Cryptography-Digest Digest #850, Volume #9 Thu, 8 Jul 99 13:13:06 EDT
Contents:
Re: Summary of 2 threads on legal ways of exporting strong crypto (John Savard)
Re: MP3 Piracy Prevention is Impossible (fungus)
Re: Why this simmetric algorithm is not good? ([EMAIL PROTECTED])
Re: Is Stenography legal? (Patrick Juola)
Re: Is Stenography legal? (Patrick Juola)
Re: Netiquette Question (Mok-Kong Shen)
Re: Why this simmetric algorithm is not good? ([EMAIL PROTECTED])
Re: Is Stenography legal? (Mok-Kong Shen)
Re: Can Anyone Help Me Crack A Simple Code? ([EMAIL PROTECTED])
Re: I don't trust my sysadmin ([EMAIL PROTECTED])
Re: Summary of 2 threads on legal ways of exporting strong crypto ([EMAIL PROTECTED])
exporting damaged strong crypto source code ([EMAIL PROTECTED])
Stream Cipher != PRNG ([EMAIL PROTECTED])
Re: Is Stenography legal? ([EMAIL PROTECTED])
Re: Netiquette Question ([EMAIL PROTECTED])
Re: Is Stenography legal? ([EMAIL PROTECTED])
Re: Can Anyone Help Me Crack A Simple Code? ([EMAIL PROTECTED])
Re: Summary of 2 threads on legal ways of exporting strong crypto (Paul Koning)
Re: DES-NULL attack (Paul Koning)
Re: Properties of Chain Addition? ([EMAIL PROTECTED])
----------------------------------------------------------------------------
From: [EMAIL PROTECTED] (John Savard)
Crossposted-To: talk.politics.crypto
Subject: Re: Summary of 2 threads on legal ways of exporting strong crypto
Date: Thu, 08 Jul 1999 15:11:56 GMT
Mok-Kong Shen <[EMAIL PROTECTED]> wrote, in part:
>The other (much more inconvenient yet do-able) way of exporting strong
>crypto is to use Boris Kazak's method to encode the stuff
Obviously, that technique is *not* legal, it's only a way to avoid
getting caught.
Although as a Canadian I recently celebrated our national holiday
(Canada Day, formerly known as Dominion Day, July 1st) by making my
first source code post, as my country doesn't go beyond Wassenaar,
originally, in proposing the first of the Quadibloc family of block
ciphers, I proposed a legal way of "exporting" strong crypto that
doesn't involve using the plain paper loophole...
simply make available a clear, cogent, and understandable description
of your proposed cryptographic method. One that can be easily turned
into program code by anyone with a moderate inclination to try.
John Savard ( teneerf<- )
http://members.xoom.com/quadibloc/crypto.htm
------------------------------
From: fungus <[EMAIL PROTECTED]>
Subject: Re: MP3 Piracy Prevention is Impossible
Date: Thu, 08 Jul 1999 17:58:03 +0200
[EMAIL PROTECTED] wrote:
>
> (e.g. if players are built only to handle watermarked files, removing the
> watermark makes them unplayable)
You mean like DivX??? <snigger>
--
<\___/>
/ O O \
\_____/ FTB.
------------------------------
From: [EMAIL PROTECTED]
Subject: Re: Why this simmetric algorithm is not good?
Date: Thu, 08 Jul 1999 15:00:41 GMT
In article <7m2d7k$d02$[EMAIL PROTECTED]>,
[EMAIL PROTECTED] wrote:
> This coding thing is good for for the security of the implementation
or
> is just a coding convention??
Well for cleaness and optimizations. Most compilers can optimize lines
of code if they are companded.
i.e take part of RC4
---
x = (x + 1) & 255
y = y + state[x]
---
Can be written as
---
y += state[x = (x + 1) & 255]
---
In fact RC4 can be written in about 3 or so lines of code. This makes
the code faster on most machines and more compact on microcontrollers.
It makes it harder to read as well.
Take a look a my PRNG C++ file, you will notice that the stepping of
the PRNGs look like
---
return state[x = ni[++x]] += state[y = ni[++y]];
---
Everything should be in the accumulator as required (i.e MCU
friendly). Most compilers can optimize code like this better then if
it were done in 3 or so lines...
For security reasons you want to avoid putting round keys on stack (i.e
auto/locals). This is not algorithm related but implementation
related.
Also naming locals the same as the globals (i.e procedure name and a
argument) is a bad idea, some compilers will tolerate it (in fact they
should) but who knows there might be a bug...
