Cryptography-Digest Digest #72, Volume #14 Wed, 4 Apr 01 03:13:01 EDT
Contents:
Re: How do I exchange the values of A and B (Dave Moore [EMAIL PROTECTED]>)
Re: quick LFSR question (really simple question) ("Carpe Diem")
Re: patent this and patent that (Vernon Schryver)
Re: quick LFSR question (really simple question) ("Tom St Denis")
Re: RC4/ARC4 in hardware. (Jason Stratos Papadopoulos)
Re: RC4/ARC4 in hardware. (Paul Rubin)
Re: quick LFSR question (really simple question) ("Carpe Diem")
Re: patent this and patent that ("Matt Timmermans")
RSA, block size, key space (John Smith)
Re: quick LFSR question (really simple question) ("Tom St Denis")
Re: quick LFSR question (really simple question) ("Carpe Diem")
Re: quick LFSR question (really simple question) (Steve Portly)
Re: quick LFSR question (really simple question) ("Tom St Denis")
Re: Idea - (LONG) (Nicol So)
Re: Matrix PK idea? (Jyrki Lahtonen)
----------------------------------------------------------------------------
From: Dave Moore <ROT13 => [EMAIL PROTECTED]>
Subject: Re: How do I exchange the values of A and B
Date: Tue, 03 Apr 2001 22:16:00 -0400
Back when Dinosaurs roamed the Earth and 64K was fully populated memory this
was a classic.
Assuming "A" and "B" contain integers, reverse their contents without using a
3rd storage location.
A' = A xor B
B' = B xor A' = B xor (A xor B) = A
A''= A' xor B' = (A xor B) xor A = B
Three instructions, and depending on the processor sometimes faster than using
a 3rd location. But OBTUSE ! Doing this without comments was a capital
offense.
On Tue, 03 Apr 2001 23:17:39 GMT, Mikito Harakiri
<[EMAIL PROTECTED]> wrote:
>Is something along the lines below possible?
>
>a = a.encrypt(b);
>b = a.decrypt(a);
>a = a.getKey();
>
>or, maybe, some more symmetric version?
>
>"Robert C. Martin" <[EMAIL PROTECTED]> wrote in message
>news:[EMAIL PROTECTED]...
>>
>> "Charlie Kilmer" <[EMAIL PROTECTED]> wrote in message
>> news:[EMAIL PROTECTED]...
>> > How do I exchange the values
>> > int A = x;
>> > int B= y;
>> >
>> > here x and y are the values
>> >
>> > how do exchange the values so that
>> > int A = y;
>> > int B = x;
>> >
>> > --without using a temp to make it happen.
>> >
>>
>> This is an old trick:
>>
>> A ^= B;
>> B ^= A;
>> A ^= B;
>>
>> (Where ^= is the xor/assignment operator)
>
PGP key available from "http://covad.net/~watcher/"
Dave Moore
------------------------------
From: "Carpe Diem" <[EMAIL PROTECTED]>
Subject: Re: quick LFSR question (really simple question)
Date: Tue, 3 Apr 2001 21:15:57 -0500
> What the heck are you yapping about?
I guess:
http://www-s.ti.com/sc/psheets/scta036a/scta036a.pdf
------------------------------
From: [EMAIL PROTECTED] (Vernon Schryver)
Subject: Re: patent this and patent that
Date: 3 Apr 2001 19:57:20 -0600
In article <[EMAIL PROTECTED]>, Terry Ritter <[EMAIL PROTECTED]> wrote:
> ...
>Please. Adding? XOR? Patented? I don't think so....
How can someone who is neither uniformed nor short of intellectual
honesty make such a statement?
Recall the infamous XOR cursor patent. (What was its number? Asking
http://www.delphion.com/ for "cursor, xor" produces wonderful items
including some that would have been old news to me if I'd heard of
them 10 years before they were filed. but I don't or recognize see
the infamous XOR cursor among them.)
