bunch of fixes

Toolkit.Foundation/AesEncryptor.cs

@@ -0,0 +1,34 @@
+using System.Security.Cryptography;
+
+namespace Toolkit.Foundation;
+
+public class AesEncryptor : 
+    IEncryptor
+{
+    private const int IvSize = 16;
+
+    public byte[] Encrypt(byte[] data, 
+        byte[] key)
+    {
+        if (key.Length != 32)
+        {
+            throw new ArgumentException("Key must be 256 bits (32 bytes).");
+        }
+
+        using Aes aes = Aes.Create();
+        aes.Key = key;
+        aes.GenerateIV();
+
+        using MemoryStream memoryStream = new();
+        memoryStream.Write(aes.IV.AsSpan(0, IvSize));
+
+        using (ICryptoTransform encryptor = aes.CreateEncryptor(aes.Key, aes.IV))
+        using (CryptoStream cryptoStream = new(memoryStream, encryptor, CryptoStreamMode.Write))
+        {
+            cryptoStream.Write(data, 0, data.Length);
+            cryptoStream.FlushFinalBlock();
+        }
+
+        return memoryStream.ToArray();
+    }
+}