Cryptography-Digest Digest #317, Volume #13 Tue, 12 Dec 00 18:13:01 EST
Contents:
Re: About governments and my ex-relatives in Finland and the U.S.A. ... basically my
ex-spouse had around 350000 US dollars and then my ex-relatives (Finland and US )
collaborated in their efforts to force me to leave the U.S.A. without any of this
money . (Greggy)
Re: Bilderbergs --- see also who are there from Finland ... these are people who
have sold Finland out .... of course Henry Kissinger and Bill Clinton have been in
Bilderbergs too (Greggy)
Re: Sr. Cryptographer/mathematician (Greggy)
Re: Sr. Cryptographer/mathematician (Bob Silverman)
Re: ---- Are AES algorithms export restricted? (Greggy)
Password encryption ("Chris Sanger")
Re: ---- Are AES algorithms export restricted? (Greggy)
Re: ---- Are AES algorithms export restricted? (Greggy)
Re: ---- Are AES algorithms export restricted? (Greggy)
Re: ---- Are AES algorithms export restricted? (Greggy)
Re: ---- Are AES algorithms export restricted? (Greggy)
Re: ---- Are AES algorithms export restricted? (Greggy)
Re: Newbie ("Chris")
Re: Is brute for the only way? (Bryan Olson)
Re: On using larger substitutions (Mok-Kong Shen)
----------------------------------------------------------------------------
From: Greggy <[EMAIL PROTECTED]>
Crossposted-To: alt.2600,alt.security
Subject: Re: About governments and my ex-relatives in Finland and the U.S.A. ...
basically my ex-spouse had around 350000 US dollars and then my ex-relatives (Finland
and US ) collaborated in their efforts to force me to leave the U.S.A. without any of
this money .
Date: Tue, 12 Dec 2000 21:58:17 GMT
In article <[EMAIL PROTECTED]>,
Error_404 <[EMAIL PROTECTED]> wrote:
> basically he's saying that there's a government conspiracy to causew
him to
> have a divorce, and leave the country, where he will never be admitted
> again
Hmm... So what?
>
> Greggy wrote:
>
> > In article <3a2d4b5b$0$94481$[EMAIL PROTECTED]>,
> > "Huckleberry Hoshimoto" <[EMAIL PROTECTED]> wrote:
> > > OK - we're clear on 5 points:
> > > (1) Your a maste-oid
> > > (2) You're exactly were you belong (outta HERE)
> > > (3) Your ex-relatives have some common sense (& are probably
> > celebrating
> > > like crazy!)
> > > (4) You're STILL whining to others who couldn't care less
> > > (5) You are unclear on the concept of "Subject" vs. "Body Text"
> > >
> > > Our response is (or should be):
> > > "What's your point?"
> >
> > How did you get ANY of that stuff out of his post? I cannot figure
out
> > what he is saying at all.
> >
> > >
> > > "Markku J. Saarelainen" <[EMAIL PROTECTED]> wrote in
message
> > > news:90j1u3$6f9$[EMAIL PROTECTED]...
> > >
> > >
> >
> > --
> > I prefer my fourth amendment rights over a dope free
> > society, even if the latter could actually be achieved.
> > Al Gore and the Florida Robes - More than just another rock group;
> > a clear and present danger to America's national security.
> >
> > Sent via Deja.com http://www.deja.com/
> > Before you buy.
>
>
--
I prefer my fourth amendment rights over a dope free
society, even if the latter could actually be achieved.
Al Gore and the Florida Robes - More than just another rock group;
a clear and present danger to America's national security.
