Cryptography-Digest Digest #38, Volume #14 Thu, 29 Mar 01 17:13:01 EST
Contents:
Re: texts on factoring? ([EMAIL PROTECTED])
Re: texts on factoring? (Paul Rubin)
Re: texts on factoring? ("Carpe Diem")
Re: Idea - (LONG) (Mok-Kong Shen)
Re: There is a saying is Finnish: "Annetaan Lubevichia peraan" ... this (Frank
Gerlach)
Re: texts on factoring? (Mike Rosing)
Re: texts on factoring? ("Tom St Denis")
How good are ... ? (Peter Engehausen)
Re: texts on factoring? ("Tom St Denis")
Re: texts on factoring? ("Tom St Denis")
Re: Encryption of Encrypted Material results in strength??? (Keill Randor)
Re: texts on factoring? (Neil Couture)
Re: Encryption of Encrypted Material results in strength??? (Curtis Williams)
Re: Encryption of Encrypted Material results in strength??? ("Joseph Ashwood")
Re: DES key replacement. (Frank Gerlach)
Re: Encryption of Encrypted Material results in strength??? (Jim Gillogly)
Re: Encryption of Encrypted Material results in strength??? ("Bas Bloemsaat")
Re: texts on factoring? ("Dann Corbit")
Re: DES key replacement. ("Sam Simpson")
Re: rc4 ("Edmond Ho")
Re: DES key replacement. (Mok-Kong Shen)
Re: DES key replacement. (Mok-Kong Shen)
----------------------------------------------------------------------------
From: [EMAIL PROTECTED]
Subject: Re: texts on factoring?
Date: 29 Mar 2001 17:23:40 GMT
Tom St Denis <[EMAIL PROTECTED]> wrote:
> I was wondering what are the "good" texts on algebraic number theory and
> factoring ?
The one everyone used to recommend years ago is "Prime Numbers and
Computer Methods for Factorization" by Hans Riesel. The version I've
seen is from 1985, although I think there's an updated second edition.
I haven't really looked at this stuff in a while, so can't comment on
how "up-to-date" this is, and I haven't seen the Koblitz book everyone
else is talking about...
--
Steve Tate --- srt[At]cs.unt.edu | Gratuitously stolen quote:
Dept. of Computer Sciences | "The box said 'Requires Windows 95, NT,
University of North Texas | or better,' so I installed Linux."
Denton, TX 76201 |
------------------------------
From: Paul Rubin <[EMAIL PROTECTED]>
Subject: Re: texts on factoring?
Date: 29 Mar 2001 09:24:55 -0800
"Sam Simpson" <[EMAIL PROTECTED]> writes:
> I think Koblitz is a good book, but is quite expensive.
Geez, you're right, the 2nd ed. is $43.95 from bn.com. I remember when
I got the 1st ed it was only $20 or so, which was unusually low for a
Springer GTM book.
Tom if you're going to college soon, it's possible that the college
library will have these books and you can read them there.
------------------------------
From: "Carpe Diem" <[EMAIL PROTECTED]>
Subject: Re: texts on factoring?
Date: Thu, 29 Mar 2001 11:58:36 -0600
I see that everybody is suggesting Koblitz. I believe it is a good book but
when it comes to learn the math behind applications like cryptography, but I
think it is better learn it as pure math and then understand how it can be
applied to what we are trying to do. You can never get a solid education on
the field if you learn only what is needed in order to understand the
application.
Just a suggestion. Read Koblitz after you have learned the math he talks
about.
-- Carpe Diem
"Paul Rubin" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]...
> "Sam Simpson" <[EMAIL PROTECTED]> writes:
> > I think Koblitz is a good book, but is quite expensive.
>
> Geez, you're right, the 2nd ed. is $43.95 from bn.com. I remember when
> I got the 1st ed it was only $20 or so, which was unusually low for a
> Springer GTM book.
>
> Tom if you're going to college soon, it's possible that the college
> library will have these books and you can read them there.
------------------------------
From: Mok-Kong Shen <[EMAIL PROTECTED]>
Subject: Re: Idea - (LONG)
Date: Thu, 29 Mar 2001 20:13:01 +0200
"John A. Malley" wrote:
>
> Shannon showed us that perfect secrecy with short keys requires a cipher
> with very particular characteristics.
> AFAIK there is no published demonstration of any block cipher algorithm
> having the characteristics of an ideal system per Shannon's definition.
