Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

There exists many syncing and backup solutions out there, but I have yet to find a setup that will cover ALL the following behavior:

enter image description here

I want the ability to designate local folder B as the "encrypted mirror" of local folder A (A and B exist on the same machine). That is, whenever I add files to A, the file is automatically encrypted and put into folder B, and when I remove a file from A, that file is also removed from B.

The encryption should be file-based (no containers required) and should preferably have no limit on folder/file size, and the key is that this needs to happen automatically (once I set up the link between A and B all operations should be behind the scenes).

I'm looking for a Windows solution...think of it as a "locally encrypted Dropbox". Can this be done? I don't mind connecting multiple services together to achieve this, but most encryption/syncing services are rather narrow in the way they can be used.

share|improve this question
Are A and B on the same machine? If not, are they on the same local/home network, or are they connected across the Internet? – Mike Rowave Sep 6 '11 at 2:43
They are on the same machine. – donnyton Sep 6 '11 at 2:50
Could you tell us more about your use case? Why are you mirroring files on the same machine? And what are you protecting the encrypted files from if they're just copies of unencrypted files? – Isaac Rabinovitch Nov 24 '12 at 22:21
up vote 2 down vote accepted

Some products that seem worth trying :

SecretSync (Dropbox oriented, free and commercial versions)
Toucan (free)
AASync ($29)
BestSync (starting at $19.95 plus 30-day trial)

(Disclaimer: I have no experience with any of them.)

share|improve this answer

I was looking for exactly the same solution and came across Allway Sync which does exactly what you described - it sync'es two folders, both ways with encryption/decryption feature. It's not free, as far as I remember it costs ~$20 - definitely worth the money though, I've been using it for 2+ years now.

What is also important and what you are missing in your model, is the fact that all files are encrypted using ZIP compression & encryption so you can download any file from Dropbox (web) and open it using jzip, winzip etc. provided you know the password. This is especially useful when you want to do it quickly as a guest on any machine, without installing any additional software.

Cons are that folder structure and file names are not obscured.

share|improve this answer
I think there is an option to do this now. It might just be the file names though. – Tom Jenkinson Mar 27 '13 at 8:59

Personally, I think you'd be better off with an encrypted filesystem rather then a per file basis. You can use a combination of truecrypt and synchtoy on Windows, or rsync or any other number of synchronization programs on a Linux based system. That way, the synchronization program sees the files on both sides simply as files, but anyone not mounting the truecrypt partition will only see the encrypted files. Otherwise, you might look into Microsofts EFS, I'm not that familiar with it but I understand it does do per file encryption.

share|improve this answer
EFS will give him problems when he goes to download the file onto a different computer. – surfasb Sep 6 '11 at 7:25

Since A and B are on the same machine, I'm going to assume that B is an external hard drive (and therefore easier to steal and more vulnerable to accidental loss when you transport it, hence the need for encrypting B without encrypting A).

So all you'd need to do is encrypt the external drive B with something like TrueCrypt or FreeOTFE, and use any of the various file sync software to sync A with B. Once you provide the password or keyfile to mount B, the sync software won't know or care that B is encrypted.

share|improve this answer
That's not the case: B only needs to be encrypted because I am pushing it to my dropbox as well. And sometimes I will want to access and decrypt the files from the internet, so they have to be encrypted on a file basis and not on a volume. – donnyton Sep 6 '11 at 6:12
If you were running Linux, ecryptfs or encfs would do what you want. But they're not available for Windows, and I'm not aware of anything with equivalent functionality that is. – Mike Rowave Sep 6 '11 at 13:23

Try this as well.


I've been using it for a few days and am ok with it so far.


  1. it encrypts and compresses to 7zip.
  2. it also encrypts filenames
  3. "Hot file" monitor changes
  4. Filename exclude filters
share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.