Cryptography-Digest Digest #566, Volume #9 Wed, 19 May 99 15:13:03 EDT
Contents:
Re: prime numbers and the multplicative inverse (Patrick Juola)
Re: Crypto export limits ruled unconstitutional (Patrick Juola)
Re: prime numbers and the multplicative inverse (Robert G. Durnal)
Re: prime numbers and the multplicative inverse (Patrick Juola)
Re: Encryption starting ([EMAIL PROTECTED])
Re: where can i find a frequency list? (Pete)
Reasons for controlling encryption ("Markku J. Saarelainen")
Re: Scramdisk/Norton query ("N")
Re: prime numbers and the multplicative inverse (Chris Monico)
Re: prime numbers and the multplicative inverse (John Savard)
PK Security (Mark E Drummond)
CRC16 polynomials (Russell Harper)
Re: symmetric boolean functions ("Gary Forbis")
looking for independant encryption strength analysis ("Matthew Bennett")
Re: Crypto export limits ruled unconstitutional (John Savard)
----------------------------------------------------------------------------
From: [EMAIL PROTECTED] (Patrick Juola)
Subject: Re: prime numbers and the multplicative inverse
Date: 19 May 1999 09:41:46 -0400
In article <[EMAIL PROTECTED]>,
John Savard <[EMAIL PROTECTED]> wrote:
>[EMAIL PROTECTED] wrote, in part:
>
>>I haven't been able to find an answer to this question. Why does IDEA
>>use a prime field for it's multiplication?
>
>>Does the field need to be prime to have a multiplicative inverse?
>
>Yes. If it is not prime, then numbers not relatively prime to the
>modulus have no inverse; if it is prime, every nonzero number has an
>inverse.
Did you really mean to write this, Mr. Savard? It seems to violate
the definition of a field I learned in college some years back.
-kitten
------------------------------
From: [EMAIL PROTECTED] (Patrick Juola)
Crossposted-To: talk.politics.crypto
Subject: Re: Crypto export limits ruled unconstitutional
Date: 19 May 1999 09:38:52 -0400
In article <[EMAIL PROTECTED]>,
wtshaw <[EMAIL PROTECTED]> wrote:
>In article <[EMAIL PROTECTED]>, Mok-Kong Shen
><[EMAIL PROTECTED]> wrote:
>>
>> Further, I believe that such translation software can be well built
>> table-driven. That is, through changing the table entries, one
>> easily gets different texts. This could provide some degree of privacy
>> when transfering crypto programs. Thus it is indeed feasible to
>> 'secretly' export genuinely (in all sense) executable codes (assembler
>> and machine instructions) of crypto materials of any strength as
>> (protected) plain English texts, showing once again the absolute
>> nonsense of crypto laws and Wassenaar regulations.
>>
>
>It might be interesting to construct such a program that would only make
>true statements as well. Stuff that appears to be random nonsense is no
>challenge to produce.
Yes, it might be interesting. So might warp drive. Given how
appallingly bad we are at producing natural-seeming text w/o regard
to truth, I vaguely expect warp drive first.
-kitten
------------------------------
From: [EMAIL PROTECTED] (Robert G. Durnal)
Subject: Re: prime numbers and the multplicative inverse
Date: 19 May 1999 14:21:09 GMT
In <7hrsm5$9hd$[EMAIL PROTECTED]>, Bob Silverman <[EMAIL PROTECTED]> wrote:
: In article <7hrgi1$1or$[EMAIL PROTECTED]>,
: [EMAIL PROTECTED] wrote:
: > I haven't been able to find an answer to this question. Why does IDEA
: > use a prime field for it's multiplication?
: I'm not sure I understand the question. Do you mean why it uses
: GF(p) as opposed to GF(2^n)?? Or do you ask why it uses a finite
: field in the first place?
: >
: > Does the field need to be prime to have a multiplicative inverse?
: Huh? *Every* element in a field (except 0) has a multiplicative
: inverse. What do you really want to ask here?
