title: C# quickest two-way string shortening
body: <p>What is the quickest and best performance way to turn a string into a string of numbers and/or letters, then reverse engineer to the original string. Similar to turning a string into it's hash code, but that's a one-way conversion. I need a two-way method. I'm creating a simple url shorting service and I don't want to deal with a database.</p>
  
  <p>I considered MD5 encrypting/decrypting via a private key, but I imagine there's another way that might be better on performance. </p>
  
  <p>If encrypting/decrypting is the way to go, then which is the easiest on the processor?</p>
  
  <p>Thanks!</p>