Solve issue tuya#1 tuya#1

AesUtil.cs

@@ -10,65 +10,61 @@
 class AesUtil {
 
     public static string DecryptMessage(IMessage message, string accessKey) {
-        message.Properties.TryGetValue("em", out var decrypt_model);
-        Console.WriteLine($"Received: {decrypt_model}");
-        string data = Encoding.UTF8.GetString(message.Data);
+        message.Properties.TryGetValue("em", out var decryptModel);
+        Console.WriteLine($"Received: {decryptModel}");
+        var data = Encoding.UTF8.GetString(message.Data);
         ArgumentNullException.ThrowIfNull(data, nameof(data));
-        JObject payloadJson = (JObject)JsonConvert.DeserializeObject(data);
-
-        if (decrypt_model == "aes_gcm") {
-            return DecryptByGcm(payloadJson["data"].ToString(),accessKey.Substring(8,16)).Replace("\f","").Replace("\r","").Replace("\n","").Replace("\t","").Replace("\v","").Replace("\b","");
-        } else {
-            return DecryptByEcb(payloadJson["data"].ToString(),accessKey.Substring(8,16)).Replace("\f","").Replace("\r","").Replace("\n","").Replace("\t","").Replace("\v","").Replace("\b","");
-        }
+        var payloadJson = (JObject?)JsonConvert.DeserializeObject(data);
+        if (payloadJson == null) return string.Empty;
+
+        return decryptModel == "aes_gcm" ?
+            DecryptByGcm(payloadJson["data"].ToString(),accessKey.Substring(8,16)).Replace("\f","").Replace("\r","").Replace("\n","").Replace("\t","").Replace("\v","").Replace("\b","")
+            : DecryptByEcb(payloadJson["data"].ToString(),accessKey.Substring(8,16)).Replace("\f","").Replace("\r","").Replace("\n","").Replace("\t","").Replace("\v","").Replace("\b","");
     }
 
     //decrypt_by_gcm
-    private static string DecryptByGcm(string decryptStr, string Key) {
-        byte[] cadenaBytes = Convert.FromBase64String(decryptStr);
-        byte[] claveBytes = Encoding.UTF8.GetBytes(Key);
-        // The first 12 bytes are the nonce
-        byte[] nonce = new byte[12];
-        Array.Copy(cadenaBytes, 0, nonce, 0, nonce.Length);
+    private static string DecryptByGcm(string decryptStr, string key)
+    {
+        var encryptedBytes = Convert.FromBase64String(decryptStr);
+        var keyBytes = Encoding.UTF8.GetBytes(key);
+
+        var nonce = new byte[12];
+        Array.Copy(encryptedBytes, 0, nonce, 0, nonce.Length);
+
+        var ciphertext = new byte[encryptedBytes.Length - nonce.Length - 16];
+        Array.Copy(encryptedBytes, nonce.Length, ciphertext, 0, ciphertext.Length);
+
+        var tag = new byte[16];
+        Array.Copy(encryptedBytes, encryptedBytes.Length - 16, tag, 0, tag.Length);
 
-        // The data to decrypt (excluding nonce and tag)
-        byte[] ciphertext = new byte[cadenaBytes.Length - nonce.Length - 16];
-        Array.Copy(cadenaBytes, nonce.Length, ciphertext, 0, ciphertext.Length);
+        var plaintext = new byte[ciphertext.Length];
+        using var aesGcm = new AesGcm(keyBytes, 16);
+        aesGcm.Decrypt(nonce, ciphertext, tag, plaintext);
 
-        // The last 16 bytes are the authentication tag
-        byte[] tag = new byte[16];
-        Array.Copy(cadenaBytes, cadenaBytes.Length - 16, tag, 0, tag.Length);
-
-        using (AesGcm aesGcm = new AesGcm(claveBytes))
-        {
-            byte[] plaintext = new byte[ciphertext.Length];
-            aesGcm.Decrypt(nonce, ciphertext, tag, plaintext);
-            return System.Text.Encoding.UTF8.GetString(plaintext);
-        }
+        return Encoding.UTF8.GetString(plaintext);
     }
 
     //decrypt_by_aes
-    private static string DecryptByEcb(string decryptStr, string Key) {
-        try{
-            byte[] cadenaBytes = Convert.FromBase64String(decryptStr);
-            byte[] claveBytes = Encoding.UTF8.GetBytes(Key);
+    private static string? DecryptByEcb(string decryptStr, string key)
+    {
+        try
+        {
+            var encryptedBytes = Convert.FromBase64String(decryptStr);
+            var keyBytes = Encoding.UTF8.GetBytes(key);
 
-            RijndaelManaged rijndaelManaged = new RijndaelManaged();
-            rijndaelManaged.Mode = CipherMode.ECB;
-            rijndaelManaged.BlockSize = 128;
-            rijndaelManaged.Padding = PaddingMode.Zeros;
-            ICryptoTransform desencriptador;
-            desencriptador = rijndaelManaged.CreateDecryptor(claveBytes, rijndaelManaged.IV);
-            MemoryStream memStream = new MemoryStream(cadenaBytes);
-            CryptoStream cryptoStream;
-            cryptoStream = new CryptoStream(memStream, desencriptador, CryptoStreamMode.Read);
-            StreamReader streamReader = new StreamReader(cryptoStream);
-            string resultStr = streamReader.ReadToEnd();
+            using var aes = Aes.Create();
+            aes.Mode = CipherMode.ECB;
+            aes.BlockSize = 128;
+            aes.Padding = PaddingMode.Zeros;
 
-            memStream.Close();
-            cryptoStream.Close();
-            return resultStr;
-        }catch (Exception ex){
+            using var decryptor = aes.CreateDecryptor(keyBytes, null);
+            using var memStream = new MemoryStream(encryptedBytes);
+            using var cryptoStream = new CryptoStream(memStream, decryptor, CryptoStreamMode.Read);
+            using var reader = new StreamReader(cryptoStream);
+            return reader.ReadToEnd();
+        }
+        catch (Exception ex)
+        {
             Console.WriteLine(ex);
             return null;
         }