Cryptography-Digest Digest #345, Volume #13 Sat, 16 Dec 00 18:13:00 EST
Contents:
Re: Visual Basic Source Code (Simon Best)
Re: Software PRNG.. (Terry Ritter)
The world is closing in .... shall you kill me .... the future is in the air .. can
feel it everywhere ... shall you take me to the heaven ... shall you .. will you ...
in the wind of change .... http://www.scorps.com/movies/woc.ram (Markku J. Saarelainen)
Re: Sr. Cryptographer/mathematician (JPeschel)
Re: Encryption detail added to cipher page (Jim Gillogly)
Re: Homebrew Block Cipher: Moonshine (Simon Johnson)
Re: Protocol for computer go (Francois Grieu)
Re: Q: Result of an old thread? (Bryan Olson)
Re: Q: Result of an old thread? (Walter Hofmann)
Re: Sr. Cryptographer/mathematician (Tom St Denis)
----------------------------------------------------------------------------
From: Simon Best <[EMAIL PROTECTED]>
Reply-To: [EMAIL PROTECTED]
Subject: Re: Visual Basic Source Code
Date: Sat, 16 Dec 2000 18:59:21 +0000
Paul Schlyter wrote:
>
> In article <3a3a348d$0$90273$[EMAIL PROTECTED]>,
> Jason Bock <[EMAIL PROTECTED]> wrote:
>
> > Paul Schlyter <[EMAIL PROTECTED]> wrote in message
> > news:91cov5$75j$[EMAIL PROTECTED]...
[...]
> >> 1. VB is based on BASIC, a programming language which ought to have
> >> become extinct long ago. But thanks to Bill Gates it's still here,
> >> more widespread than ever. Bill Gates once started out with BASIC
> >> (he wrote the first BASIC interpreted for the Mits Altair back in
> >> 1976 or so), and he returned to BASIC, incarnated as VB, ASP,
> >> WordBasic and possibly something else as well. "Basic forever".....
> >
> > You need to do your homework on this one. First, saying that BASIC
> > "ought to have been extinct long ago" is purely a matter of opinion.
>
> It's an opinion, yes, but it's a well-founded opinion. E. Dijkstra
> expressed this decades ago: "The teaching of BASIC, in schools,
> should be considered a criminal act!" -- admittedly that opinion is
> somewhat extreme. Beginner's All Symbolic Instruction Code (=BASIC)
> does has its use though, as an easy introduction to simple
> programming for people who won't become programmers.
[...]
Wasn't BASIC originally devised as a language to be used for teaching
programming? It's a bad programming language, and hence a good tool for
teaching programming, _if_ the teacher is a good programmer and a good
programming teacher.
Because BASIC makes it so easy to do things very badly, and get in a
hideous mess, learning good programming with it is something that has to
be conciously and explicitly done. If that's how the teacher makes use
of BASIC in lessons, then the pupils benefit. Pupils can be guided to
learn various valuable lessons on good and bad programming (they can be
lead to find out the hard way very easily with BASIC, if necessary).
With some other language that imposes various constraints 'for the
programmer's own good' there isn't so much opportunity for that.
So, I suggest that BASIC really belongs where it was originally
intended: in schools, but with good programming teachers.
Just a thought!
Simon
--
_______________________________________________________________________________
Personal: [EMAIL PROTECTED]
Yellow Skies: [EMAIL PROTECTED] http://www.yellowskies.com
Everyone does their own signature to be different. How does that work?
------------------------------
From: [EMAIL PROTECTED] (Terry Ritter)
Subject: Re: Software PRNG..
Date: Sat, 16 Dec 2000 19:08:01 GMT
On Sat, 16 Dec 2000 07:46:31 GMT, in
<[EMAIL PROTECTED]>, in sci.crypt Benjamin Goldberg
<[EMAIL PROTECTED]> wrote:
>Terry Ritter wrote:
>[snip]
>> >Ouch.. I checked it out briefly. Well, the only problem I've
>> >discovered so far is the fact that the information size is
>> >huge.. d'oh!
