Encrypted Container on WebDAV Server, mount failed

Hey guys,

I am looking for a backup solution, which creates encrypted backup on a webdav server. I found this solution and that should theoretically work :). Unfortunately, it does not. Maybe you can help me:

First I tried everything locally to ensure that everything works:

1. I created a 1TB container file using dd:

dd if=/dev/urandom of=container bs=1G count=1024

2. binding the container as a loop device:

losetup /dev/loop0 container

3. Encrypt everything using luks

cryptsetup -c aes-xts-plain -y -s 512 luksFormat /dev/loop0

4. open luks, format as ext4 and mount:

cryptsetup luksOpen /dev/loop0 container 
mkfs.ext4 /dev/mapper/container 
mount -t ext4 /dev/mapper/container /media/mountpoint

Then I used rsync to finish my first backup and everything worked.

Now I transferred the file to the NAS of a friend of mine. He shares the folder which contains the container using webdav over ssl. I mounted the webdav my system and trying to mount the container file again.

The problem I have now is that the system seems to download the file first. Isn't it possible to just mount the file? Am I missing something?

I would appreciate your help!

Thanks a lot!