Messages in this thread | | | Subject | Re: [PATCH] Delete cryptoloop | Date | Sun, 25 Jul 2004 22:58:05 +0200 | From | Fruhwirth Clemens <> |
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On Sun, 2004-07-25 at 21:44, Marc Ballarin wrote: > Fruhwirth Clemens <clemens-dated-1091642568.f246 <at> endorphin.org> writes: > > > > > Probably I'm missing the point, but at the moment this looks like a > > chosen plain text attack. As you know for sure, this is trivial. For > > instance, AES asserts to be secure against this kind of attack. (See the > > author's definition of K-secure..). > > It assures against key revovery through chosen plain text attacks. As written > before, the purpose of this attack is not to break encryption, but to prove > the existence of a file *known to* and *prepared by* the attacker.
If an attacker has some means to put a file on the encrypted hard disk, I'm not considering it a big breakthrough if he can find out the position of that file. I'm sure this information can be gained by forensic block access pattern analysis anyway.
> The exploit generates a rather simple bit pattern with a size of 1024 bytes. > When this pattern - the watermark - is encrypted, dm-crypt's output has some > special properties - independent of cipher or key size. > For example, encoding nr. 1, always produces a cyphertext block, where bytes > 0-15 are equal to bytes 512-523.
I'm starting to wonder why this is called an attack. The results of this ``attack'' can't be used in any way. In the worst case, a cipher text/plain text pair can be obtained. I'm repeating it one more time: ciphers are designed to resist further attacks steaming from known-plain text attacks.
Have a look at http://clemens.endorphin.org/OnTheProblemsOfCryptoloop . That's an attack!
> On dm-crypt's mailing list, I have given a description how this can be refined > easily to improve reliability of detection and determine a file's layout on > the encrypted volume.
I'm sorry, I consider this useless information.
-- Fruhwirth Clemens <clemens@endorphin.org> http://clemens.endorphin.org [unhandled content-type:application/pgp-signature] | |