HDTenEightyP/NetNews huggingface dataset:
From: Graham.Shaw@newcastle.ac.uk (G.D.Shaw)
Newsgroups: sci.crypt
Subject: Differential cryptanalysis and random headers
Date: 26 Sep 92 09:59:44 GMT
Organization: University of Newcastle upon Tyne, UK NE1 7RU

Some questions:

Is differential cryptanalysis exclusively applicable to situations
where a chosen plaintext attack is possible?

If so, does the use of a random header followed by encryption in a
chaining mode defeat such an attack?

Finally, is vulnerability to differential cryptanalysis (or indeed
chosen plaintext attacks in general) believed to imply vulnerability
to other types of attack?

Graham Shaw (dph3gds@tuda.ncl.ac.uk)
Department of Physics, Durham University, England.
Newsgroups: sci.crypt
From: kellmeye@ux1.cso.uiuc.edu (kellmeyer steven l)
Subject: Paradox database encryption
Organization: University of Illinois at Urbana
Distribution: sci.crypt
Date: Sat, 26 Sep 1992 21:30:29 GMT

I am planning on using Borland's Paradox for storing information of 
a highly personal nature (part of our expanding net will soon be
linking in a counseling center).  Does anyone know if the security
level of this software is reasonably good?  I don't expect it to
stand up to a really devious hack, but I'd like to be able to assure
the client (the counseling center director) that Paradox encryption
schemes will keep out 99.9% of intruders (it's a big campus, so one
in 1000 may really be a little low, but you get the idea). 

I know from reading this group that WordPerfect encryption is easily
defeated, so I'll warn him about that.  We are also considering Foxpro,
since they claim to be coming out with encryption capabilities for
their database.  I know I could ask the companies themselves, but I
tend to doubt that I would get an unbiased opinion of the utility of
their encryption schemes :)

I already downloaded PGP 2.0, and would love to see a windowed front-end
for it (the counselors who would need to use it would be easily confused
by UNIX-like switch options).  

Any help on any of these issues would be GREATLY appreciated.  Thanks.

Steve Kellmeyer
kellmeye@ux1.uiuc.edu
-- 

Steve Kellmeyer 
kellmeye@ux1.cso.uiuc.edu
Newsgroups: sci.crypt
From: ken@halcyon.com (Ken Pizzini)
Subject: Re: Various Tangents
Summary: more tangents
Organization: The 23:00 News and Mail Service
Date: Tue, 6 Oct 1992 22:55:42 GMT

In article <1992Oct6.192856.12630@csi.uottawa.ca> cbbrowne@csi.uottawa.ca (Christopher Browne) writes:
>And I think a good point has been brought up:
>
>For most of the people playing with PGP, the actual security of the
>system is really not ALL that important.
[...]
>What's important for most of the people around here is that playing
>with PGP is FUN.  
>
>- It's FUN to feel that you get to "fool" sundry government agencies
>- It's FUN to try to figure out ways of breaking the system
>- It's FUN to try to figure out ways of strengthening the system
>
>There may be a few professionals around this group; most of the people
>here probably aren't, at least with respect to cryptology.

I agree, and two more points I'd like to toss in:

- PGP lets us explore user interfaces for crypographic communications
- Using programs like PGP help create a legal presumption that
  ordinary folk encrypt messages (i.e. it's not a "profile" for
  illicit activities, like unsing large quantities of cash has become)

		--Ken Pizzini
Newsgroups: sci.crypt
From: smb@ulysses.att.com (Steven Bellovin)
Subject: Re: Differential cryptanalysis and random headers
Date: Sun, 27 Sep 1992 15:29:21 GMT
Organization: AT&T Bell Laboratories

In article <1992Sep27.090739.1@zodiac.rutgers.edu>, leichter@zodiac.rutgers.edu writes:
> It is PRIMARILY applicable in such situations - but EXCLUSIVELY applicable?
> That's hard to say.  In the long run, known plaintext generally (though not
> always) gives you the same results as chosen plaintext; it just may take
> longer.

