windows file copy internals (on the fly encryption

Question

I have to write an on-the-fly encryptor for Windows to encrypt all copied files, To implement this I need some detail about how windows FileCopy works.

So I need a description such as the following: the CreateFile is called, creates a destination file and then reads from source file and then writes to the destination file using WriteFile...

Note that I cannot use any (File system) filter driver; I've to use a user-mode hook.