Tom
--
PGP key is at:
'http://mypage.goplay.com/tomstdenis/key.pgp'.
Free PRNG C++ lib:
'http://mypage.goplay.com/tomstdenis/prng.html'.
Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't.
------------------------------
From: [EMAIL PROTECTED] (Patrick Juola)
Subject: Re: Is Stenography legal?
Date: 8 Jul 1999 11:22:16 -0400
In article <[EMAIL PROTECTED]>,
Mok-Kong Shen <[EMAIL PROTECTED]> wrote:
>Robert G. Durnal wrote:
>
>> First, I think you mean STEGANOGRAPHY, not STENOGRAPHY. But it is
>> legal, and not against EAR. In fact, EAR does NOT apply to sending of coded
>> messages, but only to the dissemination of encryption software itself. And
>> steganography is not encryption.
>
>If an encryption software is coded and sent (a coded message), is this
>against EAR? Presumably yes. But how is that to be controlled?
Well, if The Man is smart enough to think to look for steganographic
patterns in Email leaving the country, it's easy enough to find.
It becomes a question of your cleverness in hiding against His in
finding.
-kitten
------------------------------
From: [EMAIL PROTECTED] (Patrick Juola)
Subject: Re: Is Stenography legal?
Date: 8 Jul 1999 11:20:11 -0400
In article <[EMAIL PROTECTED]>,
Mok-Kong Shen <[EMAIL PROTECTED]> wrote:
>Patrick Juola wrote:
>>
>
>> I do not believe that it is the case that "a certain crypto law
>> lists certain specific algorithms as forbidden"; the regs require
>> individual approval for use/export.
>
>In such a case the power of the bureaucrats is virtually infinite.
>The approval could depend e.g. on the applicant's personal
>characteristics.
Even were the approval completely objective, it would still be
possible/reasonable to require approval instead of having a list
of forbidden algorithms. As it happens, there are procedures
for judicial review (as evidenced in the Bernstein case) to keep
the government as a whole from acting in a completely arbitrary
and capricious fashion.
But you seem to be under some impression that just because a set
of regulations are arbitrary and capricious, they can't be
promulgated or enforced. To which my only response is : Welcome
to Real Life.
-kitten
------------------------------
From: Mok-Kong Shen <[EMAIL PROTECTED]>
Subject: Re: Netiquette Question
Date: Thu, 08 Jul 1999 17:32:30 +0200
John Savard wrote:
>
> In general, if I recieve a message by E-mail containing information
> related to a posting that I feel is relevant enough to deserve being
> preserved in a thread,
>
> I post the information,
>
> but I respect the E-mail sender's privacy by not identifying who sent
> the E-mail, while still acknowledging that the source of the
> information was an E-mail, and not me.
>
> Although I believe that is a reasonable procedure, unless it is
> specifically noted in the E-mail that the information is confidential
> for whatever reason, perhaps a more cautious procedure is expected?
There can obviously be quite different opinions. I tend to think
that it all depends on the content. If the content is neutral, i.e.
the rendering public of the association of the content with the
sender of the mail can do no harm, I don't deem it necessary to
delete the sender's name, unless specifically requested by the
sender. It is thus a matter of judgement in general and that
can err of course sometimes. On mailing lists a post direct from
the sender may arrive earlier than the the copy that goes through
the list owner. A few times I received mails that I assumed were
also posted to the lists. I responded immediately to the lists,
quoting the mails, but it turned out that the mails were only sent
to me. In such situations it could happen that the senders may be a
bit angry. That obviously depends on the senders' 'sensitivity'.
M. K. Shen
------------------------------
From: [EMAIL PROTECTED]
Subject: Re: Why this simmetric algorithm is not good?
Date: Thu, 08 Jul 1999 14:39:50 GMT
In article <7lssta$csb$[EMAIL PROTECTED]>,
[EMAIL PROTECTED] wrote:
> In article <[EMAIL PROTECTED]>,
> fungus <[EMAIL PROTECTED]> wrote:
> > procedure cipher(Key : uint128 ; plain: file ; cipher : file)
> > begin
> > setRandomSeed(Key);
> > while not EOF(plain)
> > begin
> > p := getNext128bits(plain) xor Random(0..2^128-1)
> > writeNext128bits(cipher, p)
> > end
> > end
>
> Not to be picky but the procedure name should not be the same as any
> paramaters or locals. It makes it clearer and avoids compiler errors.
