Cryptography-Digest Digest #928, Volume #9 Fri, 23 Jul 99 04:13:03 EDT
Contents:
Re: another news article on Kryptos ([EMAIL PROTECTED])
Re: A Good Key Schedule (Christopher)
Re: How Big is a Byte? (was: New Encryption Product!) ([EMAIL PROTECTED])
Re: What the hell is XOR? (Christopher)
Re: why is it that nowadays people have to protect their conversations (Robert
McGwier)
Re: How Big is a Byte? (was: New Encryption Product!) ([EMAIL PROTECTED])
Re: How Big is a Byte? (was: New Encryption Product!) ([EMAIL PROTECTED])
Re: Q. Passphrase Key-Rate Authentication (Christopher)
Re: How Big is a Byte? (was: New Encryption Product!) ([EMAIL PROTECTED])
Re: How Big is a Byte? ([EMAIL PROTECTED])
Re: Q: Interaction of cross-posted follow-ups? ([EMAIL PROTECTED])
Re: Length of public key in PGP? (Wim Lewis)
Help with finding key... (Jaye Mathisen)
Re: another news article on Kryptos (Mok-Kong Shen)
----------------------------------------------------------------------------
Date: Thu, 22 Jul 1999 00:45:09 -0400
From: [EMAIL PROTECTED]
Subject: Re: another news article on Kryptos
Jim Gillogly wrote:
>
> Mok-Kong Shen wrote:
> >
> > Douglas A. Gwyn wrote:
> > >
> > > http://www.washingtonpost.com/wp-srv/national/daily/july99/kryptos19.htm
> >
> > I have a (very very) stupid question:
> >
> > Jim Gillogly has "tried on the order of 20 billion trial decryptions
> > spread over two dozen different systems with perhaps 5 or 10 variations
> > each, on average". If there were much more candidate systems and (known
> > and less well-known or unknown) variations being tried, couldn't it
> > happen that a decryption of a sufficiently short ciphertext becomes
> > ambiguous, i.e. there would be more than one readable probable
> > plaintexts? How can one go about to exclude such a possibility?
>
> There are 97 characters in this cryptogram. The chance of having it
> decrypt to two totally different plausible plaintexts is negligible.
> The precise value of "negligible" is left as an exercise for the reader,
For a "real" message this is indetectably close to zero, but we aren't
dealing with a "real" message. <evil thought> What is the chance that
the author designed the text to be ambiguous? Didn't Dennis Ritchie
show a comparably long sentence with multiple (semi-sensible)
decryptions?
> but I'll point out that 20 billion isn't a very big number as key spaces
> go, and one doesn't expect that it would take more than two or three
> 8-byte blocks to nail down a 56-bit DES key beyond a shadow of a doubt.
>
> --
> Jim Gillogly
> Mersday, 26 Afterlithe S.R. 1999, 17:14
> 12.19.6.6.14, 12 Ix 2 Xul, Eighth Lord of Night
------------------------------
From: [EMAIL PROTECTED] (Christopher)
Subject: Re: A Good Key Schedule
Date: Thu, 22 Jul 1999 23:42:13 -0400
In article <[EMAIL PROTECTED]>, Mok-Kong Shen
<[EMAIL PROTECTED]> wrote:
_ John Savard wrote:
_ >
_ >
_ > Well, from knowing any one of the DES subkeys, you can recover 48 of
_ > the bits in the 56 bit key. If a hash function were used, then a
_ > transformation that was not invertible would be used.
_
_ I see your point. However, since you use one hash function, I suppose
_ you have to employ a keyed one in order to obtain from one passphrase
_ a number of different keys for use in the various steps of your
_ algorithm. Would you please tell how do you obtain the keys for the
_ hash function?
_
_ M. K. Shen
I would think repeatedly hashing the phrase into each previous result
would do the trick.
------------------------------
Date: Thu, 22 Jul 1999 01:25:16 -0400
From: [EMAIL PROTECTED]
Crossposted-To: alt.folklore.computers
Subject: Re: How Big is a Byte? (was: New Encryption Product!)
Don Stokes wrote:
>
> In article <[EMAIL PROTECTED]>, <[EMAIL PROTECTED]> wrote:
> >wtshaw wrote:
> >You can use base 1 by noting the implied addition between the successive
> >digits of a number. E.g. 13 base ten implies 1*ten^1 plus 3*ten^0. In
> >base one you have the same construction so that 1111 base one is 1*one^3
> >plus 1*one^2 plus 1*one^1 plus 1*one^0 = 4 base 10. The powers all
> >collapse and any number is represented by that many digits, all ones.
