Encrypting Your Dropbox, SkyDrive, Box, or Google Drive On The Fly


Dropbox is awesome, but it doesn’t encrypt your data before transferring them to the cloud. Not that I don’t trust Dropbox, in fact, I trust them fully regarding the data safety. But it would be nice if the data are gibberish to anyone else other than me. And the concern applies to many other cloud services as well, such as OneDrive, Google Drive, etc.

BoxCryptor is a cryptographic virtual harddisk that encrypts all data on the fly using the AES-256 standard. Encrypted data is stored in an arbitrary directory of your choice. For example, one that is synced to the Dropbox.

So how exactly it works?

Assuming you’ve already had Dropbox installed on one of your computers. Once you also have BoxCryptor installed, select the default Dropbox folder as the source directory that stores the encrypted data, and assign a drive letter, e.g. X to it.

Boxcryptor - Advanced Settings
Boxcryptor – Advanced Settings

Click OK, and type in the password used as the key to encrypt the data. Note that this password will be used on the other computer you are sharing data through Dropbox. Once done, you will see a virtual drive appears in the Windows Explorer after this, as well as a quick access point right in the Favorites.

Boxcryptor - drives

From now on, start dropping files to X: drive instead of Dropbox folder as you normally do. The data you dropped to the X: drive will be encrypted automatically on the fly and put in the Dropbox folder.

Here I dropped two files into X: drive Dropbox folder, all shown in green after being encrypted.

Boxcryptor - encrypted files

When you look them again in your regular Dropbox folder, they have .bc extension name attached indicating they are encrypted by Boxcryptor.

Boxcryptor - encrypted files in Dropbox

And you won’t be able to access them without Boxcryptor. But on the other computer that has both Dropbox and BoxCryptor installed, these two files automatically got downloaded and decrypted.

It works quite magically.

What’s important?

The password is the key information to access your encrypted data. Because BoxCryptor never sees and stores your password, you won’t have the option to retrieve or reset it if you forget it. It’s simply that if you forget the initial password you set when you sign up, you will loose the access to your encrypted data. It’s your own responsibility to remember this piece of vital information. In fact, one of the steps you have to agree on during the initial setup, you will have to check to agree on this agreement before using the service.

Boxcryptor - agreement to never forget your password
Boxcryptor – agreement to never forget your password

How many platforms are supported?

One thing I complained was the lack of a broad range of supported platforms. Not anymore. Now the cloud services it supports include Dropbox, OneDrive, Google Drive, Box, and SugarSync. And you can run it on all main platforms, including Windows, Linux, OS X, iOS, and Android. Pretty amazing.

What’s the catch then?

The only catch seems to be its pricing model, which still offers a free package that offers AES-256 and RSA encryption with a limitation that you can only use one cloud service at a time, meaning that if you have both Dropbox and SkyDrive installed, you can only use one with Boxcryptor at a time. You will have to sign up for an annual subscription plan, $48/year for unlimited personal use or $96/year for unlimited business use, if you want to use more services on multiple devices.

My next wish

Well, when will this run on Windows Phone and Windows RT?


  1. You mentioned that you create a Boxcryptor folder that you move the files to. So do you use twice the space? Also how does it work with multiple computers synced with OneDrive?

    • No, it only stores the encrypted version in the cloud. You will need the other computer have both OneDrive and Boxcrptor installed to be able to read the files.

  2. I have the same question as John. Is the original file kept in the OneDrive folder on the PC and another encrypted file also kept in a Boxcryptor folder on the same PC while also having the encrypted file in the Boxcrypter cloud? In other words, 2 files on the PC and 1 in OneDrive?
    And if using the same OneDrive service on 2 or more PC’s on the same ISP in the same house, do you need to pay $48/year or is it considered a single use of Boxcrypter?

    • No, Boxcryptor is just the encryption tool that does the encryption. It doesn’t offer a cloud space like OneDrive or Dropbox. When installed, it creates a virtual disk that links to your OneDrive folder. Anything dropped into the virtual disk will be encrypted and saved in OneDrive. In other words, there is only one copy of the file in OneDrive and that is encrypted.

      If you only use one cloud service on 2 devices, the free version works perfectly.

  3. And what happens if the makers of boxcryptor stop supporting the tool and comes with an update of Windows 10 that makes boxcryptor fail in working? Is your valuable data lost?


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