I'm not sure I agree in this case.  Differential cryptanalysis is based
on the reaction of the system to *pairs* of inputs.  While knowing the
plaintext, even in a block-chaining situation, is generally useful, in
differential cryptanalysis you'd be more or less dependent on luck to produce
the right input pairs.  And if you need 2^47 pairs of chosen plaintext,
you'd probably need a lot more known plaintext.

There's another reason to have some confidence about DES in this respect:
the original designers knew about differential cryptanalysis, and designed
DES to resist it.  Certainly, there may be other, more powerful, attacks
that can be launched against it, but I'm not convinced that they'll use
differential cryptanalysis as a major element.
Newsgroups: sci.crypt
From: strnlght@netcom.com (David Sternlight)
Subject: Re: Message interception
Organization: Netcom - Online Communication Services (408 241-9760 guest)
Distribution: all
Date: Tue, 6 Oct 1992 16:08:57 GMT

In article <1992Oct4.064606.582@duphy4.physics.drexel.edu> lane@duphy4.physics.drexel.edu writes:
>Obviously one way that messages could be intercepted is by tapping off
>of a line (phone or RS232) between a terminal and the mainframe it is
>connected to....no doubt this is part of the reason why PGP is discouraged
>on mainframe systems.

The wise user with security needs having financial value will use a
desktop or portable computer, not a dumb terminal. He will use PGP on
his portable, and send the encrypted text to the mainframe for
retransmission.

So does anyone know when the rumored PGP for the Mac will be ready?
From: jerryp@key.COM (J. R. Pendleton)
Newsgroups: sci.crypt
Subject: DES source for PC?
Keywords: DES C-source PC
Date: 6 Oct 92 00:58:38 GMT
Organization: Employer not involved in this.

Sometime ago someone on this group was kind enough to point me
towards ftpable source code for a PC implementation of the DES.

I am trying recover a *bunch* of things lost in a hard disk
crash.  Would someone be kind enough to re-point me?

Many thanks.

(I'll bet this is a FAQ...)

                                                     Jerry Pendleton
---------------------------

-- 
J. R. Pendleton, who does not speak for Key Computer Labs or Amdahl Inc.
 uucp: jerryp@key.amdahl.com  Voice : (510)623-2146  Amateur : KC6RTO
      "Eagles soar, but weasels never get sucked into jet engines"
          "An Independant dealer of Mary Kay Beauty products"
From: leichter@zodiac.rutgers.edu
Newsgroups: sci.crypt
Subject: Re: Differential cryptanalysis and random headers
Date: 27 Sep 92 13:07:39 GMT
Organization: Rutgers University Department of Computer Science

In article <Bv6JrL.B1L@newcastle.ac.uk>, Graham.Shaw@newcastle.ac.uk
(G.D.Shaw) writes:
| Some questions:
| 
| Is differential cryptanalysis exclusively applicable to situations
| where a chosen plaintext attack is possible?
| 

It is PRIMARILY applicable in such situations - but EXCLUSIVELY applicable?
That's hard to say.  In the long run, known plaintext generally (though not
always) gives you the same results as chosen plaintext; it just may take
longer.

| If so, does the use of a random header followed by encryption in a
| chaining mode defeat such an attack?
| 

Unknown.  However, there tend to be plenty of possible inputs that can be
used as a basis for differential cryptanalysis.  As you would expect, the
published work so far focuses on using inputs that are particularly convenient
for this purpose - hence, chosen plaintext.  If you work harder, can you get
the same results using other kinds of input?  No one knows - or at least no
one has published such results.

| Finally, is vulnerability to differential cryptanalysis (or indeed
| chosen plaintext attacks in general) believed to imply vulnerability
| to other types of attack?
| 

Beyond the fact that vulnerability to chosen plaintext probably implies vul-
nerability to known plaintext:  Unknown.  Without a sound theory, talking
about "other TYPES of attack" is philosophy, not mathematics or science.
Differential cryptanalysis is the first published mode of attack against
DES-style algorithms that actually distinguished in a non-trivial way among
different members of the class of such algorithms.  Until it appeared, the
only publically known criteria for distinguishing among such algorithms were
some fairly obvious requirements like not making the boxes implement linear or
affine transformations.  Once you avoided those, all other algorithms seemed
equally hard - and there was no plausible attack on any of them, once you used
"enough" rounds.  But where "enough" came from, and why it mattered, was a
mystery.

