feat(infra): create initial encryption implementations

src/FiscalOS.Infra/Security/FileKeyRing.cs

@@ -0,0 +1,90 @@
+
+namespace FiscalOS.Infra.Security;
+
+public sealed class FileKeyRing : IKeyRing, IDisposable
+{
+  private const string KeyFileExtension = ".key";
+  private FileKeyRingOptions _options;
+  private readonly IFileSystem _fileSystem;
+  private readonly IDisposable? _optionsChangeHandler;
+  private readonly Dictionary<string, KeyRingEntry> _keys = [];
+  private string KeyRingPath => _fileSystem.Path.GetFullPath(_options.KeysDirectoryPath, AppContext.BaseDirectory);
+
+  private FileKeyRing(IOptionsMonitor<FileKeyRingOptions> options, IFileSystem fileSystem)
+  {
+    _fileSystem = fileSystem;
+    _options = options.CurrentValue;
+
+    LoadKeys();
+
+    _optionsChangeHandler = options.OnChange(options =>
+    {
+      _options = options;
+      LoadKeys();
+    });
+  }
+
+  public static FileKeyRing From(IServiceProvider serviceProvider)
+  {
+    var options = serviceProvider.GetRequiredService<IOptionsMonitor<FileKeyRingOptions>>();
+    var fileSystem = serviceProvider.GetRequiredService<IFileSystem>();
+
+    return new(options, fileSystem);
+  }
+
+  public static FileKeyRing From(IOptionsMonitor<FileKeyRingOptions> options, IFileSystem fileSystem)
+  {
+    return new(options, fileSystem);
+  }
+
+  public KeyRingEntry GetKey(string keyId)
+  {
+    if (_keys.TryGetValue(keyId, out var key))
+    {
+      return key;
+    }
+
+    throw new KeyNotFoundException($"Key with ID '{keyId}' not found in the key ring.");
+  }
+
+  public KeyRingEntry GetPrimaryKey()
+  {
+    return GetKey(_options.PrimaryKeyId);
+  }
+
+  private void LoadKeys()
+  {
+    _keys.Clear();
+
+    if (_fileSystem.Directory.Exists(KeyRingPath))
+    {
+      var keyFiles = _fileSystem.Directory.GetFiles(KeyRingPath, $"*{KeyFileExtension}");
+
+      foreach (var keyFile in keyFiles)
+      {
+        var keyId = _fileSystem.Path.GetFileNameWithoutExtension(keyFile);
+        var key = _fileSystem.File.ReadAllText(keyFile).Trim();
+
+        if (string.IsNullOrEmpty(key) is false)
+        {
+          _keys[keyId] = KeyRingEntry.From(keyId, key);
+        }
+      }
+    }
+  }
+
+  public void Dispose()
+  {
+    _optionsChangeHandler?.Dispose();
+  }
+
+  public async Task<KeyRingEntry> SaveKeyAsync(string key)
+  {
+    var id = Guid.NewGuid().ToString();
+    var entry = KeyRingEntry.From(id, key);
+    var filename = id + KeyFileExtension;
+    var entryPath = _fileSystem.Path.Combine(KeyRingPath, filename);
+    await _fileSystem.File.WriteAllTextAsync(entryPath, key).ConfigureAwait(false);
+    return entry;
+  }
+}