My information security model right now is "if you want the data that I am storing on the cloud, you can have it" and I would like to change that to "if you want the data and have a $5 wrench, you can have it." To that end I am considering using rsyncrypto to perform encrypted backups in a bandwidth efficient manner. The
rsyncrypto program does this by changing
the encryption schema from plain CBC to a slightly modified version. This modification ensures that two almost identical files, such as the same file before an after a change, when encrypted using rsyncrypto and the same key, will produce almost identical encrypted files.
The wiki provides a little more information about the encryption algorithm
Rsyncrypto uses the standard CBC encryption mode, except every time the decision function triggers, it uses the original IV for the file instead of the previous cypher block.
rsyncrypto provide any appreciable security benefit over simply uploading unencrypted files to cloud based storage?