>
> Anyone aware of such work? Pointers to papers welcome :-)
I don't think that I have properly understood your previous
post and very probably I also misundertood what you wrote
above. Hence dumb question: If you have the four plaintexts
as follows:
m1=00
m2=01
m3=10
m4=11
and change the ciphertexts correspondingly, would that
affect your argumentations as far as perfect security
is concerned? If not, then you have now a block cipher,
isn't it? Wouldn't that be what you want presently?
M. K. Shen
------------------------------
From: Frank Gerlach <[EMAIL PROTECTED]>
Subject: Re: There is a saying is Finnish: "Annetaan Lubevichia peraan" ... this
Date: Thu, 29 Mar 2001 20:29:56 +0200
So what is that ? A lesson in applied anti-semitism ?
[EMAIL PROTECTED] wrote:
> When I grew up as a child in Varkaus, Finland (a city of 15000 people) in
> 1960s, 1970s and 1980s, there was a traditional Finnish saying: "Annetaan
> Lubevichia peraan". This was said in the situations in which somebody had
> hurt you and you wanted to have a revenge against this attacker who hurt you.
> Lubevich is actually an Ultra-Orthodox Jew. In this saying Lubevich can be
> interpreted as a great tool of a revenge. But if you translate it directly to
> English is means "Lubevich is to be given to the back" or "Give Lubevich to
> the back". But basically it is interpreted that "Send a Lubevich behind the
> person who hurt you in order to get a revenge". Or in Finnish "Anna
> viikatemiehen kostaa takaa". This is just an element of Finnish.
>
> Markku J. Saarelainen
> Independent Consultant
>
> ----- Posted via NewsOne.Net: Free (anonymous) Usenet News via the Web -----
> http://newsone.net/ -- Free reading and anonymous posting to 60,000+ groups
> NewsOne.Net prohibits users from posting spam. If this or other posts
> made through NewsOne.Net violate posting guidelines, email [EMAIL PROTECTED]
------------------------------
From: Mike Rosing <[EMAIL PROTECTED]>
Subject: Re: texts on factoring?
Date: Thu, 29 Mar 2001 12:45:52 -0600
[EMAIL PROTECTED] wrote:
>
> Tom St Denis <[EMAIL PROTECTED]> wrote:
>
> > I was wondering what are the "good" texts on algebraic number theory and
> > factoring ?
>
> The one everyone used to recommend years ago is "Prime Numbers and
> Computer Methods for Factorization" by Hans Riesel. The version I've
> seen is from 1985, although I think there's an updated second edition.
>
> I haven't really looked at this stuff in a while, so can't comment on
> how "up-to-date" this is, and I haven't seen the Koblitz book everyone
> else is talking about...
I second that, Riesel's book has lots of good descriptions and Pascal
code too which helps to understand the theory. I've got both books
on my shelf and found both helpful.
Patience, persistence, truth,
Dr. mike
------------------------------
From: "Tom St Denis" <[EMAIL PROTECTED]>
Subject: Re: texts on factoring?
Date: Thu, 29 Mar 2001 19:10:06 GMT
"Sam Simpson" <[EMAIL PROTECTED]> wrote in message
news:DSJw6.962$[EMAIL PROTECTED]...
> Tom St Denis <[EMAIL PROTECTED]> wrote in message
> news:2LJw6.159996$[EMAIL PROTECTED]...
>
> <SNIP>
>
> > > I think Koblitz is a good book, but is quite expensive.
> >
> > It's only 45$ at Amazon
> >
>
http://www.amazon.com/exec/obidos/ASIN/0387942939/qid=985830984/sr=1-1/ref=s
> > c_b_2/102-5941110-7696927
>
> It's only 230 odd pages though!
>
> I wouldn't say it was bad value for money _if you need some of the
content_,
> which you obviously do.
I need basics... if I read a book on NFS right now I could possibly use it
as a door stop...
Tom
------------------------------
From: Peter Engehausen <[EMAIL PROTECTED]>
Crossposted-To: sci.crypt.random-numbers
Subject: How good are ... ?
Date: Thu, 29 Mar 2001 18:15:23 -0100
Reply-To: [EMAIL PROTECTED]
Hi!
How strong are chiphers who work *only* with pseudorandom numbers...?
It surely depends on the generator, but if it's an average one,
initialized by a good pass phrase?
How can they be broken? Any usefull links or papers known?
