frequently questioned answers

Unfortunately, at this point, there is no documentation except for Doxygen-based, which you can generate, using make dox.

As of 2.0 there is also a reference implementations of OP and RP in test/ directory.

You can, but the part of the C application that interacts with opkele will be written in C++. Basically, that would turn your C application into C++ one.

Not likely, for a number of reasons:

• it depends on some libraries that aren't really native for windows and I doubt are well suited for use in Visual C++;
• If you manage to make them work with Visual C++, you'll have to do the same to libopkele;
• Although, I believe it's possible to use Visual C++ for web-applications, it is not widely used for this purpose, so I assume (and we confirmed that via email) that you're talking about regular GUI app, which is not exactly where you would use OpenID, anyway;

There is no prebuilt doxygen docs on the site (yet). You can build it without actually compiling opkele (which doesn't take ages, anyway) or you can browse git repository on the web. The documentation is in the include/opkele/*.h.

But to answer the question if this is what you need you probably just need to know whether you want to implement OpenID for your web site and you are using C++ as a development language. If yes, then probably you want libopkele, as it is the only OpenID C++ library. If not, then not likely.