title: File Encryption and Decryption issue
body: <p>I've been playing around with encrypting and decrypting files in VC# Express 2010.</p>
  
  <p>All the tutorials and documentation I've seen require two <code>FileStream</code>s in order to encrypt the file - one for reading the unencrypted version, and the other for encrypting. When I actually wrote the code it kept throwing an error telling me it could not open the file because it was opened by another process at the output filestream.</p>
  
  <p>I'm assuming that's because the file is opened by the input filestream. So that means I have to specify a different filename? So even after the operation is successful I'll now have the original unencrypted file in the directory and a separate encrypted version? Doesn't that defeat the point? Or am I doing something wrong here? My code is similar to this...</p>
  
  <pre><code>public string filename = "test.xml";
  using (FileStream input = new FileStream(filename, FileMode.Open, FileAccess.Read))
  using (FileStream output = new FileStram(filename, FileMode.Open, FileAccess.Write))
  using (....all the crypto stream and transform stuff...)
  {
      ...do the encryption....
  }
  </code></pre>