Then consider these wonderful examples of the patent filer's art:
http://www.delphion.com/details?&pn=US06025810__
http://www.delphion.com/details?&pn=US05443036__
http://www.delphion.com/details?&pn=US05446889__
http://www.delphion.com/details?&pn=US06073150__
Other great examples include the Motorola-Codex patent on TCP/IP
header compression whose only problem was that it was filed after
that stuff was already shipping, or the other Motorola-Codex patent
that essentially patents x.25 only 20+ years too late.
I wonder how many patents are as bad as those or the various "blocking"
patents seen in the 19th Century history of firearms and the late 20th
Century history of ink jet printers. It would be interesting if a
disinterested party could survey patents to see how many are silly
variations of paper clips and how many are real inventions. It would
require someone without the technical phobia and ignorance of typical
judges and juries. It also could not one of those with vested interests
in continuing and expanding the current system, such as "intellectual
property professionals." It would also require a real masochist, since
anyone with enough technical education to hope to judge patents can earn
far more and have far more fun with a lot less pain than in such a project.
Besides, such a project would be futile because there is not the slightest
hope that the patent mess will be other than made worse by the lawyers
including the courts and Congress. They are compelled to extend their
sphere of control over any parts of society that show signs of working
well without their attentions.
Vernon Schryver [EMAIL PROTECTED]
------------------------------
From: "Tom St Denis" <[EMAIL PROTECTED]>
Subject: Re: quick LFSR question (really simple question)
Date: Wed, 04 Apr 2001 02:24:44 GMT
"Carpe Diem" <[EMAIL PROTECTED]> wrote in message
news:9ae010$b10$[EMAIL PROTECTED]...
> > What the heck are you yapping about?
>
> I guess:
> http://www-s.ti.com/sc/psheets/scta036a/scta036a.pdf
>
I wrote C code not VHDL. All I want to know is if I interpreted the meaning
of the tap values correctly.
if you can't respond to this DONT BLOODYWELL REPLY.
Geez. Use some common sense. Did I ask what an LFSR is ? No. Did I ask
how to calc pi to 2000000 places? No.
All I want to know is if the taps are right.
I think I will just check it manually since getting correct information on
this subject appears to be futile.
Tom
------------------------------
From: Jason Stratos Papadopoulos <[EMAIL PROTECTED]>
Subject: Re: RC4/ARC4 in hardware.
Date: 4 Apr 2001 02:29:13 GMT
Matt Hayes <[EMAIL PROTECTED]> wrote:
: I have performed a few websearches but can't really find the answers I am
: looking for.
You must have missed Motorola's MPC180.
www.mot.com
jasonp
------------------------------
From: Paul Rubin <[EMAIL PROTECTED]>
Subject: Re: RC4/ARC4 in hardware.
Date: 03 Apr 2001 19:46:26 -0700
"Matt Hayes" <[EMAIL PROTECTED]> writes:
> In particular, I would like to know:
> a) what rates of data throughput have been achieved by RC4 implementations
> in hardware? what is the fastest ever?
> b) if it is possible to purchase a fast RC4/ARC4 IP Core and what throughput
> rates can be expected.
Are you a serious customer for something like this?
------------------------------
From: "Carpe Diem" <[EMAIL PROTECTED]>
Subject: Re: quick LFSR question (really simple question)
Date: Tue, 3 Apr 2001 21:50:16 -0500
I was just answering the question that I had in my post. THE ONE YOU MADE .
My intention was to make it clear to you that he thought you were talking
about a hardware implementation (I do not know why!). If you have this
attitude towards everybody who misunderstands you when you make a question,
you will not get a lot of answers.
"Tom St Denis" <[EMAIL PROTECTED]> wrote in message
news:MBvy6.12905$[EMAIL PROTECTED]...
>
> "Carpe Diem" <[EMAIL PROTECTED]> wrote in message
> news:9ae010$b10$[EMAIL PROTECTED]...
> > > What the heck are you yapping about?
> >
> > I guess:
> > http://www-s.ti.com/sc/psheets/scta036a/scta036a.pdf
> >
>
> I wrote C code not VHDL. All I want to know is if I interpreted the
meaning
> of the tap values correctly.