Are there entirely different attacks, different in the sense that the induce
a distinct subdivision of "good" and "bad" members of this class of algorithms
(or even, perhaps, break ALL such algorithms)?  No one knows - or at least no
one has said publically.
							-- Jerry
From: ssyun@iso.ma.utexas.edu (SungSik Yun)
Newsgroups: sci.crypt
Subject: Where is FAQ?
Summary: where is FAQ
Keywords: where is FAQ
Date: 30 Sep 92 03:21:54 GMT
Distribution: sci
Organization: University of Texas at Austin Mathematics

Hello?
I'd like to know where is the FAQ file for this group.
( I searched the group "news.answers", but was not there.)
Also I want to know what is PGP.
Do you have any info?
Thank you for your concern.

-- 

SungSik Yun---UT austin:Mathematics ||| E-mail:ssyun@math.utexas.edu
ph:(512)471-1242 (office)           |||        ssyun@cs.utexas.edu
From: fulk@cs.rochester.edu (Mark Fulk)
Subject: Re: A question in Recursion Theory
Keywords: recursion
Organization: Computer Science Department University of Rochester
Date: Wed, 30 Sep 1992 14:03:56 GMT

My previous post on this matter was poorly worded, and contained some
mistakes in the presentation of the proof.  Herewith an improvement:

Let f be the left projection function for some pairing function.
Let J be the set of natural numbers.

We construct I by deleting elements from N; note that this makes I co-r.e.
In the construction, we will refer to certain requirements R_i:

R_i: range phi_i is finite or there is y in N such that phi_i(y) not in I.

We will also restrain some numbers into I for requirements R_i.  These
restraints can be broken for higher-priority (lower-numbered) requirements,
but the standard finite-injury argument will establish that every requirement
gets met.  The point of these restraints is that the range of f restricted
to I (f|I) will still be N; this forces any section of f|I to have an
infinite range, since a section must be in injection.

Stage s:

   Search for s steps for all i such that: requirement i is not met,
   and there are x,y such that phi_i(x) = y, f(y)=x, and y is not
   restrained into I for any requirement i'<i.

   Let i0 be the least such i found; let x0 and y0 be corresponding
   values of x and y.

   Delete y0 from I.

   find y'>y0 such that y' has not yet been deleted from I, and such that
   f(y') = f(y0) = x0, 

   Mark requirement i0 as being met.

   For all requirements i>i0 that are marked as met, remove the mark
   (that is, start treating them as unmet).

End stage s.

I will leave the verification up to the reader.  The basic structure of
the proof is that every requirement will be met, either by default
(phi_i has finite range) or by being met in the construction.  The
latter will happen to each requirement at most a finite number of times
(2^(i-1) will do it).  Then note that meeting every requirement is enough
to establish that f|I has no section.

Mark
-- 
Mark A. Fulk			University of Rochester
Computer Science Department	fulk@cs.rochester.edu
-- 
Mark A. Fulk			University of Rochester
Computer Science Department	fulk@cs.rochester.edu
Newsgroups: sci.logic
From: holmes@opal.idbsu.edu (Randall Holmes)
Subject: Re: Textbooks for Set Theory and Logic
Keywords: set theory, logic
Organization: Boise State University
Date: Thu, 1 Oct 1992 22:38:49 GMT

