Critical security issue

[kilburn]

There are 2 ways to handle this issue:

1. Deal with the untarring and (fixed) permission handling in an inaccessible directory, mv the properly checked result to the user folder
2. Implement backup signing (we can easily implement a signature file which is calculated by encrypting the md5 hash of the archive file).

I'm strong in favour of the 2nd option, but open to your opinions...