Re: encrypted filesystem on pre-existing filesystem?

[Matthias Hentges <eebe@gmx.net>]

Hello,

Am Sam, 2002-10-19 um 08.32 schrieb Bill Wagner:
> I've got a few boxes running testing/unstable and I'd like to test
> running encrypted filesystems on some of them.
> 
> My question is if it's possible to set up a pre-existing reiserfs or
> ext3 filesystem for encryption.

Yes it is possible.

>   From what I've seen, it's more or less
> mounting it as loopback with losetup but it appears you've got to set up
> the encryption before creating the filesystem. 

Well, sort of :)

You create a new file (with the size of the soon-to-be encrypted FS)
*ontop* of your regular ReiserFS (or ext2/3, JFS...) with the dd
command.

ie:	dd if=/dev/urandom of=~/.crypto bs=1024k count=10

Thats will create a 10Mb File.

For the next step you need to have a kernel supporting cryto and a
patched mount/losetup.

Set up a loop-device for this file with:

	losetup -e ciphername /dev/loop0 ~user/.crypto

Now make some FS on that file:

	mke2fs /dev/loop0 (or mk.reiserfs..)

Thats basically it. I'd recommend reading the "Encryption HOWTO" to make
things a bit clearer.

>  Is it typically best to
> use the 'AES' encryption with a extremely long pass phrase, BTW?

I am no expert for ciphers. I personally use the Twofish cipher with 
one hell of a long pass phrase ;)


> PS:  Will this ever be an option available at install time (or is it
> already and I just missed it?)
> 

I dont know an answer to that.

-- 
Matthias Hentges <eebe@gmx.net>