[Khufu] Pre-Computing the S-Boxes and obtaining aux. keys

From: Nikola Skoric (nick-news_at_net4u.hr)
Date: 10/30/04 

Date: Sat, 30 Oct 2004 17:43:05 +0200

Hello,

I'm trying to implement Khufu algoritm for my cryptography class. I
started with absolutely no information on my hands and achieved in
finding a paper (http://groups.google.com/groups?q=khufu+pre-
computing+s-boxes&hl=en&lr=&selm=7982%40hoptoad.uucp&rnum=2) written by
Ralph C. Merkle, the author of the algorithm, describing the
algorithm... the only problem is that's not enough to implement this
algorithm without making some wild assumptions. The algorithm can be
devided into 2 stages:

1) generating material needed for encription:
        a) generating the S-Boxes (which are not fixed but are generated
every time from the key)
        b) generating 4 different instances of "32-bit auxiliary key
material"
2) encrypting the plaintext

The 2nd part is well explained in the article. It is far from simple,
but I do have enough info to code the algorithm. The 1st part is what
bugs me. The chapter "Making the Initial and Standard S-Boxes" (lines
1017-1068) gives only the very basic principles of generating the
Initial S-Box required to compute remaining S-Boxes (quote: "The first
criteria is met rather simply by publishing the algorithm used to
generate the standard S-box (publication is planned in the near
future)."), and chapter "Pre-Computing the S-Boxes" (lines 365-439)
seems pretty vague and incomplete. Not to mention that algorithm for
generating the "32-bit auxiliary key material" is not even mentioned.

So, my questions are: has anybody here ever tried to implement Khufu
consistently and does anybody know where could I obtain instructions
regarding how to compute S-Boxes and auxiliary keys from the key
provided by user? I'd be absolutely thrilled if anybody helped. 

-- 
"Stara boljka se leci starim lekom...
Dabome vinom, ta nebi valjda mlekom?"

Relevant Pages

  • Re: determining differential characteristics
    ... Obviously, every algorithm is ... One common structure is a Feistel block cipher, where the round F-function ... is built up out of S-boxes. ... table of all possible differential characteristics for the S-boxes, ...
    (sci.crypt)
  • Re: What is a key
    ... >> I am trying to find out what it means to use a key in the encryption ... the key is just an aspect of an encryption algorithm ... the S-boxes in DES are not ...
    (sci.crypt)
  • Re: DES Expansion Permute + S-Boxes Duplicates ?
    ... > of zero). ... > Have I made an error in my algorithm? ... > on the S-Boxes, or are these values still kept confidental? ... Don Coppersmith revealed some design criteria for the DES S-boxes and ...
    (sci.crypt)
  • Re: DES Expansion Permute + S-Boxes Duplicates ?
    ... > through the Expansion Permutation and S-Boxes (with a key ... > of zero). ... > Have I made an error in my algorithm? ... > on the S-Boxes, or are these values still kept confidental? ...
    (sci.crypt)