> Also the line could have read
>
> -=-
> while not EOF(plain)
> writeNext128Bits(cipher, getNext128bits(plain) xor Random(...));
> -=-
>
> Just a coding thing...
>
> Tom
> --
> PGP key is at:
> 'http://mypage.goplay.com/tomstdenis/key.pgp'.
>
> Sent via Deja.com http://www.deja.com/
> Share what you know. Learn what you don't.
>
Hi,
This coding thing is good for for the security of the implementation or
is just a coding convention??
Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't.
------------------------------
From: Mok-Kong Shen <[EMAIL PROTECTED]>
Subject: Re: Is Stenography legal?
Date: Thu, 08 Jul 1999 17:10:12 +0200
Robert G. Durnal wrote:
>
> First, I think you mean STEGANOGRAPHY, not STENOGRAPHY. But it is
> legal, and not against EAR. In fact, EAR does NOT apply to sending of coded
> messages, but only to the dissemination of encryption software itself. And
> steganography is not encryption.
If an encryption software is coded and sent (a coded message), is this
against EAR? Presumably yes. But how is that to be controlled?
M. K. Shen
------------------------------
Date: Wed, 07 Jul 1999 12:07:50 -0400
From: [EMAIL PROTECTED]
Subject: Re: Can Anyone Help Me Crack A Simple Code?
Paul Schlyter wrote:
>
> In article <[EMAIL PROTECTED]>, <[EMAIL PROTECTED]> wrote:
>
> > Roger Carbol wrote:
> >
> >> How many different light colours are known?
> >
> > An arbitrarily large number. How finely can you divide electromagnetic
> > frequencies? An infinite number if you accept colors like heat,
> > microwave, radio, x-ray, gamma.
>
> Microwave, radio, x-ray, gamma are COLORS ??????
>
> Since my eyes cannot see any of these, am I color-blind? I must
> be, since I cannot see these "colors"..... <g>
>
> You're doing the common mistake of believing "color" is just another
> word for "wavelength". It's not. Wavelength is a physical property,
> while color is a perception in our eyes. Almost all natural colors
> we see are NOT pure spectral (monochromatic) colors, and some colors
> cannot even be assigned a "dominant wavelength". What wavelengths
> would you assing to these colors: white, gray, black, brown, purple
> ????
Yes, color <> wavelength. But there is considerable overlap. When we
speak about the "color of light" we are speaking about monochromatic
lights rather then mixtures. White/gray/black are all the same color
(mixture) at different intensities. Brown is a mixture. Indigo is a
monochromatic color that only some humans can detect. Deep red is a
monocromatic color that only some humans can detect. Assuming an
enhanced eyeball there is no reason to consider hard X-ray not a color.
But there are real reasons why brown is not a wavelength. True
White(tm) should include all kinds of electromagnetic light from a
wavelength of ~40 billion light-years down to the fermi distance of
10^-33m (IIRC). Now that's a color!
>
>
>
> > The human eye can distinguish around 100,000 colors of visible light.
>
> ...and perhaps only 100 or so different spectral (monochromatic) colors.
>
>
> --
> ----------------------------------------------------------------
> Paul Schlyter, Swedish Amateur Astronomer's Society (SAAF)
> Grev Turegatan 40, S-114 38 Stockholm, SWEDEN
> e-mail: [EMAIL PROTECTED] [EMAIL PROTECTED] [EMAIL PROTECTED]
> WWW: http://hotel04.ausys.se/pausch http://welcome.to/pausch
------------------------------
Date: Wed, 07 Jul 1999 12:10:59 -0400
From: [EMAIL PROTECTED]
Subject: Re: I don't trust my sysadmin
Jerry Coffin wrote:
>
> In article <[EMAIL PROTECTED]>, [EMAIL PROTECTED] says...
>
> [ ... ]
>
> > > I haven't checked in quite a while, but the last time I looked, there
> > > was only one OS on the A1 evaluated products list.
> >
> > By this do you mean a product whose candidacy for A! certification has
> > been evaluated (presumably failing), or a product whose evaluation
> > affirmed an A1 rating?
> >
> > Details would be nice.
>
> It was affirmed in that rating. As I mentioned in a later post, it's
> no longer on the list -- I haven't checked why it was removed, but my
> guess would be that the processor it ran on has been discontinued.
