Cryptography-Digest Digest #15, Volume #13 Fri, 27 Oct 00 11:13:01 EDT
Contents:
Re: Image on glasses of the cover guy in Secrets & Lies (John Savard)
Re: Perfect Compression Possible? (John Savard)
Re: Rijndael and PGP (SCOTT19U.ZIP_GUY)
Re: Is OPT the only encryption system that can be proved secure? (SCOTT19U.ZIP_GUY)
Re: Is OPT the only encryption system that can be proved secure? (Richard Heathfield)
Re: ciphertext smaller than blocksize (SCOTT19U.ZIP_GUY)
Re: Image on glasses of the cover guy in Secrets & Lies ("Jeff Moser")
Re: BEST BIJECTIVE RIJNDAEL YET? (Tim Tyler)
Re: Collision domain in crypt()? ([EMAIL PROTECTED])
Re: DATA PADDING FOR ENCRYPTION (Tim Tyler)
Re: Collision domain in crypt()? ([EMAIL PROTECTED])
Re: CHAP security hole question (John Myre)
Re: Is OPT the only encryption system that can be proved secure? (SCOTT19U.ZIP_GUY)
Re: BEST BIJECTIVE RIJNDAEL YET? (SCOTT19U.ZIP_GUY)
Re: Questions about DES (John Myre)
Re: Is OPT the only encryption system that can be proved secure?
([EMAIL PROTECTED])
Re: End to end encryption in GSM ("P.J. Mc Kenna")
Re: Q: Computations in a Galois Field ([EMAIL PROTECTED])
Re: algo to generate permutations ("Eric Bink")
----------------------------------------------------------------------------
From: [EMAIL PROTECTED] (John Savard)
Subject: Re: Image on glasses of the cover guy in Secrets & Lies
Date: Fri, 27 Oct 2000 12:32:27 GMT
On Fri, 27 Oct 2000 11:49:18 +0100, Daniel James
<[EMAIL PROTECTED]> wrote, in part:
>Looking at it in a mirror, and employing a little thought and guesswork it
>looks like:
> You have requested an insecure
> document
That first part I was able to make out, but the later text was too
fuzzy for me. Although it's a Mac dialogue box, that's a standard
browser message, so Bruce is contemplating whether or not to fill out
an unencrypted form at a web site.
John Savard
http://home.ecn.ab.ca/~jsavard/crypto.htm
------------------------------
From: [EMAIL PROTECTED] (John Savard)
Subject: Re: Perfect Compression Possible?
Date: Fri, 27 Oct 2000 12:34:16 GMT
On Fri, 27 Oct 2000 11:47:08 GMT, Simon Johnson
<[EMAIL PROTECTED]> wrote, in part:
>I was wondering if it was possible to generate a perfect compression
>algorithm using the Berlekamp-Massey algorithm. If you took an normal
>piece of plain-text, and let the algorithm chew away for a long while
>eventually it would produce an LFSR that would exactly reproduce the
>plain-text right?
>Is there something preventing this, or am i correct in my observation?
The pigeonhole principle means that, unless the plaintext *looks* like
LFSR output, the resulting LFSR won't be smaller than the plaintext.
John Savard
http://home.ecn.ab.ca/~jsavard/crypto.htm
------------------------------
From: [EMAIL PROTECTED] (SCOTT19U.ZIP_GUY)
Subject: Re: Rijndael and PGP
Date: 27 Oct 2000 13:08:25 GMT
[EMAIL PROTECTED] (Tom St Denis) wrote in <8tbp0q$cl8$[EMAIL PROTECTED]>:
>In article <[EMAIL PROTECTED]>,
> [EMAIL PROTECTED] (SCOTT19U.ZIP_GUY) wrote:
>> I disagree strongly. THere is no proof that Twofish is any stronger
>> than Rijndael. And since it is the winner and carries the AES blessing
>> we may see stinky two fish dead and buried. Since it will no longer
>> have that fresh smell in the public eye. I aslo don't think security
>> is a big concern for PGP convenince and speed to the user is its main
>> virture. IF they wanted security better ciphers and better compression
>> methods would have been in place long ago.