In article <chomicki.717970449@antares.cis.ksu.edu.cis.ksu.edu> chomicki@cis.ksu.edu (Jan Chomicki) writes:
>I will be teaching a Set Theory and Logic course to first-year computer
>science graduate students. The course should provide them with some basic
>mathematical sophistication, as well as theorem proving skills. The
>students should already have some knowledge of mathematics, e.g.,
>calculus.
>
>I intend to cover naive and axiomatic set theory, and propositional
>and predicate logic. Specific topics include: cardinal and ordinal
>numbers, transfinite induction, ZFC, proof systems (Hilbert- and
>Gentzen-style, possibly resolution), soundness and completeness of
>proof systems, some basic model theory.
>
>I would appreciate any recommendations for or against using certain
>textbooks. I may actually use two books: one for Set Theory and one for
>Logic. Thank you.
>
>-- 
>Jan Chomicki				Computing and Information Sciences
>chomicki@cis.ksu.edu			234 Nichols Hall
>Phone: (913) 532-6350			Kansas State University
>Fax: (913) 532-7353			Manhattan, KS 66506-2302

A very impressive book is "An Introduction to Mathematical Logic and
Type Theory:  To Truth through Proof"  by Peter B. Andrews, Academic
Press, 1986.  It is a good intro to logic and model theory.  You could
use it for set theory if you were willing to do what is essentially
Russell's theory of types instead of Zermelo; if you wanted to do
Zermelo-style set theory specifically, use Halmos's Naive Set Theory?
I think that the type theory and accompanying lambda-calculus in
Andrews might be more useful for CS types.


-- 
The opinions expressed		|     --Sincerely,
above are not the "official"	|     M. Randall Holmes
opinions of any person		|     Math. Dept., Boise State Univ.
or institution.			|     holmes@opal.idbsu.edu
Newsgroups: sci.logic
From: hau4@ellis.uchicago.edu (sven  hauptfeld)
Subject: Re: "Solvability" in Chess
Reply-To: hau4@midway.uchicago.edu
Organization: University of Chicago Computing Organizations
Date: Sat, 26 Sep 1992 07:30:26 GMT

In article <12609@sail.LABS.TEK.COM> tcmaint@sail.LABS.TEK.COM (-Broadband Network Maintenance) writes:
>
>Ok, is chess solvable?

YES !!!!! 

>  I hope we never find out.

We have already found out.

> Enjoyment from the game 
>comes in part from not knowing the out come.

Outcome of what? Of the game? That has nothing to do with solvability. Of your
question above? We know. Of the actual process of solving? We won't know in
forseeable future, but even if computers 'know' it one day, it will still be
impossible for an OTB player to memorize it.

> Look at its history, the rise
>and fall of openings, ideas, ect. What fun!
>Not only that if chess is solved we won't be having this type of discussion
>now would we? 

Of course we would. You are completely wrong. Even if some supercomputer were 
able to play optimally, it would have little impact on OTB play. Nobody has
ECO in their head, and ECO is just a little piece at the root of the tree of
all possible positions.

>And of course we can not over look the fun in trying solve 
>chess, and beat our opponet.

Solving chess and beating an opponent are just as different as an architect
designing a house and a construction worker connecting two-by-fours.

	Sven
From: sa114984@longs.lance.colostate.edu (Steven Arnold)
Newsgroups: sci.logic
Subject: A set cannot contain itself as a member
Keywords: recursion
Date: 5 Oct 92 20:13:28 GMT
Organization: Colorado State University, Fort Collins, CO  80523


	I am not an expert in set theory or the predicate
calculus, but I was leafing through a book on the subject and the
following informal "proof" occured to me.  Could any of you experts out
there tell me if this contains a major flaw -- and if so, what it
is?  Thanks.

	The proposition to be proven is: A set can never contain
itself as a member.
	Suppose X is an arbitrary set which contains itself as a
member.  All other members within the set can be symbolized as
'g'; therefore,

		X = {g,X}		(1)

(Of course, g may be the empty set.)
	Eq. 1 can be expanded as follows:

		X = {g, X'}
		        /\
		       {g,X''}
		          /\
			 {g,X'''}

...and so on forever.  (The ' symbol is merely meant to
distinguish an X of one iteration from that of another.)  X'',
for example, is equivalent to {g,X'''}; X''' is equivalent to
{g,X''''}, etc etc.
	The number of X's below X'' is infinite; nonetheless, it
is certainly true that X' contains X'' as well as all the X's
contained by X''; therefore X' contains one more X than X''!  It
follows that X' != X'', for X' contains an X not contained in X''. 
By the same reasoning, X != X', because X contains one more X
than does X'.  Therefore, for any arbitrary set X, X cannot
contain itself as a member.

