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I am experimenting with using eCryptfs on top of dropbox, and I am encountering some issues.
My system is GNU/Linux, openSUSE 12.2 to be exact.
My setup is thus: I have set up two instances of VirtualBox running openSUSE 12.2, lets call them VM1 and VM2. Dropbox, as usual, is synchronizing everything in ~/Dropbox. To create my eCryptfs setup I do the following on both the VMs:
mkdir -m 500 ~/ecryptfs_upper
mkdir -m 700 ~/Dropbox/ecryptfs_lower
sudo mount -t ecryptfs Dropbox/ecryptfs_lower/ ecryptfs_upper/
I configure eCryptfs with:
key type: passphrase
cipher: aes
key bytes: 16
plaintext passthrough: no
filename encryption: yes
If I now proceed to create a file in ~/ecryptfs_upper on VM1, it will show up correctly on VM2 as well. However when I then change this file on one VM it sometimes (often but not always for some reason) will not appear to be updated on the other VM.
If I inspect the underlying files in ~/Dropbox/ecryptfs_lower on the two VMs they are identical (sha256sum produces the same hash), so dropbox has correctly managed to synchronize them. But the corresponding files in ~/ecryptfs_upper are still different! I have to umount then again mount eCryptfs to have the changes show up correctly.
The problem seems to be that when dropbox updates a file in the eCryptfs lower directory, eCryptfs doesn't notice the change. Presumably eCryptfs is assuming that all changes will go through the mount. For most use cases that is obviously a fair assumption, but when using eCryptfs to encrypt synchronized cloud storage like dropbox, it is obviously a big problem.
I've seen several people advocating using eCryptfs with dropbox, but I haven't seen this problem mentioned. Does anyone know of a fix (a way to turn off the cache that eCryptfs seems to be using for example), or of some alternative to eCryptfs that would not suffer from this problem?
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Be aware of the cryptographic weaknesses in EncFS if you are relying on it for something critical (https://defuse.ca/audits/encfs.htm). There's work underway on a 2.0 version which may or may not address those, but no releases as yet.
– darrend – 2015-11-04T00:56:47.3402
EncFS does indeed seem to not suffer from this problem, making it much more suitable for this task. I also found https://github.com/timoc/encfsbox, which provides a nice conflict handling mechanism to the dropbox+EncFS combination, making it a very nice solution indeed.
– Quantumboredom – 2013-02-03T19:23:54.8201
On Windows, Mac, and mobile, you can use BoxCryptor to make it easier to access the encrypted data.
– hrunting – 2013-02-03T19:43:24.383