>
>The funny thing is that PGP outperforms your ideas in compression and
>encryption. It uses deflate which is a much better codec then "huffman
>coding" and it uses well trusted symmetric ciphers (and not some random
>awfully inefficient design).
The truth asshole is that bijective compression has not been out
very long so there are fewer methods. And size is not the only way
to judge compression when one encrypts but the concept seems beyound
your reach of lgoic so I will not go there you can't learn.
The good NEWS is Matt has come up with a very hot bijective compressor
that beats the socks off 90% of the other compressors in the market.
his code also combines it with Rijndael in a modifed CBC bijective way
so one gets all in one package. But you don't need to use it. Wait
for the PGP people to poorly impliment the AES cipher so that it is
easier for the NSA to break.
>
>How about giving your rants a rest?
Talk about the kettle calling the pot black!
>
>Tom
>
>
>Sent via Deja.com http://www.deja.com/
>Before you buy.
>
David A. Scott
--
SCOTT19U.ZIP NOW AVAILABLE WORLD WIDE
http://www.jim.com/jamesd/Kong/scott19u.zip
Scott famous encryption website **now all allowed**
http://members.xoom.com/ecil/index.htm
Scott LATEST UPDATED source for scott*u.zip
http://radiusnet.net/crypto/ then look for
sub directory scott after pressing CRYPTO
Scott famous Compression Page
http://members.xoom.com/ecil/compress.htm
**NOTE EMAIL address is for SPAMERS***
I leave you with this final thought from President Bill Clinton:
------------------------------
From: [EMAIL PROTECTED] (SCOTT19U.ZIP_GUY)
Subject: Re: Is OPT the only encryption system that can be proved secure?
Date: 27 Oct 2000 12:57:09 GMT
[EMAIL PROTECTED] wrote in <8tbhk0$7b8$[EMAIL PROTECTED]>:
>Tim
>Thanks for your esoteric reply, but I dont think that Scott had this in
>mind when he referd to PK and PGP.
>
Not sure what you are talking about. But Tim writes my
on thoughts as what gets communicated far than what I usually
write as they get mangled in others peoples minds. So assume
he was better at explain what he thought I meant than what you
thought I meant.
>Perhaps he will answer directly...I also have been meaning to ask him
>about his cipher, whether its a conventional product/feistel network
>cipher .....
It is my own design I prefer to call it a cipher that is
based on a single cycle look up table 19 by 19. The key is
such that any single cycle table is possible. The users password
can be any size for any key. Since the key used for message is
actully encrypted by the password and stored in a encrypted key
file. THe sturcture is like comparing IDEA to a BLock except the
WHOLE file is treated as a single block. What words you wish to
call it is up to you. However if you go to Horsts description of
it at me webpage you can see it explained or look at the source
code.
Aparrently its not conventional our maybe Mr wagner would not have
shot his mouth off is quickly to say the slide attack would destroy
it. He was proved wrong and one time admitted he could not follow
the code even though it was source code.
David A. Scott
--
SCOTT19U.ZIP NOW AVAILABLE WORLD WIDE
http://www.jim.com/jamesd/Kong/scott19u.zip
Scott famous encryption website **now all allowed**
http://members.xoom.com/ecil/index.htm
Scott LATEST UPDATED source for scott*u.zip
http://radiusnet.net/crypto/ then look for
sub directory scott after pressing CRYPTO
Scott famous Compression Page
http://members.xoom.com/ecil/compress.htm
**NOTE EMAIL address is for SPAMERS***
I leave you with this final thought from President Bill Clinton:
------------------------------
Date: Fri, 27 Oct 2000 14:23:53 +0100
From: Richard Heathfield <[EMAIL PROTECTED]>
Subject: Re: Is OPT the only encryption system that can be proved secure?
"SCOTT19U.ZIP_GUY" wrote:
>
<snip>
>
> Aparrently its not conventional our maybe Mr wagner would not have
> shot his mouth off is quickly to say the slide attack would destroy
> it. He was proved wrong and one time admitted he could not follow
> the code even though it was source code.
I have spent four evenings studying what you are pleased to describe as
source code.
