From: Milan Broz <mbroz@redhat.com>
To: Alexander Konovalenko <alexkon@gmail.com>
Cc: dm-crypt@saout.de, Arno Wagner <arno@wagner.name>
Subject: Re: [dm-crypt] LUKS header size
Date: Tue, 03 Aug 2010 13:02:26 +0200 [thread overview]
Message-ID: <4C57F742.1050707@redhat.com> (raw)
In-Reply-To: <AANLkTi=6RytcDRKMUtvajjjT3z9TB_u6QTSS1Xo7dV0U@mail.gmail.com>
On 08/03/2010 12:41 PM, Alexander Konovalenko wrote:
> On Mon, Aug 2, 2010 at 05:01, Arno Wagner <arno@wagner.name> wrote:
>>
>> sorry, but you will have wiped the salt in the header, which
>> makes recovery impossible. You will also have wiped all keys
>> (they take about the first 8.5MB), which again does make recovery
>> impossible. In fact, any recovery from this would mean that
>> LUKS is badly broken security-wise.
>
> 8.5 MB? I thought a LUKS header usually takes only 2056 512-byte
> sectors, which is slightly more than 1 MiB. I wonder where does that
> belief come from. Almost all LUKS partitions I've been dealing with
> have been created by Ubuntu's debian-installer. So debian-installer's
> default must be the culprit.
LUKS header is just 2 sectors, but keyslots are quite large.
Read http://code.google.com/p/cryptsetup/wiki/FrequentlyAskedQuestions#5._Backup_and_Data_Recovery
> What's the recommended LUKS header size?
There is no such thing. Allocated size depends on used key size and device alignment.
With 512bits key is area used for LUKS usually 4040 sectors (unaligned, ~2MB)
(it is LUKS header + reserved space for 8 keyslots)
Just check luksDump & "Payload" offset.
Milan
next prev parent reply other threads:[~2010-08-03 11:02 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-03 10:41 [dm-crypt] LUKS header size Alexander Konovalenko
2010-08-03 11:02 ` Milan Broz [this message]
2010-08-03 11:18 ` Arno Wagner
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