>
> if you can't respond to this DONT BLOODYWELL REPLY.
>
> Geez. Use some common sense. Did I ask what an LFSR is ? No. Did I ask
> how to calc pi to 2000000 places? No.
>
> All I want to know is if the taps are right.
>
> I think I will just check it manually since getting correct information on
> this subject appears to be futile.
>
> Tom
>
>
------------------------------
From: "Matt Timmermans" <[EMAIL PROTECTED]>
Subject: Re: patent this and patent that
Date: Wed, 04 Apr 2001 02:54:05 GMT
Absolutely true. Unfortunately, though the patent system is well intended,
the implementation is broken.
The real trouble with all of the software patents around these days is that
you stand a good chance of infringing patent claims by accident.
Reinvention by accident happens all the time, because no software engineer
can be aware of all the patents that exist (after all, that's not their
job), and ideas that begin as novelties become obvious as the state of the
art advances in other areas -- even if nobody tells you. At this point a
patent hinders innovation rather than fostering it.
This problem is made much worse by the inescapable fact that there is no
organization in the world that is at all _qualified_ to judge patent
applications in a field as diverse as comp.sci. (probably other fields as
well, but I can't speak for those). The result is that a lot of truly
trivial ideas _do_ get patented successfully, with the attidude that if
someone disagrees with the award then they can argue about it in court.
This attitude, of course completely ignores the fact that arguing in court
_and_ researching patents are both expensive enough that many small business
can't effectively do either. When a small company produces software, its
walking through a mine field, praying that no mines explode, and that if a
mine _does_ explode, that it's one of Mom and Pop's little mines, and not
one of Microsoft or IBM's big ones.
"Carpe Diem" <[EMAIL PROTECTED]> wrote in message
news:9ads39$9ss$[EMAIL PROTECTED]...
> Patents ( on really new inventions ) are a way to reward somebody for the
> work that has been done. You are saying that glory and fame should be
enough
> as a reward. The problem is that fame and glory are not very sweet when
you
> do not have the money to pay the rent.
> Being rewarded economically provides you the *neccessary* means to do
other
> research, and invent other things.
>
>
>
------------------------------
Date: Tue, 03 Apr 2001 22:53:50 -0400
From: John Smith <[EMAIL PROTECTED]>
Subject: RSA, block size, key space
How is block size determined? When one picks a public key and
figures out the corresponding private key, he now needs to
encrypts the plaintext. How does one decide what block size to
use to encrypt the plaintext and how does the receiver know what
the block size to use to decrypt the ciphertext?
Can one choose a block size without affecting key space?
====== Posted via Newsfeeds.Com, Uncensored Usenet News ======
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
======= Over 80,000 Newsgroups = 16 Different Servers! ======
------------------------------
From: "Tom St Denis" <[EMAIL PROTECTED]>
Subject: Re: quick LFSR question (really simple question)
Date: Wed, 04 Apr 2001 03:02:32 GMT
"Carpe Diem" <[EMAIL PROTECTED]> wrote in message
news:9ae21b$bq5$[EMAIL PROTECTED]...
> I was just answering the question that I had in my post. THE ONE YOU MADE
.
> My intention was to make it clear to you that he thought you were talking
> about a hardware implementation (I do not know why!). If you have this
> attitude towards everybody who misunderstands you when you make a
question,
> you will not get a lot of answers.
I posted C source code. What would make you think I was talking about a
hardware implementation?
Tom
------------------------------
From: "Carpe Diem" <[EMAIL PROTECTED]>
Subject: Re: quick LFSR question (really simple question)
Date: Tue, 3 Apr 2001 22:09:00 -0500
I think you should read the name of the poster. I am not the one who thought
you were talking about hardware. You flamed Steve Portly when he talked
about pinouts. I answered to your post by explaining that he misunderstood
your question. I do not know the reason of the misunderstanding. I was just
pointing out his interpretation.
By the way, I know you posted C source code. However the concept of a LFSR
is inherently related to hardware. I guess this is the reason Portly started
talking about pinouts.
