Cryptography-Digest Digest #454, Volume #9 Fri, 23 Apr 99 15:13:02 EDT
Contents:
Re: Common Passowrds ("Trevor Jackson, III")
threshold schemes +Simmons (toto)
Re: 128 bit DES ([EMAIL PROTECTED])
Re: choosing g in DH (Bob Deblier)
Re: Thought question: why do public ciphers use only simple ops like shift and XOR?
(wtshaw)
Random Additive Generator (For ciphers) ([EMAIL PROTECTED])
Re: Adequacy of FIPS-140 (R. Knauer)
Re: Random Additive Generator (For ciphers) ([EMAIL PROTECTED])
Re: SHA-1 as f-function in Feistel construction (Bob Silverman)
Re: BEST ADAPTIVE HUFFMAN COMPRESSION FOR CRYPTO (SCOTT19U.ZIP_GUY)
Re: Random Additive Generator (For ciphers) (Gustaf Dellkrantz)
Re: xtea paper (was PGP=NSA) (Paul Rubin)
Re: Thought question: why do public ciphers use only simple ops like shift and XOR?
(SCOTT19U.ZIP_GUY)
----------------------------------------------------------------------------
Date: Fri, 23 Apr 1999 20:15:03 -0400
From: "Trevor Jackson, III" <[EMAIL PROTECTED]>
Subject: Re: Common Passowrds
Mok-Kong Shen wrote:
>
> Nathan Christiansen wrote:
> >
>
> >
> > What I am looking for is a list that contains what they use as their password.
> >
> > For Example:
> >
> > 1. Spouse's name.
> > 2. Spouse's name backwards.
> > 3. Social Security Number.
>
> So you want, among others, a list of all social security numbers
> of your country??
He wants a list of data element names not data element values. I.e.,
the table descriptor or framework not the table contents.
>
> M. K. Shen
------------------------------
From: toto <[EMAIL PROTECTED]>
Subject: threshold schemes +Simmons
Date: Fri, 23 Apr 1999 10:45:54 +0200
I'm searching for a Gustavus J. Simmons article writen in 1991and
entitled "The geometry of shared secret schemes" or more generaly his
home page.
Thanks for your help.
------------------------------
From: [EMAIL PROTECTED]
Subject: Re: 128 bit DES
Date: Fri, 23 Apr 1999 11:26:45 GMT
=====BEGIN PGP SIGNED MESSAGE=====
Hash: SHA1
> What do you mean by "better"? It is generally agreed that 3DES
> is the most trustworthy cipher available at the moment. The
> others haven't been subject to anywhere near the same amount of
> analysis.
>
> CAST, Blowfish, RC6 et al may have some interesting properties,
> but I doubt anyone would called them "better" in terms of
> security.
How do you judge secure though? Neither of the ones you
mentioned have been cracked yet...
Tom
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=ZdlQ
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--
PGP public keys. SPARE key is for daily work, WORK key is for
published work. The spare is at
'http://members.tripod.com/~tomstdenis/key_s.pgp'. Work key is at
'http://members.tripod.com/~tomstdenis/key.pgp'. Try SPARE first!
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------------------------------
From: Bob Deblier <[EMAIL PROTECTED]>
Subject: Re: choosing g in DH
Date: Fri, 23 Apr 1999 13:42:50 +0200
Roger Schlafly wrote:
> Michael J. Fromberger wrote in message
> <7foilt$5r6$[EMAIL PROTECTED]>...
> >Actually, the value of g should be chosen to be a primitive element
> >(also known as a "generator") modulo p. A value g is a generator
> >modulo p if the smallest value x such that g^x = 1 (mod p) is (p - 1).
>
> No, the earlier advice was better. There are some attacks if g is a
> generator. It is safer to choose g to have prime order.
Any pointers on where I can find more information on that?
------------------------------
From: [EMAIL PROTECTED] (wtshaw)
Subject: Re: Thought question: why do public ciphers use only simple ops like shift
and XOR?
Date: Fri, 23 Apr 1999 01:40:23 -0600
In article <7fnujg$2tj$[EMAIL PROTECTED]>, SCOTT19U.ZIP_GUY
<[EMAIL PROTECTED]> wrote:
>
> Your feelings are correct except for one small point. The AES contest
> is not about having secure encryption. The NSA would never allow a good
> common method to be blessed by the government for general use.
> So that is why you will never see a blessed super cipher method made
> of completely different methods. Unless each method added information
> at each pass so that they could be broken independitly.