I am not surprised that Mr Wagner was unable to follow it.
If the reader cannot understand the source code, there are two possible
places to lay the blame, not just one.
--
Richard Heathfield
"Usenet is a strange place." - Dennis M Ritchie, 29 July 1999.
C FAQ: http://www.eskimo.com/~scs/C-faq/top.html
K&R Answers: http://users.powernet.co.uk/eton/kandr2/index.html
------------------------------
From: [EMAIL PROTECTED] (SCOTT19U.ZIP_GUY)
Subject: Re: ciphertext smaller than blocksize
Date: 27 Oct 2000 13:11:45 GMT
[EMAIL PROTECTED] (Marc) wrote in <[EMAIL PROTECTED]>:
>>Do look up "ciphertext stealing". It's even in the section
>>"Terminating Block Cipher Use" on my page
>
>Ciphertext stealing is a nice method for keeping the ciphertext
>size identical to plaintext size, when the plaintext is larger
>or equal to the blocksize of the algorithm.
>
>Does anyone know a similarily clever method for handling plaintexts
>*smaller* than the blocksize? The only that comes to my mind is
>to pad the plaintext with zeros, encrypt it, and crop it to the
>plaintext size. Then the ciphertext can be built by XOR with
>the plaintext.
>
Let me but it to you this way Matts TImmermans code handles
files of all sizes and compresses and encrypts in the same
program in a bijective way ( one to one mapping) So the problem
is sloved and you have code to look at.
David A. Scott
--
SCOTT19U.ZIP NOW AVAILABLE WORLD WIDE
http://www.jim.com/jamesd/Kong/scott19u.zip
Scott famous encryption website **now all allowed**
http://members.xoom.com/ecil/index.htm
Scott LATEST UPDATED source for scott*u.zip
http://radiusnet.net/crypto/ then look for
sub directory scott after pressing CRYPTO
Scott famous Compression Page
http://members.xoom.com/ecil/compress.htm
**NOTE EMAIL address is for SPAMERS***
I leave you with this final thought from President Bill Clinton:
------------------------------
From: "Jeff Moser" <[EMAIL PROTECTED]>
Subject: Re: Image on glasses of the cover guy in Secrets & Lies
Date: Fri, 27 Oct 2000 08:25:06 -0500
> Looking at it in a mirror, and employing a little thought and guesswork it
> looks like:
I did mine reading backwards, but the mirror does help with the fuzzy words.
After looking a little more.. I agree:
You have requested an insecure
document. The document and any
information you send back could be
observed by a third party while in
transit.
For more information on security
(Choose page prfs through the view menu.)
Do not show again Cancel OK
Thanks,
Jeff
------------------------------
From: Tim Tyler <[EMAIL PROTECTED]>
Subject: Re: BEST BIJECTIVE RIJNDAEL YET?
Reply-To: [EMAIL PROTECTED]
Date: Fri, 27 Oct 2000 13:12:57 GMT
Tom St Denis <[EMAIL PROTECTED]> wrote:
: [EMAIL PROTECTED] (SCOTT19U.ZIP_GUY) wrote:
:> If you folks check at comp.compression you we see a note
:> from Matt Timmermans on his super bijective PPM compressor
:> with a built in bijective RIJNDAEL in modied CBC mode.
[...]
:> http://www3.sympatico.ca/mtimmerm/bicom/bicom.html
: Perhaps us "know nothing" people prefer to leave our security to
: security related algorithms.
I believe that's why the product includes a bijective version of Rijndael
- without that there would be no security at all.
The PPM bijective compressor is intended to minimise known probable
plaintext before encryption, reduce bandwidth and maximise the
number of possible decrypts that look like plausible messages.
--
__________ Lotus Artificial Life http://alife.co.uk/ [EMAIL PROTECTED]
|im |yler The Mandala Centre http://mandala.co.uk/ ILOVEYOU.
------------------------------
From: [EMAIL PROTECTED]
Subject: Re: Collision domain in crypt()?
