Victor A. Borisov (blaster@rd.relcom.msk.su) writes:

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.

And Lyle_Seaman@transarc.com replies:

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?

(Excerpt from sci.crypt faq deleted)

I think that Victor's friend proposes a second function, f(), which is not the same as DES. He is saying that for every set of three keys used for triple-DES (k2,k3,k4), there is a key (k1) such that: f(k1,text) = DES(k2,DES(k3, DES(k4,text))) It seems to me this is different than saying DES is a group, since f != DES. Am I mistaken?