>
We can expect that there are tactics and strategies on file for finding a
way for the government to get itself out of the corner that it has painted
itself into. Whether any of them will work or is going to be acceptable
is up for grabs.
As seen in many cases before, our government is adept at doing
inconsistent things, even, alas, contradicting itself in statements of
mission and policy. As in any level of organization, individual to
government, the devil is in the details, that is which values are given
more weight at the time. In time of war....well, we will see...rather not
have to have any war that might be abused for ulterior motives aside from
those well recognized.
--
Life's battles do not always go to the stronger of faster man...
But, sooner or later always go to the fellow who thinks he can.
------------------------------
From: [EMAIL PROTECTED]
Subject: Random Additive Generator (For ciphers)
Date: Fri, 23 Apr 1999 11:39:34 GMT
=====BEGIN PGP SIGNED MESSAGE=====
Hash: SHA1
Would this round function be secure
A = A + (B xor R1)
B = B + (A xor R2)
Given R1 and R2 are random and cannot
be predicted (with a chance greater then
1 out of 2^32).
Thanks,
Tom
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Version: PGPfreeware 6.0.2i
iQA/AwUBNyBatfIPgV4W6pz7EQJR2wCeOBizSXn/raU8bKLDhF/nb43Onb0An0gM
IwyT3020WVvFxRKZYHjey9DL
=rkoQ
=====END PGP SIGNATURE=====
--
PGP public keys. SPARE key is for daily work, WORK key is for
published work. The spare is at
'http://members.tripod.com/~tomstdenis/key_s.pgp'. Work key is at
'http://members.tripod.com/~tomstdenis/key.pgp'. Try SPARE first!
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------------------------------
From: [EMAIL PROTECTED] (R. Knauer)
Subject: Re: Adequacy of FIPS-140
Date: Fri, 23 Apr 1999 12:28:03 GMT
Reply-To: [EMAIL PROTECTED]
On Fri, 23 Apr 1999 13:05:07 -0400, "Trevor Jackson, III"
<[EMAIL PROTECTED]> wrote:
>So, your thesis is that if we have a source of random number to use to
>select a text stream and to select a position within the text stream
>then we could use the text stream as a source of random numbers.
Something like that. You left out details.
>If you have an algorithm for deterministicly selecting text streams and
>offsets I do not need to exhaust the possible combinations. Only the
>one the algorithm selects.
The algorithm can select any possible text using any possible offset.
Bob Knauer
European Parliament's Scientific and Technological Options Assessment,
Appraisal of Technologies of Political Control, including Mark-Free
Torture, implemented by the British military in Northern Ireland:
http://jya.com/stoa-atpc.htm
------------------------------
From: [EMAIL PROTECTED]
Subject: Re: Random Additive Generator (For ciphers)
Date: Fri, 23 Apr 1999 13:17:28 GMT
>
> (The following assumes the question is about a round function for a block
> cipher and that addition is done (mod 2^32), or something equally nice)
Probably yes.
>
> Depends on R1 and R2... If R1 and R2 depend only on the key, this round
> function is very weak... (Hint, avalanche from higher to lower bits...)
This is correct. Hmm, good point. I was just thinking of random numbers
though (in theory).
>
> On the other hand, if R1 and R2 are complex functions of A and B this might be
> secure, depending on the functions used. The only way this could be done is if
> R1=f(B) and R2=g(A) for some functions f and g, but this looks a lot like a
> Feistel-cipher with addition as linear combiner.
>
> Conclusion: This does not look like a useful round function for a block
> cipher.
Thanks for the feedback, I had similar thoughts about it.
Tom
--
PGP public keys. SPARE key is for daily work, WORK key is for
published work. The spare is at
'http://members.tripod.com/~tomstdenis/key_s.pgp'. Work key is at
'http://members.tripod.com/~tomstdenis/key.pgp'. Try SPARE first!
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------------------------------
From: Bob Silverman <[EMAIL PROTECTED]>
Subject: Re: SHA-1 as f-function in Feistel construction
Date: Fri, 23 Apr 1999 13:51:26 GMT
In article <[EMAIL PROTECTED]>,
(RDJ) wrote:
> I'm wondering how effective the scheme described in the subject might
> be? For instance:
> using 256 bit blocks, the f-function would return the first 128 bits
> of the hash of the right-half of the data block and a subkey.
>
> just a thought
> I'm just learning about cryptography, so please pardon my naive
> musings.
I think it would be too slow to be practical.