>>
>> I suppose the file does seem large, but to me it does not seem nearly
>> as large as it did several years ago. We might all like to have a
>> file that answered exactly what we wanted to know and nothing else,
>> but different people want different things.
>
>Perhaps if you could have two versions of your glossary -- one big huge
>files, and one which is divided chunks, for instance one page per
>letter, plus an index.
Having a glossary in chunks means that just a few chunks will get
downloaded, which means that most links will not work.
The whole point of my Glossary is the advantage gained from hypertext
look-up and immediate display of unfamiliar concepts. This allows one
to pursue the concepts one needs without lengthy and disconcerting
interruptions to understand sub-concepts, as always happens with books
or papers. The advantage is only available if sub-topic links are
present and they work.
>Those with fast computers and fast connections, or who want to download
>the glossary, would of course use the huge version, and those who want
>to use it for a quick reference -- eg, see one definition and then go
>back to whatever they were doing -- would use the indexed and chunked
>version.
>
>I should also point out... even loading the glossary from a local file
>takes time. If you are using it for one reference, then loading up
>section P to look up primitive would be much faster than loading the
>whole glossary to look up primitive.
I suggest starting earlier. When you think you are going to need the
Glossary, open a new browser window and let that load the file in the
background while you do other things. Then it will be there when you
need it, complete with all the working links.
>--
>There are three methods for writing code in which no bug can be found:
>1) Make the code so straightforward that there are obviously no bugs.
>2) Make the code so complicated that there are no obvious bugs.
>3) Insist that any apparent bugs were really intentional features.
The situation is not hopeless. In my own work, as a goal, I try to
write a test routine for every procedure I write. The math guys will
furiously exclaim that my approach solves nothing, because then the
test routines need tests. But, in practice, test routines are far
less clever than those under test, and the routines under test do test
the tests. That is, to miss an error in a test routine requires the
routine under test to cooperate by hiding the error. While that does
happen, it is extremely rare. In a sense writing the tests is more
work, but I typically find over 95 percent of found bugs this way,
which means far less complex debugging at the end.
The reason I bring it up is that, in my experience, there is virtually
*no* level of code which is so clear that it can contain no bug. I
have found errors in 4-line routines that looked so good that I was
very tempted to omit the tests.
In the end, bugs which do slip by the tests are relatively easy to
find, because with few errors there is typically little interaction
between them. When found, the problem is added to the appropriate
test routine, and the problem routine is modified until it again
passes the test.
---
Terry Ritter [EMAIL PROTECTED] http://www.io.com/~ritter/
Crypto Glossary http://www.io.com/~ritter/GLOSSARY.HTM
------------------------------
From: Markku J. Saarelainen <[EMAIL PROTECTED]>
Crossposted-To: alt.2600,alt.security,comp.security
Subject: The world is closing in .... shall you kill me .... the future is in the air
.. can feel it everywhere ... shall you take me to the heaven ... shall you .. will
you ... in the wind of change .... http://www.scorps.com/movies/woc.ram
Date: Sat, 16 Dec 2000 19:34:34 GMT
The distant memories are here today .. too much to bear .. shall you
kill me ... will you do it .. in the wind of change .. let the freedom
bell to ring ... let me to be free ... let the freedom bell to
ring ....
http://www.scorps.com/movies/woc.ram
Sent via Deja.com
http://www.deja.com/
------------------------------
From: [EMAIL PROTECTED] (JPeschel)
Date: 16 Dec 2000 20:11:03 GMT
Subject: Re: Sr. Cryptographer/mathematician
Tom St Denis [EMAIL PROTECTED] writes:
>In article <[EMAIL PROTECTED]>,
> [EMAIL PROTECTED] (JPeschel) wrote:
>> Tom St Denis [EMAIL PROTECTED] writes:
>>
>> >I was right in the first place. "Your" is the flipside of "mine"
>> >and "You're" is the flipside of "I Am"
>> >
>> >So I could interpret it as "Mine better to ..." makes NO SENSE!