Date: Fri, 27 Oct 2000 13:47:56 GMT
[EMAIL PROTECTED] wrote:
> Which algorithm did you use? Did it begin with SHA or was it MD5, or
> Tiger, or RipeMD. If it was, please, I beg of you, publish the input
> and their hashes, any collisions of those hashes would be of extreme
> interest. If it wasn't one of those algorithms you might want to retry
> with one of those algorithms, any of them should provide collision-free
> operation for 4 million values.
It was MD5..
Unfortunately, I don't have that hash list any more.. I overwrote it with
the 32-char digests.
But I can can tell you that I was seeding the MD5 hash with a unique email
address, first and last name, current timestamp, current PID and a pseudo
random number which I thought should generate enough variety to give me unique
hashes..
It's not "high" security, I just want someone not to be able to sequentially
walk the data or be able to trivially brute-force it.
------------------------------
From: Tim Tyler <[EMAIL PROTECTED]>
Subject: Re: DATA PADDING FOR ENCRYPTION
Reply-To: [EMAIL PROTECTED]
Date: Fri, 27 Oct 2000 13:36:18 GMT
Bryan Olson <[EMAIL PROTECTED]> wrote:
:> John Myre wrote:
:> : Tim Tyler wrote:
:> :> Something simple like appending a 1 and padding with 0s
:> :> to the end of the block can allow up to 2^128 - 1 out of
:> :> 2^128 keys to be rejected without any further knowledge
:> :> of the plaintext - possibly enough to reject all but
:> :> one message.
:>
:> : Nobody with any sense cares, and you know why.
: [...] can you imagine someone so clueless as to expect his message
: space won't have enough redundancy to cover a couple hundred (or
: several thousand) bits of key equivocation?
Surely it is *very* easy to imagine such a case.
What about the man sending short messages, for example?
What about the man who forwards an encrypted message he has
intercepted back to his HQ for decipherment?
Even if there *are* over 128 bits of existing redundancies in every single
one of his messages - that's no justification for adding a load more.
: Or that bijective compression reduces redundancy better than schemes
: that compress better?
That is not among the claims that are made for it. Note that in theory
the most efficient compressors (in terms of size) are all bijective.
Non-bijective compressors must all fail to fill their range completely -
and thus contain inefficiencies.
--
__________ http://alife.co.uk/ http://mandala.co.uk/
|im |yler [EMAIL PROTECTED] http://hex.org.uk/ http://atoms.org.uk/
------------------------------
From: [EMAIL PROTECTED]
Subject: Re: Collision domain in crypt()?
Date: Fri, 27 Oct 2000 13:50:18 GMT
David Schwartz <[EMAIL PROTECTED]> wrote:
>> I'm in need of a simple hash function for ~4 million items, with a digest of
>> approx 10-14 chars; MD5 et al at 32 characters is simply overkill. Am I
>> in the right ballpark?
> MD5 creates a 128-bit hash, which is 16 characters. If you encounter
> any collisions, post them and you will get instant fame as none are
> known.
The digest from MD5 is 16 bytes (32 chars). I was not suggesting that MD5 has
any collisions, but when I chopped the last 8 bytes off, I had several collisions
with existing records.
------------------------------
From: John Myre <[EMAIL PROTECTED]>
Subject: Re: CHAP security hole question
Date: Fri, 27 Oct 2000 07:46:58 -0600
Vernon Schryver wrote:
<snip>
> Maybe I'm wrong, but, for example, it strikes me as
> impossible make small secrets unguessable.
<snip>
The fundamental improvement made by the newer protocols
is that the guessing has to occur on-line. That is,
the only way to check a guess (not requiring an intractable
amount of work) is to interact with the server. This
means that the server can prevent too many guesses (by
disabling the account after "too many" incorrect logins).
Another aspect of these protocols is that the server's
data, if stolen, is still not enough to allow login.
The stolen data does allow an off-line guessing attack,
so that is a problem, but at least now the attacker has
to steal the data *and* do a dictionary attack; either
by itself is not enough.
The latest proposals allow for spreading the server
knowledge around, so that you have to compromise
several servers to break the security.
JM
------------------------------
From: [EMAIL PROTECTED] (SCOTT19U.ZIP_GUY)
Subject: Re: Is OPT the only encryption system that can be proved secure?
