Cryptography-Digest Digest #937, Volume #12 Mon, 16 Oct 00 16:13:01 EDT
Contents:
Re: CHES 2001 Workshop (Tom St Denis)
Re: SHA-256 implementation in pure C (free) (Tom St Denis)
Re: gender vs. sex [was Rijndael implementations] (wtshaw)
Re: CHES 2001 Workshop (Tom St Denis)
Re: Basic skills and equipment... (Tom St Denis)
Re: On block encryption processing with intermediate permutations (Bryan Olson)
Pegwit group started to make a alternative to PGP based on ECC ("Benny Nissen")
Updated Free SHA-256 Source Code (Tom St Denis)
Re: MS's fast modular exponentiation claims II (Jim Gillogly)
workshop on privacy and security (Alfred John Menezes)
Re: Basic skills and equipment... (Bob Silverman)
Re: More on the SDMI challenge (Daniel Leonard)
Re: On block encryption processing with intermediate permutations (Mok-Kong Shen)
The sci.crypt FAQ (Dido Sevilla)
Re: algo to generate permutations ([EMAIL PROTECTED])
Re: Basic skills and equipment... (Tom St Denis)
----------------------------------------------------------------------------
From: Tom St Denis <[EMAIL PROTECTED]>
Crossposted-To: comp.arch.fpga,comp.arch.arithmetic
Subject: Re: CHES 2001 Workshop
Date: Mon, 16 Oct 2000 18:11:21 GMT
In article <[EMAIL PROTECTED]>,
Mike Rosing <[EMAIL PROTECTED]> wrote:
> Tom St Denis wrote:
> >
> > Would a paper on a block cipher geared towards low end
microcontrollers
> > be suited for this conference?
> >
>
> Probably, but the number of papers accepted is very small. Unless
you're
> working for a professor or corporation that's part of the "in" group,
you
> might as well not waste your effort. I'm missing a lot of conferences
> this year 'cause I can't afford the trip to Europe. At least the
people
> on the other side of the pond are finally getting a lower cost
conference!
Well I want to submit my paper on TC8, I have a hardware design team
(some really nice people from opencores.org), I have a embedded
software design team (myself and a friend) and I am writting the
technical paper.
The TC8 *draft* paper
(http://www.geocities.com/tomstdenis/tc8_draft.zip) is available. It's
one of my "better" papers as I tried to include more background and
technical information.
I am working on the cryptanalysis right now, I found a related key
theoretical attack and I have to work out the probability of it
working...
Tom
Sent via Deja.com http://www.deja.com/
Before you buy.
------------------------------
From: Tom St Denis <[EMAIL PROTECTED]>
Subject: Re: SHA-256 implementation in pure C (free)
Date: Mon, 16 Oct 2000 18:12:55 GMT
In article <[EMAIL PROTECTED]>,
Anton Stiglic <[EMAIL PROTECTED]> wrote:
> Tom St Denis wrote:
>
> > Personally I think both algorithms are stupid but SHA-256 has more
use
> > then SHA-512. Like who would put 2^256 effort to forge a msg
anyways?
> >
> > Tom
>
> There is not just that to consider. For example, someone
> might want to implement a variation of the DSS scheme,
> using a q of 512 bits. There are probably many other
> examples as well...
True, well I would use SHA-256 to hash random strings into nice 256-bit
keys for symmetric ciphers.
> But on another note: thanks for posting an implementation
> of SHA-256, that's very cool!
Your welcome, the code is free to use and so far bug-free (passes all
test vectors). If you use it in a package please let me know just so I
can feel all warm and fuzzy :)
Tom
Sent via Deja.com http://www.deja.com/
Before you buy.
