This projects provides a C# / .Net interface to the Windows Integrated Authentication API, 

better known as SSPI (Security Service Provider Interface).



The SSPI API provides an interface for real authentication protocols, such as Kerberos or 

NTLM, to be invoked transparently by client and server code in order to perform authentication

and such. These authentication protocols are better known as security packages. SSPI API 

exposes these packages using a common API, and so a program may invoke one or the other with

only minor changes in design. SSPI also supports the 'negotiate' 'meta' package, that allows 

a client and server to decide dynamically which real security provider to use, and then itself

provides a passthrough interface to the real package.



==== Usage ====



Typically, a client acquires some form of a credential, either from the currently logged on

user's security context, by acquiring a username and password from the user, or by some other

means. The server acquires a credential in a similar manner. Each uses their credentials to 

identify themselves to each other.



A client and a server each start with uninitialized security contexts. They exchange negotiation

and authentication tokens to perform authentication, and if all succeeds, they create a shared 

security context in the form of a client's context and a server's context. The effectively shared

context agrees on the security package to use (kerberos, NTLM), and what parameters to use 

for message passing. Every new client that authenticates with a server creates a new security 

context.



From the software perspective, a client security context initializes itself by exchanging 

authentication tokens with a server; the server initializes itself by exchanging authentication

tokens with the client.



This API provides raw access to the authentication tokens created during the negotiation and 

authentication process. In this manner, any application can integrate SSPI-based authentication

by deciding for themselves how to integrate the tokens into their application protocol.



The project is broken up into 3 chunks:



 * The NSspi library, which provides safe, managed access to the SSPI API.

 * NsspiDemo, a quick demo program to show how to exercise the features of NSspi locally

 * UI demo programs TestClient and TestServer (that have a common dependency on TestProtocol) that

   may be run on separate machines, that shows how one might integrate SSPI into a custom 

   application.



==== More information ====



If you would like to understand the SSPI API, feel free to browse the following references:



MSDN documentation on the SSPI API

	http://msdn.microsoft.com/en-us/library/windows/desktop/aa374731(v=vs.85).aspx



MSDN article on SSPI along with a sample Managed C++ SSPI library and UI client/servers.

	http://msdn.microsoft.com/en-us/library/ms973911.aspx