> >Note that in base one there is no need for zero as there is no
> >difference between powers, so no need for place holders.
>
> Using "0" to represent zero is after all an anomaly -- no other number
> has a leading placeholder. If you want to make the rules consistent,
> zero should be represented as a null string.
>
> Given that, if you use a character set of 0,1,2,3,4,5,6 ... for representing
> numbers in a given base, 4(10) should be represented as 0000(1), not 1111...
Yes, but when you are tallying things I bet you draw little lines rather
than little circles. Because there is only one symbol it does not
matter which we select. Perhaps you would be more comforablte with
4(10) = !!!!(1) or ||||(1)?
>
> -- don
------------------------------
From: [EMAIL PROTECTED] (Christopher)
Subject: Re: What the hell is XOR?
Date: Fri, 23 Jul 1999 01:36:24 -0400
In article <[EMAIL PROTECTED]>,
[EMAIL PROTECTED] (Stephen C. Gilardi) wrote:
_ I sometimes find it useful to think of an XOR operation as a "Controlled
_ Inverter".
I like the analogy to three-way light switches - the switches are the
input bits, and the light is the output bit. For the mildly curious:
http://quakes.newscientist.com/lastword/answers/lwa221gadgets.html
has a description and diagram of three-way switches.
------------------------------
From: Robert McGwier <[EMAIL PROTECTED]>
Subject: Re: why is it that nowadays people have to protect their conversations
Date: Fri, 23 Jul 1999 05:30:40 GMT
Do you put aluminum foil on your head every night?
"Markku J. Saarelainen" wrote:
>
> ... why is it that nowadays people have to protect their conversations
> from CIA's eavesdropping .. .. of course, this is because of CIA's
> economic and business intelligence program that started late 1980's
> against its allies for the benefit of some specific industrial
> enterprises and corporations .... when they were talking about changing
> their mission, this new mission has been followed for many years already
> ... do not believe what you hear from the mass media, popular news
> sources or from some officials ... they are running the cover story in
> most cases .. there are currently many CIA intelligence operations going
> on .. some are pretending to be promoting and developing specific sales
> and marketing business / market intelligence software applications for
> specific companies for the benefit of some other enterprises ...sources
> and methods .....excellent ..... in addition, there are software
> companies that are actively involved in some specific CIA covert actions
> and operations .... also there are total ghost businesses and
> development groups that are shadowing specific businesses for the
> benefit of certain industrial groups .... just focus on ownership
> structures ... investment bankers and some technology providers ...
------------------------------
Date: Thu, 22 Jul 1999 01:43:19 -0400
From: [EMAIL PROTECTED]
Crossposted-To: alt.folklore.computers
Subject: Re: How Big is a Byte? (was: New Encryption Product!)
wtshaw wrote:
>
> In article <7n58s3$q0s$[EMAIL PROTECTED]>, REMOVE X AND Y
> <[EMAIL PROTECTED]> wrote:
>
> > But zero isn't the first number. It's the zero-th number.
> >
> > Cheerio,
> > Vega
> >
> > Michael D. ([EMAIL PROTECTED]) wrote:
> > : I think that a major problem that we all have is that our mothers, yes, mine
> > : as well as yours, taught us that the first number is one(1) rather than
> > : zero(0). It was cute when we were three(3), but now, as a result of that
> > : conditioning, we cannot do math in our heads.
>
> Zero has no value in itself as it expresses the absence of a number in a
> particular place.
There is a difference between zero the number and zero the digit. You
are using the second to replay to the first.
>
> Consider a real problem in which the choice is between numbering beginning
> with one and numbering beginning with zero. You might number 1, 2, 3, 11,
> 12, 13, etc, or 00, 01, 02, 10, 11, 12, etc. The use is, of course,
> addressing, defining locations in memory or in something like a key. It
> does not matter which system you use as long as you and whoever you are
> communicating with are on the same track.
> --
> When I talk about running the bases, it's not baseball.
------------------------------
Date: Thu, 22 Jul 1999 01:49:54 -0400
From: [EMAIL PROTECTED]
Crossposted-To: alt.folklore.computers
Subject: Re: How Big is a Byte? (was: New Encryption Product!)
John Savard wrote:
>
> [EMAIL PROTECTED] (Finder Keeper) wrote, in part:
>
> >But zero isn't the first number. It's the zero-th number.
>
> >Michael D. ([EMAIL PROTECTED]) wrote:
> >: I think that a major problem that we all have is that our mothers, yes, mine
> >: as well as yours, taught us that the first number is one(1) rather than
> >: zero(0). It was cute when we were three(3), but now, as a result of that
> >: conditioning, we cannot do math in our heads.