------------------------------
From: [EMAIL PROTECTED] (wtshaw)
Subject: Re: gender vs. sex [was Rijndael implementations]
Date: Mon, 16 Oct 2000 11:40:37 -0600
In article <[EMAIL PROTECTED]>, Chris Jones
<[EMAIL PROTECTED]> wrote:
> "Douglas A. Gwyn" <[EMAIL PROTECTED]> writes:
>
> > John Savard wrote:
> > > The use of 'gender' instead of 'sex' to denote whether an individual
> > > is male or female was introduced for a specific political purpose: to
> > > categorize the identification of humans as male or female as a social
> > > construction as opposed to a biological reality.
> >
> > Yes, that's a fair summation, and it should be clear what is wrong
> > with trying to "rewrite" reality.
>
> This has nothing to do with the previous subject line, nor the charter of this
> group. (Plus I disagree with your premise. It seems as likely to me that
> gender is used to avoid saying sex, for fear of offending prudes.)
40) *Quaver lazy, know God can't be a prude from His jinx.
--
Production technology goes wrong when the producers do not
understand the users. --Patrick Whitney
------------------------------
From: Tom St Denis <[EMAIL PROTECTED]>
Crossposted-To: comp.arch.fpga,comp.arch.arithmetic
Subject: Re: CHES 2001 Workshop
Date: Mon, 16 Oct 2000 18:18:59 GMT
In article <8sfgc1$ra9$[EMAIL PROTECTED]>,
Tom St Denis <[EMAIL PROTECTED]> wrote:
> The TC8 *draft* paper
> (http://www.geocities.com/tomstdenis/tc8_draft.zip) is available.
It's
> one of my "better" papers as I tried to include more background and
> technical information.
Arrg that at
http://www.geocities.com/tomstdenis/files/tc8_draft.zip
Tom
Sent via Deja.com http://www.deja.com/
Before you buy.
------------------------------
From: Tom St Denis <[EMAIL PROTECTED]>
Subject: Re: Basic skills and equipment...
Date: Mon, 16 Oct 2000 18:15:50 GMT
In article <[EMAIL PROTECTED]>,
Mike Rosing <[EMAIL PROTECTED]> wrote:
> Alexandros Andreou wrote:
> >
> > Hello all!
> > I am beginning to enjoy cryptography, but I don't know where to
start from.
> > What are the essential mathematics skills one should have?
Moreover, which
> > books/online text files would you recommend? Any special
> > (freeware/open-source) computer programs?
>
> There is an incredable amount on the web. Do a web search on crypto,
and
> read everything you get. Use what you read from that to get more
search
> words - especially of stuff you don't understand. Sooner or later
you'll
> run into the same reference more than 5 times - and you'll probably
want
> to get it from the library or buy it.
>
> It doesn't matter where you start! There's too much to learn at once,
> so go in a direction that feels comfortable. As you get into it and
> build up confidence, you'll find other things you want to learn. It's
> pretty amazing really, you can spend your whole life studying crypto,
> and you still won't know everything :-)
I strongly agree with you here Mike :-o
However, a good place to start is to read the sci.crypt faq and learn
some crypto diction. It will help you use the terms "randomized
chained ciphertext packet format" in a sentence and sound smart....
hehehe
Seriously learn the basic terminologies, what a symmetric cipher is,
what an asymmetric cipher is, what a random number generator is (or a
pseudo-rng), etc...
Once you have the basics you can go in almost any direction.
Tom
Sent via Deja.com http://www.deja.com/
Before you buy.
------------------------------
From: Bryan Olson <[EMAIL PROTECTED]>
Subject: Re: On block encryption processing with intermediate permutations
Date: Mon, 16 Oct 2000 18:34:26 GMT
Mok-Kong Shen wrote:
> Now please kindly answer the following
> question. You said of 'siblings'. How does the opponent
> determine the locations of the siblings he is considering?
See the section starting with:
| Now how do we determine which pairs of 1-block ciphertext
| descended from the same state before the last permutation?
Siblings are exactly those ciphertexts of the same plaintext
for which the encryption process proceeded identically up to
but not including the last permutation.
--Bryan
Sent via Deja.com http://www.deja.com/
Before you buy.