: --
: Bob Silverman
: "You can lead a horse's ass to knowledge, but you can't make him think"
I would put it differently. Every element in a field which is
*RELATIVELY PRIME* to the field size has a multiplicative inverse. But for
example 2 has no inverse mod 4.
===========
My home page URL=http://members.tripod.com/~afn21533/ Robert G. Durnal
Hosting HIDE4PGP, HIDESEEK v5.0, PGE, TinyIdea (link) [EMAIL PROTECTED]
and BLOWFISH in both Windows and mini-DOS versions. [EMAIL PROTECTED]
EAR may apply, so look for instructions.
------------------------------
From: [EMAIL PROTECTED] (Patrick Juola)
Subject: Re: prime numbers and the multplicative inverse
Date: 19 May 1999 10:27:49 -0400
In article <7huhcl$3nua$[EMAIL PROTECTED]>,
Robert G. Durnal <[EMAIL PROTECTED]> wrote:
>In <7hrsm5$9hd$[EMAIL PROTECTED]>, Bob Silverman <[EMAIL PROTECTED]> wrote:
>: In article <7hrgi1$1or$[EMAIL PROTECTED]>,
>: [EMAIL PROTECTED] wrote:
>: > I haven't been able to find an answer to this question. Why does IDEA
>: > use a prime field for it's multiplication?
>
>: I'm not sure I understand the question. Do you mean why it uses
>: GF(p) as opposed to GF(2^n)?? Or do you ask why it uses a finite
>: field in the first place?
>
>: >
>: > Does the field need to be prime to have a multiplicative inverse?
>
>: Huh? *Every* element in a field (except 0) has a multiplicative
>: inverse. What do you really want to ask here?
>
> I would put it differently. Every element in a field which is
>*RELATIVELY PRIME* to the field size has a multiplicative inverse. But for
>example 2 has no inverse mod 4.
Which means that the set of integers mod 4 is *not a field.* It's
"merely" a ring.
-kitten
------------------------------
From: [EMAIL PROTECTED]
Subject: Re: Encryption starting
Date: Wed, 19 May 1999 12:53:48 GMT
> I am relatively new in encryption, and I'm looking for a good start to
> medium level encryption book just to get me a good start. I know the basic
> concept such as stream ciphering and block ciphering, but I need more in
> depth detail. Anyone have any good suggestions? Thank you very much.
>
>
Read sci.crypt first, lots of good easy info. Then try to find AC
(Applied Cryptography) from Scheiner (see www.counterpane.com, sorry if
the name is spelt wrong). Then try to read some papers. I have many
easy read papers (tea, xtea, rc5, rc6, blowfish, etc...) that I could
send you.
Just play with ideas, and you will see how they are good/bad. Try to
explain an algorithm, and the theory behind it. For example recently I
learnt about multiplication in prime groups, and primitive exponential
generators. (in IDEA and SAFER)
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!
--== Sent via Deja.com http://www.deja.com/ ==--
---Share what you know. Learn what you don't.---
------------------------------
From: [EMAIL PROTECTED] (Pete)
Subject: Re: where can i find a frequency list?
Date: 19 May 1999 16:33:39 GMT
actually, i'm not trying to brea RSA or DES. all i want is to work on a
book of cryptograms. :-)
peter
: In general (and vastly oversimplified), most of the "high frequency"
: stuff in linguistic distributions is general, language-specific but
: not document-specific information. For example, the most common words
: in almost any English document of interest are words like 'the' and 'of';
: high-frequency, low-meaning "function words."
: When you subtract out the high frequency digraphs, you'll be left with
: the underlying distribution of the low(er) frequency words in the
: document of interest, which tend to be very strongly associated with
: the content and register of the document. So the words that are moderately
: common in (e.g.) a Ph.D. dissertation will have little to do with the
: words that are moderately common in an issue of _Sports Illustrated_;
: furthermore, the January _Sports Illustrated_ may well have little to
: do with the July _SI_ as the content will have changed so radically.
