After successfull connection and data sending to a https server (ISS), I could not use Available property of SecureSocket to check whether there is anything that server sent back. The same is true fo the Poll method with SelectMode.SelectRead.

I've read the new version is 1.0.13.672, while the downlodable zip contains the following in the AssemblyInfo
[assembly: AssemblyVersion("1.0.13.671")]

oops iss-->iis of course

Thanks, it was a bug in the Available property. I've uploaded a new version of the library [1.0.13.673] and the Available property should be fixed now.

Also note that the Poll method is currently unsupported. After reading your post I realized that this is not documented anywhere, so I added a little section to the Security Library docs. You can view it online over here:
http://www.mentalis.org/soft/projects/seclib/docs/ssl_todo.html