title: How to AES Encrypt in .NET without an IV
body: <p>We have a legacy part of our Classic ASP application that use some code which is supposed to encrypt/decrypt strings with Rijndael (AES). This code was found on <a href="http://www.frez.co.uk/vb6.aspx" rel="nofollow noreferrer">the Internet here</a> (Rijndael AES Block Cipher (VB Version)). I already found a question on SO that references this exact library and which <a href="https://stackoverflow.com/questions/5987186/aes-encrypt-string-in-vb-net">ask almost the same thing as me</a>, but I suspect at least one thing that goes wrong (other than adding the length of the data to encrypt at the beginning of the bytes array). The vbScript implementation does not look like to add an IV at all to the data to encrypt. So, I am not able to match the same encryption with RijndaelManaged since it :</p>
  
  <ol>
  <li>automatically generates a different IV every time</li>
  <li>absolutely requires an IV</li>
  </ol>
  
  <p>Does someone knows if it is possible to AES encrypt something in .Net without specifiying an IV (empty) ?</p>