: This *might* be an interesting way to do document classification -- but
: the cryptographic applications are limited.
: -kitten
--
NEWS FLASH: Just compiled a new kernel 2.3.0! YEAH!!!
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================================================================
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------------------------------
From: "Markku J. Saarelainen" <[EMAIL PROTECTED]>
Subject: Reasons for controlling encryption
Date: Wed, 19 May 1999 10:41:11 -0700
I have heard various reasons why commercial encryption is being
controlled and what real motives are behind these control maneuvers. I
would like to learn more what you think that real motives behind many
encryption control issues are and how, if true, this might be tied to
some commercial and business interests.
Thanks,
Markku
------------------------------
From: "N" <[EMAIL PROTECTED]>
Subject: Re: Scramdisk/Norton query
Date: Wed, 19 May 1999 17:24:32 GMT
Thanks for your response.
It prompted me to retry something I had tried previously, but with greater
vigour.
I deleted all the protected files (using Norton), removed Norton protection
and rebooted to DOS. I then went into c:\recycled\nprotect for a scout
around (this is the directory where the troublesome files had always resided
and also the location from where Norton had indicated they had been
deleted). And there they were - still. All alone, with no other protected
files ('cause these had been removed before booting to DOS). So I simply
deleted them under DOS.
I loaded Windows again and reinitialised Norton protection. So far,
thankfully, they haven't reappeared, so maybe the problem has now finally
been solved. I would, of course, still like to know how these files got
there in the first place. It seems that when they made their first
appearance in that directory, they were not included in the Norton protected
files log, which, perhaps, might have been the reason for their stubborn
refusal to disappear from the protected recycle bin.
Regards
N
[EMAIL PROTECTED] wrote in message <7hratd$u74$[EMAIL PROTECTED]>...
>Go to your dos prompt.
>c:
>cd c:\recycled
>dir
>
>Do you see any files of those sizes?
>
>Mount your encrypted drive (Let's call it N)
>n:
>cd n:\recycled
>dir
>
>Do you see any files of those sizes?
>
>Maybe you aren't missing any space and Norton just doesn't know they are
>gone, and it stores the information somewhere else.
>
>I'm not sure what you did exactly nor where those files "appear".
>
>It could be that Norton tries to read encrypted stuff and gets confused.
>
>Link.
>
>In article <E3I%2.6769$[EMAIL PROTECTED]>,
> "N" <[EMAIL PROTECTED]> wrote:
>> Hey!
>>
>> I thought my original thread had died!
>>
>> I seem to have three SVL files appearing randomly -
>> 00007337.svl (19.0K)
>> 00000011.svl (1Mb)
>> 00000055.svl (200Mb)
>>
>> and try as I might, I just can't rid myself of them! They are all
>deleted
>> by "(unknown)" and all had
>> C:\Recycled\Nprotect as their original location.
>>
>> I don't think it's Norton at fault, but it is peculiar that Norton
>seems to
>> deem the phantom files as having resided in the protected recycle bin
>> *prior* to deletion! Strange, eh?!
>>
>> If anyone can give me back my 201.02Mb of lost space, or at least
>explain
>> these goings-on, please do!
>>
>> N
>>
>> Joshua Falkin wrote in message
>> <[EMAIL PROTECTED]>...
>> >I Stumbled across this same problem. There's got to be a bug in the
>> >Scram disk program....Why is there a hidden svl container on my hard
>> >drive that I did not create???
>> >I found it by sending the contents of what appeared to be an empty
>> >Recycled bin to WinZip. there it was, 200mb of who knows what?
>> >
>> >
>> >
>> >On Fri, 23 Apr 1999 23:44:45 GMT, "N" <[EMAIL PROTECTED]>
>wrote:
>> >
>> >>Can anyone tell me why deleted files with an SVL extension keep
>appearing
>> in
>> >>my Norton protected recycle bin, even though no container files have
>been
>> >>loaded or deleted and the Scramdisk utility program has not been
>running?
