title: Which compression/encryption should I take?
body: <p>We've developed a service, which sends e-mails... quite trivial at this step.</p>
  
  <p>The next step will be: handling the bounces.<br>
  To implement this I need to add some information into the headers... Let's say it's a simple string (to keep the question really basic).</p>
  
  <p>Which compression/encryption (.net-built-in prefered) should I take, when I'm looking for an algorithm which includes a checksum internally (I do not want to create a CRC or alikes and add it to the headers either) - so, changing some char of the encrypted/compressed string doesn't mean it's valid!</p>
  
  <p>This need not be a "high-sofisticated" algorithm, as I just want a basic detection against changes/injections...</p>
  
  <p>Just to be clear: There must be a chance to decompress/decrypt!</p>