>
> Somehow, I think people do realize that zero, not one, is the additive
> identity, and most people can do addition in their heads. And yet, it
> is true that when I play cribbage, it is sort of confusing that if my
> hand counts 8, I have to leave only 7 spaces between the pegs...but I
> think that would be true regardless of what convention we used for
> counting.
>
> And it is true that one begins counting with the first object, and if
> one has a first object, one has one object.
I disagree completely. If you are counting the sheep crossing the road,
and at some point in time I inquire as to the elapsed count you will
give me a natural not an ordinal number. If my query follows
immediately after the start of your count you have zero sheep not one.
So zero is the starting number.
You may argue that you didn't "start counting" until the first sheep
arrived, but you were watching the road in the same state prior to the
first sheep as prior to the second sheep except for the value of your
"current count". So I maintain that you "started counting" when you
started watching for sheep, not when the first sheep arrived.
B. Kernigan identified this as the most important issue in programming
in an interview with Unix Magazine (Journal?) about 8 years ago.
>
> So if one wishes to count pebbles, one considers the first pebble
> counted to be pebble 1, and that does not cause confusion.
>
> Naturally, though, the first memory storage location one counts is
> location 0, since we want to use all possible combinations that a
> group of however many digits - binary, decimal, whatever - can refer
> to. This is not a big deal for such a specialized application, and
> cannot be "remedied" without creating more problems than it solves.
>
> John Savard ( teneerf<- )
> http://www.ecn.ab.ca/~jsavard/crypto.htm
------------------------------
From: [EMAIL PROTECTED] (Christopher)
Subject: Re: Q. Passphrase Key-Rate Authentication
Date: Fri, 23 Jul 1999 01:11:51 -0400
In article <[EMAIL PROTECTED]>,
[EMAIL PROTECTED] (John Savard) wrote:
[part about biometrics needing smart algorithms]
_ Let's say that a typing style is a point in a five-dimensional space.
_ So you have five numbers. No matter how you pre-define zones for those
_ five numbers, a user's typing style may just happen to be on the
_ boundary between two zones, leading to his typing style having more
_ than one hash code.
_
_ But if you include the _least significant bits_ for each of those five
_ dimensions, then you are constructing a set of zones whose centering
_ is adapted to the individual user. Then, if you produce a hash of the
_ most significant bits _of the differences, along each dimension,
_ between the user's typing style and the corresponding entry in the LSB
_ vector_, you *can* generate a unique code that the user will, by his
_ typing, produce most of the time.
I'm not sure what the LSB-vector is in this case. More importantly,
somehow I missed how the lsb's produce anything centered to that typist.
Along This Line : look for the longest delay between keypresses - use that
distance - the character position within the phrase
In the hash-n-test phase, try it with the top three values (of longest
pauses) before deciding this might not be the owner. This is pretty much
based on the suggestions for PGP passphrases, to use groups of words with
some other non-alpha characters thrown in. The ackward-ness of typing $
instead of S might cause a consistant pause by the owner; and since the
value used is hashed along with other stuff, it shouldn't be a weakness.
------------------------------
Date: Thu, 22 Jul 1999 01:41:53 -0400
From: [EMAIL PROTECTED]
Crossposted-To: alt.folklore.computers
Subject: Re: How Big is a Byte? (was: New Encryption Product!)
Tim Shoppa wrote:
>
> Gergo Barany wrote:
> >
> > In article <7n58s3$q0s$[EMAIL PROTECTED]>, Finder Keeper wrote:
> > >But zero isn't the first number. It's the zero-th number.
> >
> > It's the zeroth number, but because zero is the number with which we
> > start counting, the zeroth number is the first number of counting, which
> > makes zero the first number.
>
> These young C programmers and their delusions. Fortran programmers,
> of course, know that 1 is truly the first number.
Nah. Algol programmers know that -1 is often used as a special value,
and special values are often mistakenly used as indicies. So all arrays
should be based at -1. See common implementations of ctype.h where this
technique protects against isascii(EOF) referencing invalid memory.
>
> Tim.
------------------------------
Date: Thu, 22 Jul 1999 01:38:30 -0400
From: [EMAIL PROTECTED]
Crossposted-To: alt.folklore.computers
Subject: Re: How Big is a Byte?
Douglas A. Gwyn wrote:
>
> Ian Stirling wrote:
> > Hence, in base 1, the number
> > "11111" is equal to 5, "111 11" is also equal to 5, as is "111011"
>
> In base one, if the notation is to be perfectly consistent with that
> used for higher (integer) bases, the only available digit is "0",
> and thus the only value expressible is precisely zero. However, you
> can adjust the rules for this borderline case and use tally marks,
> so long as you're prepared to use an empty string to represent zero.