>> >>
>> >>When I remove them from the bin, they always reappear, often within
>> minutes!
>> >>They normally have a name such as 00000011.svl or 00007337.svl, for
>> example,
>> >>and range in size from 20K to 200Mb! I have tried excluding this
>file
>> >>extension from Norton Protection, but to no avail. Norton cannot
>identify
>> >>which program deleted them, but since the Scramdisk utility program
>isn't
>> >>running presumably it must be work of the driver SD.VXD?
>> >>
>> >>It does seem to be a gross waste of space for spurious files as
>large as
>> >>200Mb to be taking up this kind of space continually!
>> >>
>> >>Thanks
>> >>N
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >
>>
>>
>
>
>--== Sent via Deja.com http://www.deja.com/ ==--
>---Share what you know. Learn what you don't.---
------------------------------
From: [EMAIL PROTECTED] (Chris Monico)
Subject: Re: prime numbers and the multplicative inverse
Date: Tue, 18 May 99 22:46:54 GMT
In article <7huhp5$4og$[EMAIL PROTECTED]>,
[EMAIL PROTECTED] (Patrick Juola) wrote:
>In article <7huhcl$3nua$[EMAIL PROTECTED]>,
>Robert G. Durnal <[EMAIL PROTECTED]> wrote:
>>In <7hrsm5$9hd$[EMAIL PROTECTED]>, Bob Silverman <[EMAIL PROTECTED]>
wrote:
>>: In article <7hrgi1$1or$[EMAIL PROTECTED]>,
>>: [EMAIL PROTECTED] wrote:
>>: > I haven't been able to find an answer to this question. Why does
IDEA
>>: > use a prime field for it's multiplication?
>>
>>: I'm not sure I understand the question. Do you mean why it uses
>>: GF(p) as opposed to GF(2^n)?? Or do you ask why it uses a finite
>>: field in the first place?
>>
>>: >
>>: > Does the field need to be prime to have a multiplicative
inverse?
>>
>>: Huh? *Every* element in a field (except 0) has a multiplicative
>>: inverse. What do you really want to ask here?
>>
>> I would put it differently. Every element in a field which is
>>*RELATIVELY PRIME* to the field size has a multiplicative inverse.
But for
>>example 2 has no inverse mod 4.
>
>Which means that the set of integers mod 4 is *not a field.* It's
>"merely" a ring.
Indeed. Perhaps this will help the thread a bit:
Def: A nonempty set, G, together with a binary operation, *, is called
a group if:
1) a*(b*c) = (a*b)*c for all a,b,c\in G
2) There exists 1\in G s.t. 1*g=g*1=g for all g\in G.
3) For all g\in G there exists h\in G s.t. hg=hg=1
If, in addition, a*b=b*a for all a,b\in G, G is an abelian group. In
this case, we typically write the binary operation as + instead of *,
and the identity element as 0 instead of 1.
Def: A ring is an abelian group, (R,+), together with a binary
operator, *, satisfying:
1) a*(b*c) = (a*b)*c
2) a*(b+c) = a*b + a*c
3) (a+b)*c = a*c + b*c
If, in addition, there exists 1\in G s.t. 1*a=a*1=a for all a\in R, R
is a ring with identity.
If a*b=b*a for all a,b\in R, R is a commutative ring.
Def: An integral domain is a comm. ring with 1, R, s.t. a*b=0 ==> a=0
or b=0.
Def: A field is an integral domain, F, satisfying:
For all a\in F with a!=0, there exists b\in F s.t. ab=ba=1
Lemma: A finite integral domain is a field.
Pf: Consider the automorphism induced by multiplication by a nonzero
element.
Examples:
* Z_2 (the integers modulo 2) is a field.
* Z_p, for p prime, is a field.
