Can we encrypt copied files on target machine?

Jacob Martinson jmartinson at
Thu Oct 11 06:00:03 EST 2001

Why not rsync to a system where you are the root user?  

On Wed, Oct 10, 2001 at 08:27:35PM +0100, Jose' Sebrosa wrote:
> 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

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