These are the API docs auto-generated by running DocFx version 2.78.3 over BouncyCastle version 2.6.2 C# source code.
This is not provided by, or affiliated with, the Legion of the Bouncy Castle. It is a helpful resource I generated from the published source code for my own use. I have posted it publicly in case anyone else finds the lack of an official API documentation source frustrating.
There is a little bit of overview documentation in PDF form on BouncyCastle's official website and a great deal of external specification and interoperability documents as well.
The API link on the menu above is my attempt to fill the gap. You'll likely want to start in the Crypto, Security and Utilities namespaces.
-Blake
Important Note: The BC in bcdev.com has nothing to do with BouncyCastle.