Sent via Deja.com
http://www.deja.com/
------------------------------
From: Greggy <[EMAIL PROTECTED]>
Crossposted-To: alt.security,comp.security
Subject: Re: Bilderbergs --- see also who are there from Finland ... these are people
who have sold Finland out .... of course Henry Kissinger and Bill Clinton have been in
Bilderbergs too
Date: Tue, 12 Dec 2000 21:59:51 GMT
In article <[EMAIL PROTECTED]>,
Chris Ahlstrom <[EMAIL PROTECTED]> wrote:
> "Markku J. Saarelainen" wrote:
> >
> > http://ourworld.compuserve.com/homepages/grattan_healy/Bild-az-
tab.html
> >
> > Ahlstr�m, Krister, President and CEO, Ahlstr�m Group
>
> Cool, almost the same spelling as my name! But you're message
> means nothing to me. Can you explain it? Thanks!
Well, if he explains it like his last post, you will be left even more
confused.
>
> Chris Ahlstrom
>
--
I prefer my fourth amendment rights over a dope free
society, even if the latter could actually be achieved.
Al Gore and the Florida Robes - More than just another rock group;
a clear and present danger to America's national security.
Sent via Deja.com
http://www.deja.com/
------------------------------
From: Greggy <[EMAIL PROTECTED]>
Subject: Re: Sr. Cryptographer/mathematician
Date: Tue, 12 Dec 2000 21:55:44 GMT
In article <915q8n$q4s$[EMAIL PROTECTED]>,
Tom St Denis <[EMAIL PROTECTED]> wrote:
> In article <915k33$m6t$[EMAIL PROTECTED]>,
> [EMAIL PROTECTED] wrote:
> > Tom St Denis <[EMAIL PROTECTED]> wrote:
> > > In article <2IfZ5.17746$[EMAIL PROTECTED]>,
> > > "Kevin" <[EMAIL PROTECTED]> wrote:
> >
> > >> - Computaional complexity theory
> >
> > > "Computational" also referred to "Combinatorics"
> >
> > Ummmmm..... no, not even close.
>
> Well something dealing with complexity is normally a combinatoric
> thing... well from what I have seen, sorry.
>
> > >> - Number theory
> > >> - Numerical analysis
> >
> > > These two are the same!
> >
> > Again, not even remotely close.
>
> How do they differ? Number theory is the analysis of fields, rings,
> structures and the relationship between different groups, etc.
> Numerical analysis is...?
The analysis of numericals, of course... :)
>
> > You seem to have posted trying to show that the original poster
didn't
> > know what they were talking about, but unfortunately you stepped in
it
> > pretty big time showing that you need some big clues...
>
> I try :-)
>
> Tom
>
> Sent via Deja.com
> http://www.deja.com/
>
--
I prefer my fourth amendment rights over a dope free
society, even if the latter could actually be achieved.
Al Gore and the Florida Robes - More than just another rock group;
a clear and present danger to America's national security.
Sent via Deja.com
http://www.deja.com/
------------------------------
From: Bob Silverman <[EMAIL PROTECTED]>
Subject: Re: Sr. Cryptographer/mathematician
Date: Tue, 12 Dec 2000 21:56:05 GMT
In article <[EMAIL PROTECTED]>,
"M.S. Bob" <[EMAIL PROTECTED]> wrote:
> Tom St Denis wrote:
> > >
> > > >> - Computaional complexity theory
> > >
> > > > "Computational" also referred to "Combinatorics"
> > >
> > > Ummmmm..... no, not even close.
> >
> > Well something dealing with complexity is normally a combinatoric
> > thing... well from what I have seen, sorry.
> >
> > > >> - Number theory
> > > >> - Numerical analysis
> > >
> > > > These two are the same!
> > >
> > > Again, not even remotely close.
> >
> > How do they differ? Number theory is the analysis of fields, rings,
> > structures and the relationship between different groups, etc.
> > Numerical analysis is...?
<snip>
> You have a very limited insight into mathematics, and your are
> repeatedly are mistaken in thinking you have a better grasp of
> mathematics than you do, and unfortunately expressing this misguided
> grasp in this forum. You fail to comprehend the size of the realm of
> mathematics.
> Number theory is the study of the properties of usually the whole
> numbers, and rational numbers (fractions).
>
> Numerical analysis is the study of computing numerical data.
