Cryptography-Digest Digest #208, Volume #14 Sun, 22 Apr 01 14:13:01 EDT
Contents:
Re: Gurus please: -- show weaknesses (Jim Gillogly)
Gurus: Please show weaknesses in this (Brett)
Re: ancient secret writing (Mok-Kong Shen)
Re: basics of cryptography (Pille2)
Re: basics of cryptography (Pille2)
Re: Changing children into drug addicts ("Dramar Ankalle")
Re: basics of cryptography ("Tom St Denis")
Re: basics of cryptography ("Tom St Denis")
Re: PRNG quality ("Tom St Denis")
Re: Any unbroken knapsack cryptosystem? ("Roman E. Serov")
Re: basics of cryptography (Pille2)
Re: Gurus: Please show weaknesses in this ("Scott Fluhrer")
Re: PRNG quality ("Trevor L. Jackson, III")
Re: basics of cryptography ("Bill Goldman")
RSA and IDEA ("Gizmo")
cbgb ("Dramar Ankalle")
Re: basics of cryptography (Pille2)
----------------------------------------------------------------------------
From: Jim Gillogly <[EMAIL PROTECTED]>
Subject: Re: Gurus please: -- show weaknesses
Date: Sun, 22 Apr 2001 09:18:05 -0700
Brett wrote:
> I would encrypt the plaintext with a keyphrase...
> I would then select another new
> key for the NEXT message to be sent ... and would encrypt
> this new key with the current
> key.
...
> Key: STEVE JOBSSTEVE JOBS
> Msg: MY MESSAGEBILL GATES
>
> ciphertext: EREHJSBPIXUBQGEGKHGK
Consider what happens with known plaintext. If the opponent captures
your first message in plaintext ("MY MESSAGE") and ciphertext, he
reverses it to get the key ("STEVE JOBS") and then applies that key
to get the next key, then never loses touch with the system in the
future. Like any autokey system, it's also subject to ct-only analysis.
> Then I put in some type of checksum of the two
> halves of the plaintext message at the end ... say, I
A plaintext checksum is a gift from heaven for the cryptanalyst, who
can use it to confirm guesses.
--
Jim Gillogly
Hevensday, 26 Astron S.R. 2001, 17:35
12.19.8.2.12, 13 Eb 10 Pop, Seventh Lord of Night
------------------------------
From: Brett <[EMAIL PROTECTED]>
Subject: Gurus: Please show weaknesses in this
Date: Sun, 22 Apr 2001 12:39:13 -0400
Reply-To: [EMAIL PROTECTED]
=====BEGIN PGP SIGNED MESSAGE=====
Hash: SHA1
Hi,
I'm new to this group, but wonder if I can generate
interest in the following method of encryption, in hopes
that some of the more experienced of the group can point
out its weaknesses (if any).
It's based on the Vigenere cipher (at end of post
for those who need reminding), with a twist. I would
use it on messages that aren't very long (500 characters
or less).
I would encrypt the plaintext with a keyphrase (not
something simple as seen below, but some rediculous
jumble of unicode letters (65536 in all)) by a standard
Vigenere-like process. I would then select another new
key for the NEXT message to be sent (I don't want to
use the same key every time -- that would lead to break-
ability) and would encrypt this new key with the current
key.
I would then add a checksum to check for data
fidelity and to disuade tinkering with the code in
transit. I'll give an example using ASCII letters
rather than Unicode, as it'll be easier to follow.
The principle is the same (the ciphertext is based
on a 27x27 Vigenere square ... the 27th one is the
spacebar character " " ):
Current message: MY MESSAGE
Current key: STEVE JOBS
Next Key: BILL GATES
-- start encryption:
Key: STEVE JOBSSTEVE JOBS
Msg: MY MESSAGEBILL GATES
ciphertext: EREHJSBPIXUBQGEGKHGK
Then I put in some type of checksum of the two
halves of the plaintext message at the end ... say, I
add all the unicode values up of all the letters in the
plaintext message and put the last two digits of it at
the end, do the same with the new key to build a 4-digit
checksu,. So the transmitted item is this:
EREHJSBPIXUBQGEGKHGK1595
Thus, the current message and new key could be decrypted
on the other side with the current key, the new key for the
next message would be known by both sides, and the checksum
would exist to make sure no monkey-business happened in
between. This way, the keyphrase would never be used more
than once. The key would also never be shorter than the
message ... if the operator tried to encrypt a longer message
than the length of the key, two messages would be sent, one
with the current key for the first 500 letters, with the
second key attached, and the second message encrypted with
the second key and a third key attached.