Also, if I may ask:
How would you invert the Hash to decrypt?
Bob Silverman
"You can lead a horse's ass to knowledge, but you can't make him think"
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------------------------------
From: SCOTT19U.ZIP_GUY <[EMAIL PROTECTED]>
Subject: Re: BEST ADAPTIVE HUFFMAN COMPRESSION FOR CRYPTO
Date: Fri, 23 Apr 1999 14:00:59 GMT
In article <[EMAIL PROTECTED]>,
Mok-Kong Shen <[EMAIL PROTECTED]> wrote:
> SCOTT19U.ZIP_GUY wrote:
> >
> > In article <[EMAIL PROTECTED]>,
> > Mok-Kong Shen <[EMAIL PROTECTED]> wrote:
> > > SCOTT19U.ZIP_GUY wrote:
> > > >
> > >
> > > > for a quick not complete explained it is this:
> > > > 1) the compressed file ends exactly on a byte boundary and sent as suchh
> > > > 2) the compressed file has filler in the last byte.
> > > > 3) the compressed file is truncated so last symbol is not fully written
> > >
> > > I suppose that for files that are to compressed not all 256 symbols
> > > of ASCII are used. So one could certainly choose one that is not
> > > used as the end-of-file symbol and then fill the last byte with
> > > anything, if needed. That would give the receiver the certitude
> > > that the file indeed ends and has not been truncated. What is your
> > > opinion? (One could use a pair or a triple of symbols as end-of-file,
> > > if all 256 symbols are used.)
> > >
> > > M. K. Shen
> > >
> >
> > 2 Points
> > 1) If a file is compressed and then you examin it in terms of
> > 8 bits symbols then you would expect all 256 symbols to appear
> > since a file this is compressed would hopefully approach that
> > of a random file.
>
> You misunderstood me. I mean a file that is to be compressed (normally
> an ordinary text file, program source, etc.) with extremely rare
> exceptions doesn't use all 256 symbols. So one of the unused
> symbols can be specified in the Huffman table to serve as an
> end-of-file mark.
>
> > 2) If you use a set of symbols as the end of file in the
> > compressed text. It gives tremendous information to an attacker
> > if one only looks at the last few blocks and if encrypted with
> > the small key AES or DES type of methods one need only try keys
> > or recovery methods that examin the last few blocks of encrypted
> > text to check for a file with the end of file marks.
> > When one finds a match it is very likely the solution to the
> > whole encryption. One should never allow for a constant ending
> > pattern in the compressed text. One should use compression that
> > forces the attacker to least do a full pass of the encrypted text
> > before a solution can be ruled out. One should never ever leave
> > the kind of hooks that are in products like PGP if one wants real
> > security.
>
> There are likely to be many candidates for the symbol that is choosen
> as the end-of-file symbol. How is the analyst going to guess that
> in the Huffman encoded form? He knows that that must be somewhere
> among the last bunch of bits but no more. That doesn't seem to
> leek any information to him (moreover that symbol is used only once).
> If an encryption is any good, then even using a fullstop to end
> sentences is acceptable. I think that providing an end-of-file
> does have a programming advantage.
>
> M. K. Shen
>
Sir we had very long private communications about scott16u at one
time. You claimed you where going to do a write up on it. But then
you stopped. If you can't understand what I am saying I think this
thread should end until you program an example. I can tell from your
arguments you have never written an adaptive huffman compression on
your own.
If you think the method should envovle information such that the
one to one feature is not allowed fine. But if you think your doing
the one to one thing and your approach is correct then show code
for it as I have.
David A. Scott
--
http://cryptography.org/cgi-bin/crypto.cgi/Misc/scott19u.zip
http://members.xoom.com/ecil/index.htm
NOTE EMAIL address is for SPAMERS
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------------------------------
From: Gustaf Dellkrantz <[EMAIL PROTECTED]>
Subject: Re: Random Additive Generator (For ciphers)
Date: Fri, 23 Apr 1999 13:08:41 GMT
In article <7fpm5m$jra$[EMAIL PROTECTED]>,
[EMAIL PROTECTED] wrote:
>
> Would this round function be secure
>
> A = A + (B xor R1)
> B = B + (A xor R2)
>
> Given R1 and R2 are random and cannot
> be predicted (with a chance greater then
> 1 out of 2^32).
>
> Thanks,
> Tom
(The following assumes the question is about a round function for a block
cipher and that addition is done (mod 2^32), or something equally nice)
Depends on R1 and R2... If R1 and R2 depend only on the key, this round
function is very weak... (Hint, avalanche from higher to lower bits...)
