Rijndael decryption returning 16 character response only C#

 If you are decrypting data using the Rijndael encryption algorithm in C# and getting a 16-character response, it's possible that the decrypted data is in a byte array format, and you are converting it directly to a string. When you convert binary data to a string, it might not display as expected if the data contains non-printable characters.

To handle this, you should first convert the decrypted byte array to a valid string format using an appropriate character encoding, such as UTF-8. Here's an example of how to do this:

```csharp

using System;

using System.Security.Cryptography;

using System.Text;

// Your encrypted data as a byte array

byte[] encryptedData = ...;

// Rijndael decryption

using (Rijndael rijAlg = Rijndael.Create())

{

    // Set your decryption key and IV

    using (ICryptoTransform decryptor = rijAlg.CreateDecryptor())

    {

        using (MemoryStream msDecrypt = new MemoryStream(encryptedData))

        {

            using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))

            {

                using (StreamReader sr = new StreamReader(csDecrypt, Encoding.UTF8))

                {

                    // Read the decrypted data as a string

                    string decryptedString = sr.ReadToEnd();

                    Console.WriteLine(decryptedString);

                }

            }

        }

    }

}

```

Ensure that you set the correct key and IV for your decryption process. The `Encoding.UTF8` argument in the `StreamReader` constructor is important for converting the decrypted bytes to a readable string.