From: Mark <mark@coombs.anu.edu.au>
Date: Thu, 3 Jun 93 19:53:30 PDT
To: cypherpunks@toad.com
Subject: Re: CryptoStacker, long term vision
Message-ID: <9306040253.AA14575@toad.com>
MIME-Version: 1.0
Content-Type: text/plain


>A related topic to encrypted disk drives.  Anybody who has a desire to
>see their data around long term makes backups of their drives.  At
>least one of these backups is usually physically near the drive in
>question.
>
>What good it is to have an encrypted disk if the backups are not also
>encrypted?
>
>Backups occur at the file system level, where an encrypted file system
>does not appear encrypted, so that work here does not directly
>leverage to encrypted backups.

This problem is most easily solved by copying the entire partion/file
that is encrypted as blocks. These blocks are size according to the
destination media. If you use floppies you break the encrypted fs/file
into (e.g.) 1.44 meg chunks, if you use tape you can throw the whole
block at the media, similarly with another hardisk.

The unix/linux/386bsd 'dd' program is especially useful for this purpose
and I assume there are similar utils for dos.

For replacement you simply dump the whole lot back as one encrypted file
system.

This method should be faster than grabbing individual files and backing
them up as the program just has to seek to a specified place and start
reading a defined amount of [encrypted] data.

Mark
mark@coombs.anu.edu.au