We have tried several weeks to get the built-in X509 support of .NET working for our solution. After this time, we now know that it is hard to handle, slow, throws unmeaning exceptions and insecurely caches all key operations on the HD.

We then purchased SecureBlackbox and we were done in three (!) days! It's simply unbelievable. Great work and we would have payed any price for SBB.