SSPI functions as a common interface to several Security Support Providers (SSPs): A Security Support Provider is a dynamic-link library (DLL) that makes one or more security packages available to applications.
SSPI的功能是作为众多安全支持提供程序（SSP）的通用接口：安全支持提供者（Security Support Provider）是可以为应用程序提供一种或多种安全功能包的动态链接库（dynamic-link library）。