C++ What is the easiest library to crypt any file? [on hold]

I do a research about ransomware and want to create a simple software to test our local protection software, which recognize file modifications. I want to encrypt and decrypt all files in windows documents and pictures.

I am looking for a library, which is easy to use and applicable in Visual Studio 2010. Maybe there is already an existing project, which I can reuse.

Thanks for your support.