✨ File encryption

✨ Shared login status across sites

DysonNetwork.Drive/Storage/FileEncryptor.cs

@@ -0,0 +1,60 @@
+using System.Security.Cryptography;
+
+namespace DysonNetwork.Drive.Storage;
+
+public static class FileEncryptor
+{
+    public static void EncryptFile(string inputPath, string outputPath, string password)
+    {
+        var salt = RandomNumberGenerator.GetBytes(16);
+        var key = DeriveKey(password, salt, 32);
+        var nonce = RandomNumberGenerator.GetBytes(12); // For AES-GCM
+
+        using var aes = new AesGcm(key, 16); // Specify 16-byte tag size explicitly
+        var plaintext = File.ReadAllBytes(inputPath);
+        var magic = "DYSON1"u8.ToArray();
+        var contentWithMagic = new byte[magic.Length + plaintext.Length];
+        Buffer.BlockCopy(magic, 0, contentWithMagic, 0, magic.Length);
+        Buffer.BlockCopy(plaintext, 0, contentWithMagic, magic.Length, plaintext.Length);
+
+        var ciphertext = new byte[contentWithMagic.Length];
+        var tag = new byte[16];
+        aes.Encrypt(nonce, contentWithMagic, ciphertext, tag);
+
+        // Save as: [salt (16)][nonce (12)][tag (16)][ciphertext]
+        using var fs = new FileStream(outputPath, FileMode.Create, FileAccess.Write);
+        fs.Write(salt);
+        fs.Write(nonce);
+        fs.Write(tag);
+        fs.Write(ciphertext);
+    }
+
+    public static void DecryptFile(string inputPath, string outputPath, string password)
+    {
+        var input = File.ReadAllBytes(inputPath);
+
+        var salt = input[..16];
+        var nonce = input[16..28];
+        var tag = input[28..44];
+        var ciphertext = input[44..];
+
+        var key = DeriveKey(password, salt, 32);
+        var decrypted = new byte[ciphertext.Length];
+
+        using var aes = new AesGcm(key, 16); // Specify 16-byte tag size explicitly
+        aes.Decrypt(nonce, ciphertext, tag, decrypted);
+
+        var magic = "DYSON1"u8.ToArray();
+        if (magic.Where((t, i) => decrypted[i] != t).Any())
+            throw new CryptographicException("Incorrect password or corrupted file.");
+
+        var plaintext = decrypted[magic.Length..];
+        File.WriteAllBytes(outputPath, plaintext);
+    }
+
+    private static byte[] DeriveKey(string password, byte[] salt, int keyBytes)
+    {
+        using var pbkdf2 = new Rfc2898DeriveBytes(password, salt, 100_000, HashAlgorithmName.SHA256);
+        return pbkdf2.GetBytes(keyBytes);
+    }
+}