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



On Tue, Feb 09, 2010 at 09:02:35AM -0500, Mikulas Patocka wrote:
> 
> What is the fix for arc4? Copy the internal state after a key schedule and 
> restore it with every encryption?

arc4 should be a blkcipher, not a cipher.  Then it can have an IV
which is where thie should be stored.
 
> I think blacklisting "arc4" is better, because it provides a fix now. 
> Otherwise, people will just keep on arguing what is the "clean" solution 
> and nothing gets done.

The crypto layer makes no guarantee that every algorithm that is
available is suitable for a particular application such as disk
encryption.  FWIW we also export an algorithm called null!

People should not be making uninformed choices on crypto algorithms.

Cheers,
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