Steve
Xref: sparky sci.logic:1588 sci.math:12329 rec.games.chess:8199
From: mlounela@viita3.helsinki.fi (Mikko Lounela)
Newsgroups: sci.logic
Subject: Re: cardinality
Date: 28 Sep 92 07:23:58 GMT
Distribution: sci
Organization: University of Helsinki, Department of General Linguistics


I asked about cardinality a few days ago.

Got it.

Thank you very much.
--


*----------------Mikko Lounela---Mlounela@viita3.helsinki.fi---------------------*
|                                                            | I wonder if       |
|   tel:  (90-)3514107                                       | there is supposed |
|   Peltokylantie 3 A 1   Hki 74                             | to be something   |
|                                                            | funny in this box.|
*---------------*********************************************--------------------*
| All the opinions ariund here are ones of UN or Finnish Governement,            |
| I have nothing to do with them.                                                |
*--------------------------------------------------------------------------------*
Newsgroups: sci.logic
From: sandy@festival.ed.ac.uk (Sandy Nicholson)
Newsgroups: sci.logic
Subject: Re: cardinality
Date: 28 Sep 92 15:35:14 GMT
Distribution: sci
Organization: Edinburgh University Computing Service

In article <1992Sep25.113936.19246@news.nd.edu>, nik@csgi48.dcs.leeds.ac.uk
(Nik Silver) writes (much deleted):

|> On the other hand, when we consider the (countably) infinite numbers w and
|> w+1 we find that they are ordinally different (w+1 comes after w) but
|> have the same cardinality. They have the same cardinality because we can
|> define a bijection f from w+1 to w as follows:
|> 	f(n)   = n+1 for n finite,
|> 	f(w)   = w,
|> 	f(w+1) = 0.

I presume this was a momentary lapse---clearly the (von Neumann) ordinal w+1
is not a member of the ordinal w+1, any more than w is a member of w.
The bijection should be something along the lines of:

      f(n) = n+1  for all finite n
      f(w) = 0

[I apologize to those readers of this newsgroup who took this obvious error
in their stride. However, I felt it was worth correcting in view of the
intended audience (those with no prior understanding of the concept of
cardinality).]
--
Sandy Nicholson (sandy@festival.ed.ac.uk)
Department of Mathematics and Statistics, Edinburgh University, Scotland
Xref: sparky sci.logic:1581 sci.math:12308 rec.games.chess:8182
From: e343mh@tamuts.tamu.edu (Michael Hand)
Subject: Re: A set cannot contain itself as a member
Organization: Texas A&M University, College Station
Date: Wed, 7 Oct 1992 01:17:05 GMT

Marko Amnell writes:
 >The existence of non-well-founded sets can be made into an axiom, the
 >Anti Foundation Axiom (AFA).  The resulting theory is very interesting
 >mathematically and has practical and theoretical applications.  See
 >
 >Peter Aczel, _Non-Well-Founded Sets_.  CSLI Lecture Notes 14, (1988).

One interesting application is in Barwise & Etchemendy's (I think)
*The Liar*.  This book is worth reading.
B-o} Michael

_______________________________________________________________________
-----------------------------------------------------------------------
Michael Hand                     phone (409)845-5660, fax (409)845-0458
Dept of Philosophy, Texas A&M Univ, College Station TX 77843-4237 U.S.A.
Newsgroups: sci.logic,sci.math,rec.games.chess
From: allis@cs.rulimburg.nl (Victor Allis)
Newsgroups: sci.logic,sci.math,rec.games.chess
Subject: Re: "Solvability" in Chess
Date: 29 Sep 92 09:30:31 GMT
Organization: University of Limburg

keith@cco.caltech.edu (Keith Allan Schneider) writes:

>What about simpler games, such as checkers, or othello.  Has anyone "solved"
>these?

Checkers and Othello have not been solved. Jonathan Schaeffer is working
hard on Checkers, and if anyone will solve it before 2000 it will
probably be him (although I feel that the game will last longer than
2000).