"Tom St Denis" <[EMAIL PROTECTED]> wrote in message
news:c9wy6.13119$[EMAIL PROTECTED]...
>
> "Carpe Diem" <[EMAIL PROTECTED]> wrote in message
> news:9ae21b$bq5$[EMAIL PROTECTED]...
> > I was just answering the question that I had in my post. THE ONE YOU
MADE
> .
> > My intention was to make it clear to you that he thought you were
talking
> > about a hardware implementation (I do not know why!). If you have this
> > attitude towards everybody who misunderstands you when you make a
> question,
> > you will not get a lot of answers.
>
> I posted C source code. What would make you think I was talking about a
> hardware implementation?
>
> Tom
>
>
------------------------------
From: Steve Portly <[EMAIL PROTECTED]>
Subject: Re: quick LFSR question (really simple question)
Date: Tue, 03 Apr 2001 22:26:27 -0500
Carpe Diem wrote:
> I think you should read the name of the poster. I am not the one who thought
> you were talking about hardware. You flamed Steve Portly when he talked
> about pinouts. I answered to your post by explaining that he misunderstood
> your question. I do not know the reason of the misunderstanding. I was just
> pointing out his interpretation.
> By the way, I know you posted C source code. However the concept of a LFSR
> is inherently related to hardware. I guess this is the reason Portly started
> talking about pinouts.
>
> "Tom St Denis" <[EMAIL PROTECTED]> wrote in message
> news:c9wy6.13119$[EMAIL PROTECTED]...
> >
> > "Carpe Diem" <[EMAIL PROTECTED]> wrote in message
> > news:9ae21b$bq5$[EMAIL PROTECTED]...
> > > I was just answering the question that I had in my post. THE ONE YOU
> MADE
> > .
> > > My intention was to make it clear to you that he thought you were
> talking
> > > about a hardware implementation (I do not know why!). If you have this
> > > attitude towards everybody who misunderstands you when you make a
> > question,
> > > you will not get a lot of answers.
> >
> > I posted C source code. What would make you think I was talking about a
> > hardware implementation?
> >
> > Tom
> >
> >
Brain fart, sorry :-) I realise now that you were talking about memory
registers.
------------------------------
From: "Tom St Denis" <[EMAIL PROTECTED]>
Subject: Re: quick LFSR question (really simple question)
Date: Wed, 04 Apr 2001 04:13:34 GMT
"Steve Portly" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]...
>
>
> Carpe Diem wrote:
>
> > I think you should read the name of the poster. I am not the one who
thought
> > you were talking about hardware. You flamed Steve Portly when he talked
> > about pinouts. I answered to your post by explaining that he
misunderstood
> > your question. I do not know the reason of the misunderstanding. I was
just
> > pointing out his interpretation.
> > By the way, I know you posted C source code. However the concept of a
LFSR
> > is inherently related to hardware. I guess this is the reason Portly
started
> > talking about pinouts.
> >
> > "Tom St Denis" <[EMAIL PROTECTED]> wrote in message
> > news:c9wy6.13119$[EMAIL PROTECTED]...
> > >
> > > "Carpe Diem" <[EMAIL PROTECTED]> wrote in message
> > > news:9ae21b$bq5$[EMAIL PROTECTED]...
> > > > I was just answering the question that I had in my post. THE ONE YOU
> > MADE
> > > .
> > > > My intention was to make it clear to you that he thought you were
> > talking
> > > > about a hardware implementation (I do not know why!). If you have
this
> > > > attitude towards everybody who misunderstands you when you make a
> > > question,
> > > > you will not get a lot of answers.
> > >
> > > I posted C source code. What would make you think I was talking about
a
> > > hardware implementation?
> > >
> > > Tom
> > >
> > >
>
> Brain fart, sorry :-) I realise now that you were talking about memory
> registers.
Ok maybe my brain to english translator is offline. But...
I WANT TO KNOW IF THE TAPS WERE IMPLEMENTED CORRECTLY.
Ok given the source will it implement a LFSR with the taps as specified?