------------------------------
From: "Benny Nissen" <[EMAIL PROTECTED]>
Subject: Pegwit group started to make a alternative to PGP based on ECC
Date: Mon, 16 Oct 2000 20:46:17 +0200
Hi
Just to inform you about some new work going on
Pegwit is a program for performing public key encryption and authentication
using an elliptic curve. Pegwit is a simple Open Source alternative to PGP
Go to the eGroups site at http://www.egroups.com/invite/pegwit and click
the "JOIN" button to join the group.
To start sending messages to members of this group, simply send email to
[EMAIL PROTECTED]
If you do not wish to belong to pegwit, you may visit the eGroups web site
to modify your subscriptions:
http://www.egroups.com/mygroups
Regards,
Moderator, pegwit
Benny Nissen
------------------------------
From: Tom St Denis <[EMAIL PROTECTED]>
Subject: Updated Free SHA-256 Source Code
Date: Mon, 16 Oct 2000 18:35:41 GMT
At http://www.geocities.com/tomstdenis/files/sha256.c is my free SHA-
256 implementation in C. I added two helper routines (sha_memory and
sha_file) so if you downloaded a copy earlier you can get this.
:)
Tom
Sent via Deja.com http://www.deja.com/
Before you buy.
------------------------------
From: Jim Gillogly <[EMAIL PROTECTED]>
Subject: Re: MS's fast modular exponentiation claims II
Date: Mon, 16 Oct 2000 18:51:37 +0000
JCA wrote:
>
> I asked a few days ago a question about some claims the MS made (at
> Crypto '95,
> I believe) to the effect that they possess an algorithm that outperforms
> Montgomery's
> techniques when doing modular exponentiation. Much to my surprise, given
> the high
> caliber of some of the regulars in this group, nobody has said anything
> yet.
I don't see anything in the Crypto '95 table of contents that looks like
what you describe. Do you have an author or title? Perhaps there would
be more comment if there were enough information to identify the claim you
reference.
--
Jim Gillogly
Trewesday, 25 Winterfilth S.R. 2000, 18:49
12.19.7.11.9, 12 Muluc 12 Yax, Fourth Lord of Night
------------------------------
From: [EMAIL PROTECTED] (Alfred John Menezes)
Subject: workshop on privacy and security
Date: 16 Oct 2000 18:41:35 GMT
If you live close to Toronto (Canada), you might be interested in
attending the 1st Annual Privacy and Security Workshop on Nov 10.
Details below.
- Alfred
====================================================================
6th CACR Information Security Workshop
1st Annual Privacy and Security Workshop
Incorporating Privacy into the Security Domain: Issues and Solutions
====================================================================
Centre for Applied Cryptographic Research (CACR)
University of Waterloo, Waterloo, Ontario, Canada
November 10, 2000
8:30 am - 4:30 pm
The Fields Institute, 222 College Street, Room 230,
Toronto, Ontario.
The Sixth CACR Information Security Workshop, also
titled the 1st Annual Privacy and Security Workshop,
will be held on Friday, November 10, 2000 at the Fields
Institute, Toronto, Ontario. This workshop, organized
jointly with the Information & Privacy Commission,
Ontario, will focus on issues and solutions that arise
when incorporating privacy into the security domain.
Privacy is a growing issue in the area of technology
(both wired and wireless applications). Privacy needs
to be understood as a separate issue to that of
security. It also needs to be addressed in the design
and implementation of any system using PKI, wired
and/or wireless technologies. This includes everything
from devices to databases.
This workshop provides an opportunity for participants
to develop a working vocabulary of privacy issues which
technology needs to address for consumer acceptance.
The workshop will also speak to the need for public and
private sector organizations to address the privacy
issues inherent in using these technologies.
Additionally, tools to assess the privacy impact of
technologies will be covered.
The intended audience includes technology and security
experts, CIO's, senior technology executives,
cryptographers, and engineers.
Sponsors:
* Certicom Corp.