Date: 27 Oct 2000 13:44:46 GMT
[EMAIL PROTECTED] (Richard Heathfield) wrote in
<[EMAIL PROTECTED]>:
>"SCOTT19U.ZIP_GUY" wrote:
>>
><snip>
>>
>> Aparrently its not conventional our maybe Mr wagner would not have
>> shot his mouth off is quickly to say the slide attack would destroy
>> it. He was proved wrong and one time admitted he could not follow
>> the code even though it was source code.
>
>I have spent four evenings studying what you are pleased to describe as
>source code.
Did you look at the new improved listing found at radinet. There
are a few changes to make it more portable. But not many. The scott16u
version was moded by a guy in germany so that it complies on many more
systems. It is not for scott19u but it could give you ideas.
The hardest part of scott19u was placing the file in memory and
overlaying on it in various 19bit continuous strurctures that have
different origins that are not offset by 19bits. I really don't
see how to do this in other versions of C.
>
>I am not surprised that Mr Wagner was unable to follow it.
>
>If the reader cannot understand the source code, there are two possible
>places to lay the blame, not just one.
>
>
I really suspect Wagner was lying and that he never had
the balls to give it an honest look in the first place. Most
pompous assholes just make general statements with out every
looking and few have the nerve to question there integrity.
David A. Scott
--
SCOTT19U.ZIP NOW AVAILABLE WORLD WIDE
http://www.jim.com/jamesd/Kong/scott19u.zip
Scott famous encryption website **now all allowed**
http://members.xoom.com/ecil/index.htm
Scott LATEST UPDATED source for scott*u.zip
http://radiusnet.net/crypto/ then look for
sub directory scott after pressing CRYPTO
Scott famous Compression Page
http://members.xoom.com/ecil/compress.htm
**NOTE EMAIL address is for SPAMERS***
I leave you with this final thought from President Bill Clinton:
------------------------------
From: [EMAIL PROTECTED] (SCOTT19U.ZIP_GUY)
Subject: Re: BEST BIJECTIVE RIJNDAEL YET?
Date: 27 Oct 2000 13:58:11 GMT
[EMAIL PROTECTED] (Tim Tyler) wrote in <[EMAIL PROTECTED]>:
>Tom St Denis <[EMAIL PROTECTED]> wrote:
>: [EMAIL PROTECTED] (SCOTT19U.ZIP_GUY) wrote:
>
>:> If you folks check at comp.compression you we see a note
>:> from Matt Timmermans on his super bijective PPM compressor
>:> with a built in bijective RIJNDAEL in modied CBC mode.
>
>[...]
>
>:> http://www3.sympatico.ca/mtimmerm/bicom/bicom.html
>
>: Perhaps us "know nothing" people prefer to leave our security to
>: security related algorithms.
>
>I believe that's why the product includes a bijective version of Rijndael
>- without that there would be no security at all.
>
>The PPM bijective compressor is intended to minimise known probable
>plaintext before encryption, reduce bandwidth and maximise the
>number of possible decrypts that look like plausible messages.
I made the mistake of replying to Tommy thought it funny that
he tried to put himself in the same class as those I was targetting.
I was not. Tom is not yet in that class as he is wet behind the ears.
I know that it is useless to reply to him he seldom listens then
gets mad and starts using false identites to boster his point of view.
I hope there are no logic errors in Matts code. I have not seen
any yet but I think it is a great start. To those that thought
decent bijective compression not possible and Matt combines it
with a bijective implimentation of Rijndael. It was great work.
I hope the people who invented Rijndeal take a look at the product
and comment on it since I am sure code like this could code become a
standard. But I fear the AES and other manager types will not
give it the light of day so that inferior combinations of compression
with Rijndael will become the norm unless the inventors check
it soon and put out there honest views. I don't know much about
them but I would trust there views on this implementation far above
the views of MR BS and his crony Wagner.
