public override byte[] PerformEncryption(string appSkey) { byte[] pt; if (!CfList.Span.IsEmpty) { pt = AppNonce.ToArray().Concat(NetID.ToArray()).Concat(DevAddr.ToArray()).Concat(DlSettings.ToArray()).Concat(RxDelay.ToArray()).Concat(CfList.ToArray()).Concat(Mic.ToArray()).ToArray(); } else { pt = AppNonce.ToArray().Concat(NetID.ToArray()).Concat(DevAddr.ToArray()).Concat(DlSettings.ToArray()).Concat(RxDelay.ToArray()).Concat(Mic.ToArray()).ToArray(); } Aes aes = new AesManaged(); aes.Key = ConversionHelper.StringToByteArray(appSkey); aes.IV = new byte[16]; aes.Mode = CipherMode.ECB; aes.Padding = PaddingMode.None; ICryptoTransform cipher; cipher = aes.CreateDecryptor(); var encryptedPayload = cipher.TransformFinalBlock(pt, 0, pt.Length); RawMessage = new byte[encryptedPayload.Length]; Array.Copy(encryptedPayload, 0, RawMessage, 0, encryptedPayload.Length); return(encryptedPayload); }