>
> Your incorrect description of number theory is closer to algebra.
An elucidation. Both number theory and numerical analysis are similar
in that they both use numerical algorithms. The primary difference
between them is that number theory computations take place in a
DISCRETE domain, while the domain for numerical analyis is primarily
that of CONTINUOUS functions.
One solves an equation mod p in number theory.
One solves an equation (ordinary, functional, differential, integral
etc. ) over R or C in numerical analysis.
One normally gets exact answers in no. theory and approximations
in numerical analysis.
--
Bob Silverman
"You can lead a horse's ass to knowledge, but you can't make him think"
Sent via Deja.com
http://www.deja.com/
------------------------------
From: Greggy <[EMAIL PROTECTED]>
Subject: Re: ---- Are AES algorithms export restricted?
Date: Tue, 12 Dec 2000 22:04:24 GMT
In article <90kt9e$ncq$[EMAIL PROTECTED]>,
[EMAIL PROTECTED] (Bill Unruh) wrote:
> In <90jucc$ik$[EMAIL PROTECTED]> Greggy <[EMAIL PROTECTED]> writes:
>
> >It just seemed to me as I was reading another post here that none of
> >the AES algorithms could possibly be export restricted from within
the
> >US since they were all published during the AES contest. Am I
> >correct? Or did I miss something in my thinking here?
> They are all export restricted. It is entirely legal to export printed
> copies of algorithms. It is just not legal to export code without a
> license (unless it is opensource code, in which case it does not need
a
> license, ..... read the law.)
I did and I got more confused. Thus, my post...
See, I read the BXA regs and asked the lady at BXA for help
understanding them. Her response was that I had to read them for
myself and figure them out myself. But the terms are scary - like they
were deliberately written in a different language to entrap me.
--
I prefer my fourth amendment rights over a dope free
society, even if the latter could actually be achieved.
Al Gore and the Florida Robes - More than just another rock group;
a clear and present danger to America's national security.
Sent via Deja.com
http://www.deja.com/
------------------------------
From: "Chris Sanger" <[EMAIL PROTECTED]>
Subject: Password encryption
Date: Tue, 12 Dec 2000 22:10:15 GMT
ok 2 passwords
name-Christopher Sanger
Id number-400881
password-S906ER37
name Samuel Stevenson
id number-400898
password-S043EL51
its easy to see the letters come from 1st letter in last name and last 2
letters in first name but the numbers are the tricky part i included our id
numbers but i am not sure if they have anything to do with it. anyone wanna
work on the code? Please Reply asap
------------------------------
From: Greggy <[EMAIL PROTECTED]>
Subject: Re: ---- Are AES algorithms export restricted?
Date: Tue, 12 Dec 2000 22:10:40 GMT
In article <[EMAIL PROTECTED]>,
Richard Heathfield <[EMAIL PROTECTED]> wrote:
> Brian Gladman wrote:
> >
> > "Mok-Kong Shen" <[EMAIL PROTECTED]> wrote in message
> > news:[EMAIL PROTECTED]...
> >
> > > Bill Unruh wrote:
> > > >
> > > > Greggy <[EMAIL PROTECTED]> writes:
> > > >
> > > > >It just seemed to me as I was reading another post here that
none of
> > > > >the AES algorithms could possibly be export restricted from
within the
> > > > >US since they were all published during the AES contest. Am I
> > > > >correct? Or did I miss something in my thinking here?
> > > > They are all export restricted. It is entirely legal to export
printed
> > > > copies of algorithms. It is just not legal to export code
without a
> > > > license (unless it is opensource code, in which case it does
not need a
> > > > license, ..... read the law.)
> > >
> > > They are all freely available outside of nations having
> > > export regulations via the web page of NIST. So I suppose
> > > one way to cope with the situation could be to leave a
> > > stub in the delivered code of an application containing
> > > such an algorithm as a component and let the customer to
> > > download the necessary piece of 'sinister' and 'forbidden'
> > > stuff himself and plug it in.
