Way back in April, Microsoft published a very good article by Robert Bogue entitled Remote Authentication in SharePoint Online Using Claims-Based Authentication. This article describes one way to get the FedAuth cookie required to talk to SharePoint online via any of its many interfaces. While the article is very informative and the associated code works, I didn't like the implementation as it involved the web browser control and PInvoke (The former has a lot of overhead, the latter requires full trust).
So, I decided to try to do the same thing using tried and true screen-scraping techniques. I got it working and shortly thereafter I discovered this post and sample by Wictor Wilén – How to do active authentication to Office 365 and SharePoint Online. Wiktor's approach is more robust than my screen-scraping solution and it uses Windows Identity Foundation directly to use the active federation service provided by the STS is located at https://login.microsoftonline.com/extSTS.srf. Wiktor's approach is also more efficient and requires fewer round-trips to the server to do the job.
He also posted it a few days before I got mine working!
If Wiktor's solution is so much better than mine, why am I posting this?
The reason is that Wiktor's solution depends on Windows Identity Foundation and mine will work on any platform capable of dealing with HTTP and cookies – including Windows XP and various non-Windows development stacks. Although the sample is written in C# you should have no trouble converting it to the language of your choice. Hopefully, the sample will be helpful to a few folks. J
You can download the sample from here. It consists of a Visual Studio 2010 C# solution containing a console application and a class library. If you do not have Visual Studio (Express will work) and you are looking at this sample because you are using something other than .NET, the file you want to look at is O365AuthenticationScraper.cs. It is heavily commented and should be easy to follow.