>>
>> You need to pay more attention in school and less to sci.crypt.
>
>It is actually "You are better ..." maybe you should learn English?
>
I see. You not only know more about mathematics than
mathematicians, you now proclaim to know more about
writing than professional writers. :-)
Your interpretation and explication above makes little sense in that I've never
heard of "flipside" referred to as grammatical component of
a sentence.
The thread, however, started with your objection to Matt
when he wrote:
"Your rather gritty usenet manner is sometimes entertaining..."
You wrote:
"'You're rather...' hehehehe... Just trying to have some fun,"
in an unnecessary attempt to correct him.
Your correction was wrong; Matt was right.
You later gave the example:
"'You are better off...' is correct, or less formally 'You're
better off.""
This is correct, but the structure in these examples is
not the same as the structure in Matt's sentence.
Joe
__________________________________________
Joe Peschel
D.O.E. SysWorks
http://members.aol.com/jpeschel/index.htm
__________________________________________
------------------------------
From: Jim Gillogly <[EMAIL PROTECTED]>
Subject: Re: Encryption detail added to cipher page
Date: Sat, 16 Dec 2000 12:47:22 -0800
Gianna Stefani wrote:
>
> Xi has now added encryption details, and some clues, to its cipher
> challenge page
>
> http://www.xarabungha.btinternet.co.uk/xicrypt/xichallenge.htm
>
> All attacks welcomed I think . . .
The page says it's encrypted with a mixed-alphabet (26 different
random alphabets) Vigenere-type cipher with a repeating key shorter
than the length of the plaintext, followed by a keyed transposition
cipher of unspecified type with a relatively short key.
Sounds potentially solvable if the transposition type were known.
The transposition can be solved independent of the polyalphabetic
using a scoring function that rewards good IC peaks or repeated
strings. The resulting mixed-alphabet Vig could then be solved
using standard methods given enough ciphertext or cribs -- this
is like the "Fuer GOD" cipher of World War I. I think I've
eliminated simple incomplete columnar transposition as the
transposition type.
The IC of the ciphertext is 0.042, which is high for random text.
This suggests the Vig keyword is relatively short. With a long
keyword the IC approaches 0.038, and with keyword 1 it's about
0.066. Sinkov suggets period 5 typically has an IC of about 0.044
and period 10 about 0.041, so a period between 5 and 10 would be
credible for the Vigenere key. A thrice-repeated trigraph (YRO)
appears at intervals divisible by 7, so I'll guess the Vig has
period 7. This could result from three repeated chunks in the
plaintext encrypted by the same part of the key that are
significantly longer than the chunk size of the transposition.
I note that the reward for breaking this cipher is a free copy
of the software that implements the broken cipher. That doesn't
seem worth a great deal of effort, oder?
--
Jim Gillogly
26 Foreyule S.R. 2000, 20:28
12.19.7.14.10, 8 Oc 13 Mac, Second Lord of Night
------------------------------
From: Simon Johnson <[EMAIL PROTECTED]>
Subject: Re: Homebrew Block Cipher: Moonshine
Date: Sat, 16 Dec 2000 21:25:45 GMT
In article <[EMAIL PROTECTED]>,
[EMAIL PROTECTED] wrote:
> Simon Johnson wrote:
> >
> > > Laziness. Or, rather, more interested in other bits of the
cipher, so I
> > > was just lazy with this bit. I will come up with one of my own,
though,
> > > and (hopefully) learn from it (as you suggest).
> >
> > Actually, s-boxes (generally) give a cipher most of its security.
Its a
> > good idea to spend your time designing a good set of s-boxes for
your
> > cipher. After all, you want it to last as long as possible without a
> > break. :)
>
> Indeed. I'll have to spend time getting myself up to speed with good
> S-box design and analysis. And, of course, spend time practicing
these
> things.