Reasons for the above:
1) A key phrase of equal length to the plaintext makes
it a polyalphabetic substitution with up to 65536 alphabets
and up to 500 letters per key ... thus total keys are:
65536 ^ 500 (an enormous number I'm sure).
2) Since no repetition of the keyphrase is employed,
the cryptanalytic techniques of looking for repititions of
sets of letters like seeing "DWM" several times might
clue you in that this is "the" would not work. (Babbage
and Kasiski employed this technique to first crack the
Vigenere cipher about 150 years ago, but it relies heavily
on the key being repeated often on long messages to work)
The checksum defeats anyone who tries to paste in a
false second half to the transmitted passage (in attempt
to have the second computer send back a message encrypted
with some type of key the codecracker could use to his/her
advantage)
I would love any replies.
Brett
- - ------- below this is Vigenere cipher for reference:
A B C D E F G H ... X Y Z %
---------------------------
A|B C D E F G ... Y Z % A
B|C D E F G ... Y Z % A B (I substituted
C|D E F G ... Y Z % A B C % for " " for
D|E F G ... Y Z % A B C D clarity)
etc.
Letter of plaintext on left, letter of key on top,
whatever these coordinates line up to ... key that letter
into as the ciphertext
But note, my Vigenere-style cipher would have 65536
rows and columns in it, not just 27.
=====BEGIN PGP SIGNATURE=====
Version: PGPfreeware 5.5.3 for non-commercial use <http://www.pgp.com>
iQA/AwUBOuMJIlmsYkIq5977EQJcGgCfZ7f+miCQCq/H3pJZwsY0mw5DARgAoKGi
dWWrUTkXAf2fd89jNCBGj07T
=/LFF
=====END PGP SIGNATURE=====
------------------------------
From: Mok-Kong Shen <[EMAIL PROTECTED]>
Subject: Re: ancient secret writing
Date: Sun, 22 Apr 2001 18:37:19 +0200
Jim Gillogly wrote:
>
[snip]
> One of the more interesting of these is the Voynich Manuscript, which
> may or may not have underlying meaning. So far advanced cryptanalysis
> (as applied by Brig. Tiltman, W. F. Friedman, and the other leading
> lights) has not availed to decrypt it.
I tend also to think that there is a substantial probability
of the more recent stuffs like the Voynich Manuscript
being a hoax intended to fool people. More sensible
seems to spend resources on the very ancient findings of
archeology. But these are apparently very very hard to
attack, since we have no knowledge at all of the
languages involved. BTW, wouldn't that mean that a secret
(artificial) language -- one that is for limited universe
of discourse and has quite different syntax and entirely
different words (both dependent on a key) and can be
translated automatically to English -- could be of some
value as a component of an encryption system? (I realize
that its implementation could be very expensive.)
M. K. Shen
------------------------------
From: Pille2 <[EMAIL PROTECTED]>
Subject: Re: basics of cryptography
Date: Sun, 22 Apr 2001 18:40:33 +0200
in Beitrag [EMAIL PROTECTED] schrieb Brett unter [EMAIL PROTECTED] am
22.04.2001 18:03 :
> Pille2 wrote:
>
>> How do i calculate the possibilities for monoalphabetic and polyalphabetic
>> ciphers or is there no difference?
>
> For monoalphabetic cipher (substitution cipher seen in "cryto-quote"
> newspaper games) the number of keys available is expressed in mathematics
> as "25!" ("25 factorial") or 25 * 24 * 23 * 22 * 21 ... etc. If you allow
> for some letters to represent themselves ("J" is "J") then it is 26!
>
> For polyalphabetic ciphers (Vigenere style with a keyphrase) the
> number of keys is (n ^ 26) where n is the number of characters in the
> keyphrase.
>
> Brett
Exactly what i needed, thanks
Philipp
------------------------------
From: Pille2 <[EMAIL PROTECTED]>
Subject: Re: basics of cryptography
Date: Sun, 22 Apr 2001 18:40:05 +0200
> Philipp,
>
> Try the following links
> http://www.und.nodak.edu/org/crypto/crypto/resources.html
> http://www.simonsingh.com
> http://home.ecn.ab.ca/~jsavard/crypto.htm
>
> and for something more recent there always is:
> http://fermat.ma.rhbnc.ac.uk/~fauzan/papers/report.pdf
>
> Very recommended is the HAC for all crypto-math
> http://www.cacr.math.uwaterloo.ca/hac/
>
>
> Hope this is helpful to you.