* Information & Privacy Commission, Ontario
* MasterCard International
* MITACS
* Mondex International Limited
* Pitney Bowes
Organizers:
* Mike Gurski (Conference Chair)
Information & Privacy Commission, Ontario
* Alfred Menezes
Centre for Applied Cryptographic Research (CACR)
University of Waterloo
* Sherry Shannon
Centre for Applied Cryptographic Research (CACR)
and SVI Consulting
Speakers:
* Stefan Brands, Zero-Knowledge Systems
* Jason Catlett, Junkbusters.com
* Ann Cavoukian, Information & Privacy Commission,
Ontario
* Peter Cullen, Royal Bank of Canada
* Jo Anne DeLaurentis, Mondex Canada
* Guy Herriges, Management Board Secretariat,
Ontario Government
* Peter Hope-Tindall, Data Privacy Partners Ltd.
* Mike Knowles, IBM
* Barry Sookman, McCarthy Tetrault
* Dave Wallace, Management Board Secretariat,
Ontario Government
* Brenda Watkins, Treasury Board Secretariat,
Government of Canada
Workshop Program
November 10, 2000 (Friday)
* 8:30 - 8:30
o Registration and continental breakfast
* 8:30 - 8:45
o Introduction and Welcome
* 8:45 - 9:45
o Incorporating Privacy into Technology:
Understanding the Issues, Identifying the
Principles
* 9:45 - 10:15
o Knowing the Legal Framework
* 10:15 - 10:30
o Coffee Break
* 10:30 - 11:30
o Introducing Privacy into PKI: From Algorithms
to Architecture
* 11:30 - 12:30
o Privacy and Wirless Technolgy
* 12:30 - 2:00
o Lunch
o Privacy and Biometrics: From Business to
Criminals
* 2:00 - 2:45
o Business Responses to Privacy in the Security
Domain
* 2:45 - 3:00
o Coffee Break
* 3:00 - 4:00
o Tools for Introduction Privacy into
Technology
* 4:00 - 4:30
o Wrap Up
Registration
There is no registration fee for guests invited by the
sponsors (Certicom, Information & Privacy Commission,
MasterCard, MITACS, Mondex, and Pitney Bowes). The
registration fee for other participants is as follows:
* Cdn $300 (US $150).
* For participants affiliated with an academic
institution: Cdn $100 (US $50).
Please register as soon as possible as space is limited
for this workshop; registration is on a first-come
first-serve basis.
To register, complete, in full, the attached
REGISTRATION FORM and return it along with your payment
to: Mrs. Frances Hannigan, C&O Dept., University of
Waterloo, Waterloo, Ontario, Canada N2L 3G1. You may
also register by email ([EMAIL PROTECTED]) or
by phone (Frances Hannigan: 519-888-4027).
------------------------cut from here---------------------------------
6th CACR INFORMATION SECURITY WORKSHOP REGISTRATION FORM
Fullname:
_________________________________________________________
Affiliation:
_________________________________________________________
Address:
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
E-Mail Address:
_________________________________________________________
Telephone #:
_________________________________________________________
**Make Cheque/Money Order Payable in Cdn or US funds only to:
CACR
Credit Card payments cannot be accepted
-------------------------cut from here-------------------------------
For further information or to return your Registration,
please contact:
Mrs. Frances Hannigan
Department of Combinatorics & Optimization
University of Waterloo
Waterloo, Ontario, Canada N2L 3G1
e-mail: [EMAIL PROTECTED]
Fax: (519) 725-5441
Phone: (519) 888-4027
==========================================================================
------------------------------
From: Bob Silverman <[EMAIL PROTECTED]>
Subject: Re: Basic skills and equipment...
Date: Mon, 16 Oct 2000 18:55:34 GMT
In article <8sfgkd$ret$[EMAIL PROTECTED]>,
Tom St Denis <[EMAIL PROTECTED]> wrote:
<snip>
> > > Hello all!
> > > I am beginning to enjoy cryptography, but I don't know where to
> start from.