>
> I'm not sure what other sort of details I can supply -- I saw a
> machine running it while I was in the USAF, but I only saw it on a
> tour -- I never got to play with it, so I can't say much about it
> except that they were darn proud of it. FWIW, it was in on the
> infamous "vaults", with extremely tight EM shielding around the entire
> room, including Beryllium tabs sticking out around the edges of the
> door to seal things entirely shut from any possible EM leakage when
> the door was shut, and the machine wasn't supposed to be used if the
> door was open. In all honesty, the machine itself didn't seem nearly
> as memorable as the signs warning you about seeing a doctor
> _immediately_ if you accidentally cut yourself on the Beryllium...
Be is narsty stuff. How did they get power into the box? In the middle
80's I spent some time in what was then the biggest faraday cage ever,
up in Canada. They were constantly complaining about the problem of
getting clean power through the cage.
------------------------------
Date: Wed, 07 Jul 1999 12:13:27 -0400
From: [EMAIL PROTECTED]
Crossposted-To: talk.politics.crypto
Subject: Re: Summary of 2 threads on legal ways of exporting strong crypto
Mok-Kong Shen wrote:
>
> [EMAIL PROTECTED] wrote:
> >
>
> > > Very detailed descriptions which one could translate one-to-one
> > > to codes have already been done. If I don't err, RSA has recently
> > > published a RFC on BSAFE just in that way. Someone conjectured
> > > that there RSA has a mechanism for automatically converting that to
> > > C and reciprocally.
> >
> > Exactly the point. The fact that true translation can be mechanized
> > does not detract tahat a true translation is an expression of ideas, and
> > thus protected speech.
>
> Unfortunately the said conjecture has not be verified. It seems
> quite unlikely that it is possible (at least for the near future)
> to have a software that can convert between an ARBITRARY program
> code and its faithful (useful) natural language description.
Multi-lingual translation is simply a concatenation of individual
translators from a particular programming language to a particular
natural language and back. Once the first translator exists additional
ones would not be surprising.
------------------------------
Date: Wed, 07 Jul 1999 12:28:28 -0400
From: [EMAIL PROTECTED]
Crossposted-To: talk.politics.crypto
Subject: exporting damaged strong crypto source code
John Savard wrote:
>
> Mok-Kong Shen <[EMAIL PROTECTED]> wrote, in part:
>
> >The other (much more inconvenient yet do-able) way of exporting strong
> >crypto is to use Boris Kazak's method to encode the stuff
>
> Obviously, that technique is *not* legal, it's only a way to avoid
> getting caught.
>
> Although as a Canadian I recently celebrated our national holiday
> (Canada Day, formerly known as Dominion Day, July 1st) by making my
> first source code post, as my country doesn't go beyond Wassenaar,
>
> originally, in proposing the first of the Quadibloc family of block
> ciphers, I proposed a legal way of "exporting" strong crypto that
> doesn't involve using the plain paper loophole...
>
> simply make available a clear, cogent, and understandable description
> of your proposed cryptographic method. One that can be easily turned
> into program code by anyone with a moderate inclination to try.
How close can this description get to source code before it _is_ source
code? For example, is pseudo-code source code? Do the inspectors "know
it when they see it"?
Your non-email address sparked an alternate approach to the problem.
You publish something that is not your (nor anyone else's) mailing
address. The characteristic you chose to distinguish your non-address
from a real address is one that, I presume, was selected _because_ it
cannot be changed into a true address automatically. Pseudocode would
have this same flavor, there being no automated way to translate into a
particular dialect of a real compiler.
Perhaps there are transforms that can be applied to source code that are
analogous to the anti-spam transforms applied to email addresses.
Transforms that are idiosyncratic to a particular program yet not easily
mechanized would render source code into not source code. Function
overloading, operator redefinition, and polymorphism could be useful for
creating invalidation transforms that a human could easily reverse but a
program could not.
>
> John Savard ( teneerf<- )
> http://members.xoom.com/quadibloc/crypto.htm
------------------------------
From: [EMAIL PROTECTED]
Subject: Stream Cipher != PRNG
Date: Thu, 08 Jul 1999 16:22:40 GMT
In a private email I was told that stream ciphers and PRNGs are
completely different beasts. Am I missing something? I always thought
Stream ciphers were PRNGs which are difficult to solve (i.e
intractable).
Can someone please set me straight. RC4 is a stream cipher or PRNG (or
both?) what about SEAL?
Tom
--
PGP key is at:
'http://mypage.goplay.com/tomstdenis/key.pgp'.
Free PRNG C++ lib:
'http://mypage.goplay.com/tomstdenis/prng.html'.
Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't.
------------------------------
Date: Wed, 07 Jul 1999 12:33:11 -0400
From: [EMAIL PROTECTED]
Subject: Re: Is Stenography legal?