David A. Scott
--
SCOTT19U.ZIP NOW AVAILABLE WORLD WIDE
http://www.jim.com/jamesd/Kong/scott19u.zip
Scott famous encryption website **now all allowed**
http://members.xoom.com/ecil/index.htm
Scott LATEST UPDATED source for scott*u.zip
http://radiusnet.net/crypto/ then look for
sub directory scott after pressing CRYPTO
Scott famous Compression Page
http://members.xoom.com/ecil/compress.htm
**NOTE EMAIL address is for SPAMERS***
I leave you with this final thought from President Bill Clinton:
------------------------------
From: John Myre <[EMAIL PROTECTED]>
Subject: Re: Questions about DES
Date: Fri, 27 Oct 2000 08:05:21 -0600
Simon Johnson wrote:
>
> In article <8tbf4u$5lk$[EMAIL PROTECTED]>,
> Steven Wu <[EMAIL PROTECTED]> wrote:
<snip>
> > 3) Today, what are effective ways to attack DES ?
>
> 'The fasted attack at the time of writing requires 2^43 plain-texts and
> over 50 days using 12 HP9000/735 workstations' - Applied Cryptography.
<snip>
The most "effective" way to attack DES is still by simple
brute-force (guess the key), because the other attacks
still require more known plaintext than is possible in
most situations.
JM
------------------------------
From: [EMAIL PROTECTED]
Subject: Re: Is OPT the only encryption system that can be proved secure?
Date: Fri, 27 Oct 2000 14:10:00 GMT
In article <[EMAIL PROTECTED]>,
[EMAIL PROTECTED] (SCOTT19U.ZIP_GUY) wrote:
> [EMAIL PROTECTED] wrote in <8tbhk0$7b8$[EMAIL PROTECTED]>:
>
> >Tim
> >Thanks for your esoteric reply, but I dont think that Scott had this
in
> >mind when he referd to PK and PGP.
> >
>
Please read your last message.
You claim that there is some inherent weakness in Public Key crypto in
reference to PGP
> Not sure what you are talking about. But Tim writes my
> on thoughts as what gets communicated far than what I usually
> write as they get mangled in others peoples minds. So assume
> he was better at explain what he thought I meant than what you
> thought I meant.
>
> >Perhaps he will answer directly...I also have been meaning to ask him
> >about his cipher, whether its a conventional product/feistel network
> >cipher .....
>
> It is my own design I prefer to call it a cipher that is
> based on a single cycle look up table 19 by 19. The key is
> such that any single cycle table is possible. The users password
> can be any size for any key. Since the key used for message is
> actully encrypted by the password and stored in a encrypted key
> file. THe sturcture is like comparing IDEA to a BLock except the
> WHOLE file is treated as a single block. What words you wish to
> call it is up to you. However if you go to Horsts description of
> it at me webpage you can see it explained or look at the source
> code.
Sounds the same as the AES hasty pudding cipher....have you checked that
one out?
>
> Aparrently its not conventional our maybe Mr wagner would not have
> shot his mouth off is quickly to say the slide attack would destroy
> it. He was proved wrong and one time admitted he could not follow
> the code even though it was source code.
>
> David A. Scott
> --
> SCOTT19U.ZIP NOW AVAILABLE WORLD WIDE
> http://www.jim.com/jamesd/Kong/scott19u.zip
> Scott famous encryption website **now all allowed**
> http://members.xoom.com/ecil/index.htm
> Scott LATEST UPDATED source for scott*u.zip
> http://radiusnet.net/crypto/ then look for
> sub directory scott after pressing CRYPTO
> Scott famous Compression Page
> http://members.xoom.com/ecil/compress.htm
> **NOTE EMAIL address is for SPAMERS***
> I leave you with this final thought from President Bill Clinton:
>
Sent via Deja.com http://www.deja.com/
Before you buy.
------------------------------
From: "P.J. Mc Kenna" <[EMAIL PROTECTED]>
Crossposted-To: alt.cellular.gsm
Subject: Re: End to end encryption in GSM
Date: Fri, 27 Oct 2000 15:36:12 +0100
Jouni Hiltunen <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]...
> Greetings, first apologies in cross posting this to
> hell and back, but I'm really interested in
> extending privacy to cellular communications.
Worried in case ECHELON can read you telling Microsoft passwords to
interested parties?
