Re: [gentoo-user] Secure Cloud Backup

[Florian Philipp <lists@binarywings.net>]

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Am 02.01.2012 22:50, schrieb James Broadhead:
> I have a pile of files, and a personal svn repo totalling around 13GiB
> which I want to back up to cheaply to 'the cloud'.  I would also like
> it to be non-trivial for someone with access to the cloud servers to
> decrypt my data.
> 
> I have a 50GB free account for Box.net, but would consider others if
> they have significant advantages. The box.net account is only allowed
> upload files of max 100MiB at a time.
> 
> Now one problem facing me is that most cloud services don't give
> assurances of bit parity, so I'd like to be able to recover most of
> the files if I lost my local copies and there were bits missing from
> the uploaded backup. This makes the one-big-encrypted-file approach a
> no-go.
> 
> My current approach is to use split-tar, with the intention of
> encrypting each file separately. (Is this worse / equivalent to having
> one big file with ECB ? )

I could be wrong but I don't think you will find any reasonable
encryption tool that only offers encryption equivalent to ECB. The
number of files should not matter as the encryption tool can use a
randomized IV with CBC.

> http://www.informatik-vollmer.de/software/split-tar.php
> ...but this seems to have difficulty sticking below the 100MiB
> individual file limit (possibly there are too many large files in the
> svn history).
> 

Why not split them further when the files are still above the 100M limit
after splitting them with that tool? split + cat should do the trick.

> Any thoughts? I'm sure that many of you face this problem.
> 

Well, I have no experience with their service (although I always planned
to use them), but maybe you can try these guys [1]. They don't have file
size limits and support everything working over ssh (including sshfs) as
well as duplicity for file encryption. Of course, having only US
locations could be a no-go depending on your legal
considerations/restrictions.

[1] http://www.rsync.net/

Regards,
Florian Philipp



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