> Best regards,
> Daniel
> Best regards,
> Daniel
Thanks a lot!
Philipp
------------------------------
From: "Dramar Ankalle" <[EMAIL PROTECTED]>
Crossposted-To:
alt.support.depression.medication,sci.psychology.psychotherapy,alt.support.anxiety-panic,alt.support.depression,alt.support.depression.manic,alt.religion.scientology,alt.clearing.technology
Subject: Re: Changing children into drug addicts
Date: Sun, 22 Apr 2001 12:48:44 -0400
SSRIHater <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]...
> Incestous paedophile [EMAIL PROTECTED] (Mark Probert) wrote:
> >She was fix by them.
>
> Is English your native language?
>
> >They killed her.
>
> Just like you killed Eve Brown (pregnant with your child) and dumped her
> dead body at a construction site in Brooklyn...
>
> --
> "You shall not lie with mankind as with womankind; it is an abomination"
> Leviticus 18:22 "And if a man lie with mankind, as with womankind, both
of
> them have committed abomination: they shall be put to death" Leviticus
20:13
> "And the men likewise gave up natural relations with women and were
consumed
> with passion for one another, men committing shameless acts with men and
> receiving in their own persons the due penalty for their error." Romans
1:27
> "Do you not know that the unrighteous will not inherit the kingdom of God?
> Do not be deceived; neither the immoral, nor idolaters, not adulteres, nor
> HOMOSEXUALS, nor thieves, nor the greedy, nor drunkards, nor revilers, nor
> robbers will inherit the kingdom of God." 1 Corinthians 6:9,10
Green Day Lyrics - Warning
This is a public service announcment
This is only a test
Emergency evacuation protest
May impair your ability to operate machinery
Canıt quite tell, just waht it means to me
Keep out of reach of children
Donıt talk to strangers
Get your philosophy from a bumper sticker
Warning: Live without warning
Warning: Live without warning
Better homes and safety-sealed communities?
Did you remember to pay the utility?
Caution: police line: you better not cross
Is it the Cop or am I the one that`s really dangerous?
Sanitation, Expiration date, Question Everything?
Or shut up and be the victim of authority
Warning: Live without warning
Warning: Live without warning
Better homes and safety-sealed communities?
Did you remember to pay the utility?
Caution: police line: you better not cross
Is it the Cop or am I the one that`s really dangerous?
Sanitation, Expiration date, Question Everything?
Or shut up and be the victim of authority
Warning: Live without warning
Warning: Live without warning
This was a public service announcement
This was only a test
CHARLES BLACK DEA
------------------------------
From: "Tom St Denis" <[EMAIL PROTECTED]>
Subject: Re: basics of cryptography
Date: Sun, 22 Apr 2001 16:47:01 GMT
"Pille2" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]...
> If you know so much why can´t you give the aswer?
>
> And sorry because of probable/possible i´m not english nor american so my
> english may not be the best.
> Btw. I don´t want to wirte a book it´s just a work for a school lesson.
I hope you are not teaching!
And I did answer part of your question about mono ciphers.
Tom
------------------------------
From: "Tom St Denis" <[EMAIL PROTECTED]>
Subject: Re: basics of cryptography
Date: Sun, 22 Apr 2001 16:47:31 GMT
"Pille2" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]...
> in Beitrag [EMAIL PROTECTED] schrieb John Savard unter
> [EMAIL PROTECTED] am 22.04.2001 17:00 Uhr:
>
> > How to calculate the number of ways a cipher may be keyed may indeed
> > not be spelled out in books on cryptography. But you might wish to
> > consult references on combinatorics for the needed background.
> >
> > As Mr. St. Denis noted, a monalphabetic cipher can be arranged with
> > 26! alphabets; the substitute for A can be any letter, that for B can
> > be any other letter, and so on, so the number is 26 * 25 * .... * 1.
> >
> > For Vigenere, the number of possibilities depends on the length of the
> > key. So if the key is, for example, from 8 to 13 letters long, then
> > there are 26^8 + 26^9 + .... + 26^13 possible keys... but in that
> > case, the key will probably be a word, not a random string of letters,
> > so the number of keys is really much smaller.
> >
> > The Enigma could be set up in an enormous number of ways, so some
> > indication of how to do this kind of calculation might be found in
> > some of the books on the Enigma.
