/LoginView.xaml

@@ -23,9 +23,10 @@
         <Button
             Grid.Row="2"
             Margin="0,10"
+            Command="{Binding LoginCommand}"
             HeightRequest="50"
             MaximumWidthRequest="200"
-            Text="Login"
+            Text="{loc:Translate Login}"
             VerticalOptions="Start" />
     </Grid>
 </base:ContentPageFormBase>

src/NuSocial/Views/MainView.xaml

@@ -6,10 +6,8 @@
     xmlns:base="clr-namespace:NuSocial.Core.View"
     xmlns:loc="clr-namespace:NuSocial.Helpers"
     xmlns:viewModels="clr-namespace:NuSocial.ViewModels"
-    Title="{Binding Title}"
     x:DataType="viewModels:MainViewModel"
-    x:TypeArguments="viewModels:MainViewModel"
-    Shell.NavBarIsVisible="False">
+    x:TypeArguments="viewModels:MainViewModel">
     <VerticalStackLayout>
         <Label
             HorizontalOptions="Center"

src/NuSocial/Views/RegisterView.xaml

@@ -33,7 +33,7 @@
                     <toolkit:GravatarImageSource
                         CacheValidity="1"
                         CachingEnabled="True"
-                        Email="{Binding AccountId}"
+                        Email="{Binding PublicKey}"
                         Image="Robohash" />
                 </Image.Source>
             </Image>
@@ -123,11 +123,23 @@
             Padding="10,0,0,0"
             RowDefinitions="Auto,Auto"
             RowSpacing="5">
-            <Label FontAttributes="Bold" Text="{loc:Translate AccountId}" />
+            <HorizontalStackLayout>
+                <Label FontAttributes="Bold" Text="{loc:Translate AccountId}" />
+                <Label
+                    Margin="5,0"
+                    FontSize="10"
+                    Text="{loc:Translate TapToRegenerate,
+                                         StringFormat='({0})'}"
+                    VerticalTextAlignment="Center" />
+            </HorizontalStackLayout>
             <Label
                 Grid.Row="1"
-                Text="{Binding AccountId}"
-                VerticalOptions="Center" />
+                Text="{Binding PublicKey}"
+                VerticalOptions="Center">
+                <Label.GestureRecognizers>
+                    <TapGestureRecognizer Command="{Binding RegenerateCommand}" />
+                </Label.GestureRecognizers>
+            </Label>
         </Grid>
 
         <Button