Othello, in my opinion will not be solved for quite some time, certainly
not before 2000.

The only solved non-trivial games so far are Connect-Four (1988)
Qubic (1980, 1991) and Go-Moku (1992).

Victor Allis.
Newsgroups: sci.logic
From: jim@uvmark.uucp (Jim Todhunter)
Newsgroups: sci.logic,sci.math,rec.games.chess
Subject: Re: "Solvability" (long & pedantic)
Date: 28 Sep 92 16:33:43 GMT
Organization: Vmark Software, Inc.


When I returned to my office, I looked up my references and found I had
made a horrible mistake in misremembering the results concerning Checkers
and Go.  The references I have on the subject are:

 Fraenkel, A. S., M. R. Garey, D. S. Johnson, T. Scheafer, and Y. Yesha
        [ 1978 ], "The complexity of Checkers on an NxN board -- Preliminary
        report," Proc. 19th Ann. Symp. on Foundations of Computer Science,
        IEEE Computer Society, Long Beach, CA, 55-64.

 Lichtenstein, D., and M. Siper [1978], "GO is Pspace hard," Proc. 19th
        Ann. Symp. on Foundations of Computer Science, IEEE Computer Society,
        Long Beach, CA, 48-54.

Regards,

Jim Todhunter
-- 
James W. Todhunter, Director, Research & Development
jim%uvmark@merk.com
VMark Software, Inc.  30 Speen Street  Framingham, MA  01701-1800 USA
Telphone: (508) 879-3311  Facsimile: (508) 879-3332
Xref: sparky sci.logic:1602 sci.math:12368 rec.games.chess:8230
From: tcmaint@sail.LABS.TEK.COM (-Broadband Network Maintenance)
Newsgroups: sci.logic,sci.math,rec.games.chess
Subject: Re: "Solvability" in Chess
Date: 28 Sep 92 23:54:43 GMT
Followup-To: sci.logic
Organization: Tektronix, Inc., Beaverton,  OR.



There is talk about chess being a 0 sum game, win loss, or draw. No fooling!

Of course we could award points at the end of the game based on the value of
pieces left, P=1, B = 3, ect. Winning the game would need a value. If you 
win  a game you would be awared the winning value plus points for the pieces.
Or the K may be assigned points, . . . you get the idea.

--Bruce
Newsgroups: sci.logic
From: bob@sparkie.nrri.umn.edu (Robert I. Benett)
Subject: Logic Programming
Organization: U of Minnesota, Natural Resources Research Institute
Distribution: usa
Date: Tue, 29 Sep 1992 02:19:03 GMT

Hello,

I am investigating parallel or distributed processing of Logic programs.

Anyone have any suggestions for reading material??



Bob Bennett
bob@sparkie.nrri.umn.edu
From: chomicki@cis.ksu.edu (Jan Chomicki)
Newsgroups: sci.logic
Subject: Textbooks for Set Theory and Logic
Date: 1 Oct 1992 20:13:15 GMT
Organization: Kansas State University, Dept. of Computing and Information Sciences
Distribution: world
NNTP-Posting-Host: antares.cis.ksu.edu
Keywords: set theory, logic

I will be teaching a Set Theory and Logic course to first-year computer
science graduate students. The course should provide them with some basic
mathematical sophistication, as well as theorem proving skills. The
students should already have some knowledge of mathematics, e.g.,
calculus.

I intend to cover naive and axiomatic set theory, and propositional
and predicate logic. Specific topics include: cardinal and ordinal
numbers, transfinite induction, ZFC, proof systems (Hilbert- and
Gentzen-style, possibly resolution), soundness and completeness of
proof systems, some basic model theory.

I would appreciate any recommendations for or against using certain
textbooks. I may actually use two books: one for Set Theory and one for
Logic. Thank you.

-- 
Jan Chomicki				Computing and Information Sciences
chomicki@cis.ksu.edu			234 Nichols Hall
Phone: (913) 532-6350			Kansas State University
Fax: (913) 532-7353			Manhattan, KS 66506-2302
Newsgroups: sci.logic