Parent Classes and somewhat generic functions

[Jesse Lovelace]

Hi all, I'm making another open-source program that uses Crypto++ and 
I'm having trouble doing what I want.  I'm abstracting out the Crypto++ 
from the rest of my program by containing Crypto++ in a cryptography 
manager.

*The point*:  I want the user to be able to select (almost) any 
combination of cipher modes and ciphers, something like  this:

<code>
template<typename T>
   SymmetricCipher * getMode(CryptDefines::Mode mode, const 
SecByteBlock& key,
                             const unsigned int keylength,
                             const SecByteBlock& iv)
       throw (CryptoManager::AlgoError)
   {
       switch (mode) {
           case(CryptDefines::CBC_CTS):
               return new CBC_CTS_Mode<T>::Encryption(key, keylength, iv);
</code>

Which is in turned called by a cipher switching function.  Sadly with 
the templates and multiple inheritance of the lib I'm not sure what base 
class to return--in this case it tells me that Encryption isn't a type 
which I see--any suggestions one how to make something like this work?

Thanks for any help,
jesse