I was trying to use Secure Socket Extensions to perform integrated Windows authentication on sockets, which was expected to be easier than using SSPI. A client winsock2 application running as some user on computer A connects to a server running on computer B (listening on an overlapped sockets using an I/O completion port). The server must get the user token securely and figure out if the user belongs to certain local user group to allow or disallow the request execution. No encryption is necessary, authentication/authorization is sufficient. Since I could not find how to implement that with Secure Socket Extensions, I had to implement it using SSPI, so technically I solved the problem. However it would be great if Microsoft provided a sample or a more detailed documentation how to achieve the same goal easier and with less code using Secure Socket Extensions. Thank you for your support!