Can we encrypt copied files on target machine?

[Jose' Sebrosa]

The problem
-----------

I want to copy a file from machine A (master) to machine B (backup) but I would
like to stop root user on machine B to easily look at the file contents.  So I
encrypt the file to send at machine A and send just the encrypted version to
machine B (which has no means to decrypt the file).

Then I make a small change in the file in the machine A and want to send the
new version to machine B.  If I simply repeat the procedure (encrypt at A and
rsync with B) I lose the rsync advantages, since a local change in the raw file
leads to a global change in the encrypted file.


The solution?
-------------

Maybe I can split the raw file at A in several parts, encrypt them separately
and send them as separated files to B, along with info on how to rebuild the
file from the *decrypted* parts (remember, B doesn't know how to decrypt).  The
problem then would be to keep at A a record of the parts sent do B, in order to
decide how to split the file the next time A wants to send it to B (the
spliting is not trivial, since the parts must be equal to those already at B if
possible).

So eventually I finish using the rsync algorythm, not to do the final copy of
files from A to B, but to do the splitting of the raw file at A into parts.  I
just need to build an auxiliary file with info on how to join the parts,
instead of the parts already joined.


The questions
-------------

Can rsync do the spliting and build info on how to join instead of joining?
Does anyone have this kind of problem?
Has the problem an easier solution?
Am I missing something?

Thanks,
Sebrosa