[Discuss] cloud storage

[Tom Metro]

Jay Kramer wrote:
> I always wondered how well rsync would work at mirroring if the files
> were encrypted prior to syncing.

Lousy, though with modern hardware and fast networks, you might not
notice that full files are being transferred any time a minor portion is
changed.

There are projects to address this problem:
http://sourceforge.net/projects/rsyncrypto/

They do so by doing both compression (using the rsync friendly version
of gzip) and encryption in small blocks, rather than chaining keys (or
compression dictionaries) across an entire file. This creates a weaker
encryption, but probably good enough for most people.

If you're really paranoid, per-file encryption isn't the way to go,
anyway. You need to break up your files into a collection of data
buckets, with no detectable file affiliation, and then sync the buckets.
Though being able to observe which buckets get updated frequently is
still a bit of information leakage.

 -Tom

-- 
Tom Metro
Venture Logic, Newton, MA, USA
"Enterprise solutions through open source."
Professional Profile: http://tmetro.venturelogic.com/