>
> > I'm glad to see more home-brewers out there :)
> >
> > Yours,
> >
> > Simon.
>
> Are you also a homebrewer, then?
Yeah, got one in the works.... :)
The more you post these algorithms, the less secure you think your
proposed cipher will be, but i care more and more if they get broken;
its all good fun, i don't intend ever using my own ciphers. :)
Simon.
=====
Hi, i'm the signuture virus,
help me spread by copying me into Signiture File
Sent via Deja.com
http://www.deja.com/
------------------------------
From: Francois Grieu <[EMAIL PROTECTED]>
Subject: Re: Protocol for computer go
Date: Sat, 16 Dec 2000 22:53:20 +0100
[EMAIL PROTECTED] wrote :
> 2. For each move, the current player publishes its move, and then
> someone (it doesn't really matter who) publishes a timestamp,
> which is the elapsed time since the start of the game. Both
> players and any observers check that this timestamp is
> approximately correct.
> A player's move is required to be a deterministic function (which
> is calculated by the replay program) of all previous moves and
> their timestamps.
At least one change is needed:
A player's move is required to be a deterministic function
(which is calculated by the replay program) of some previous
moves and timestamps, as follow:
let T(j) be the timestamp for the jth half-move in the game,
with first with half-move 1. Replay program shall be feb
with T(j+1)-T(j) for odd j if it moves first, for even j
if it moves second. This information should be made
available to the replay program by the referee, after the
replay program has announced half-move j, together with the
opponent's half move j+1.
Without such precaution, a human can influence the speed of the
play program and easily pass information to the replay program.
For example, the value of T(j) could be even or odd to inform
the replay program to choose an offensive or defensive move.
Great care should be taken by the referee that no extra bit of
information can reach the replay program: moves and delta of
timestamps shall be in an unambiguous format. Since the programmer
can probably choose the moment of the replay to some extend, the
replay program shall not be allowed to know this information, nor
the date/time information for the (hash-protected content) zip
file the replay program came from, and a fortiori not the log
file. It should be stressed that even a single bit of side channel
(like and attack/defend hint in the midgame) is of considerable
practical value.
Even with all these precautions, the timestamps still leave some
room for side channel: for example if the adversary makes good
use of the program's thinking time, T(j+1)-T(j) [known to the
replay program] tends to be low when T(j)-T(j-1) [chosen easily
by a human] is high.
I think this side channel could be closed by requiring the replay
program not only to tell its move, but also when in the log it
must be. That is, the replay program should announce the value
T(j)-T(j-1) together with half-move j. Then there is the issue
of precision. What if the replay program is off-by-one ?
Another potential side channel is with with network tricks to
infuence the timestamps slightly (say making T(j+1)-T(j)
even or odd).
Maybe the sad the conclusion is that the single most practical
thing is to dissalow program to be influenced by time at all.
After all, some excellent programs have ignored it entirely.
Francois Grieu
------------------------------
From: Bryan Olson <[EMAIL PROTECTED]>
Subject: Re: Q: Result of an old thread?
Date: Sat, 16 Dec 2000 21:53:35 GMT
Mok-Kong Shen wrote:
> Bryan Olson wrote:
> > Mok-Kong Shen wrote:
> > > Bryan Olson wrote:
> > > > There's the problem that S is singular, so AS will
> > > > also be singular. While you can't get an inverse
> > > > and find a unique solution for B, you can set up the
> > > > linear equations to solve for B, and use _any_ of the
> > > > non-singular solutions.
> > >
> > > Could you elaborate a bit, perhaps with a mini-example?
> >
> > You have two square matrices, call them AS and ASB.
> >
> > Solve for B in AS * B = ASB
> >
> > If you don't know how, take the columns of ASB one at a time,
> > and solve for the columns of B one at a time. If you don't
> > know how, read chapter one of an introduction to linear
> > algebra. You'll find small examples there too.