> >
> > John Savard
> > http://home.ecn.ab.ca/~jsavard/crypto.htm
>
>
> Thanks that was what i wanted to know...
Not to be a meany but I did give you that info in my original reply.
Tom
------------------------------
From: "Tom St Denis" <[EMAIL PROTECTED]>
Subject: Re: PRNG quality
Date: Sun, 22 Apr 2001 16:48:03 GMT
"William A. McKee" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]...
> I was wondering ... if you have two different PRNG (pseudo random number
> generator) named P and Q, does the resulting PRNG (P xor Q) give you any
> better (more random) results than just P or Q alone?
Nope, look at LFSRs for example. (i.e read HAC or Applied Crypto)
Tom
------------------------------
From: "Roman E. Serov" <[EMAIL PROTECTED]>
Subject: Re: Any unbroken knapsack cryptosystem?
Date: Sun, 22 Apr 2001 20:17:08 +0400
What about Chor-Rivest variant of knapsack? Was it really broken?
------------------------------
From: Pille2 <[EMAIL PROTECTED]>
Subject: Re: basics of cryptography
Date: Sun, 22 Apr 2001 19:06:04 +0200
> Not to be a meany but I did give you that info in my original reply.
>
> Tom
>
Ok where is it?
Here?
> Just not thought threw.
>
> In a monoalphabetic you sub one letter for another. So if you have N
> letters there are N! ways to create the required permutation.
>
> etc..
>
> Hmm perhaps you should **read** some texts before writting one. I tried to
> start a book on block ciphers and quickly got swamped with "what the heck is
> that letter thingy!".
>
> Tom
>
>
Or here?
> Anyone who says "books ain't got no answers" then says "I want to write one"
> is either ignorant or a retard. Which one are you?
>
> And anything is possible the word you want is "probable". i.e "How
> probrable is....". Seriously read some papers or texts on the subject. You
> can get quite a bit of free info on the web if you use this new fangled
> thing called a *****SEARCH ENGINE*****.
>
> Tom
Philipp
PS: And no i´m not teaching, very funny. I´m just a student who wants to
prepare a talk on that stuff and i don´t think you should talk to me in that
way.
------------------------------
From: "Scott Fluhrer" <[EMAIL PROTECTED]>
Subject: Re: Gurus: Please show weaknesses in this
Date: Sun, 22 Apr 2001 09:59:51 -0700
Brett <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED]...
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
>
> Hi,
>
> I'm new to this group, but wonder if I can generate
> interest in the following method of encryption, in hopes
> that some of the more experienced of the group can point
> out its weaknesses (if any).
>
>
> It's based on the Vigenere cipher (at end of post
> for those who need reminding), with a twist. I would
> use it on messages that aren't very long (500 characters
> or less).
>
> I would encrypt the plaintext with a keyphrase (not
> something simple as seen below, but some rediculous
> jumble of unicode letters (65536 in all)) by a standard
> Vigenere-like process. I would then select another new
> key for the NEXT message to be sent (I don't want to
> use the same key every time -- that would lead to break-
> ability) and would encrypt this new key with the current
> key.
This is vulnerable to standard "crib-dragging" techniques. Namely, the
attacker guesses that, at position N, a standard phrase (such as " the ")
appears. Then, you uses that derive the keyphrase at those locations, and
use the keyphrase at those locations to decrypt other places in the message
where it appears (and if it is used to decrypt the next message key, the
attacker can then decrypt parts of the next message). If those text in
those other positions are implausible, he tries another N. If all the other
texts are plausible, then he accepts it. By trying various N and various
phrases, an analyst can quickly find enough of the message to make finding
the rest pretty trivial.
Oh, and about your checksum:
> Then I put in some type of checksum of the two
> halves of the plaintext message at the end ... say, I
> add all the unicode values up of all the letters in the
> plaintext message and put the last two digits of it at
> the end, do the same with the new key to build a 4-digit
> checksu,.
Consider what would happen with the checksum if the attacker incremented one
character of the ciphertext, and decremented another...
--
poncho
------------------------------
From: "Trevor L. Jackson, III" <[EMAIL PROTECTED]>
Subject: Re: PRNG quality
Date: Sun, 22 Apr 2001 17:35:55 GMT
"William A. McKee" wrote:
> I was wondering ... if you have two different PRNG (pseudo random number
> generator) named P and Q, does the resulting PRNG (P xor Q) give you any
> better (more random) results than just P or Q alone?
