I currently use org-encrypt to encrypt entries and epa to encrypt entire org files successfully. I was wondering though, if org supports any out-of-the-box encryption feature for attachments. 

I've been using an encrypted file volume on OSX for attachments. The nice thing about the enc. volume is that it's a volume in a file, so it's easy to check it into github and it doesn't expose the file tree either (Actually, I think this could be extended to include the whole org repository). Also, once you unlock it, it is mounted and stays like this until you reboot the OS (you can also auto-mount it) so it's transparent.

I recently got a Linux box and I'm searching for a cross-platform solution. Is there anything like this for Linux? What do you use to encript your attachments and or org files? 

Thanks in advance,

- Marcelo.