I have been looking for a way to synchronise an encrypted Truecrypt volume. This is a tricky problem, as a truecrypt volume is simply a large (possibly several GB) file, which appears as a disk drive when mounted with truecrypt. I have been looking into this technology lately as a method to have a safe location to store documents which which can’t be accessed by anyone else. Truecrypt is perfect for this, and as I have been listening on security now lately, it is still pretty much a very impressive solution for encryption on windows – and it’s free. I have heard bad things about dropbox being able to access your whole computer and similar things so truecrypt seems a perfect solution. So I’m very satisfied using the various simple to use options truecrypt has, the next problem is backup. I want to be able to backup my encrypted volume. The encrypted truecrypt volume is simply a large file sitting on my computer, each time I modify the contents of the volume, the encrypted volume changes. Herein lies the problem, I need to be able to backup only the part of the volume that has changed – otherwise for example if I change the name of a file in the truecrypt volume, the whole volume would need to be resynchronised with the backup location. This is called Block level synchronisation, where only modified parts of a file are synchronised. Dropbox does Block level synchronisation, so it is possible to use dropbox with a truecrypt volume – but that still has the problem of using dropbox… The best source of various solutions I found is here. The one I have got to work is Syncovery, there are others on GitHub which were free, but Syncovery seems the best option – even if it does cost ~$35.
This allows me to have a remote backup of a truecrypt volume – where the remote location doesn’t need access to the contents of the volume. With this solution only encrypted noise is sent out of my computer to the backup 🙂
To get this to work:
- Create Truecrypt volume (needs to be a volume not a partition so the sync software can access the encrypted data).
- Set truecrypt to change modification date when modifications are made. (Settings>Preferences>Windows>Uncheck Preserve modification…)
- Create Syncovery Profile (with block level mode).
– Select Advanced Mode from the start screen
– Create New profile with Standard Copying mode
– Select Partial File Updating (in the Special tab sheet)
- Since my backup drive is portable, I attached it and synchronised it locally.
- After the first synchronisation, it will create a database of the files, so the second time should be much faster. I tested this by putting the backup on a remote machine over wifi and making a small change to the contents of the source truecrypt volume. It ran through the whole 12GB volume in no time at all 😀