Next Generation of Cryptography for Microsoft Windows Vista

The Cryptography API: Next Generation(CNG) is a new and agile framework in Windows Vista, which implements an extensible provider model that allows you to load a provider by specifying the required cryptographic algorithm rather than having to hardcode a specific provider. 

The advantage is that an algorithm provider can be replaced or upgraded and you will not have to change your code in any way to use the new provider. Also, if some algorithm is determined to be unsafe in the future, a more secure version of that algorithm can be installed with no effect to your code. To facilitate this, you load a CNG provider by identifying the cryptographic algorithm that you require, not the specific provider. Most of the CNG APIs require a provider or an object created by a provider.