> >
> > This won't necessarily solve the problem because any software that
contains
> > an interface designed to support a plug-in cryptographic capability
may
> > itself be subject to export controls even though it contains no
> > cryptography.
> >
> > This has changed a bit recently but I believe that some controls on
such
> > software still exist in the US.
>
> I was about to reply "have you ever considered living in a *free*
> country?" when I remembered R.I.P., and the UK Govt's latest attempt
to
> legislate to permit long-term storage of traffic data (including phone
> traffic).
>
> So, instead, I have a question:
>
> Are there any civilised countries left in the world which do /not/
seek
> to micro-manage their populations in this way? Specifically:
>
> 1) no monitoring of email, Web access, traffic data, etc
> 2) no restrictions on use, import, or export of cryptographic
binaries,
> source, or data
> 3) good standard of living
> 4) beaches which are pleasant, clean, warm, and sunny
>
> (The last two being more or less my definition of "civilised")
>
> Where might such a Utopia be found?
At the end of your Glock?
--
I prefer my fourth amendment rights over a dope free
society, even if the latter could actually be achieved.
Al Gore and the Florida Robes - More than just another rock group;
a clear and present danger to America's national security.
Sent via Deja.com
http://www.deja.com/
------------------------------
From: Greggy <[EMAIL PROTECTED]>
Subject: Re: ---- Are AES algorithms export restricted?
Date: Tue, 12 Dec 2000 22:11:48 GMT
In article <[EMAIL PROTECTED]>,
[EMAIL PROTECTED] wrote:
> On Wed, 06 Dec 2000 14:44:29 +0000, Richard Heathfield <> wrote:
> >So, instead, I have a question:
> >
> >Are there any civilised countries left in the world which do /not/
seek
> >to micro-manage their populations in this way? Specifically:
> >
> >1) no monitoring of email, Web access, traffic data, etc
> >2) no restrictions on use, import, or export of cryptographic
binaries,
> >source, or data
> >3) good standard of living
> >4) beaches which are pleasant, clean, warm, and sunny
> >
> >(The last two being more or less my definition of "civilised")
>
> I was about to say "Finland", but then I saw your qualification #4,
which
> sort of leaves Finland out :-).
Hey, let's just take over one of the non principle islands of Hawaii
and secede from the state and the union. Maybe coconut island
(Giligan's island).
--
I prefer my fourth amendment rights over a dope free
society, even if the latter could actually be achieved.
Al Gore and the Florida Robes - More than just another rock group;
a clear and present danger to America's national security.
Sent via Deja.com
http://www.deja.com/
------------------------------
From: Greggy <[EMAIL PROTECTED]>
Subject: Re: ---- Are AES algorithms export restricted?
Date: Tue, 12 Dec 2000 22:15:11 GMT
In article <[EMAIL PROTECTED]>,
Richard Heathfield <[EMAIL PROTECTED]> wrote:
> CiPHER wrote:
> >
> > In article <[EMAIL PROTECTED]>,
> > Mok-Kong Shen <[EMAIL PROTECTED]> wrote:
> >
> > > Since monitoring can be performed by a foreign country
> > > (see Echelon) and we know how many are those powers
> > > that can do that, from (1), the answer to your question
> > > is clearly the null set.
> > >
> > > M. K. Shen
> >
> > Which was along the lines of what I was about to post...
> >
> > ...plus just because a country doesn't have legislation in place to
> > allow them to arhcive and analyse your communications doesn't mean
they
> > aren't doing it.
>
> That doesn't matter, as far as I'm concerned, because I'm quite happy
to
> pit my meagre wits against a Government's supercomputers (if it ever
> came to that). What annoys me about the UK is that they don't have to
> even turn their supercomputers on - they can just knock on (or down)
my
> door and demand the key, and it'll stand up in court.
Too bad you guys cannot own guns. Those were the reasons we demanded
our right of gun ownership to be acknowledged in the first place.
