From: blaster@rd.relcom.msk.su (Victor A. Borisov)
Date: Tue, 12 Oct 93 02:59:54 PDT
To: cypherpunks@toad.com
Subject: RE: Breaking DES
Message-ID: <AAqydkiSCE@rd.relcom.msk.su>
MIME-Version: 1.0
Content-Type: text/plain


>   The other reason is that it was initially feared that DES was a group.
>   That is, encryption with k1 and k2 might be equivalent to single encryption
>   with some unknown (to you and me) key k3.  But a cryptanalyst or a brute-
>   force cracker would neither know nor care that you double-encrypted.
>
>   It has now been proved that DES is not a group.  What isn't clear to me
>   is whether it's ``mostly closed'', though I suspect not.
It can be right, but we can use some intermidiant operation. For example:
DES(randomHeader+DES(zip(DES (text, k1)), k2), k3)

        DES (text, k) - encryption text "text" by key k;
        randomHeader - some good random text;
        zip - some archiver.
--- 
Victor A. Borisov aka blaster;	Relcom R&D;
Email: blaster@rd.relcom.msk.su;
Phone: +7(095)-943-4735; +7(095)-198-9510;
	=== Don`t panic! ===