On the other hand, if R1 and R2 are complex functions of A and B this might be
secure, depending on the functions used. The only way this could be done is if
R1=f(B) and R2=g(A) for some functions f and g, but this looks a lot like a
Feistel-cipher with addition as linear combiner.
Conclusion: This does not look like a useful round function for a block
cipher.
/Gustaf
--
Gustaf Dellkrantz ([EMAIL PROTECTED])
My opinions only and so on...
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------------------------------
From: [EMAIL PROTECTED] (Paul Rubin)
Subject: Re: xtea paper (was PGP=NSA)
Date: Fri, 23 Apr 1999 15:37:04 GMT
In article <7fpiei$gsa$[EMAIL PROTECTED]>,
<[EMAIL PROTECTED]> wrote:
>You are right, I should have published results,
>but I am sorta newer and haven't found any
>good resources on learning cryptanalysis.
Check out Bruce Schneier's "Course in Block Cipher Cryptanalysis" at
www.counterpane.com. If you work all the way through it you'll really
know a lot when you're done.
------------------------------
From: SCOTT19U.ZIP_GUY <[EMAIL PROTECTED]>
Subject: Re: Thought question: why do public ciphers use only simple ops like shift
and XOR?
Date: Fri, 23 Apr 1999 14:30:35 GMT
In article <[EMAIL PROTECTED]>,
[EMAIL PROTECTED] (wtshaw) wrote:
> In article <7fnujg$2tj$[EMAIL PROTECTED]>, SCOTT19U.ZIP_GUY
> <[EMAIL PROTECTED]> wrote:
> >
> > Your feelings are correct except for one small point. The AES contest
> > is not about having secure encryption. The NSA would never allow a good
> > common method to be blessed by the government for general use.
> > So that is why you will never see a blessed super cipher method made
> > of completely different methods. Unless each method added information
> > at each pass so that they could be broken independitly.
> >
> We can expect that there are tactics and strategies on file for finding a
> way for the government to get itself out of the corner that it has painted
> itself into. Whether any of them will work or is going to be acceptable
> is up for grabs.
>
> As seen in many cases before, our government is adept at doing
> inconsistent things, even, alas, contradicting itself in statements of
> mission and policy. As in any level of organization, individual to
> government, the devil is in the details, that is which values are given
> more weight at the time. In time of war....well, we will see...rather not
> have to have any war that might be abused for ulterior motives aside from
> those well recognized.
These inconsistent things are done for a reason. One branch of the
government can promise you something in exchange for something but
when you keep your promise then another branch can punish you for the
very same action. That way those in power can really do what the hell
they want because there are so many laws rules and organiszations
they are routinely selectively applied. As an example is the tax
structure. It cost a lot of money to collect and process the taxs
any comgress man knows a simple flat tax would save the government
money and be best for the population as a whole and it could make
the size of government smaller. But this will never happen it is
designed to keep citizens in fear instead of helping them. Also
as a recent stufy showed for a family of 4 with a simple tax set
up the mahority of CPA's could not do the tax forms correctly.
The govenment likes this. If you vote wrong or whatevery you can
be charged with falsefying your income taxes. This tool is to
powerful for government to throw away. The governments main
concern is to keep the status quo and to control. Not to help
people.
Next silly thing your going to tell me is that if the Pres
comitted perjury he would be punished in court like any other
man. I still think the shootings in Colorado are more the result
of the mixed signals we send our kids. We teach them about
truth and justice and fair play. But then the first taste of
justice is a dishonest traffic ticket. As an example when I
was a kid I got a ticket and went to court and won. Back then
they where misdemeanors and you had the protection of the Bill
of Rights. My dad explained that most who fought won. Becasue
if your are guilty the time and trouble to fight the ticket
could be thought of as punishment. And if you are not guiltiy
the thrill of being right and winning made you proud to be an
american. But this is not the case today. The samething is now
an infraction and you have no rights. Clever of them to change
the bill of rights buy redefining offenses. This kind of
corruption the justice system teaches kids right a way that
there is no reason to be honest. Belief in justice is for
fools. That is what we teach are kids. Hell as a kid I took
a gun to school for an NRA saftey class. They wanted us to
use are own 22's. Would that happen today hell no.
David Scott
--
http://cryptography.org/cgi-bin/crypto.cgi/Misc/scott19u.zip
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