--
I prefer my fourth amendment rights over a dope free
society, even if the latter could actually be achieved.
Al Gore and the Florida Robes - More than just another rock group;
a clear and present danger to America's national security.
Sent via Deja.com
http://www.deja.com/
------------------------------
From: Greggy <[EMAIL PROTECTED]>
Subject: Re: ---- Are AES algorithms export restricted?
Date: Tue, 12 Dec 2000 22:19:05 GMT
> Presumably, some enterprising Irishman has a Website offering
amazingly
> secure crypto products to anyone in the world, at very reasonable
> prices. :-) If not, why not? And if so, then the American restrictions
> seem particularly pointless.
Let's get something straight. The American export rules are only
enforcible against Americans. Thus, regardless of who else in the
world can spew out all the strong crypto they want, it is the American
public that is being regulated (strangled) by these rules. Why?
Because it is the nature of the American government to keep its people
in fear. This particular niche is so small that those few it effects
have little sympathy from the masses to draw upon. Just one more group
divided from the whole and conquered.
It is not about encryption or terrorism. It is about control.
Gun control is not about guns or violence. It is about control.
--
I prefer my fourth amendment rights over a dope free
society, even if the latter could actually be achieved.
Al Gore and the Florida Robes - More than just another rock group;
a clear and present danger to America's national security.
Sent via Deja.com
http://www.deja.com/
------------------------------
From: Greggy <[EMAIL PROTECTED]>
Subject: Re: ---- Are AES algorithms export restricted?
Date: Tue, 12 Dec 2000 22:24:59 GMT
Regarding those 'nasty' seven countries we cannot export to...
How to convert Lybia (for example) to a well mannered republic:
Give their top ten percent students 4 year college educations in
America, all expenses paid. Let them live here for four years. Then
force them to return to their home land. There, as the elitests of
their people, they can effect the most change in politics for their
society. Let them yearn for the freedoms they see here. Let them
bring back with them what they tasted and desire for their children to
their own people.
It takes time, perhaps two or three decades, but it will be from the
ground up without any blood.
> "Simon Johnson" <[EMAIL PROTECTED]> wrote in message
> news:90m5m4$phu$[EMAIL PROTECTED]...
> > In article <wGqX5.3809$I5.28736@stones>,
> > "Brian Gladman" <[EMAIL PROTECTED]> wrote:
> > >
> > > "Greggy" <[EMAIL PROTECTED]> wrote in message
> > > news:90jucc$ik$[EMAIL PROTECTED]...
> > > > It just seemed to me as I was reading another post here that
none of
> > > > the AES algorithms could possibly be export restricted from
within
> > the
> > > > US since they were all published during the AES contest. Am I
> > > > correct? Or did I miss something in my thinking here?
> > >
> > > You are correct in respect of 'public domain' source code but the
> > situation
> > > in respect of actual implementations is more complex.
> > >
> > > For example, it seems unlikely that a high grade AES
implementation in
> > > hardware would be free of export controls from the ***US***.
> > >
> > > But things have changed a lot recently so even this might now be
> > possible -
> > > I am not up to date on where things stand in the US.
> > >
> > > Brian Gladman
> > >
> > >
> > Yes, but i can export the circuit diagrams right?
>
> I would guess it depends where you live and what your circuit diagrams
> describe.
>
> > I hate these laws, they are really stupid..... It doesn't stop us
from
> > distributing Crypto.... it just makes it annoying.
>
> Agreed. Things got better here in the UK and then got worse again
with RIP
> and its GAK provisions.
>
> But at least we are pretty open on crypto export now - provided we
don't
> want to export to a few 'nasty' countries there are really no
restraints of
> any significance (IANAL but this is my take on the UK position).
>
> > RIP is non-sensical -> If i claim my cipher-text was encrypted using
> > the OTP then they are forced to cryptoanalyse the underlying
algorithm
> > to prove me incorrect (which is infeasible for any good algorithm).
How
> > on earth can they enforce this notion?
