Re: linux-kernel-digest V1 #740

Evan Jeffrey (ejeffrey@eliot82.wustl.edu)
Mon, 10 Feb 1997 18:28:35 -0600


>
>From: Jeremey Barrett <jeremey@veriweb.com>
>Date: Mon, 10 Feb 1997 00:46:27 -0800 (PST)
>Subject: Encrypted "virtual" disk
>
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>I am interested in writing a cryptographic "virtual" disk or filesystem.
>My goals/ideas are the following:

Correct me if I am just being blind, but how do your desired features differ
from using the loop device w/ the currently available des or idea patches.
If you would like different encryption, it should be relatively easy to use
the existing hooks in the loop device to do the encryption.

> o The crypto-fs code would require a passphrase upon mounting. It would
> be nice to auto-unmount after a period of time specified by mount.

Instead you use the crypto info upon seting up the loop device. It could
be auto unmounted in user space.

> o When a file is read by something in user-space, the crypto-fs
> maps the request to some part of the file as it exists in the mind
> of the underlying "real" file system, reads the requested portion,
> and then decrypts it.

The loop device doesn't use the filesystem calls. Therefore it requres that
the loop file exist on a physical disk on the system and (I think) that the
file is contigious. So if your system would allow NFS mounted encrypted fs,
that would be really cool.

Evan Jeffrey