Linux cryptographic layer development
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From: Sebastian Andrzej Siewior <linux-crypto@ml.breakpoint.cc>
To: Mikulas Patocka <mpatocka@redhat.com>
Cc: Milan Broz <mbroz@redhat.com>,
	dm-devel@redhat.com, Alasdair G Kergon <agk@redhat.com>,
	linux-crypto@vger.kernel.org
Subject: Re: [PATCH] dm-crypt: disable block encryption with arc4
Date: Tue, 26 Jan 2010 14:34:13 +0100	[thread overview]
Message-ID: <20100126133413.GA5511@Chamillionaire.breakpoint.cc> (raw)
In-Reply-To: <Pine.LNX.4.64.1001260722080.20780@hs20-bc2-1.build.redhat.com>

* Mikulas Patocka | 2010-01-26 07:27:18 [-0500]:

>> yes, I think it is better.
>> (...and I just forgot to add that test to dm-crypt after that suggestion.)
>> 
>> Milan
>
>Hmm, there is salsa20 that has block size 1, larger initialization 
>vectors, and can be used to encrypt disks (although salsa20 doesn't 
>currently work with dm-crypt, because it doesn't accept "ecb(), cbc(), 
>etc." chaining modes --- but if you remove the chaining mode manually, it 
>works).
>
>You should rather add a flag CRYPTO_ALG_CHANGES_STATE to determine that a 
>cipher can't be used to encrypt disks.

Just because it will work does not make it a good idea.

SALSA20 is a stream cipher not a block cipher.
Block ciphers are used to encrypt data.
Stream ciphers are used to create one time pads, a set of encryption
keys, ...
There are block modes like CTR which can turn a block cipher into a
stream cipher. Those should not be used for disk encryption as well.

>
>Mikulas

Sebastian

  reply	other threads:[~2010-01-26 13:34 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-01-25 18:29 [PATCH] dm-crypt: disable block encryption with arc4 Mikulas Patocka
2010-01-25 18:39 ` Milan Broz
2010-01-26  9:22   ` Sebastian Andrzej Siewior
2010-01-26 10:48     ` Milan Broz
2010-01-26 12:27       ` Mikulas Patocka
2010-01-26 13:34         ` Sebastian Andrzej Siewior [this message]
2010-01-26 17:11           ` Mikulas Patocka
2010-02-09  7:37         ` Herbert Xu
2010-02-09 14:02           ` Mikulas Patocka
2010-02-09 20:42             ` Herbert Xu
2010-02-09 14:57           ` Sebastian Andrzej Siewior
2010-02-09 20:45             ` Herbert Xu
2010-02-09 21:12               ` Sebastian Andrzej Siewior
2010-02-09 21:45                 ` Herbert Xu
2010-02-12  8:42                   ` [PATCH] crypto/arc4: convert this stream cipher into a block cipher Sebastian Andrzej Siewior
2010-02-12  9:34                     ` Adrian-Ken Rueegsegger
2010-02-12  9:57                       ` Sebastian Andrzej Siewior
2010-02-14 20:42                     ` Sebastian Andrzej Siewior
2010-02-15  0:10                       ` Herbert Xu
2010-02-15  8:49                         ` Sebastian Andrzej Siewior
2010-02-16 12:51                     ` Herbert Xu
2010-02-21 20:01                       ` Sebastian Andrzej Siewior
2010-02-22  0:45                         ` Herbert Xu
2010-02-22  0:52                           ` Herbert Xu
2010-02-22 22:08                             ` Sebastian Andrzej Siewior
2010-02-23  0:32                               ` Herbert Xu
2010-03-14  8:24                                 ` Sebastian Andrzej Siewior
2010-03-14  9:06                                   ` Herbert Xu
     [not found]                       ` <Pine.LNX.4.64.1002221400090.31819@hs20-bc2-1.build.redhat.com>
2010-02-23  0:15                         ` Herbert Xu
2010-01-26 12:59   ` [dm-devel] [PATCH] dm-crypt: disable block encryption with arc4 Alasdair G Kergon
2010-01-25 18:39 ` Mikulas Patocka

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