>
> They can't - it was a displacement activity - politicians solving an
easy
> but irrelevant problem because they cannot solve the real one (in
this case
> the UK politicans claimed that the police needed GAK to stop
paedophiles!).
>
> Brian Gladman
>
>
--
I prefer my fourth amendment rights over a dope free
society, even if the latter could actually be achieved.
Al Gore and the Florida Robes - More than just another rock group;
a clear and present danger to America's national security.
Sent via Deja.com
http://www.deja.com/
------------------------------
From: Greggy <[EMAIL PROTECTED]>
Subject: Re: ---- Are AES algorithms export restricted?
Date: Tue, 12 Dec 2000 22:21:36 GMT
In article <90m5m4$phu$[EMAIL PROTECTED]>,
Simon Johnson <[EMAIL PROTECTED]> wrote:
> In article <wGqX5.3809$I5.28736@stones>,
> "Brian Gladman" <[EMAIL PROTECTED]> wrote:
> >
> > "Greggy" <[EMAIL PROTECTED]> wrote in message
> > news:90jucc$ik$[EMAIL PROTECTED]...
> > > It just seemed to me as I was reading another post here that none
of
> > > the AES algorithms could possibly be export restricted from within
> the
> > > US since they were all published during the AES contest. Am I
> > > correct? Or did I miss something in my thinking here?
> >
> > You are correct in respect of 'public domain' source code but the
> situation
> > in respect of actual implementations is more complex.
> >
> > For example, it seems unlikely that a high grade AES implementation
in
> > hardware would be free of export controls from the ***US***.
> >
> > But things have changed a lot recently so even this might now be
> possible -
> > I am not up to date on where things stand in the US.
> >
> > Brian Gladman
> >
> >
> Yes, but i can export the circuit diagrams right?
>
> I hate these laws, they are really stupid..... It doesn't stop us from
> distributing Crypto.... it just makes it annoying.
No, the rules are not about distribution, encryption, terrorism, etc.
They are about control. Controlling you.
--
I prefer my fourth amendment rights over a dope free
society, even if the latter could actually be achieved.
Al Gore and the Florida Robes - More than just another rock group;
a clear and present danger to America's national security.
Sent via Deja.com
http://www.deja.com/
------------------------------
From: "Chris" <[EMAIL PROTECTED]>
Subject: Re: Newbie
Date: Tue, 12 Dec 2000 16:35:56 -0600
I am also new to cryptography, where and what should I start with (I have
done most of the simple ciphers and stuff like that from books)?
Chris
"Michael" <[EMAIL PROTECTED]> wrote in message
news:XrWW5.92541$[EMAIL PROTECTED]...
> Thank you very much for your informative reply.
> It is all too often in niche' groups that outsiders are ridiculed.
> I freely admit I don't have a clue. But I do have and interest and have
> made some effort.
> I will check out the web links right away and I will get _The
Codebreakers_
> .
>
> Thanks again.
>
> Michael
>
> "M.S. Bob" <[EMAIL PROTECTED]> wrote in message
> news:[EMAIL PROTECTED]...
> > Michael wrote:
> > >
> > > I am confused. Isn't it paramount to keep the algorithm secret?
> >
> > It has not been the suggested practice to design and analysis ciphers
> > based on such an assumption since 1883.
> >
> > Kerchkhoff's Principle: The security of the crypto-system must not
> > depend on keeping secret the crypto-algorithm. The security depends only
> > on keeping secret the key.
> >
> > This advice is best followed, as it is based on historical observation,
> > that many "secret systems" collapse under any unanticipated scrutiny.
> > Under estimating the ability of the opponent has caused many failures in
> > historic crypto-systems.
> >
> > I strongly recommend you read either _The Code Book_ by Simon Singh
> > (easy reading) or _The Codebreakers_ by David Kahn ('the' crypto history
> > reference) so that you don't have to repeatedly invent old broken
> > ciphers. You will also see just how far the opponent can go to 'fiddle'
> > with or investigate your crypto-system. The history is pretty
> > interesting, and I am not normally interested in historic books.
