Re: 2.4 and cryptofs on raid1 - what will be cached and how many times

From: Bryan Andersen (bryan@bogonomicon.net)
Date: Tue Mar 04 2003 - 06:07:38 EST


Vlad Harchev wrote:

>>A potential attacker can use this to look for the ext2 superblock,
>>which gives him the same data both encrypted an unencrypted. A real
>
>
> I've got an impression that in case of loopback with encryption the
> superblock will also be encrypted.
> If one forgets known cleartext attacks, one can place the filesystem at
> some offset.

Yes it would be encrypted. Unfortunately it is predictable data and as
such it is much easier to crack. Better set that offset at a location
computed from the encryption key.

On a side note I find it interesting that many people sugest compressing
a file before encrypting it. Take a look at the first few bytes of
every compressed file. Unless your going to get rid of that header...

>>cryptofs would go through great pains to take such advantages away.

- Bryan

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