Thanks,
Peter
------------------------------
From: "Tom St Denis" <[EMAIL PROTECTED]>
Subject: Re: texts on factoring?
Date: Thu, 29 Mar 2001 19:11:24 GMT
"Paul Rubin" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]...
> "Sam Simpson" <[EMAIL PROTECTED]> writes:
> > I think Koblitz is a good book, but is quite expensive.
>
> Geez, you're right, the 2nd ed. is $43.95 from bn.com. I remember when
> I got the 1st ed it was only $20 or so, which was unusually low for a
> Springer GTM book.
>
> Tom if you're going to college soon, it's possible that the college
> library will have these books and you can read them there.
I doubt that. "College" in Canada is like "State Colleges" in the states.
It's not the most academic thing in the world. Plus Most people here think
IT training actually implies a skill!
Tom
------------------------------
From: "Tom St Denis" <[EMAIL PROTECTED]>
Subject: Re: texts on factoring?
Date: Thu, 29 Mar 2001 19:11:56 GMT
"Mike Rosing" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]...
> [EMAIL PROTECTED] wrote:
> >
> > Tom St Denis <[EMAIL PROTECTED]> wrote:
> >
> > > I was wondering what are the "good" texts on algebraic number theory
and
> > > factoring ?
> >
> > The one everyone used to recommend years ago is "Prime Numbers and
> > Computer Methods for Factorization" by Hans Riesel. The version I've
> > seen is from 1985, although I think there's an updated second edition.
> >
> > I haven't really looked at this stuff in a while, so can't comment on
> > how "up-to-date" this is, and I haven't seen the Koblitz book everyone
> > else is talking about...
>
> I second that, Riesel's book has lots of good descriptions and Pascal
> code too which helps to understand the theory. I've got both books
> on my shelf and found both helpful.
I will look up Riesel's book too (wow about 10 books so far)
Tom
------------------------------
From: Keill Randor <[EMAIL PROTECTED]>
Subject: Re: Encryption of Encrypted Material results in strength???
Date: Thu, 29 Mar 2001 18:39:23 +0000
>I have been told that encrypting an encrypted message actually decreases the security.
>I am not a cryptographer, but will accept that on faith.
It all depends on how it has been encrypted - (obviously).
I can imagine that there are circumstances which will cause, (I call it a compound
encrypt - I am an amateur, but I have my own system, and ways of looking at - (and
labelling) things, which seems to work (for me)), a 'compound' encrypt to be weaker
than a single one, but (hopefully) they are few and far between.
My own system has no problems with them - (it supports 'compound' encrypts and
multiple keys - (if there is a difference) - inherantly).
(Most so-called asymmetrical encryption systems, such as PKI, are not, really - they
are also 'compound' encrypts). (i.e. A+(B*C)=D).
(A true asymmetrical encryption system, (which mine is), would be, for example:
A+B=C (encrypt), then C-B=A, (symmetrical), C-D=E, C+F=G, etc. (decrypt).
'Compound' encrypts, (such as PKI), can have the distinction of being neither
symmetrical, or asymmetrical, but incorporate both. The problem with symmetrical and
'compound' encrypts, are that if all the peices to the encryption side are gained,
they can still be solved - unlike a true asymmetrical system, where even if the
encryption side is known, it will not help for decrypting it, (which is completely
seperate).
[EMAIL PROTECTED]
_______________________________________________
Submitted via WebNewsReader of http://www.interbulletin.com
------------------------------
From: Neil Couture <[EMAIL PROTECTED]>
Reply-To: [EMAIL PROTECTED]
Subject: Re: texts on factoring?
Date: Thu, 29 Mar 2001 19:25:04 GMT
Handbook of Applied Cryptography, A Menezes.
available at :
http://cacr.math.uwaterloo.ca/hac/
Tom St Denis wrote:
> I was wondering what are the "good" texts on algebraic number theory and
> factoring ?
>
> --
> Tom St Denis
> ---
> http://tomstdenis.home.dhs.org
------------------------------
From: Curtis Williams <[EMAIL PROTECTED]>
Subject: Re: Encryption of Encrypted Material results in strength???
Date: Thu, 29 Mar 2001 19:31:46 GMT
On Thu, 29 Mar 2001 18:39:23 +0000, Keill Randor
<[EMAIL PROTECTED]> wrote:
>
>
>>I have been told that encrypting an encrypted message actually decreases the
>security.
>>I am not a cryptographer, but will accept that on faith.
>
I missed the beginning of this thread.
