So far I have a Debian NAS with a samba share accessible from a Windows client by user credentials. Within that share I have a folder of images encrypted by ecryptfs. A friend of mine have agreed to "host" a synced copy of my encrypted images on his NAS, but at the same time I want a synced copy/access of decrypted images on my Windows machine.

One idea is if some encryption tool on NAS is able to always maintain two folders of the same data; one encrypted, one decrypted? and then share them accordingly with btsync or similar. disadvantage of this would be double the space used.

Better specified suggestion of above or other solutions to my problem are greatly appreciated!


If you were using a tool like eCryptfs that decrypts file "on-the-fly", you could mount and share the decrypted data in a "Visible" folder, and also separately share the encrypted data in the ".Private" folder.

The "Visible" folder's decrypted data is only visible while mounted, and it doesn't take up any extra disk space since it's not a hard on-disk decrypted copy (that would be extremely insecure). Unmounting it stops the decryption and leaves only the encrypted ".Private" folder.

See the eCryptfs documentation here http://ecryptfs.org/documentation.html

Especially these entries:

EncFS works similarly, isn't supposed to require root access, but isn't usually installed by default on most distro's I've seen (like Mint, Ubuntu...)

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  • Thanks a lot! didn't realize at first that my idea actually was the basic functionality of ecryptfs even without the disadvantage. So what I have done is two folders both in the share, one for encrypted data mounted to the one for decrypted data. Only my user can access the decrypted one. Since both needs to be shared I don't like the idea of using the .private folder but as you say I could make a separate share because there is no reason for a user to see a folder not accessible. Maybe i'll clean that up at some point. – Nil0 Jan 6 '15 at 9:22
  • @SteffenThorlund You're welcome, there's just too many features & tools in Debian (even a "basic" install) to know them all. If your question's answered now you can "accept" / check-mark an answer :-) – Xen2050 Jan 6 '15 at 17:18
  • EncFS seems more suited for the job than ecryptfs. In its "Unique fatures", EncFS team explain that it "Works on top of network filesystems", while on ecryptfs there is a long standing bug (opened in 2008 and not perceived as a priority) making it unstable on stacked file systems (NFS, CIFS, Samba, WebDAV and aufs are mentioned in the bug title). – WhiteWinterWolf Mar 28 '16 at 8:46

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