SecureDrive(IDEA), Realdeal and plaintext attack

[Mark M.]

-----BEGIN PGP SIGNED MESSAGE-----

On Thu, 18 Jul 1996, Jean-Francois Avon wrote:

> IDEA is reputed to be resistant against known plaintext attacks.
> But I did not read about wether or not it is resistant to 
> several-plaintexts (?choosen plaintext) attack.
> 
> If the sectors were not salted, each zeroed sectors would translate in 
> an identical way on the encrypted disk.  So, there would be only one 
> cyphertext-plaintext pair repeated over many empty sectors.
> 
> If you salt the encryptor, there are many different cyphertexts 
> corresponding to one single plaintext.
> 
> Can the salt be figured out by an attacker?

It doesn't matter whether an attacker knows the salt.  Sectors that are zeroed
are indistinguishable from secrtors that have data.  An attacker wouldn't know
which sectors are composed of zeroes.

- -- Mark

PGP encrypted mail prefered
Key fingerprint = d61734f2800486ae6f79bfeb70f95348
http://www.voicenet.com/~markm/  


-----BEGIN PGP SIGNATURE-----
Version: 2.6.3
Charset: noconv

iQCVAwUBMe6HIbZc+sv5siulAQHpIgP+L8fJC/NMixjiQxdHuIJAkPxKqWpY3PBC
KlqubQddtQG5CYWEjmC3aLks/kBVHLw/WGg7QM4C3Hl6Hmp/X85qiNCME6rhYjZq
1Jqbit1FVRHOEz9Nw7suOZlabHkQDTx9mEYvq0bWtAlPRXizWz60UwBt5W+n3SBT
hpO/gwkvWs4=
=4raq
-----END PGP SIGNATURE-----