> >
> > To get a feel for the "real-world" I suggest you read several essays:
> >
> > Why Cryptosystems Fail by Ross Anderson
> > http://www.cl.cam.ac.uk/users/rja14/wcf.html
> >
> > Why Cryptography Is Harder Than It Looks by Bruce Schneier
> > http://www.counterpane.com/whycrypto.html
> >
> > Security Pitfalls in Cryptography by Bruce Schneier
> > http://www.counterpane.com/pitfalls.html
> >
> > Memo to the Amateur Cipher Designer by Bruce Schneier
> > http://www.counterpane.com/crypto-gram-9810.html#cipherdesign
> >
>
>
------------------------------
From: Bryan Olson <[EMAIL PROTECTED]>
Subject: Re: Is brute for the only way?
Date: Tue, 12 Dec 2000 22:26:15 GMT
Terry Neckar asked wrote:
> Without doing a brute force program, does anyone know of a reverse
> algorithm for the following?
>
> If I know what the ending value of answer is, how can I quickly solve
> for the value of key?
>
> ----------------------------------------------
> answer = 1;
>
> for(x=0; x<5432; x++)
> answer = (answer * key) % 27218753;
>
> ----------------------------------------------
Assuming no overflow in the computation above, do
the following:
Compute z = answer ^ 2204759 mod 27218753, perhaps
using algorithm 14.79 from HAC.
Use algorithm 3.34 from HAC 3 times to find all the
mod 27218753 8th roots of z. Any of these plus any
multiple of 27218753 are possible values of key.
Read Paul Rubin's response which gives good advice even
though he mis-transcribed 27218753 into 2721873.
Note that:
27218753 is prime,
GCD(5432, 27218753-1) = 8,
2204759 * 5432 is conguent to 8 mod (27218753-1).
HAC is on-line at:
http://www.cacr.math.uwaterloo.ca/hac/
--Bryan
Sent via Deja.com
http://www.deja.com/
------------------------------
From: Mok-Kong Shen <[EMAIL PROTECTED]>
Subject: Re: On using larger substitutions
Date: Tue, 12 Dec 2000 23:55:26 +0100
Simon Johnson wrote:
>
> Mok-Kong Shen <[EMAIL PROTECTED]> wrote:
> >
> > A general 16-bit substitution table is commonly considered
> > impractical because of the large storage space required,
> > not to say using a number of such tables.
>
> You could generate two 8-bit s-boxes and pass divide a 16-bit word up
> into two chunks and pass it through the two s-boxes, then contatenate
> the two results.
This is done in the scheme described before the cyclic
shift.
> To be 100% certain of how the s-boxes work together, i would suggest
> combining the two 8-bit s-boxes into a 16x16 then testing that. Then
> when you present your algorithm, in a paper, you would then just
> publish the two 8x8 s-boxes.
>
> This would use less memory, and would have the same characterstics as
> the tested and presumably optimal 16x16.
With only two 8-bit substitutions applied to the two bytes,
there will not be any interaction between the two groups
of bits. The cyclic shift and the application of the
other two 8-bit substitutions are intended to achieve some
interactions.
The simple scheme as given is certainly hardly suitable
for obtaining a good 16-bit S-box to be used in a block
cipher. The term substitution used is more in the sense
of the classical polyalphabetical substitution, where
one uses a secret key to construct a number of
substitutions (columns of a big table). On computer one
would naturally do the same as 8-bit substitutions.
Similar 16-bit substitutions would evidently be hampered
by the storage (and generation) problem. Thus I did
something that is in principle not very far away from the
old Playfair (though I believe is better) and consequently
is not to be expected to have superb quality from the
outset. The intention is that, given a key, one can very
simply realize a number of such substitutions which
should perform better than directly using the 8-bit
substitutions (these can be generated with a PRNG).
Sorry for any confusion that I might have caused.
M. K. Shen
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