> Here is the problem, present GSM system offers you
> an illusion of privacy, communications are
> supposedly secured by encryption. However, depending
> on the operator and country you might have weak or
> no encryption and no way to verify how your
> communications are secured. Also encryption only
> happens over the air interface i.e. between phone
> and base station from there on all communications
> are plain. To make matters worse, standards require
> manufacturers to design legal interception gateways
> into the switches.
>
> What I have in mind is program which you could
> download into your phone which allows Diffie/Hellman
> key exchange and encryption of the following call to
> make sure your private conversations remain private.
In reality you would have to encrypt your call before it got to the CODEC.
You could bypass it entirely with a data call at a high enough bit rate,
essentially doing an encrypted VoIP call. I don't know if a regular 14.4kbps
GSM call without all the voice overhead would give enough data throughput to
cope. Perhaps HSCSD would give the guaranteed* bit rates necessary.
In any event the person at the other end would need to be able to
encrypt/decrypt too. Some change to the GSM call-setup protocol would have
to be made that would tell the receiver's phone that the upcoming call is an
encrypted bidirectional VoIP stream over HSCSD. Good luck getting that
through the relevant committee!
In any event I suspect that today's phones aren't up to the task without
cranking the ever-present ARM CPUs up to higher MHz which would probable
mean greater power consumption.
> Anybody interested in developing a program to do
> that? I sure as hell cannot do it myself,
I suspect that if I could do it, I would have a very different job.
> Anyone interested in e-mailing me, please use the
> public key below. Post the follow-ups to sci.crypt
>
> Jouni Hiltunen
* Yes, I know HSCSD isn't guaranteed but I can dream, can't I?
> -----BEGIN PGP PUBLIC KEY BLOCK-----
> Version: PGPfreeware 6.5.3 for non-commercial use
> <http://www.pgp.com>
>
> mQGiBDj8X6oRBADfW0QUWoXeQPV5Cys3xKXK4obFDX9NrR2p/1G6q9w8uC7AWh1z
^
Shouldn't that be a "W"? B-)
------------------------------
From: [EMAIL PROTECTED]
Subject: Re: Q: Computations in a Galois Field
Date: 27 Oct 2000 14:36:18 GMT
Tom St Denis <[EMAIL PROTECTED]> wrote:
> In article <8tb8u9$is$[EMAIL PROTECTED]>,
> "kihdip" <[EMAIL PROTECTED]> wrote:
>> Field:
>> In abstract algebra, a commutative ring in which all non-zero
>> elements have a multiplicative inverse. (This means we can divide.)
> If every element of a ring is a unit then i believe it's also a field.
Ummm.... since the definition of "unit" in a commutative ring is an
element with a multiplicative inverse, I'd say you just repeated the
definition given above.... (although you need to make sure you say
all *non-zero* elements are units)
--
Steve Tate --- srt[At]cs.unt.edu | Gratuitously stolen quote:
Dept. of Computer Sciences | "The box said 'Requires Windows 95, NT,
University of North Texas | or better,' so I installed Linux."
Denton, TX 76201 |
------------------------------
From: "Eric Bink" <[EMAIL PROTECTED]>
Subject: Re: algo to generate permutations
Date: Fri, 27 Oct 2000 17:08:08 +0200
stephane longchamp <[EMAIL PROTECTED]> wrote in message
news:8s6sio$aga$[EMAIL PROTECTED]...
> Do someone know an algo to generate all permutations of a string of
letters
> ?
If you have access to a C++ compiler and a decent implementation of the STL,
you don't have to re-invent the wheel, because next_permutation() does
exactly
what you want:
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main(int argc, char* argv[])
{
if (argc != 2) return 1; // Nah!
string arg(argv[1]);
sort(arg.begin(), arg.end()); // Initial sort of the argument
string v(arg); // This one holds the
permutations
do
{
cout << v.c_str() << endl;
next_permutation(v.begin(), v.end());
} while (v.compare(arg));
return 0;
}
This does everything you want: only distinct permutations are output
and they are in lexicographical order as well.
For example for input "BABA" or "AABB" or some such string, the output is:
AABB
ABAB
ABBA
BAAB
BABA
BBAA
-- Eric
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