Patrick Juola wrote:
>
> In article <[EMAIL PROTECTED]>,
> Mok-Kong Shen <[EMAIL PROTECTED]> wrote:
> >Patrick Juola wrote:
> >>
> >
> >> I do not believe that it is the case that "a certain crypto law
> >> lists certain specific algorithms as forbidden"; the regs require
> >> individual approval for use/export.
> >
> >In such a case the power of the bureaucrats is virtually infinite.
> >The approval could depend e.g. on the applicant's personal
> >characteristics.
>
> Even were the approval completely objective, it would still be
> possible/reasonable to require approval instead of having a list
> of forbidden algorithms. As it happens, there are procedures
> for judicial review (as evidenced in the Bernstein case) to keep
> the government as a whole from acting in a completely arbitrary
> and capricious fashion.
>
> But you seem to be under some impression that just because a set
> of regulations are arbitrary and capricious, they can't be
> promulgated or enforced. To which my only response is : Welcome
> to Real Life.
Government is not reason. Government is force. -- George Washington
------------------------------
From: [EMAIL PROTECTED]
Subject: Re: Netiquette Question
Date: Thu, 08 Jul 1999 16:16:33 GMT
In article <[EMAIL PROTECTED]>,
[EMAIL PROTECTED] (John Savard) wrote:
> In general, if I recieve a message by E-mail containing information
> related to a posting that I feel is relevant enough to deserve being
> preserved in a thread,
>
> I post the information,
>
> but I respect the E-mail sender's privacy by not identifying who sent
> the E-mail, while still acknowledging that the source of the
> information was an E-mail, and not me.
>
> Although I believe that is a reasonable procedure, unless it is
> specifically noted in the E-mail that the information is confidential
> for whatever reason, perhaps a more cautious procedure is expected?
If you want to make emails private do the following
a) Say in the message that it's confidential
b) PGP encrypt the message (or at least ROT13 it!)
Normally when I receive PGP messages I assume it's a private msg.
Tom
--
PGP key is at:
'http://mypage.goplay.com/tomstdenis/key.pgp'.
Free PRNG C++ lib:
'http://mypage.goplay.com/tomstdenis/prng.html'.
Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't.
------------------------------
From: [EMAIL PROTECTED]
Subject: Re: Is Stenography legal?
Date: Thu, 08 Jul 1999 16:20:03 GMT
In article <[EMAIL PROTECTED]>,
Mok-Kong Shen <[EMAIL PROTECTED]> wrote:
> If an encryption software is coded and sent (a coded message), is this
> against EAR? Presumably yes. But how is that to be controlled?
Is ROT13 against EAR? I think they only care about the inability to
read our private messages (i.e I sent private email with PGP ...).
What does that say about your privacy in the states?
In Canada all I have to worry about is pepper spray by a Mountie (or
getting punched by our prime minister...). I have not heard of any
cases in Canada concerning cryptography (possibly the senate has
debated the spelling, they are good at wasting time AND money :( ).
Tom
--
PGP key is at:
'http://mypage.goplay.com/tomstdenis/key.pgp'.
Free PRNG C++ lib:
'http://mypage.goplay.com/tomstdenis/prng.html'.
Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't.
------------------------------
Date: Wed, 07 Jul 1999 11:57:24 -0400
From: [EMAIL PROTECTED]
Subject: Re: Can Anyone Help Me Crack A Simple Code?
I'm referring to a number the Air Force generated for visual
discrimination. Also, there is wide variation in sensitivity across the
population. I'm sure you could find someone with the equivlent of 20/10
for color sensitivity.
S.T.L. wrote:
>
> <<The human eye can distinguish around 100,000 colors of visible light.>>
>
> I've actually heard figures of a few million, but less than 16 million and more
> than 100,000. (It was in connection with someone saying how 24bit color
> monitors are already overkill, and 32bit color is insane.) Oh well.
>
> Moo-Cow-ID: 67 Moo-Cow-Message: message
>
> -*---*-------
> S.T.L. ===> [EMAIL PROTECTED] <=== BLOCK RELEASED! 2^6972593 - 1 IS PRIME!
> Quotations: http://quote.cjb.net Main website: http://137.tsx.org MOO!
