Hi everybody,
  I apologize for sending large undescriptive code.

Here is the clear explanation.

I am trying to ecrypt/decrypt  a stream object and return a stream
object to the calling function.

The encrypt function is as follows.


public CryptoStream EncryptStream(Stream sourceStream,string
key,string initializationVector)
       {
           //Create ICryptoTransform and get the encryptor of the
service
provider.Convert the key and IV to byte array.
           
           ICryptoTransform encryptTransform =
_cryptoserviceprovider.CreateEncryptor(

UTF8Encoding.UTF8.GetBytes(key),

UTF8Encoding.UTF8.GetBytes(initializationVector));
           CryptoStream cryptStream = null;
           try
           {
               cryptStream = new
CryptoStream(sourceStream,encryptTransform,CryptoStreamMode.Write);
           }
           finally
           {
               //if(cryptStream != null)
                   //cryptStream.Close();
               
           }
           return cryptStream;

       }

This code is invoked as follows.

MemoryStream ms = new System.IO.MemoryStream()
CryptoStream es  = EncryptStream(ms,key,IV);

I am passing a MemoryStream object to the function which returns a
CryptoStream.

Then i write to the CryptoStream as follows.

StreamWriter strwtr = new StreamWriter(es);
strwtr.Write("Some text to be encrypted");

Now when i read the underlying memorystream in the cryptostream i get
some encrypted text.

StreamReader strrdr1 = new StreamReader(ms);
MessageBox.Show(strrdr1.ReadToEnd());

The code to encrypt data works fine but when i send the encrypted stream
to be decrypted i am unable to reproduce the original text.

Code to decrypt:

   public CryptoStream DecryptStream(Stream sourceStream,string
key,string initializationVector)
       {
           ICryptoTransform decryptTransform =
_cryptoserviceprovider.CreateDecryptor(

UTF8Encoding.UTF8.GetBytes(key),

UTF8Encoding.UTF8.GetBytes(initializationVector));
           CryptoStream cryptStream = null;
           try
           {
               cryptStream = new
CryptoStream(sourceStream,decryptTransform,CryptoStreamMode.Read);

               //some more logic to actually decrypt
           }
           catch(Exception ex)
           {
               string ge = ex.Message.ToString();
               MessageBox.Show(ex.Message);  
           }
           finally
           {
               if(cryptStream != null)
                   cryptStream.Close();
           }
           return cryptStream;
       }

I invoke the above function as follows.

CryptoStream decryptedResult = DecryptStream(ms,key,IV);

that is, i pass the the encrypted memory stream object (returned by
Encrypt function) in the "sourceStream" parameter of the Decrypt
function. I then return the cryptostream.

when i try to read the returned cryptostream object i get "Bad Data"
error.

I read the cryptostream as follows.

StreamReader strrdr2 = new StreamReader(decryptedResult);
MessageBox.Show(strrdr2.ReadToEnd());

I get error ("Bad Data") when the last line is executed.
When i saw the contents of decryptedResult, it was empty.
That is the stream was not decrypted.

Hope this helps.
Please let me know if u need more explanation.

I will really apperciate a early response.

Thanks a lot!