Assuming I employ proper pass phrase security all around, if I encrypt
plaintext P with Mars, and then using a separate, strong pass phrase,
encrypt the resultant ciphertext with twofish, is the resultant
strength less than the original encryption?
------------------------------
From: "Joseph Ashwood" <[EMAIL PROTECTED]>
Subject: Re: Encryption of Encrypted Material results in strength???
Date: Thu, 29 Mar 2001 11:29:58 -0800
Crossposted-To: alt.computer.security
Actually I can prove that that is simply not the case given a couple of
basic assumptions.
By assuming that the keys are independent (since they're being done in
seperate layers this is almost certainly the case). The proof is very
simple. If applying am independently keyed function could weaken the
security then an attacker could simply apply that layer for you. So the
addition of such a layer cannot weaken the first below what the attacker
could have easily done for you. In the cases of SSH and SSL/TLS they are at
least reasonably strong so adding a VPN would not notably weaken the system,
and would with high likelihood increase security.
Joe
"Ben.Russo" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]...
> Friends,
>
> I have been told that encrypting an encrypted message actually decreases
the security.
> I am not a cryptographer, but will accept that on faith.
>
> Theory aside, and considering only practical results:
> I have a situation where I am setting up a VPN Mesh network between
several office sites over the internet and am going to use CISCO IOS IPSec
VPN's.
> How much real world difference would it make to a potential cracker if I
had SSH or SSL sessions being routed through the VPN?
> Or should I really block that type of traffic and insist that users use
telnet and http instead?
>
> -Ben.
>
------------------------------
From: Frank Gerlach <[EMAIL PROTECTED]>
Subject: Re: DES key replacement.
Date: Thu, 29 Mar 2001 21:55:21 +0200
Both are right DES uses a 64 bit key, of which 8 are parity. This means that
effective length is 56bit.
Sam Simpson wrote:
> Terry Ritter <[EMAIL PROTECTED]> wrote in message
> news:[EMAIL PROTECTED]...
> >
> > On Wed, 28 Mar 2001 17:06:56 GMT, in <[EMAIL PROTECTED]>,
> > in sci.crypt "Douglas A. Gwyn" <[EMAIL PROTECTED]> wrote:
> >
> > >Yaniv Sapir wrote:
> > >> When using DES for encryption of long messages, is it a common practice
> to
> > >> replace the 64-bit key once in a while? If so, how frequent?
> > >
> > >No. Standard practice is to use the same key for the entire session.
> >
> > First, a DES key is 56 bits, not 64.
>
> To be a fussy bastard (hey, everyone else is here) this statement is
> incorrect.
>
> According to NIST FIPS46-3 for example: "A DES key consists of 64 binary
> digits......"
>
> --
> Regards,
>
> Sam
> http://www.scramdisk.clara.net/
------------------------------
From: Jim Gillogly <[EMAIL PROTECTED]>
Subject: Re: Encryption of Encrypted Material results in strength???
Date: Thu, 29 Mar 2001 20:06:24 +0000
Curtis Williams wrote:
> Assuming I employ proper pass phrase security all around, if I encrypt
> plaintext P with Mars, and then using a separate, strong pass phrase,
> encrypt the resultant ciphertext with twofish, is the resultant
> strength less than the original encryption?
No.
--
Jim Gillogly
Highday, 7 Astron S.R. 2001, 20:00
12.19.8.1.13, 7 Ben 16 Cumku, Sixth Lord of Night
------------------------------
From: "Bas Bloemsaat" <[EMAIL PROTECTED]>
Crossposted-To: alt.computer.security
Subject: Re: Encryption of Encrypted Material results in strength???
Date: Thu, 29 Mar 2001 22:23:28 +0200
> Note that, if the two encrypts use related keys, the above thereom does
not
> apply, and the reencryption may, in fact, reduce the strength, or
eliminate
> it entirely.
I've read this before, in Applied Cryptography. I wondered, what are related
keys?
------------------------------
From: "Dann Corbit" <[EMAIL PROTECTED]>
Subject: Re: texts on factoring?
Date: Thu, 29 Mar 2001 12:44:14 -0800
"Mike Rosing" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]...
> [EMAIL PROTECTED] wrote:
> >
> > Tom St Denis <[EMAIL PROTECTED]> wrote:
> >
> > > I was wondering what are the "good" texts on algebraic number theory and
> > > factoring ?
