title: How to implement "AES/CFB/NoPadding" Encryption/Decryption in WinRT C#?
body: <p>We are porting the existing code to Windows 8 now, the data file downloaded from the server is encrypted in "AES/CFB/NoPadding", and we cannot change the data encryption mode because the data file is used by a lot of existing clients. 
  </p>
  
  <p>
  In WinRT , the [SymmetricAlgorithmNames][1] doesn't contains a name to match "AES/CFB/NoPadding". And from the [SymmetricKeyAlgorithmProvider][2] document, the NoPadding algorithms don't contain "CFB"<ul>
  <li>No padding:
  <li>DES_CBC</li>
  <li>DES_ECB</li>
  <li>3DES_CBC</li>
  <li>3DES_ECB</li>
  <li>RC2_CBC</li>
  <li>RC2_ECB</li>
  <li>AES_CBC</li>
  <li>AES_ECB</li>
  </ul>
  So how can we get a [SymmetricKeyAlgorithmProvider][2] to support AES/CFB/NoPadding ?
  
  Is there 3rd party Encryption package for Metro App ?
  </p>