!!! Overview
[{$pagename}] ([SSPI]) is the foundation for [authentication] in [Windows Server 2003] and later [Microsoft Windows]. [{$pagename}] allows an [application] to use various security models available on a computer or network without changing the interface to the security system. 

[{$pagename}] is the implementation of the Generic Security Service API [GSSAPI] in [Windows Server 2003]. 

The default [Security Support Providers] in [Windows Server 2003]/[Windows Server 2008] are plugged into the [SSPI] in the form of DLLs. Additional [SSPs] can be plugged in if they are interoperable with the [SSPI].

[{$pagename}] is the implementation of the [Generic Security Service Application Program Interface] ([GSSAPI]) in [Windows Servers]:
* [Kerberos SSP] ([SPNEGO|SPNEGO])
* [Kerberos SSP]
* [NTLM SSP]
* [Schannel SSP]
* [Digest SSP]
are plugged into the [SSPI] in the form of DLLs. Additional SSPs can be plugged in if they are interoperable with the [{$pagename}].

!! SSPI in [Authentication]

The SSPI in [Windows Server 2003] and later provides a mechanism that carries [authentication] [tokens] over the existing [protocol], thus eliminating the need for communicating parties to specify a network protocol for use during [authentication]. When two parties need to be authenticated so that they can communicate, the requests for [authentication] are routed to the [SSPI], which completes the [authentication] process, regardless of the network [protocol] currently in use.

Any [application] can make a request of the [SSPI]. Each of these requests goes through the [SSPI], for [example]:
* [Winlogon] sends requests to the [Local Security Authority], which obtains tickets to access the local computer.
* Internet Explorer obtains tickets to access information about a Web site.
* An [LDAP client|DUA] obtains tickets to enable access to information in an x500 directory, such as [Microsoft Active Directory].

!! SSPI-Architecture
A "Simple" diagram of [{$pagename}]

[{Image src='Security Support Provider Interface/SSPI-Architecture.png' caption='Topo Survey' align=left width=1024 height=500 style='font-size: 120%}]. 

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!! More Information
There might be more information for this subject on one of the following:
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