It can give you a longer period. But it does not give you any randomness
(entropy) at all. The "P" in PRNG is pseudo, or fake. Since PRNGs are
deterministic their output contains no more entropy than their input, the
initial seed value. In a trivial sense the sequence P xor Q has randomness
(entropy) equal to Pseed + Qseed.
------------------------------
From: "Bill Goldman" <[EMAIL PROTECTED]>
Subject: Re: basics of cryptography
Date: Sun, 22 Apr 2001 13:46:38 -0400
Dear Philippe,
Don't take what Tom St. Denis says too personally. He's not a bad
person, but he is a young kid and somewhat emotionally immature for his age.
He tends to sometimes speak before he thinks; he "shoots from the hip", and
he is a bit rough around the edges. Some of his ideas about cryptographic
subjects are spot-on, and he does show promise, which I hope will blossom
out when he attends the University of Windsor this fall with a concentration
in computer science.
He does speak with the certainty of youth, which can be maddening when
he is demonstrably wrong, i.e., say, his views on bijective compression.
So please take what he says with a grain of salt --- his pronouncements
don't have the oracular quality that say, Bob Silverman's have. Better to
listen to a John Savard or Douglas Gwyn, or any of a dozen other seasoned
contributors to this group.
Keep up your studies, and don't get discouraged about cryptography! It
can bring you a lifetime of fascination and enjoyment.
Bill G.
"Pille2" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]...
> > Not to be a meany but I did give you that info in my original reply.
> >
> > Tom
> >
>
> Ok where is it?
> Here?
>
> > Just not thought threw.
> >
> > In a monoalphabetic you sub one letter for another. So if you have N
> > letters there are N! ways to create the required permutation.
> >
> > etc..
> >
> > Hmm perhaps you should **read** some texts before writting one. I tried
to
> > start a book on block ciphers and quickly got swamped with "what the
heck is
> > that letter thingy!".
> >
> > Tom
> >
> >
>
> Or here?
>
> > Anyone who says "books ain't got no answers" then says "I want to write
one"
> > is either ignorant or a retard. Which one are you?
> >
> > And anything is possible the word you want is "probable". i.e "How
> > probrable is....". Seriously read some papers or texts on the subject.
You
> > can get quite a bit of free info on the web if you use this new fangled
> > thing called a *****SEARCH ENGINE*****.
> >
> > Tom
>
>
> Philipp
>
> PS: And no i´m not teaching, very funny. I´m just a student who wants to
> prepare a talk on that stuff and i don´t think you should talk to me in
that
> way.
>
------------------------------
From: "Gizmo" <[EMAIL PROTECTED]>
Subject: RSA and IDEA
Date: Sun, 22 Apr 2001 19:54:02 +0200
Does anyone know where I can get information about cryptanalisys of IDEA and
RSA algorithms ?
Thank you in advance.
Genio
------------------------------
From: "Dramar Ankalle" <[EMAIL PROTECTED]>
Subject: cbgb
Date: Sun, 22 Apr 2001 13:54:00 -0400
cb LAST 4 DIGITS 1975
gb LAST 4 DIGITS 1973
Via Wanda wears Converse
CLICK ABOVE TO VISIT OUR SPONSORS [hehehehe]
Artist: Green Day
Album: Warning
Title: Waiting
Iıve been waiting for a long time
For this moment to come
Iım destined
For anything...at all
Downtown lights will be shining
On me like a diamond
Ring out under the midnight hour
No one can touch me now
And I canıt turn my back
Itıs too late ready or not at all
Iım so much closer than
I have ever known...
Wake up
Dawning of a new era
Calling...donıt let it catch you falling
Ready or not at all
So close enough to taste it
Alomost...I can embrace this
Feeling....on the tip of my tongue
Iım so much closer than
I have ever known...
Wake up
Better thank your lucks stars....
Iıve been waiting for a long time
For this moment to come
Iım destined for anything at all
Dumbstruck
Colour me stupid
Good luck
Youıre gonna need it
Where Iım going if I get there...
At all....
Wake up
Better thank your lucky stars....
------------------------------
From: Pille2 <[EMAIL PROTECTED]>
Subject: Re: basics of cryptography
Date: Sun, 22 Apr 2001 19:53:58 +0200
> Keep up your studies, and don't get discouraged about cryptography! It
> can bring you a lifetime of fascination and enjoyment.
>
> Bill G.
I will, thanks for the tips...
Philipp
------------------------------
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