I'm designing an industrial embedded system which needs some encryption. I know encryption will slow things down quite a bit since my media will be either compact flash or SD. I really only need to encrypt certain files in /etc, maybe some application specific log files, and data files.
Can I just create hard links to all the folders and files that need to be encrypted, locate them on a separate volume, and encrypt this volume? Would this be transparent to the networking stack if I encrypted the networking files that have the wpa2 passkeys in them? Or is there a way to transparently encrypt certain files in place?