* Z_n, for n composite, is not an integral domain, and hence not a
field. i.e., if n=4, then 2*2=0 in Z_4 but 2!=0, so Z_4 is not an
integral domain and hence not a field.
* Z_p[x]/<f(x)>, the polynomial ring in 1 variable over Z_p modulo an
(ideal generated by an) irreducible polymonial f(x)\in Z_p[x], is a
field. To see this, simply show that it's finite and an integral
domain and apply the above lemma. In particular, this is a field of
order p^{degree f}. This is how one gets finite fields of non-prime
order. i.e., Z_2[x]/<x^2+x+1> is a field of order 4.
* Z is an integral domain but not a field.
------------------------------
From: [EMAIL PROTECTED] (John Savard)
Subject: Re: prime numbers and the multplicative inverse
Date: Wed, 19 May 1999 18:24:33 GMT
[EMAIL PROTECTED] (Patrick Juola) wrote, in part:
>In article <[EMAIL PROTECTED]>,
>John Savard <[EMAIL PROTECTED]> wrote:
>>[EMAIL PROTECTED] wrote, in part:
>>>I haven't been able to find an answer to this question. Why does IDEA
>>>use a prime field for it's multiplication?
>>>Does the field need to be prime to have a multiplicative inverse?
>>Yes. If it is not prime, then numbers not relatively prime to the
>>modulus have no inverse; if it is prime, every nonzero number has an
>>inverse.
>Did you really mean to write this, Mr. Savard? It seems to violate
>the definition of a field I learned in college some years back.
I didn't try to look up the definition of a field: in a field, both
multiplication and addition are defined, and you are quite correct
that by using the terms given by the original poster, I wound up
answering his question in a way that involved my making an inaccurate
statement. (But not one that would fail to answer the original
poster's question accurately or mislead him.)
In IDEA, there is a step where multiplication modulo 65537 is
performed on 16-bit numbers, by means of using 0 to represent 65536.
This step required 65537 to be a prime number, because this step has
to be invertible for IDEA to work.
That was what he was asking about, and that is what I answered.
John Savard ( teneerf<- )
http://members.xoom.com/quadibloc/index.html
------------------------------
From: Mark E Drummond <[EMAIL PROTECTED]>
Subject: PK Security
Date: Wed, 19 May 1999 14:04:20 -0400
Realising that this has much to do with key-length and the algorithms
used, in a general sense, how secure is public key cryptography today?
iow, how secure is a message that has been encrypted using my Verisign
certificate (1024 bit key)?
I know of at least one person who insists that with "modern technology",
Public-Private key cryptography is moot. I continue to argue otherwise
but I'd like to hear the opinions of some of the experts on this feed.
--
_________________________________________________________________
Mark E Drummond Royal Military College of Canada
[EMAIL PROTECTED] Computing Services
Linux Uber Alles perl || die
...there are two types of command interfaces in the world of
computing: good interfaces and user interfaces.
- Dan Bernstein, Author of qmail
------------------------------
From: Russell Harper <[EMAIL PROTECTED]>
Subject: CRC16 polynomials
Date: Wed, 19 May 1999 16:39:45 GMT
The CRC16 polynomial used in XMODEM can be represented by 0x1021 =
1000000100001. Does anyone know of a link where there are other CRC16
polynomials and a description of their relative merits? Or a way to
determine them empirically?
Thanks in advance...
Russell
[EMAIL PROTECTED]
------------------------------
From: "Gary Forbis" <[EMAIL PROTECTED]>
Crossposted-To:
sci.chem,sci.econ,sci.image.processing,sci.electronics.design,sci.physics,sci.physics.fluid-dynamics,sci.math
Subject: Re: symmetric boolean functions
Date: Wed, 19 May 1999 11:15:24 -0700
I think I'm getting the hang of where you're heading.
There is a generalized function similar to checksum using weighted
constants.
It's used in ANNs. You can even use threshold values for step output. If
you want you can use a different threshold on the way up than on the way
down
though I think this would violate some condition you're wanting.
