I must be psychic: Re: Pushing hard-linked backups
Eric S. Johansson
esj at harvee.org
Tue Jan 1 06:41:16 GMT 2008
Eric S. Johansson wrote:
> Matt McCutchen wrote:
>> bOn Mon, 2007-12-24 at 18:34 -0500, Eric S. Johansson wrote:
>>> I'd love for the remote backup to be encrypted locally so one could
>>> backup to a hostile host.
>> That limits your options.
> one would think. For now, lets go with the plaintext push form of
> rsnapshot. as for encryption, I think it would be possible (assuming
> mods to rsync) to do rsync encrypted copies.
Rsyncrypto - Rsync Friendly File Encryption
Why is Rsyncrypto
Sometimes it is necessary to store files on a remote server. This is typically
needed for backup purposes. When that is done, there are two concerns that need
to be addressed:
1. How to keep the privacy of the files stored?
2. How to keep bandwidth usage to a minimum?
Both problems have rather simple solutions:
1. Encrypt the files prior to sending them. Keep the key locally.
2. Use rsync to only transfer the changes.
There is just one problem - the two solutions contradict. Plain mode encryption
of files hide the specific changes to the file, making rsync useless at
detecting in-file changes. This is where rsyncrypto comes to the rescue.
What is Rsyncrypto
Rsyncrypto is a modified encryption scheme. It is based on industry standard AES
for symmetric encryption, as well as RSA for having different keys for each file
while allowing a single key to decrypt all files. It even uses an encryption
mode that is based on CBC.
Rsyncrypto does, however, do one thing differently. It changes 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. This means that both objectives can be achieved simultaneously.
Rsyncrypto has won first price in the free software trophy competition (Trophées
du Libre) in the security category.
Just found, haven't tried. You may have better luck than I do with this piece
of software. In fact, it's highly likely you will have better luck than I do
with all pieces of software.
More information about the rsync