Re: [dm-devel] [PATCH] dm-crypt: disable block encryption with arc4

[Herbert Xu <herbert gondor apana org au>]

On Tue, Feb 09, 2010 at 03:57:05PM +0100, Sebastian Andrzej Siewior wrote:
>
> >As to blacklisting algorithms not suitable for disk encryption,
> >that is up to the dm-crypt maintainers to decide.
> 
> Herbert, what happend to the "check for streamcipher" idea you had? Is
> it gone? On the other hand it wouldn't be probably that bad to have a

Well again whether that should be done is up to the dm-crypt
maintainers.

> seprate interface to grab a block cipher _or_ a stream cipher. So

Just because something isn't a stream cipher doesn't mean that
it is safe for disk encryption.  People simply shouldn't be using
random algorithms for disk encryption.

> I can't imaging how you want to fix arc4 that it will work in dm-crypt.

I thought I've explained this before.  Just turn it into a blkcipher
and add IV.

> The algorithm relies more or less on the fact that it envolves itself
> during processing of data.

This is no different to any stream cipher.

Cheers,
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