Why do you need shift-invariance?
You can use multiplication rather than summation and get different results.
The closer to one the weight is the slower the drop off. You might even
want
to map the two value inputs to numbers close to one.
Hankel O'Fung <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]...
> Gary Forbis wrote:
>
> > I'm a bit confused by the notion of a boolean function whose output is
not
> > boolean.
> > Isn't the definition of a boolean function one whose output may take
only
> > one
> > of possible values?
>
> I was wrong. Boolean functions (or switching functions) are those that
take
> boolean (vector) inputs and generate boolean (vector) outputs. If the
range is
> (0,1), the function shouldn't be called boolean. Yet, I still need to know
any
> possible applications of symmetric or shift-invariant functions taking
boolean
> vector inputs and generate outputs in {0,1} or (0,1), especially when the
> functions are not the "classical" ones.
>
> > Would you consider the max function to be shift-invariant?
> > (example, Max(1, 2, 3) = Max (3, 1, 2) = 3)
> >
> > Checksum is shift-invariant with booleans arguments.
> > (Checksum(1, 1, 0, 1) = Checksum(1, 1, 1, 0) = 3)
>
> Yes, they are, but they are much more than shift-invariant --- they are
> symmetric, indeed. And the domain of Max() isn't {0,1}^n (or when it is,
Max
> is simply the multiple AND). But thanks. Yes, the checksum is a good
example
> (after some scaling --- I need the range of the function to be in (0,1)).
>
> BTW, a gentleman contacted me in private, and suggested me to look for the
> applications of a wider class of functions than the symmetric and
> shift-invariant ones. He was right. In fact, I am happy to know any
> applications of functions f: {0,1}^n --> (0,1) or g: {0,1} --> {0,1}, but
I
> have a more urgent need to know those for the symm. or shift-invar. cases.
>
> What we have now: parity function (hence XOR when n=2), AND, OR, max, min,
> checksum).
>
> Cheers, Hankel
>
------------------------------
From: "Matthew Bennett" <[EMAIL PROTECTED]>
Subject: looking for independant encryption strength analysis
Date: Wed, 19 May 1999 19:27:43 +0100
Hi,
Since I've had no response to my previous posting, I assume getting an
independent strength analysis of an "un-tested" encryption method is not
simple enough to be done casually by someone.
As an independent test of the encryption strength of files outputted by my
program is required for an interested company, I would be very grateful for
any information people in this newsgroup might be able to offer. Does
anyone know of a link/e-mail to someone that would be prepared to offer such
an analysis. I assume they will ask for a fee, so any likely idea of cost
would also be appreciated. Please bear in mind that I am a programmer, not
an encryption expert, so I know very little of this subject. I do however
believe the encryption produced by my program is secure, though
understandably this company would rather have an independent test performed
on the encrypted files produced.
Like I have said, any information would be a great help - though obviously
an actual "encryption strength analysis" contact is mainly what I am looking
for. I am sure I am not the only one who has needed such a service!
Best regards,
Matthew Bennett
DataCloak author
http://www.btinternet.com/~bennett/datacloak.html
------------------------------
From: [EMAIL PROTECTED] (John Savard)
Crossposted-To: talk.politics.crypto
Subject: Re: Crypto export limits ruled unconstitutional
Date: Wed, 19 May 1999 18:27:16 GMT
[EMAIL PROTECTED] (Mike Eisler) wrote, in part:
>In article <[EMAIL PROTECTED]>,
>Mok-Kong Shen <[EMAIL PROTECTED]> wrote:
>>But France had even banned domestic use of strong crypto but later
>>found it wasn't particularly clever to do that. I personally can't
>Because the boys in Menwith Hill, UK, listen in on all of France's in
>the clear communications.
I thought that France still bans domestic use of strong cryptography,
without a form of key escrow that essentially limits cryptography to
large business organizations.
John Savard ( teneerf<- )
http://members.xoom.com/quadibloc/index.html
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