plain source -> encrypted destination: rsync + gpg (--dest-filter patch)

[addady at active.co.il]

> If i recall correctly (i've not gone back to review that
> patch) that patch required whole-file transfers two avoid
> doing the operation twice per file.  If the filter is
> deterministic and particularly if changes have minimal
> cascade effect you may be able to still take advantage of
> the rsync algorithm.

You recall correctly.
It is not clear to me how using "whole-file" and still take advantage of
the rsync algorithm.

The idea of this patch seem to me very useful.
I'm plan to use it with the "rsyncable" gzip version
(http://svana.org/kleptog/rgzip.html).
The "whole-file" is not necessary is this case.  I think that the patch need
to be modifiy so that
whole-file will be a option.

Addady