If the number line is entended into the negative realm there are
alternate representations of zero. 1-1 would be one such. It's
extremely difficult to parse empty string as meaningful symbols. Teh
proliferate like virtual particles. All numbers would be embedded in a
foam of zeros.
>
> Strictly speaking, this is cheating.
Depands on what rules you are using. The original topic was arithmetic
based on the number of available fingers. The symbolic representation
of numbers is a problem distinct from the problem of the device
(fingers) used as a counter. For this context base one is perfectly
valid. Base zero, however, is in the realm with N/0 and log(N<0).
------------------------------
Date: Thu, 22 Jul 1999 02:00:26 -0400
From: [EMAIL PROTECTED]
Subject: Re: Q: Interaction of cross-posted follow-ups?
Thomas Pornin wrote:
>
> According to Mok-Kong Shen <[EMAIL PROTECTED]>:
> > It seems that the phenomenon pertains only to the case where one of
> > the cross-posted groups is moderated and nothing happens until the
> > message is processed by the moderated group.
>
> That is exactly what happens. A crossposted message is a unique entity,
> and if one of the groups is moderated, the message will not appear until
> the moderator approved it. Please note that if you crosspost to two
> different moderated groups, only the first moderator will process it;
> once approved, it will appear instantly in all groups, including the
> other moderated one.
This implies that you could force a message into a moderated group by
cross-posting to a dummy moderated group. Is this actually the case?
>
> --Thomas Pornin
------------------------------
From: [EMAIL PROTECTED] (Wim Lewis)
Subject: Re: Length of public key in PGP?
Date: Fri, 23 Jul 1999 01:53:49 +0000
In article <7n5l27$bfm$[EMAIL PROTECTED]>, <[EMAIL PROTECTED]> wrote:
>In article <[EMAIL PROTECTED]>,
> [EMAIL PROTECTED] (Wim Lewis) wrote:
>> specifically refers to PGP... it's worth noting that in PGP the RSA
>> plaintext is a session key not longer than 168 bits or so, so this
>
>Not longer than 168 bits? Why? People are talking about 1024 bit primes
>for PGP.
The *session key* is 168 bits (or 128 bits, etc., depending on the
symmetric cipher used for that message). The *RSA key* is a few thousand
bits. You should read one or all of:
- the PGP documentation: for pgp 2.6.x, all this is described in
pgpdoc1.txt. (The info might be missing from the later, GUIfied
versions; I don't know.)
- Bruce Schnier's _Applied Cryptography_, the usual reference for non-
experts who want to know about this sort of thing. Chapter 2, section
5, "Communications Using Public-Key Cryptography", should answer
your questions.
- There are probably web pages that explain this also.
The short answer: RSA is really slow and requires really long keys to
be secure. Its only advantage is that it's a public-key system. So
the actual message is encrypted using a symmetric cipher and a random
session key. The session key, which is much shorter than the whole
message, is encrypted using RSA.
--
Wim Lewis - [EMAIL PROTECTED], also hhhh.org - Seattle, WA, USA
------------------------------
From: [EMAIL PROTECTED] (Jaye Mathisen)
Subject: Help with finding key...
Date: 23 Jul 1999 05:46:50 GMT
A vendor that has some software we are looking at uses Blowfish to encrypt the password
and then store it in a disk file.
They tell me this is secure.
Since I know the original plaintext, and can produce the encrypted output, I would
like some pointers as to how to find the key they use, so I can poke little holes in
their
theory about the security of their product (which other than this issue, works pretty
well).
I have the binary as well that creates it, so I can search it from some strings.
Any tip appreciated.
------------------------------
From: Mok-Kong Shen <[EMAIL PROTECTED]>
Subject: Re: another news article on Kryptos
Date: Mon, 19 Jul 1999 20:39:27 +0200
Jim Gillogly wrote:
>
> Scheidt says in the new article that he and Sanborn wanted the cipher
> to be solvable. This means it does not have a random key as long as
> the plaintext.
I am sorry not to be able to give examples to strongly support my
conjecture. But there are languages where there can be sentences
such that the failing or wrong placing of punctuations can lead
to different meanings. I 'extrapolated' this in conceiving my
conjecture. I mean that even with a classical transposition system
there could be two different transpositions of the same bunch
of (ciphertext) characters that are both meaningful, if the plaintext
is 'particular' enough. That the author intends that his puzzle
be solvable doesn't garantee the non-existence of such possibilities,
I am afraid.
M. K. Shen
------------------------------
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