Problema
I'm familiar with rsync and have tried using it, along with other tools, to write a Perl script that does what I want. However, rsync by itself does not do what I want. Unfortunately, if a file changes slightly, the encrypted version of the file changes a lot, so rsync doesn't even work that well for single files.
Solução?
rsyncrypto is a utility to encrypt files in an rsync-friendly fashion. The rsyncrypto algorithm ensures that two almost identical files, when encrypted with rsyncrypto and the same key, will produce almost identical encrypted files. This allows for the low-overhead data transfer achieved by rsync while providing encryption for secure transfer and storage of sensitive data in a remote location.
(de Wikipedia )