

How to put Encrypted Contents on Cloud Storages - haridas
http://haridas.in/how-to-put-encrypted-contents-on-cloud-storages.html

======
gizmo686
I've used encfs for years to keep sensitive data encrypted locally, but I
found that with cloud storage, the inability to compress made that approach
less than ideal, and the dropbox client refuses to sync the file when it is
mounted. The approach I take is to create a standard filesystem, and then
reguarly compress and encrypt a copy into the Dropbox folder. The command to
do so is below: cat /overflow/dropbox.ext4 | gzip -f | openssl aes-256-cbc
-pass pass:xxx > /overflow/Dropbox/dropbox.ext4.gz.aes-256-cbc

Which I set my backup routine to run when it is finished, but you could also
set to run at regular intervals using cron. Occasionaly, you might want to
zero out the filesystem to improve compression. This can be done using "cp
/dev/zero /mnt/SecureDropbox/zero" followed by "rm /mnt/SecureDropbox/zero"

~~~
timdoug
For zeroing unused blocks, I can suggest zerofree:
<http://packages.debian.org/squeeze/zerofree>

~~~
gizmo686
There description sounds like it is intended for use in Virtual Machines

~~~
timdoug
Well sure, but it's just zeroing free blocks; that's the same operation (with
the same desired outcome) whether you're using the disk image in a virtual
machine or as an encrypted loopback device.