> > > What are the essential mathematics skills one should have?
<snip>
>
> I strongly agree with you here Mike :-o
>
> However, a good place to start is to read the sci.crypt faq and learn
> some crypto diction. It will help you use the terms "randomized
> chained ciphertext packet format" in a sentence and sound smart....
> hehehe
>
> Seriously learn the basic terminologies, what a symmetric cipher is,
<snip>
This is not a flame, but you did not answer the question that was
asked. The question asked was:
"> > > What are the essential mathematics skills one should have?"
The answer to this question need not discuss ANY crypto terminology.
--
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/
Before you buy.
------------------------------
From: Daniel Leonard <[EMAIL PROTECTED]>
Subject: Re: More on the SDMI challenge
Date: Mon, 16 Oct 2000 19:28:35 GMT
On 16 Oct 2000, Scott Craver wrote:
> Daniel Leonard <[EMAIL PROTECTED]> wrote:
> >
> >Yes, but sometimes, even scientists have to stop and ponder what they ar=
e
> >doing.=20
>=20
> =09True, but we're not cloning sheep or building warheads.
> =09We're not even developing cryptosystems that some consider
> =09a threat to national security. =20
I would place SDMI in the category :
let-screw-the-customer-for-more-money-in-our-monopolistic-music-distributio=
n-scheme
which seems to be in a category not far from building warheads if you
look at all the opposition to global market (but we drift now).
(I also jumped when the MPAA forbade importation of Japanese Godzilla
movie when Hollywood was making it own. Not only in the USA, but also in
Canada.)
> =09The question here is not whether one should refrain from=20
> =09analysis, but specifically perform analysis after the=20
> =09standard is unchangeable. I.e., with the specific goal of
> =09screwing the system designers.
Well, one of the point of those who propose to wait is that they refuse to
do the work at the place of the RIAA. But then again, not having read too
much about the rules of the contest, open source works this way : you let
people do some analysis for you (but there are assumptions that the
"original" team did its own analysis and that their goal is not to screw
anyone - again assuming that the purpose of SDMI is that from the hacker
POV). Maybe open source advocators are victim of their success (the
Big-Evil company goes open source - whoops, we were not prepared for
that).
> =09First, cryptanalysts don't do cryptanalysis because they're
> =09looking for hacks they can exploit later. Nor are they out
> =09to damage somebody's system: they're out to learn more=20
> =09about security systems. Ideally, this would help people
> =09not make stupid mistakes in the future.
Do not know much about watermarking, but I agree that for those who study
this field, this is a golden opportunity.
Well, the industry has not yet learnt that it is impossible to protect
files once they are no longer in your possesion, there are good
article about cheaters in network games that parallel the SDMI
scheme:
http://www.tuxedo.org/~esr/writings/quake-cheats.html
It says Carmark recognized the error. The same thing will happen to
SDMI. Then the industry will try a new one, and will get away with it. It
will "never" learn because the punishment is not big (hard, serious,
=2E..) enough.
(It is similar to 1984, big brother kept its grip because people had no
memory)
> =09Second, screwing the system designers will screw everyone
> =09else. If we wait until SDMI is deployed before breaking it,
> =09then lots of people will suffer along with SDMI. Device=20
> =09manufacturers will have spent gobs of useless money on ASICs=20
> =09for enforcing SDMI's scheme. Would a hacker let Diamond
> =09Multimedia pay for the mistakes of the recording industry?
Well, New Zealand forbade the selling of DVD players with region code (or=
=20
is it, your DVD player must be region-code free). What happen if a
government or a powerful consumer association (Quebec's one is
powerful - at least in Quebec, you can return almost anything within=20
10 days just because you do not like it) does not approve SDMI.
> =09And, of course, consumers will have devices that suck more=20
> =09battery power. And they will have SDMI stopping them unless they
> =09go to the trouble to download a tool which will be aggressively
> =09sued off of web sites.