For the love of all that is holy stop replying unless you can say "duh yea
tom" or "duh nope nope nope, definately nope nope".
Tom
------------------------------
From: Nicol So <[EMAIL PROTECTED]>
Subject: Re: Idea - (LONG)
Date: Wed, 04 Apr 2001 00:54:19 -0400
Reply-To: see.signature
Mok-Kong Shen wrote:
>
> ... With respect to your example,
> since the leading bit of a byte is 0 and is assumed to be
> known to the opponent, it can be said that this bit does
> not belong to the plaintext and so excluded from my 'r bits'.
Re-read my example--it was carefully chosen not to be trivial. This is
the example I gave:
> It's actually quite simple. Consider a source that outputs a sequence of
> 8-bit characters of even parity. Now a message of N characters consists
> of N*8 bits, but the amount of entropy needed to transmit the message
> with perfect secrecy is only N*7 bits. You don't need to expend 8 bits
> of shared randomness to perfectly mask a plaintext symbol--you can use
> an random even-parity character with only 7 bits of randomness.
>
> The point is: source characteristics affect the amount of key entropy
> required for perfect secrecy.
In the example, the information in each character is distributed among
all 8 bits. It is not true that any particular bit is fixed at 0 (or 1).
You can obliterate *any* one bit in each character without causing a
loss of information. On the other hand, if each character has 7 bits
worth of entropy, leaving *any* one bit not masked leaks information.
(Among even-parity characters, there are 128 valid codewords. Knowing
the value of any one bit in a character eliminates half of the
codewords.)
What the example shows is that while all 8 bits generally need to be
masked, 7 bits of randomness is sufficient to achieve perfect secrecy.
--
Nicol So, CISSP // paranoid 'at' engineer 'dot' com
Disclaimer: Views expressed here are casual comments and should
not be relied upon as the basis for decisions of consequence.
------------------------------
Date: Wed, 04 Apr 2001 10:16:33 +0300
From: Jyrki Lahtonen <[EMAIL PROTECTED]>
Subject: Re: Matrix PK idea?
Tom St Denis wrote:
>
> Here we go. You find a prime p (preferable a s.g prime) Then you make up a
> RxR matrix which is a generator in Zp^R space (somehow). Then you perform
> DH like normal using matrices.
>
> i.e R=2 you have
>
> ( )^x
> ([ G11 G12 ])
> y = ([ G21 G22 ])
> ( )
>
> The idea is that the adding of terms hinders the usage of index calculus (as
> I know it) for each of the terms of the G matrix i.e
>
> [G11 G12]^2
> [G21 G22]
> =
> [G11 G12][G11 G12]
> [G21 G22][G21 G22]
> =
> [G11G11 + G12G21 G11G12 + G12G22]
> [G21G11 + G22G21 G21G12 + G22G22]
>
> Then all the terms are taken modulo the prime.
>
> Question: Do such G matrices exist (i.e generators).
In a way, no. I guess (but won't bet any money on it until
I have thought about it for a while) that the biggest
group that a single 2x2-matrix can generate is of the size
p^2-1. This group is then easily seen to be isomorphic
to the multiplicative group of the field GF(p^2). Index
calculus in this field is about as efficient as index
calculus mod q, where q is a prime about the same size as p^2.
Can you use a variant
> of the square-mult method to compute this?
Sure thing. However, the multiplicative group of GF(p^2)
can be more efficiently represented by a vector with
two components mod p (rather than using the 4 matrix
entries).
> --
> Tom St Denis
> ---
> http://tomstdenis.home.dhs.org
--
Jyrki Lahtonen, docent
Department of Mathematics,
University of Turku,
FIN-20014 Turku, Finland
http://users.utu.fi/lahtonen
tel: (02) 333 6014
------------------------------
** FOR YOUR REFERENCE **
The service address, to which questions about the list itself and requests
to be added to or deleted from it should be directed, is:
Internet: [EMAIL PROTECTED]
You can send mail to the entire list by posting to sci.crypt.
End of Cryptography-Digest Digest
******************************
