How to read contents of MemoryStream, fed by a cryptostream

Question

I am working on some AES encryption in C#. I have a similar decryption method which functions flawlessly, however, no matter what I try I cannot read the encrypted contents of the MemoryStream

I have tried a few different ways of reading,

ms.Position = 0;
return new StreamReader(ms, Encoding.ASCII).ReadToEnd()
OR
using (StreamReader sr = new StreamReader(cs)) {
return sr.ReadToEnd();
}
OR
byte[] enc = ms.ToArray();
string ret=null;
foreach (byte b in enc) {
ret += b.ToString();
}

Here's the snippet from the code.

 using (AesManaged aesMan = new AesManaged()) {
                if (keystr.Length == aesSize/8)
                {
                    //Its a valid key
                    aesMan.KeySize = aesSize;
                    aesMan.Key = Encoding.UTF8.GetBytes(keystr);
                    aesMan.IV = Encoding.UTF8.GetBytes(ivstr);

                    ICryptoTransform encryptor aesMan.CreateEncryptor(aesMan.Key, aesMan.IV);
                    using (MemoryStream ms = new MemoryStream())
                    {
                        using (CryptoStream cs = new CryptoStream(ms, encryptor, CryptoStreamMode.Write))
                        {
                            using (StreamWriter sw = new StreamWriter(cs))
                            {
                                sw.Write(inpstr);
                                using (StreamReader sr = new StreamReader(ms)) {
                                    return sr.ReadToEnd();
                                }


                            }
                        }

I get various errors, such as the stream is not readable, or that it cannot read a closed stream, as well as a blank string being returned. Has anyone got any ideas? I'm at a loss

Answer 1

Most of those stream functions like StreamReader, StreamWriter, etc., close the underlying stream when you Dispose() them. Try not disposing them until you are done, or using the constructors that allow you to chose not to close the underlying stream. In rare cases, I've had to implement a dummy wrapper around a stream to prevent closing the underlying stream