> >
> > When the solution allows arbitrary parameters, set them
> > arbitrarily, and if the resulting array is singular, set them
> > differently. Now you have a B that will work in Best's
> > solution for S.
>
> Since AS is singular, B is not uniquely determined from
> the equation AS * B = ASB. Could any solution, say B',
> which is not identical to Bob's original matrix B, work?
Answered above.
> Why?
Same reason the scheme decrypts.
> And would such a B' be invertible?
Some are. An invertible solution works in Best's solution
for S. We could of course solve for S using a system of
linear equations without worrying about choosing an
invertible solution for B.
> I suppose the
> matter is not as simple as you depicted, though shouldn't
> be very involved on the other hand.
It's extremely simple. I suggest the material as one of
many prerequisites for cipher design.
--Bryan
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------------------------------
From: [EMAIL PROTECTED] (Walter Hofmann)
Subject: Re: Q: Result of an old thread?
Date: Sat, 16 Dec 2000 23:10:22 +0100
On Sat, 16 Dec 2000 13:58:20 +0100, Mok-Kong Shen <[EMAIL PROTECTED]> wrote:
>
>I doubt that your procedure works. The numerical mathematicians
>try hard to deal with the nearly-singular matrices through
>improving conditions etc. In the vicinity of a singular
>matrix, you need increasingly high precision to invert.
>In the limit, namely the true singular one, there is
>no inverse. Look from another standpoint: If your technique
>works, then one can 'define' an inverse for any singular
>matrix (to work in any given situations, i.e. given set of
>equations involving singular matrices).
No. I never compute the inverse of a singular matrix. I only claim that
the limit exists for the complete algorithm, not for every step
involved.
Certainly, if you try to compute AS'^-1 for epsilon->0 it will diverge.
It's just the end result which converges to S.
Viewed differently, the mapping
S ---> (AS, ASB, SB) ---> SB . ((AS)^-1.ASB)^-1 = S
from the matrix space into itself is the identity mapping except on the
set of non-invertible matricies where it is not defined.
Being the identity mapping it is continuous and the missing points are
uniquely defined by the contuinuation.
Walter
------------------------------
From: Tom St Denis <[EMAIL PROTECTED]>
Subject: Re: Sr. Cryptographer/mathematician
Date: Sat, 16 Dec 2000 22:44:16 GMT
In article <[EMAIL PROTECTED]>,
[EMAIL PROTECTED] (JPeschel) wrote:
> Tom St Denis [EMAIL PROTECTED] writes:
>
> >In article <[EMAIL PROTECTED]>,
> > [EMAIL PROTECTED] (JPeschel) wrote:
> >> Tom St Denis [EMAIL PROTECTED] writes:
> >>
> >> >I was right in the first place. "Your" is the flipside of "mine"
> >> >and "You're" is the flipside of "I Am"
> >> >
> >> >So I could interpret it as "Mine better to ..." makes NO SENSE!
> >>
> >> You need to pay more attention in school and less to sci.crypt.
> >
> >It is actually "You are better ..." maybe you should learn English?
> >
>
> I see. You not only know more about mathematics than
> mathematicians, you now proclaim to know more about
> writing than professional writers. :-)
>
> Your interpretation and explication above makes little sense in that
I've never
> heard of "flipside" referred to as grammatical component of
> a sentence.
>
> The thread, however, started with your objection to Matt
> when he wrote:
> "Your rather gritty usenet manner is sometimes entertaining..."
>
> You wrote:
> "'You're rather...' hehehehe... Just trying to have some fun,"
> in an unnecessary attempt to correct him.
>
> Your correction was wrong; Matt was right.
>
> You later gave the example:
> "'You are better off...' is correct, or less formally 'You're
> better off.""
> This is correct, but the structure in these examples is
> not the same as the structure in Matt's sentence.
Whatever.
Tom
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------------------------------
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