> "Xihribz! Peymwsiz xihribz! Qssetv cse bqy qiftrz!" e^(i*Pi)+1=0 F00FC7C8
> E-mail block is gone. It will return if I'm bombed again. I don't care, it's
> an easy fix. Address is correct as is. The courtesy of giving correct E-mail
> addresses makes up for having to delete junk which gets through anyway. Join
> the Great Internet Mersenne Prime Search at http://entropia.com/ips/ Now my
> .sig is shorter and contains 3395 bits of entropy up to the next line's end:
> -*---*-------
>
> Card-holding member of the Dark Legion of Cantorians, the Holy Order of the
> Catenary, the Great SRian Conspiracy, the Triple-Sigma Club, the Union of
> Quantum Mechanics, the Polycarbonate Syndicate, the Roll-Your-Own Crypto
> Alliance, People for the Ethical Treatment of Digital Tierran Organisms, and
> the Organization for the Advocation of Two-Letter Acronyms (OATLA)
> Avid watcher of "World's Most Terrifying Causality Violations", "When Kaons
> Decay: World's Most Amazing CP Symmetry Breaking Caught On [Magnetic] Tape",
> "World's Scariest Warp Accidents", "World's Most Energetic Cosmic Rays", and
> "When Tidal Forces Attack: Caught on Tape"
> Patiently awaiting the launch of Gravity Probe B and the discovery of M39
> Physics Commandment #13: The Electromagnetic Force Is Carried By Photons.
------------------------------
From: Paul Koning <[EMAIL PROTECTED]>
Crossposted-To: talk.politics.crypto
Subject: Re: Summary of 2 threads on legal ways of exporting strong crypto
Date: Wed, 07 Jul 1999 15:37:19 -0400
Mok-Kong Shen wrote:
>
> Paul Koning wrote:
> >
>
> > Of course you're in Germany so you don't have to deal with any
> > of these annoying regulations. But please, do the US readers of
> > this a favor and stop spouting nonsense that might get them in
> > trouble if they are foolish enough to believe you.
>
> Of the two schemes I believe that the first is certianly o.k.
> If you think otherwise, I should appreciate very much your comments.
You might re-read what I wrote, because I did comment on it.
Yes, I believe that a US person can safely post a URL that points to
a foreign site containing crypto. You'll find many such links if
you go look. Pointing to something is not export.
But you didn't explain how the material that the URL points to got
there in the first place. If it wasn't in the US at one time, then
US export rules don't apply; if it was, then they do. It's not the
pointing that's the issue, it's the material pointed to. Did you
export THAT legally?
paul
------------------------------
From: Paul Koning <[EMAIL PROTECTED]>
Subject: Re: DES-NULL attack
Date: Wed, 07 Jul 1999 11:30:46 -0400
Xcott Craver wrote:
> ...
> If you can fit a terabyte in a cubic foot of hard drives, then
> the Alex DES-NULL attack machine could be crammed into a cube
> maybe 10 stories high? Without Power or cooling or Jeffries
> tubes. That's pretty much what Alex is proposing to implement
> his chosen plaintext attack. On DES! How big is Deep-Crack
> in comparison?
A few cubic feet, and it could easily be made smaller. And it costs
about the same as a terabyte of disk space. So yes, a dictionary
attack on DES seems rather silly. (The one thing it has going for
it would be that it's MUCH faster than Deep Crack.)
paul
------------------------------
From: [EMAIL PROTECTED]
Crossposted-To: sci.math
Subject: Re: Properties of Chain Addition?
Date: Thu, 08 Jul 1999 16:14:57 GMT
In article <[EMAIL PROTECTED]>,
[EMAIL PROTECTED] (John Savard) wrote:
> [EMAIL PROTECTED] (John Savard) wrote, in part:
>
> >The VIC cipher used by Russian spies involved a technique for
> >generating pseudorandom numbers known as "chain addition".
>
> An E-mail I recieved in response to this post noted one condition
> where chain addition will result in a less-than-maximal period:
>
> whenever the modulus of the shift register cells is not prime, if all
> their contents share a common factor with this modulus (i.e., if its a
> base 10 shift register, if all the starting numbers are even, or if
> they're all either 0 or 5) then all subsequent digits generated will
> also be divisible by that number, limiting the number of states.
That would apply to mod 256 registers as well
[128][0][128][0][128][128][0][0][128][0], etc...
You can eliminate this by forcing the first cell into a known state
[1][0][128][0][1][1][129][129][130][131][4][133][7] etc...
Basically just or the first cell with 1 and you avoid this (you would
get 1 or 129 in this case).
Tom
--
PGP key is at:
'http://mypage.goplay.com/tomstdenis/key.pgp'.
Free PRNG C++ lib:
'http://mypage.goplay.com/tomstdenis/prng.html'.
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