Monitor radiation overlooking.

Hello!

     I  read   about   overlooking  of  monitor   radiation.
Introder   can   scan   the  electron-beam  radiation   from
electron-gun. He  simple  transmit  this   radiation to self
electron-gun  and sinchronize  frequance. This  method  work
with b/w  monitor.  The  overlooking of  color-monitor  more
dificult - introder will see 4 gradation of gray  (all  guns
off, work one, two, three guns). But  we can select  spesial
colors (red-blue or blue-green) and  allways will  work only
one (or two) guns. In this way  introder will  see  dark (or
light) gray screen without any information!!!
     Is it  corect?  Do now present more improve overlooking
system?

Some words about DES - I spoke with one cryptoanalisyst from
KGB and he sow, that for number crypto algotitm c(key, text)
(key is keyLength tall) present f(key, text), that for all
key1 and key2 present key with length keyLength, that
c(key2, c(key1, text))==f(key, text).

He also say, that now present f() for c()=des(), more f() wery
like des().

That`s why for decrypting of des(k1, des(k2, ... des(kN, text) ... ))
we must try 2^56 keys with spetial function.


--- 
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! ===

Excerpts from internet.cypherpunks: 15-Oct-93 Monitor radiation
overlooking. Victor A. Borisov@rd.rel (1286)

> Some words about DES - I spoke with one cryptoanalisyst from
> KGB and he sow, that for number crypto algotitm c(key, text)
> (key is keyLength tall) present f(key, text), that for all
> key1 and key2 present key with length keyLength, that
> c(key2, c(key1, text))==f(key, text).

> He also say, that now present f() for c()=des(), more f() wery
> like des().

> That`s why for decrypting of des(k1, des(k2, ... des(kN, text) ... ))
> we must try 2^56 keys with spetial function.


I had a little trouble with the English, but I think I followed the
math.  I believe Victor's KGB friend is claiming that DES is a group. 
Victor, does the following text contradict your claim?

From the Crypto FAQ:
Excerpts from netnews.sci.crypt: 4-Oct-93 Cryptography FAQ (05/10: Pr..
crypt-comments@math.ncsu (20767)

>   The security of multiple encipherment also depends on the
>   group-theoretic properties of a cipher. Multiple encipherment is an
>   extension over single encipherment if for keys K1, K2 there does
>   not exist a third key K3 such that

>   E_K2(E_K1(X)) == E_(K3)(X)                (**)

>   which indicates that encrypting twice with two independent keys
>   K1, K2 is equal to a single encryption under the third key K3. If
>   for every K1, K2 there exists a K3 such that eq. (**) is true then
>   we say that E is a group.

>   This question of whether DES is a group under this definition was
> extensively studied by Sherman, Kaliski, and Rivest [SHE88]. In their
> paper they give strong evidence for the hypothesis that DES is not a
> group. In fact DES is not a group [CAM93].

>   [CAM93] K. W. Campbell, M. J. Wiener, Proof the DES is Not a Group. In
> Proceedings of CRYPTO '92, 1993.

>   [SHE88] B. Kaliski, R. Rivest, A. Sherman, Is the Data Encryption
> Standard a Group. Journal of Cryptology, vol. 1, #1,
>           1--36, 1988.

>   I had a little trouble with the English, but I think I followed the
>   math.  I believe Victor's KGB friend is claiming that DES is a group.
>   Victor, does the following text contradict your claim?
Sorry for my poor English. I want to saw, that DES is`t group. We can`t say,
that:
A k1, k2: E k0, that des(k2, des(k1, text))=des(k0, text)
        (A mean "for all", E mean "exist");

or: E k1, k2: A k0, that des(k2, des(k1, text))!=des(k0, text)

I saw, that:
E f(k, text): A k1, k2: E k0, len(k0)=len(k1)=len(k2), that
des(k2, des(k1, test))=f(k0, text)

f() like des(), but f() is not des()!!!
My friend saw, that introder must try only 2^56 keys for des(des()).
Once more, sorry for my poor English.

PS I am sorry for my stupid letter about PGP randomizer.
--- 
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! ===