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I would like to encrypt my files for outside use (e.g. for Dropbox), but keep them unencrypted on my hard drive (for instance, to be accessible by indexing and other 3rd party software). Similar to TrueCrypt, though TrueCrypt does a slightly different thing: it mounts a virtual encrypted drive that sits in a file. The problem with that is, synching files in this mounted drive with Dropbox would lead to unencrypted Dropbox.

I am looking for an application similar to TrueCrypt that, for instance, mounts a virtual drive that mirrors an existing directory tree, except all encrypted files in it are now decrypted. Then I could sync the directory tree with Dropbox while using the mounted drive for 3rd party software. The synchronizing would involve either Windows 7 or Cygwin running under same.

Alternatively, I could manually keep two parallel directory structures: encrypted and unencrypted (though this would be an inferior approach); in this case, what's the most efficient way to synchronize them? I am talking about 20G of mostly PDF files and growing fast.

Or any other solution? Perhaps using Dropbox API?

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closed as off-topic by Xavierjazz, Ramhound, Olli, Tog, Kevin Panko Feb 6 '14 at 13:52

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions seeking product, service, or learning material recommendations are off-topic because they become outdated quickly and attract opinion-based answers. Instead, describe your situation and the specific problem you're trying to solve. Share your research. Here are a few suggestions on how to properly ask this type of question." – Ramhound, Olli, Tog, Kevin Panko
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I believe something like Spideroak might fit the bill. It would allow you to encrypt the files you upload but keep the local files unencrypted. – Ramhound Feb 6 '14 at 3:30
For me, Boxcryptor Classic works very well. It mounts in a similar way to TrueCrypt to show the unencrypted files (as a separate drive), but there is a one-to-one mapping where each file is backed by a single encrypted file. This makes it very efficient for syncing the encrypted files through Dropbox. – zelanix Feb 6 '14 at 4:10
Wuala is another service like Dropbox that stores everything on their servers in encrypted form. (Or use referal link so I can get free GBs ;) – dangph Feb 6 '14 at 7:53
I think your questions is a bit misleading, because you do not seem to understand the concept of TrueCrypt's encrypted container. If you choose to sync only the container file in Dropbox, then that's what you will have, just one file (the container). The TC container should be updated on-the-fly as soon as you dismount TC. To make TC sync upon each new file change, you'd have to write a script to: unmount TC, sync DB and then remount TC again. Not optimal, but at least TC containers supports incremental syncs. – user1147688 Mar 8 '14 at 12:28
@user1147688 I understand that I'd need to upload the whole container. I did not like this solution because I did not know TC containers support incremental synchs (how?). I also did not know I need to unmount the container before uploading it - why? Because of locking? – Ruby Mar 9 '14 at 2:48
up vote 1 down vote accepted

EncFS (Windows port) can do this with its --reverse option:

From the man page:


Normally EncFS provides a plaintext view of data on demand. Normally it stores enciphered data and displays plaintext data. With --reverse it takes as source plaintext data and produces enciphered data on-demand. This can be useful for creating remote encrypted backups, where you do not wish to keep the local files unencrypted.

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