Cryptonite is a file encryption/decryption app for Android that is based on the EncFS. It is still in active development mode and only works with rooted phone for now. It allows you to create an encrypted volume in your Dropbox folder and place files/folders into it, or decrypt your existing encrypted volume and mount it as a local folder. In both scenarios, it gives you both read/write access to your files/folders.

  1. Install Cryptonite from the Play Store.

  2. Once installed, run the app. There are three option tabs at the top – Dropbox, Local and Expert. The Dropbox tab is where you can create encrypted volume, or decrypt an encrypted volume in Dropbox. The Local tab gives you option to create an encrypted volume in your Android storage (SD card). The Expert tab comes with a terminal that allows you to run commands. This is for Advanced users only. Use it only if you are proficient enough and know what you are doing.

  3. At the Dropbox tab, tap the button “Link With Dropbox”. When prompted, select “Full Access”. This allows Cryptonite to access your encrypted folder. Assuming that Dropbox is already installed in your phone, it will load the Dropbox app and prompt you to grant permission to Cryptonite. Select “Allow”.

  4. Back to the main screen, select “Decrypt Dropbox folder”. It will then prompt you to select the encrypted folder and enter the password. Once it is done, the “Browse decrypted folder” and “Forget decryption” button will become active.

  5. Tap on the “Browse decrypted folder” button and you will be able to access to your encrypted files. At the moment, there is no in-app editor for you to view and edit your files. You will have to export the file to your SD card, view or edit it, then re-upload back to the encrypted folder. Don’t forget to delete the files after you have edited it. If you are paranoid about the privacy of your data, one alternative mean is to create an encrypted volume in your Android SD card (with Cryptonite). Mount the encrypted volume. Export your Dropbox files to this mounted volume. (The default mounted volume is at csh.cryptonite -> mnt folder). In this case, the exported file will be encrypted and you can edit it as well. Lastly, I would advise you to password protect this Cryptonite app. It wouldn’t be good if anyone can access your encrypted files/folders without your permission.