>=20
> > I for one would very much like to see the RIAA have their scheme
> >cracked just after committing to it.=20
>=20
> =09I believe that the whole DMCA fiasco stemmed from the=20
> =09misconception that cryptanalysis was the domain of Evil,=20
> =09Malicious Hackers(tm), and not, say, something people
> =09need to research at universities.
Same thing about reverse engineering, slashdot had a link, about a week
ago, to an editorial about why reverse engineering was needed : to keep
company from screwing people.
> =09Why reinforce this by performing analysis with a malicious
> =09ulterior motive? It isn't even analysis with the intent
> =09to facilitate piracy---it makes the situation worse for
> =09pirates, SDMI, hardware companies, customers, everyone.
The RIAA, even if they say they work for the artists (noble cause isn't
it), is in only for the money. The 600 millions or so they won recently
(again Mp3.com IIRC) on the behalf of the artists, they kept for
themselves. I think one famous female singer, marketed by the RIAA, sued
them to have her part of the share, maybe it is fight for the money under
the disguise of noble pursuit, but it is ironic isn't it.
==========
Daniel L=E9onard
OGMP Informatics Division E-Mail: [EMAIL PROTECTED]
D=E9partement de Biochimie Tel : (514) 343-6111 ext 5149
Universit=E9 de Montr=E9al Fax : (514) 343-2210
Montr=E9al, Quebec Office: Pavillon Principal G-312
Canada H3C 3J7 WWW : http://megasun.bch.umontreal.ca/~leonard
------------------------------
From: Mok-Kong Shen <[EMAIL PROTECTED]>
Subject: Re: On block encryption processing with intermediate permutations
Date: Mon, 16 Oct 2000 21:45:22 +0200
Bryan Olson wrote:
>
> Mok-Kong Shen wrote:
>
> > Now please kindly answer the following
> > question. You said of 'siblings'. How does the opponent
> > determine the locations of the siblings he is considering?
>
> See the section starting with:
>
> | Now how do we determine which pairs of 1-block ciphertext
> | descended from the same state before the last permutation?
>
> Siblings are exactly those ciphertexts of the same plaintext
> for which the encryption process proceeded identically up to
> but not including the last permutation.
I like to ask your favour to explain (excuse me, once again)
but in a radically simplified case, namely on a four round
DES (two cycles) with a single assumed random permutation
(not used as known information) and with (u,u) as the single
type of chosen plaintext. Could you give the procedure in
such concrete details, in particular the choice of u (if
anything special) and the determination of the locations of
the siblings desired for processing and the method of
solutions of the equations involving these, so that one can
actually write a computer program to perform exactly the
attack and be able to deduce the key bits? If your attack is
really effective, this extremely simplified case should be
easy to formulate and it would certainly have the merit of
letting every reader of this thread be convinced once for
all that you are right with your claims.
Thanks very much in advance.
M. K. Shen
------------------------------
From: Dido Sevilla <[EMAIL PROTECTED]>
Subject: The sci.crypt FAQ
Date: Tue, 17 Oct 2000 03:21:06 +0800
I've just noticed something about the sci.crypt FAQ. It's almost, well,
*stale*. From the looks of the last posting, no new information has
been added in a long time, for some parts the last update was back in
1993 (gee, back in the days when I was still in high school, and my
country didn't even have an Internet connection back then!), so much of
the information is already dated. The section on digital signatures
(part 7) is particularly so, as it talks about MD4 and MD5 as though no
one had found any collisions or other attacks that make their integrity
questionable, and there is no word about the newer hash algorithms like
SHA-1, RIPEMD-160, or Tiger. Nor any discussion about FIPS 186. There
is no word about the Advanced Encryption Standard, which has probably
been talked about on this newsgroup for at least two years, and there
doesn't seem to be any kind of discussion about symmetric block ciphers
other than DES for that matter. Part 6 has no word on elliptic curves,
or other techniques for public key crypto besides RSA and
Diffie-Hellman. No discussion about differential or linear
cryptanalysis and other more recent cryptanalytic techniques which
people here talk about a lot.