> >
> > The one everyone used to recommend years ago is "Prime Numbers and
> > Computer Methods for Factorization" by Hans Riesel. The version I've
> > seen is from 1985, although I think there's an updated second edition.
> >
> > I haven't really looked at this stuff in a while, so can't comment on
> > how "up-to-date" this is, and I haven't seen the Koblitz book everyone
> > else is talking about...
>
> I second that, Riesel's book has lots of good descriptions and Pascal
> code too which helps to understand the theory. I've got both books
> on my shelf and found both helpful.
I have "Number Theory" by Mark Herkommer which is decent and has a CD with the
sample code on it. There is a lot of non-standard stuff in the C code, but it
is easy to fix it.
--
C-FAQ: http://www.eskimo.com/~scs/C-faq/top.html
"The C-FAQ Book" ISBN 0-201-84519-9
C.A.P. FAQ: ftp://cap.connx.com/pub/Chess%20Analysis%20Project%20FAQ.htm
------------------------------
From: "Sam Simpson" <[EMAIL PROTECTED]>
Subject: Re: DES key replacement.
Date: Thu, 29 Mar 2001 22:30:35 +0100
Hey, I'm quoting from NIST....What can be a more definitve source? ;)
--
Regards,
Sam
http://www.scramdisk.clara.net/
Frank Gerlach <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]...
> Both are right DES uses a 64 bit key, of which 8 are parity. This means
that
> effective length is 56bit.
>
> Sam Simpson wrote:
>
> > Terry Ritter <[EMAIL PROTECTED]> wrote in message
> > news:[EMAIL PROTECTED]...
> > >
> > > On Wed, 28 Mar 2001 17:06:56 GMT, in <[EMAIL PROTECTED]>,
> > > in sci.crypt "Douglas A. Gwyn" <[EMAIL PROTECTED]> wrote:
> > >
> > > >Yaniv Sapir wrote:
> > > >> When using DES for encryption of long messages, is it a common
practice
> > to
> > > >> replace the 64-bit key once in a while? If so, how frequent?
> > > >
> > > >No. Standard practice is to use the same key for the entire session.
> > >
> > > First, a DES key is 56 bits, not 64.
> >
> > To be a fussy bastard (hey, everyone else is here) this statement is
> > incorrect.
> >
> > According to NIST FIPS46-3 for example: "A DES key consists of 64
binary
> > digits......"
> >
> > --
> > Regards,
> >
> > Sam
> > http://www.scramdisk.clara.net/
>
------------------------------
From: "Edmond Ho" <[EMAIL PROTECTED]>
Subject: Re: rc4
Date: Thu, 29 Mar 2001 13:50:27 -0800
thanks for the information, but i still cannot get the two to be compatible.
i may just be an doing something very stupid, so i'm going to post what i
did (keeping in mind i'm a bit new to unix):
$gcc -o rc4 rc4.c (this is the non-compacted version)
$gcc -o rc4-2 rc4-2.c (this is the first compacted version)
$echo test | rc4 1234 | rc4 1234 (this returns "test")
$echo test | rc4-2 1234 | rc4-2 1234 (this also returns "test")
$echo test | rc4 1234 | rc4-2 1234 (this should return "test", unless i have
completely misunderstood how both inplementations of rc4 work)
hopefully i didn't overlook something obvious. many thanks in advance.
ed
------------------------------
From: Mok-Kong Shen <[EMAIL PROTECTED]>
Subject: Re: DES key replacement.
Date: Fri, 30 Mar 2001 00:03:59 +0200
Sam Simpson wrote:
>
> Hey, I'm quoting from NIST....What can be a more definitve source? ;)
Frank Gerlach has given the correct explanation. The key
is 64 bits but you cannot arbitrarily choose these 64 bits.
You can freely choose only (specific) 58 of them, the
remaining 8 being parity bits, i.e. dependent on the 58.
Read the standard document, if you still have doubt about
this.
M. K. Shen
------------------------------
From: Mok-Kong Shen <[EMAIL PROTECTED]>
Subject: Re: DES key replacement.
Date: Fri, 30 Mar 2001 00:05:53 +0200
Sorry, typo. 58 should read 56.
M. K. Shen
------------------------------
** FOR YOUR REFERENCE **
The service address, to which questions about the list itself and requests
to be added to or deleted from it should be directed, is:
Internet: [EMAIL PROTECTED]
You can send mail to the entire list by posting to sci.crypt.
End of Cryptography-Digest Digest
******************************