Regardless, the FAQ still does contain a lot of useful information,
cryptography being what it is, a mathematical discipline, and one where
the strength of techniques is proven by time. However, to be slack in
updating it when new information of great interest to many appears is to
me a Bad Thing(tm). It kinda defeats the purpose of having a FAQ. Who
maintains it anyhow, and why does it seem that no one has contacted this
person in more than seven years to update it even a little?
--
Rafael R. Sevilla <[EMAIL PROTECTED]> +63 (2) 4342217
ICSM-F Development Team, UP Diliman +63 (917) 4458925
OpenPGP Key ID: 0x0E8CE481
------------------------------
From: [EMAIL PROTECTED]
Subject: Re: algo to generate permutations
Date: Mon, 16 Oct 2000 19:27:43 GMT
And another, 15x faster than the last (minus the printf()s). Still not
lexicographic order. Generating permutations comes up in attacking rc4.
/* decide the next level in permutation and recurse */
void recurse( char *string, int len, int d) {
if (d < len-3) {
int i;
char x = string[d];
for (i=d; i<len; ++i) {
char y = string[i];
string[d] = y; string[i] = x; /* swap */
recurse( string, len, d+1); /* recurse */
string[i] = y; /* restore */
}
string[d] = x; /* restore some more */
}
else { /* report */
char *a=string+d, x=*a, *b=string+d+1, y=*b, *c=string+d+2, z=*c;
*b=z; *c=y; printf( "%.*s\n", len, string);
*a=z; *b=x; printf( "%.*s\n", len, string);
*b=y; *c=x; printf( "%.*s\n", len, string);
*a=y; *b=z; printf( "%.*s\n", len, string);
*b=x; *c=z; printf( "%.*s\n", len, string);
*a=x; *b=y; printf( "%.*s\n", len, string);
}
}
/* find all permutations of the first argument */
int main( int argc, char **argv) {
if (argc == 2) {
int len;
len = strlen( argv[1]);
if (len < 2) {
printf("%.*s\n", len, argv[1]);
}
else if (len == 2) {
char x = argv[1][0], y = argv[1][1];
printf("%c%c\n", x, y);
printf("%c%c\n", y, x);
}
else {
recurse( argv[1], len, 0);
}
}
else {
printf( "'permute xxx' lists all permutations of xxx\n");
}
return 0;
}
Sent via Deja.com http://www.deja.com/
Before you buy.
------------------------------
From: Tom St Denis <[EMAIL PROTECTED]>
Subject: Re: Basic skills and equipment...
Date: Mon, 16 Oct 2000 19:43:28 GMT
In article <8sfiv0$tl6$[EMAIL PROTECTED]>,
Bob Silverman <[EMAIL PROTECTED]> wrote:
> In article <8sfgkd$ret$[EMAIL PROTECTED]>,
> Tom St Denis <[EMAIL PROTECTED]> wrote:
>
> <snip>
>
> > > > Hello all!
> > > > I am beginning to enjoy cryptography, but I don't know where to
> > start from.
> > > > What are the essential mathematics skills one should have?
> <snip>
>
> >
> > I strongly agree with you here Mike :-o
> >
> > However, a good place to start is to read the sci.crypt faq and
learn
> > some crypto diction. It will help you use the terms "randomized
> > chained ciphertext packet format" in a sentence and sound smart....
> > hehehe
> >
> > Seriously learn the basic terminologies, what a symmetric cipher is,
>
> <snip>
>
> This is not a flame, but you did not answer the question that was
> asked. The question asked was:
>
> "> > > What are the essential mathematics skills one should have?"
>
> The answer to this question need not discuss ANY crypto terminology.
Sure bob, we will have math savants that have no clue on how to talk
about cryptography. Smooth move.
Sure there is tons of math you could read, say "Number Theory by XYZ"
but if you can't comprehend things like "block chaining-mode" then
what's the point on becoming involved in cryptography?
Tom
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